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  • Articles  (1,029)
  • Oxford University Press  (1,029)
  • 2010-2014  (1,029)
  • 2011  (1,029)
  • ICES Journal of Marine Science  (96)
  • Computer Journal  (62)
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  • 1
    Publication Date: 2011-12-08
    Description: Greenstreet, S. P. R., Fraser, H. M., Rogers, S. I., Trenkel, V. M., Simpson, S. D., and Pinnegar, J. K. 2012. Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community. – ICES Journal of Marine Science, 69: 8–22. Broader ecosystem management objectives for North Sea demersal fish currently focus on restoring community size structure. However, most policy drivers explicitly concentrate on restoring and conserving biodiversity, and it has not yet been established that simply restoring demersal fish size composition will be sufficient to reverse declines in biodiversity and ensure a generally healthy community. If different aspects of community composition, structure, and function vary independently, then to monitor all aspects of community general health will require application of a suite of metrics. This assumes low redundancy among the metrics used in any such suite and implies that addressing biodiversity issues specifically will require explicit management objectives for particular biodiversity metrics. This issue of metric redundancy is addressed, and 15 metrics covering five main attributes of community composition, structure, and function are applied to groundfish survey data. Factor analysis suggested a new interpretation of the metric information and indicated that a minimum suite of seven metrics was necessary to ensure that all changes in the general health of the North Sea demersal fish community were monitored properly. Covariance among size-based and species-diversity metrics was low, implying that restoration of community size structure would not necessarily reverse declines in species diversity.
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  • 2
    Publication Date: 2011-12-08
    Description: Dankel, D. J., Aps, R., Padda, G., Röckmann, C., van der Sluijs, J. P., Wilson, D. C., and Degnbol, P. 2012. Advice under uncertainty in the marine system. – ICES Journal of Marine Science, 69: 3–7. There is some uncertainty in the fisheries science–policy interface. Although progress has been made towards more transparency and participation in fisheries science in ICES Areas, routine use of state-of-the-art quantitative and qualitative tools to address uncertainty systematically is still lacking. Fisheries science that gives advice to policy-making is plagued by uncertainties; the stakes of the policies are high and value-laden and need therefore to be treated as an example of "post-normal science" (PNS). To achieve robust governance, understanding of the characteristics and implications of the scientific uncertainties for management strategies need to come to the centre of the table. This can be achieved using state-of-the-art tools such as pedigree matrices and uncertainty matrices, as developed by PNS scholars and used in similar science–policy arenas on other complex issues. An explicit extension of the peer community within maritime systems will be required to put these new tools in place. These new competences become even more important as many countries within the ICES Area are now embarking on new policies.
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  • 3
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    Oxford University Press
    Publication Date: 2011-12-08
    Description: Browman, H.I. 2012. Quo Vadimus. – ICES Journal of Marine Science, 69: 1–2.
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  • 4
    Publication Date: 2011-12-08
    Description: Hüssy, K., Coad, J. O., Farrell, E. D., Clausen, L. A. W., and Clarke, M. W. 2012. Age verification of boarfish ( Capros aper ) in the Northeast Atlantic. – ICES Journal of Marine Science, 69: 34–40. The boarfish ( Capros aper ) is a pelagic species of recent interest to the fishing industry, with landings increasing by 〉500% over the past 3 years. The objective of the study was to provide a method for age determination based on whole sagittal otoliths, with the results to be used in stock assessment. Translucent zones laid down at regular intervals are identified by marginal increment analysis as seasonally recurring. Translucent zones are formed between September/October and March/April, regardless of fish age. The occurrence of the first annulus is validated by analysis of presumed daily growth increments. Subsequent annulus deposition is homogenous between individuals and allows general guidelines to be derived for interpreting the age of boarfish using their otoliths.
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  • 5
    Publication Date: 2011-12-08
    Description: Kim, D., Yang, E. J., Kim, K. H., Shin, C-W., Park, J., Yoo, S., and Hyun, J-H. 2012. Impact of an anticyclonic eddy on the summer nutrient and chlorophyll a distributions in the Ulleung Basin, East Sea (Japan Sea). – ICES Journal of Marine Science, 69: 23–29. The impact of the anticyclonic Ulleung Warm Eddy (UWE) on the vertical distributions of nutrient and chlorophyll a (Chl a ) concentrations in the Ulleung Basin (UB) was investigated during the contrasting summers of 2005 and 2007. The physical structure of the water column was characterized by an intrathermocline eddy (ITE) in 2005, whereas the UWE remained distant from the sampling transect in 2007. Water column structures appeared to be highly stratified, and nutrients in the surface waters were totally depleted at all stations. In 2005, an exceptionally high concentration of Chl a (5.5 mg m –3 ) was measured below the surface mixed layer in the eddy core (station D3), and values of ~2.5 mg m –3 were observed at the eddy edge (stations D2 and D4). Formation of an ITE efficiently mixed surface and deep-ocean waters, the latter supplying sufficient nutrients to generate an extremely high concentration of Chl a at the base of the subsurface layer. Overall, the results indicated that the anticyclonic UWE plays a key ecological role in supporting substantial phytoplankton biomass in the nutrient-depleted surface waters in summer and maintaining high benthic mineralization in the deep-sea sediments of the UB.
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  • 6
    Publication Date: 2011-12-08
    Description: Franchini, P., Sola, L., Crosetti, D., Milana, V., and Rossi, A. R. 2012. Low levels of population genetic structure in the gilthead sea bream, Sparus aurata , along the coast of Italy. – ICES Journal of Marine Science, 69: 41–50. The gilthead sea bream, Sparus aurata , is a coastal, commercially important fish. Contrasting results concerning the genetic structure of the species at different geographic scales have been reported. Here, an investigation is made into the population genetic structure of S. aurata along the coast of Italy, using samples analysed previously and material from new sampling sites (12) and using different microsatellite loci (10). One sample from the eastern Atlantic and three temporal replicates from one site were also included. The presence of a weak (overall F ST = 0.0072), but significant, genetic population subdivision was detected by F -statistics. Temporal replicates indicate genetic data consistency over time. Isolation by distance between the Atlantic and the coast of Italy is suggested by a Mantel test. The distributional pattern of genetic variance obtained by analysis of molecular variation reflects the geographic sampling areas, but is only partially congruent with the results obtained with fewer sites and loci. The dispersal of passive eggs/larvae by the main currents appears to contribute to shaping the gene flow. Given the intensity of sea bream aquaculture activities in Italy, the possibility that aquaculture may have partially contributed to the population genetic pattern detected cannot be excluded.
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  • 7
    Publication Date: 2011-12-08
    Description: Charrier, F., Mazel, V., Caraguel, J-M., Abdallah, Y., Le Gurun, L. L., Legault, A., and Laffaille, P. 2012. Escapement of silver-phase European eels, Anguilla anguilla , determined from fishing activities in a Mediterranean lagoon (Or, France). – ICES Journal of Marine Science, 69: 30–33. Escapement of silver eels from a Mediterranean lagoon was estimated by a capture–tagging–recapture and automated tag-reading study. The population of silver-phase eels in the lagoon was estimated to be 13.2 kg ha –1 , with an escapement rate from the commercial fishery of 76.8%.
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  • 8
    Publication Date: 2011-12-08
    Description: Jennings, S., and Lee, J. 2012. Defining fishing grounds with vessel monitoring system data. – ICES Journal of Marine Science, 69: 51–63. Methods for defining fishing grounds to support marine spatial planning and management are developed, applied, and compared. The methods are broadly applicable and repeatable because they use vessel monitoring system (VMS) data that are archived and increasingly accessible. For several fleets at regional and national scales, an attempt is made to assess how the choice of criteria for defining grounds influences (i) size, shape, and location, (ii) overlap among grounds, and (iii) the extent to which annual and multi-annual patterns of fishing activity describe grounds used seasonally or by individual vessels. The results show that grounds defined by excluding infrequently fished margins (areas with 〈10% of total fishing activity) are typically 50% smaller than total fished area. However, landings weight or value (LWV) per unit activity can be higher at the margins, with 10% of activity usually accounting for 10–20% of LWV. The removal of fishing activity in the margins, as a consequence of regulation or fleet behaviour, would lead to disproportionately greater reductions in interactions with other fisheries, sectors, and the environment. Accessible high-resolution information on the "anatomy" of all fishing grounds would better inform debates on the allocation and the use of marine space and the integration of fisheries and environmental management.
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  • 9
    Publication Date: 2011-12-08
    Description: Bentley, N., Kendrick, T. H., Starr, P. J., and Breen, P. A. 2012. Influence plots and metrics: tools for better understanding fisheries catch-per-unit-effort standardizations. – ICES Journal of Marine Science, 69: 84–88. Standardization of catch per unit effort using generalized linear models (GLMs) is a common procedure that attempts to remove the confounding effects of variables other than abundance. Simple plots and metrics are described to assist understanding the standardization effects of explanatory variables included in GLMs, illustrated with an example based on New Zealand trevally ( Caranx lutescens ) data.
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  • 10
    Publication Date: 2011-12-08
    Description: Aldrin, M., Mortensen, B., Storvik, G., Nedreaas, K., Aglen, A., and Aanes, S. 2012. Improving management decisions by predicting fish bycatch in the Barents Sea shrimp fishery. – ICES Journal of Marine Science, 69: 64–74. When the bycatch of juvenile fish within the Barents Sea shrimp fishery is too large, the area is closed to fishing for a certain period. Bycatch is estimated from sampled trawl hauls, for which the shrimp yield is recorded, along with the total number of various bycatch fish species. At present, bycatch estimation is based on a simple estimator, the sum of the number of fish caught within the area of interest within a small time window, divided by the corresponding shrimp yield (in weight). No historical data are used. A model-based estimation is proposed in which spatio-temporal models are constructed for the variation in both the yield of shrimp and the amount of bycatch in space and time. The main effects are described through generalized additive models, and local dependence structures are specified through correlated random effects. Model estimation includes historical and recent data. Experiments with both simulated and real data show that the model-based estimator outperforms the present simple estimator when a low or moderate number of samples (e.g. 〈20) is available, whereas the two estimators are equally good when the number of samples is high.
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  • 11
    Publication Date: 2011-12-08
    Description: Jiao, Y., Smith, E. P., O'Reilly, R., and Orth, D. J. 2012. Modelling non-stationary natural mortality in catch-at-age models. – ICES Journal of Marine Science, 69: 105–118. Non-stationarity in the natural mortality of many species has been discussed among research scientists, but no generally applicable models/methods have been developed where a statistical catch-at-age (SCA) model framework is used. Using the Atlantic weakfish ( Cynoscion regalis ) fishery as an example, several SCA models are developed to assess the population dynamics, then compared. Models used included (i) an SCA with constant natural mortality, (ii) an SCA with unknown natural mortality, but with a hierarchical prior distribution from a mixture of distributions based on life-history information, (iii) an SCA with age-specific unknown natural mortality, (iv) an SCA with time-varying natural mortality, following a random-walk process, and (v) an SCA with age-specific time-varying natural mortality. The last two models imply that the population dynamics are not stationary. A Bayesian approach was used to estimate parameters, and performance of the models was compared through goodness-of-fit and the retrospective patterns of the models. A simulation study was then conducted to test the uncertainty resulting from model selection, the efficiency of using the best model selected based on deviance information criterion, and whether changes in natural mortality could be detected. An SCA with time-varying natural mortality, following a random-walk process, is proposed for the example fishery here. The estimated non-stationary temporal patterns in natural mortality were linked further to climate–ocean oscillation indices, to diagnose possible mechanisms/linkages to these temporal variations in natural mortality.
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  • 12
    Publication Date: 2011-12-08
    Description: Juntunen, T., Vanhatalo, J., Peltonen, H., and Mäntyniemi, S. 2012. Bayesian spatial multispecies modelling to assess pelagic fish stocks from acoustic- and trawl-survey data. – ICES Journal of Marine Science, 69: 95–104. A Bayesian spatial model was constructed to estimate the abundance of multiple fish species in a pelagic environment. Acoustic- and trawl-survey data were combined with environmental data to predict the spatial distribution of (i) the acoustic backscattering of fish, (ii) the relative proportion of each species, and (iii) their mean length in the Gulf of Finland in the northeastern Baltic Sea. By combining the three spatial model layers, the spatial distribution of the biomass of each species was estimated. The model consists of a linear predictor on environmental variables and a spatial random effect given by a Gaussian process. A Bayesian approach is a natural choice for the task because it provides a theoretically justified means of summarizing the uncertainties from various model layers. In the study area, three species dominate pelagic waters: sprat ( Sprattus sprattus ), herring ( Clupea harengus ), and three-spined stickleback ( Gasterosteus aculeatus ). Results are presented for each model layer and for estimated total biomass for each species in 2 x 2 km lattices. The posterior mean and central 95% credible intervals of total biomass were sprat 45.7 kt (27.7–71.6), herring 24.6 kt (9.7–41.3), and three-spined stickleback 1.9 kt (0.9–3.2).
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  • 13
    Publication Date: 2011-12-08
    Description: Smith, W. K., and Solow, A. R. 2012. Missing and presumed lost: extinction in the ocean and its inference. – ICES Journal of Marine Science, 69: 89–94. The number of modern extinctions in the ocean is unknown. The actual demise of the last individual of a species is essentially unobservable, so extinction can only be inferred. Statistical methods are described for inferring extinction from sighting records, species–area considerations, and taxonomic samples collected at two different times. The methods are illustrated using a variety of real datasets, including a sighting record of the Caribbean monk seal and results from three surveys of benthic invertebrates.
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  • 14
    Publication Date: 2011-12-08
    Description: Delavenne, J., Metcalfe, K., Smith, R. J., Vaz, S., Martin, C. S., Dupuis, L., Coppin, F., and Carpentier, A. 2012. Systematic conservation planning in the eastern English Channel: comparing the Marxan and Zonation decision-support tools. – ICES Journal of Marine Science, 69: 75–83. The systematic conservation approach is now commonly used for the design of efficient marine protected area (MPA) networks, and identifying these priority areas often involves using specific conservation-planning software. Several such software programmes have been developed in recent years, each differing in the underlying algorithms used. Here, an investigation is made into whether the choice of software influences the location of priority areas by comparing outputs from Marxan and Zonation, two widely used conservation-planning, decision-support tools. Using biological and socio-economic data from the eastern English Channel, outputs are compared and it is shown that the two software packages identified similar sets of priority areas, although the relatively wide distribution of habitat types and species considered offered much flexibility. Moreover, the similarity increased with increasing spatial constraint, especially when using real-world cost data, suggesting that the choice of cost metric has a greater influence on conservation-planning analyses than the choice of software. However, Marxan generally produced more efficient results and Zonation produced results with greater connectivity, so the most appropriate software package will depend on the overall goals of the MPA planning process.
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  • 15
    Publication Date: 2011-12-08
    Description: Andersen, B. S., Ulrich, C., Eigaard, O. R., and Christensen, A-S. 2012. Short-term choice behaviour in a mixed fishery: investigating métier selection in the Danish gillnet fishery. – ICES Journal of Marine Science, 69: 131–143. The study presents a short-term effort allocation modelling approach based on a discrete choice random utility model combined with a survey questionnaire to examine the selection of métiers (a combination of fishing area and target species) in the Danish North Sea gillnet fishery. Key decision variables were identified from the survey questionnaire, and relevant proxies for the decision function were identified based on available landings and effort information. Additional variables from the survey questionnaire were further used to validate and verify the outcome of the choice model. Commercial fishers in a mixed fishery make use of a number of decision variables used previously in the literature, but also a number of decision parameters rarely explicitly accounted for, such as price, weather, and management regulation. The seasonal availability of individual target species and within-year changes in monthly catch ration were the main explanatory drivers, but gillnetters were also responsive to information on the whole fishery, fish prices, and distance travelled to fishing grounds. Heterogeneous responses were evident from geographic differences in home harbour, which underpins the need to understand alternative fishing strategies among individual gillnetters better.
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  • 16
    Publication Date: 2011-12-08
    Description: Calise, L., and Knutsen, T. 2012. Multifrequency target strength of northern krill ( Meganyctiphanes norvegica ) swimming horizontally. – ICES Journal of Marine Science, 69: 119–130. Multifrequency acoustic measurements on ex situ horizontally swimming krill were made in a novel experimental setting. An ensemble of northern krill ( Meganyctiphanes norvegica ) was introduced to a large enclosure (a mesocosm), and acoustic backscatter was sampled using a multifrequency (70, 120, and 200 kHz) echosounder (Simrad EK60). Two submerged lamps were placed at opposite sides of the mesocosm and switched on and off to induce the krill, by light attraction, to swim horizontally through the acoustic beams. By tracking echoes, animal displacement, swimming speed, and target strength ( TS ) by frequency were estimated. The dominant and secondary modes of the total-length distribution were 21.8 ± 3.0 and 27.8 ± 2.7 mm, respectively. Although krill orientation was assumed stable and the ping rate was high, the range and inter-ping variability of the average TS values were large, decreasing and increasing with frequency, respectively. The overall TS frequency response observed and concurrent measurements at 120 and 200 kHz confirm the theoretical expectation that the acoustic backscatter from the investigated organisms were confined to the Rayleigh and Geometric scattering regions, a finding that might both aid acoustic identification and size-group separation of in situ northern krill.
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  • 17
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    Oxford University Press
    Publication Date: 2011-11-24
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  • 18
    Publication Date: 2011-11-24
    Description: Glover, K. A., Skaala, Ø., Limborg, M., Kvamme, C., and Torstensen, E. Microsatellite DNA reveals population genetic differentiation among sprat ( Sprattus sprattus ) sampled throughout the Northeast Atlantic, including Norwegian fjords. – ICES Journal of Marine Science, 68: 2145–2151. Sprat ( Sprattus sprattus ), small pelagic shoaling fish, were sampled from the Celtic, North, and Baltic seas, and 10 Norwegian fjords. Significant overall genetic differentiation was observed among samples when analysed with eight microsatellite DNA loci (Global F ST = 0.0065, p 〈 0.0001). The greatest genetic differences were observed between the Baltic and all other samples (largest pairwise F ST = 0.043, p 〈 0.0001). No significant genetic differentiation was observed between a sample from the Celtic Sea (CEL) and the North Sea (NSEA; F ST = 0.001, p = 0.16), but variable levels of genetic differentiation were observed among samples collected from Norwegian fjords (pairwise F ST ranging from 0 to 0.0096, most non-significant). All fjord samples were significantly differentiated to NSEA and CEL samples. Further, all fjord samples displayed reduced allelic richness compared with NSEA and CEL samples. Clearly, sprat display population genetic differentiation throughout the Northeast Atlantic, and there may be limited connectivity between Norwegian fjord and sea-going populations.
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  • 19
    Publication Date: 2011-11-24
    Description: Mahévas, S., Vermard, Y., Hutton, T., Iriondo, A., Jadaud, A., Maravelias, C. D., Punzón, A., Sacchi, J., Tidd, A., Tsitsika, E., Marchal, P., Goascoz, N., Mortreux, S., and Roos, D. 2011. An investigation of human vs. technology-induced variation in catchability for a selection of European fishing fleets. – ICES Journal of Marine Science, 68: 2252–2263. The impact of the fishing effort exerted by a vessel on a population depends on catchability, which depends on population accessibility and fishing power. The work investigated whether the variation in fishing power could be the result of the technical characteristics of a vessel and/or its gear or whether it is a reflection of inter-vessel differences not accounted for by the technical attributes. These inter-vessel differences could be indicative of a skipper/crew experience effect. To improve understanding of the relationships, landings per unit effort (lpue) from logbooks and technical information on vessels and gears (collected during interviews) were used to identify variables that explained variations in fishing power. The analysis was undertaken by applying a combination of generalized additive models and generalized linear models to data from several European fleets. The study highlights the fact that taking into account information that is not routinely collected, e.g. length of headline, weight of otter boards, or type of groundrope, will significantly improve the modelled relationships between lpue and the variables that measure relative fishing power. The magnitude of the skipper/crew experience effect was weaker than the technical effect of the vessel and/or its gear.
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  • 20
    Publication Date: 2011-11-24
    Description: Attwood, C. G., Petersen, S. L., and Kerwath, S. E. 2011. Bycatch in South Africa's inshore trawl fishery as determined from observer records. – ICES Journal of Marine Science, 68: 2163–2174. Ship-based observer data were analysed to describe the volume, composition, utilization, and size structure of catches made by South Africa's inshore trawlers. The sampling rate was 3.5% of all trawls, including unsorted and discard samples. In all, 137 nominal species were recorded. Analysis of species composition separated the trawling grounds into seven areas, providing a framework for stratifying the ground for catch estimation and for selection of representative areas for conservation. The target species, Merluccius capensis and Austroglossus pectoralis , made up 58% of the pre-discard catch. Trachurus trachurus , Pterogymnus laniarius , Raja spp., and Chelidonichthys spp. constituted another 23%. Pre-discard catch volumes of the entire fleet were estimated. The average annual pre-discard catch of M. capensis and A. pectoralis was 9653 and 504 t, respectively, closely matching landing statistics. Argyrosomus inodorus , Rhabdosargus globiceps , Argyrozona argyrozona , and Atractoscion aequidens averaged 294, 230, 107, and 83 t annually, respectively, indicating significant overlap with the handline fishery for A. inodorus and A. argyrozona . A comparison of species composition in unsorted and discard samples revealed the species being preferentially retained. Argyrosomus inodorus and A. aequidens were trawled mainly below their size at maturity. Management needs to consider other species when determining catch or effort limits and area restrictions.
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  • 21
    Publication Date: 2011-11-24
    Description: Aanes, S., Nedreaas, K., and Ulvatn, S. 2011. Estimation of total retained catch based on frequency of fishing trips, inspections at sea, transhipment, and VMS data. – ICES Journal of Marine Science, 68: 1598–1605. The satellite-based vessel monitoring system in the Norwegian Economic Zone provides detailed information about individual trips by vessels. Vessel sizes are available through official registries, and the storage capacity for fish is estimated using the established conversion factors as a function of the vessel's gross registered tonnage. Scientists have had access to the database of both transport and fishing vessels, with records for individual trips, in addition to information about the total round weight (whole fish) of cod and haddock for trips inspected by the coastguard. The analysis assumes that trips with complete documentation of the fish on board are a random sample, so allowing estimation of the mean amount of both cod and haddock per trip, and annual totals give the number of trips per vessel annually. ICES has accepted this methodology for estimating illegal, unregulated, and unreported (IUU) catches, which has resulted in 15 000–166 000 t (3–35%) being added to the officially reported landings of Northeast Arctic cod during the years 2002–2008. IUU landings have decreased in recent years, but are so important for assessment and management that estimates continue to be made annually.
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  • 22
    Publication Date: 2011-11-24
    Description: Kindt-Larsen, L., Kirkegaard, E., and Dalskov, J. 2011. Fully documented fishery: a tool to support a catch quota management system. – ICES Journal of Marine Science, 68: 1606–1610. The Danish Government has proposed a catch quota management system (CQMS) in which fishers are obliged to report their total catches, including discards and landings, and both are counted against the formal total allowable catch (TAC). The success of a CQMS requires appropriate documentation to verify the total catch, the validity of scientific advice, and the implementation of the TACs through national catch quotas. A remote electronic monitoring (EM) system, providing full documentation of fishing operations and catches, was tested on six Danish fishing vessels operating under a CQMS for cod ( Gadus morhua ). The results showed that the EM system could provide the documentation required to support the CQMS and that it was an incentive for the participating fishers to avoid discarding cod. Changing from landings to total catch quotas would not affect the scientific-advisory processes of the International Council for the Exploration of the Sea (ICES), but it could have notable consequences for the allocation of TACs between countries.
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  • 23
    Publication Date: 2011-11-24
    Description: Shephard, S., Gerritsen, H. D., Kaiser, M. J., Truszkowska, H. S., and Reid, D. G. 2011. Fishing and environment drive spatial heterogeneity in Celtic Sea fish community size structure. – ICES Journal of Marine Science, 68: 2106–2113. The Large Fish Indicator (LFI) is a univariate size-based indicator of fish community state that has been selected to support the OSPAR fish community Ecological Quality Objective (EcoQO). To operate this EcoQO, a survey-based LFI for each OSPAR region needs to be developed. However, fish communities in these regions are spatially heterogeneous, and there is evidence of within-region spatial variation in the LFI that could confound an overall indicator series. For Celtic Sea trawl-survey sites, spline correlograms indicate positive spatial autocorrelation at a similar range (~40 km) for the LFI and for fishing effort (h year –1 ) from vessel monitoring systems. Statistical models reveal a strong negative effect on annual LFI by site of fishing effort within a radius of 40 km. There was a weak effect of fishing within 20 km and no effect at 10 km. LFI also varied significantly with substratum and with local fish community composition identified by a resemblance matrix derived from the survey data. Finally, there was a weak effect of survey year on LFI. Spatial stratification of LFI calculations may be necessary when developing size-based indicators for OSPAR or Marine Strategy Framework Directive regions.
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  • 24
    Publication Date: 2011-11-24
    Description: Petitgas, P., Doray, M., Massé, J., and Grellier, P. 2011. Spatially explicit estimation of fish length histograms, with application to anchovy habitats in the Bay of Biscay. – ICES Journal of Marine Science, 68: 2086–2095. Fish length frequency histograms from research surveys are of prime importance for identifying habitats of different life stages, as well as for stock assessment. However, no method has thus far been available for mapping these histograms as spatially varying curves. Here, a procedure is applied to map spatially connected curves, and detail is given on how it can be applied to map the length frequency histograms. At each sample location, a fish length frequency histogram is given as a vector of non-independent values. The histogram is first modelled as a polynomial expansion on the basis of orthogonal polynomials. Then, the polynomial coefficients are mapped by co-kriging, after fitting a model of co-regionalization. The length frequency map is finally derived by linearly combining maps of polynomial coefficients. An estimation variance associated with the map is also derived. Maps of anchovy length distributions are produced by applying the method to midwater trawl length data from the PELGAS acoustic surveys in the Bay of Biscay. This novel approach extends the application of kriging techniques to curves or functions, opening new perspectives for mapping more complex information than just the values of fish density.
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  • 25
    Publication Date: 2011-11-24
    Description: Hedger, R. D., Uglem, I., Thorstad, E. B., Finstad, B., Chittenden, C. M., Arechavala-Lopez, P., Jensen, A. J., Nilsen, R., and Økland, F. 2011. Behaviour of Atlantic cod, a marine fish predator, during Atlantic salmon post-smolt migration. – ICES Journal of Marine Science, 68: 2152–2162. Acoustic telemetry was used to determine the behavioural strategies of Atlantic cod ( Gadus morhua ) during Atlantic salmon ( Salmo salar ) post-smolt migration within a Norwegian fjord (Eresfjord). In all, 38 adult cod captured in the inner fjord were tagged with acoustic transmitters in 2008 and 2009, and their behaviour was determined using a fixed hydrophone array. Cod tended to aggregate in the innermost part of the fjord, occupying distinct demersal home territories, showing horizontal movements consistent with foraging. Tidal influences were not observed; cod spent more time near the surface at night. Cod behaviour during peak post-smolt migration differed from that before and after migration. First, cod tended to have more-focused spatial distributions during peak post-smolt migration, consistent with them not having to forage so far when prey were available in abundance. Second, some half the cod were detected nocturnally (but rarely during daylight) near the river mouth during peak post-smolt migration, consistent with them feeding on nocturnally migrating post-smolts. Third, cod were more common near the surface, consistent with them feeding on post-smolts migrating through near-surface waters. These patterns, however, were not shown by all the cod, suggesting that this opportunistic feeder was also preying on other species.
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  • 26
    Publication Date: 2011-11-24
    Description: Miller, E. F., Pondella II, D. J., Beck, D. S., and Herbinson, K. T. 2011. Decadal-scale changes in southern California sciaenids under different levels of harvesting pressure. – ICES Journal of Marine Science, 68: 2123–2133. A unique 38-year time-series of power-plant entrapment data collected across ~170 km of the southern California coastline was examined to describe the decadal-scale trends in common Southern California Bight sciaenid abundance in relation to oceanographic conditions. Adult catches for five of seven species declined at differing rates and severity. Declines of up to 94% were detected in historically common species such as Genyonemus lineatus , whereas historically less abundant species have increased dramatically, e.g. Umbrina roncador (2626%). Over time, the entrapped community became increasingly influenced by species with more southerly distributions, indicated by a significant decline in the average latitudinal midpoint of the community. This shift was significantly related to rising ocean temperature and took place in the early to mid-1980s. The observed species-specific abundance changes in all species except Atractoscion nobilis were significantly correlated with sea surface temperature, nearshore plankton volumetric biomass, G. lineatus or Seriphus politus nearshore larval density, or a combination of these. Patterns in A. nobilis abundance were the most isolated, likely reflecting its standing as an intensively fished species, unlike the other six species evaluated. The consistent relationship with environmental indices strongly supported the notion of a faunal shift driven by bottom-up forcing.
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  • 27
    Publication Date: 2011-11-24
    Description: Mikkonen, J., Keinänen, M., Casini, M., Pönni, J., and Vuorinen, P. J. 2011. Relationships between fish stock changes in the Baltic Sea and the M74 syndrome, a reproductive disorder of Atlantic salmon ( Salmo salar ). – ICES Journal of Marine Science, 68: 2134–2144. The M74 syndrome of Baltic salmon ( Salmo salar ), which appears as increased yolk-sac fry mortality (YSFM), impairs the reproduction of salmon stocks. Changes in the prey stocks of Baltic salmon in its two feeding areas, the southern Baltic Proper (BPr), where sprat ( Sprattus sprattus ) was the main prey species during the high incidence of M74, and the Bothnian Sea, where herring ( Clupea harengus ) is the dominant species, were analysed in relation to salmon growth and size and in relation to the incidence of M74. The high condition factor (CF 〉 1.05) of prespawning salmon predicted high YSFM. From the various stock factors of sprat and herring in the southern BPr, the biomass of sprat had the strongest positive relationships with the CF of prespawning salmon, and the total prey biomass with YSFM. It is concluded that the ample but unbalanced food resources for salmon in the BPr, primarily sprat, induce M74. By reducing the fishing pressure on cod ( Gadus morhua ) and by more effectively managing the sprat fishery in years when the cod stock is weak, the incidence of the M74 syndrome could be reduced and even prevented.
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  • 28
    Publication Date: 2011-11-24
    Description: Levesque, J. C. 2011. Commercial fisheries in the northwestern Gulf of Mexico: possible implications for conservation management at the Flower Garden Banks National Marine Sanctuary. – ICES Journal of Marine Science, 68: 2175–2190. Marine resource managers designate marine protected areas (MPAs) to conserve, protect, and enhance fragile marine resources. A form of MPAs sometimes used by resource managers in the United States is a national marine sanctuary (NMS), and for all MPAs, managers need to use updated information during sanctuary management plan reviews (MPRs). In 2006, the Flower Garden Banks NMS (FGBNMS) began its first MPR by conducting public hearings and soliciting comments. Some 66% of comments were about the potential impacts fisheries posed to the sanctuary, so a description of commercial fishery activity in the NW Gulf of Mexico can help guide resource managers make sound, informed decisions. Despite limitations on data and knowledge of fishing effort spatially for the FGBNMS, commercial landings vary by Gulf state, area, and fishing gear, with most landings from the Louisiana and Texas coasts taken with trawls and nets. The main species landed from the NW Gulf of Mexico are shrimp, yellowfin tuna, and red snapper. Some conservation measures proposed for the FGBNMS will likely impact some commercial fisheries (hook and line, bottom longline), but not others (otter trawl, pelagic longline).
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  • 29
    Publication Date: 2011-11-24
    Description: Lonergan, M., Duck, C. D., Thompson, D., Moss, S., and McConnell, B. 2011. British grey seal ( Halichoerus grypus ) abundance in 2008: an assessment based on aerial counts and satellite telemetry. – ICES Journal of Marine Science, 68: 2201–2209. Recent estimates of the total size of the British grey seal population have been based on fitting age-structured models to estimates of pup production. The estimates were sensitive to whether density-dependence was considered to act on fecundity or pup survival. This study provides an alternative estimate for abundance in 2008: 91 800 animals (95% confidence interval, CI , 78 400–109 900). The estimate is consistent with the results of existing models where population density influences pup survival. It suggests that reductions in fecundity are unlikely to have been the cause of the recent slowing of the rate of growth of the population. The estimate presented is based on aerial surveys of the entire Scottish coast and the east coast of England. The surveys were carried out in August of 2007–2009 and restricted to the 2 h each side of daylight low water. Data from 107 electronic tags deployed between 1995 and 2008 were used to estimate the proportion of animals hauled out during the surveys. Overall, the animals hauled out for 31% (95% CI 15–50%) of the survey windows. No significant effects on the proportion of animals hauled out were detected from year, location, age, sex, temperature, rainfall, or the timing of low tide.
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  • 30
    Publication Date: 2011-11-24
    Description: McGrath, S. P., Broadhurst, M. K., Butcher, P. A., and Cairns, S. C. 2011. Fate of three Australian teleosts after ingesting conventional and modified stainless- and carbon-steel hooks. – ICES Journal of Marine Science, 68: 2114–2122. In response to concerns over the fate of three Australian teleosts (mulloway, Argyrosomus japonicus , yellowfin bream, Acanthopagrus australis , and snapper, Pagrus auratus ) released with ingested recreational hooks, experiments were carried out to determine whether ejection could be promoted via different wire materials and/or their modification. Between 108 and 114 fish of each species were angled and allowed to ingest conventional or modified (with notches to reduce wire diameter by ~20%) J-hooks (~250 mm 2 ) made from three materials (stainless steel and nickel-plated and red-lacquer carbon steel), before being released into tanks and monitored with control fish for up to 61 d. Total mortalities were 35, 24, and 25% for mulloway (over 61 d), yellowfin bream (over 35 d), and snapper (over 41 d), respectively. Of the survivors, 30, 61, and 77%, respectively, ejected their hooks (and only one hook-ejected fish died). For yellowfin bream, hook ejection (and hence survival) was positively correlated with total length, and hook oxidation was the key predictor of ejection from mulloway and snapper, which could be promoted by selecting carbon-steel designs with narrow wire diameters and minimal protective coating. The choice of coating might also be important, with relatively greater mortality among mulloway and yellowfin bream that ingested nickel-plated hooks.
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  • 31
    Publication Date: 2011-11-24
    Description: Van Iseghem, S., Quillérou, E., Brigaudeau, C., Macher, C., Guyader, O., and Daurès, F. 2011. Ensuring representative economic data: survey data-collection methods in France for implementing the Common Fisheries Policy. – ICES Journal of Marine Science, 68: 1792–1799. Since 2001, Ifremer has implemented an economic data collection programme (EDCP) within the Data Collection Framework of the EU. It aims to obtain economic data from a sample of vessels representative of the entire French fishing fleet. This paper presents the strategies used for vessel sampling selection in the French EDCP and its implementation over several consecutive years. The approach is illustrated by the sampling plan for the fleet in the North Sea Channel Atlantic region. We show that the EDCP allows precise economic indicators such as gross revenue or fuel costs to be estimated for the whole fishing fleet, including small vessels (〈10 m), and consequently, it facilitates sound scientific advice regarding the Common Fisheries Policy. The apparent underestimation of landings by small vessels in official statistics is highlighted.
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  • 32
    Publication Date: 2011-11-24
    Description: Mathew, S. 2011. Fishery-dependent information and the ecosystem approach: what role can fishers and their knowledge play in developing countries? – ICES Journal of Marine Science, 68: 1805–1808. An ecosystem approach to fishery management is as much a mechanism to deal with the impact of fishing on targeted, associated, and dependent fish stocks, and on the habitat, as it is to deal with the impact of habitat degradation from natural and anthropogenic factors on fishing. In developing countries, often with little institutional capacity for generating timely and reliable information for managing fisheries, effective integration of the knowledge possessed by fishers and their communities regarding, for example, oceanographic, biological, economic, social, and cultural aspects can contribute to an ecosystem approach to fisheries. The challenge is to identify and validate such knowledge and to create policy and legal space to integrate it into management, also drawing upon good practice in industrialized countries. An attempt is made to identify such knowledge, to discuss its salient aspects, and to look at the conditions under which its practical value can be enhanced and integrated into formal fishery-management systems in developing countries.
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  • 33
    Publication Date: 2011-11-24
    Description: Blythe, J. N., da Silva, J. C. B., and Pineda. J. 2011. Nearshore, seasonally persistent fronts in sea surface temperature on Red Sea tropical reefs. – ICES Journal of Marine Science, 68: 1827–1832. Temperature variability was studied on tropical reefs off the coast of Saudi Arabia in the Red Sea using remote sensing from Aqua and Terra satellites. Cross-shore gradients in sea surface temperature (SST) were observed, including cold fronts (colder inshore) during winter and warm fronts (warmer inshore) during summer. Fronts persisted over synoptic and seasonal time-scales and had a periodic annual cycle over a 10-year time-series. Measurements of cross-shore SST variability were conducted at the scale of tens of kilometres, which encompassed temperature over shallow tropical reef complexes and the continental slope. Two tropical reefs that had similar reef geomorphology and offshore continental slope topography had identical cold fronts, although they were separated by 100 km along the Red Sea coast of Saudi Arabia. Satellite SST gradients across contours of topography of tropical reefs can be used as an index to flag areas potentially exposed to temperature stress.
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  • 34
    Publication Date: 2011-11-24
    Description: Kane, J. 2011. Multiyear variability of phytoplankton abundance in the Gulf of Maine. – ICES Journal of Marine Science, 68: 1833–1841. Significant interannual changes in phytoplankton abundance were identified in the Continuous Plankton Recorder time-series collected in the Gulf of Maine from 1961 to 2008. Abundance levels of nearly all the common taxa began to increase in 1990 and remained elevated through 2001. During that period, total numbers were above average throughout the year, with an unusual bloom in late summer. Multivariate analysis of abundance identified three consecutive multiyear periods of varying abundance levels: low to average from 1961 to 1989, above average or very high from 1990 to 2001, and below average thereafter, through 2008. Phytoplankton abundance patterns were closely aligned to the rising trends displayed by several of the common zooplankton taxa. The North Atlantic Oscillation was the only environmental variable examined that showed some association with time-series abundance trends of plankton. The index was primarily positive in the 1990s, which would favour the propagation of warm, nutrient-rich slope water into the region. Perhaps the increased influx of this water, along with feedback enrichment from abundant zooplankton stocks and reduced top-down control by the relative scarcity of the dominant copepod Calanus finmarchicus , combined with a low salinity to make the 1990s a unique decade for plankton change in the Gulf of Maine.
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  • 35
    Publication Date: 2011-11-24
    Description: Malyshev, A., and Quijón, P. A. 2011. Disruption of essential habitat by a coastal invader: new evidence of the effects of green crabs on eelgrass beds. – ICES Journal of Marine Science, 68: 1852–1856. Eelgrass ( Zostera marina ) beds have been declining in Atlantic Canada and elsewhere, partly as a result of sediment disruption and direct feeding/cutting of basal meristems by the green crab ( Carcinus maenas ). Green crabs are detrimental to eelgrass beds, and field and laboratory experiments have confirmed that the deleterious role of this invasive species is mediated by at least two mechanisms, depending on the size/age of the crabs: uprooting by adults and grazing by juveniles. Eelgrass uprooting and grazing by green crabs are likely to contribute to further declines or a lack of recovery of eelgrass beds.
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  • 36
    Publication Date: 2011-11-24
    Description: Reese, D. C., O'Malley, R. T., Brodeur, R. D., and Churnside, J. H. 2011. Epipelagic fish distributions in relation to thermal fronts in a coastal upwelling system using high-resolution remote-sensing techniques. – ICES Journal of Marine Science, 68: 1865–1874. Coastal upwelling systems are characterized by substantial spatial and temporal variability with respect to surface conditions, with fauna patchily distributed and high abundances in localized areas. Examining habitat associations on finer spatial scales than previous studies have been able to achieve would advance the understanding of important marine coastal ecosystems. This study evaluates the spatial and temporal relationships of single fish and fish schools with sea surface temperature (SST) fronts in the northern California Current upwelling system, using lidar (light detection and ranging) from an aircraft to sample surface waters over the continental shelf. High-resolution data were collected on the distribution of surface nekton and SST, then the locations of fish were analysed with respect to their proximity to SST fronts using GIS spatial analyses. Both fish schools and solitary fish were located significantly closer to fronts than would be expected by chance. The association of fish to fronts varied with the progression of the upwelling season such that fish associated less with fronts under stronger upwelling conditions. The relationships observed indicate the importance of thermal features to fish as a habitat component in a variable upwelling environment and have implications for management and conservation.
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  • 37
    Publication Date: 2011-11-24
    Description: Kopf, R. K., Davie, P. S., Bromhead, D., and Pepperell, J. G. 2011. Age and growth of striped marlin ( Kajikia audax ) in the Southwest Pacific Ocean. – ICES Journal of Marine Science, 68: 1884–1895. This study describes the first validated model of age and growth developed for striped marlin ( Kajikia audax ). Daily periodicity of otolith microincrements was corroborated by back-calculated hatch dates that matched the known spawning season in the Southwest Pacific Ocean (SWPO). Yearly annulus formation in fin-spine sections was corroborated by daily otolith microincrements and by a marginal increment analysis. Ages of females ranged from 140 d to 8.5 years in fish between 990 mm and 2872 mm lower-jaw fork length (LJFL), and ages of males from 130 d to 7.0 years in fish between 1120 mm and 2540 mm LJFL. Sex-specific differences in growth were significant, with females growing to a larger asymptotic size and greater age than males. An instantaneous growth rate of 3.1 mm d –1 at 6 months and an estimated length of 1422–1674 mm LJFL by age 1 year makes this species among the fastest growing bony fish. Implications of these findings are discussed in relation to commercial longline and recreational fisheries management of striped marlin in the SWPO and in relation to the biology of pelagic fish growth.
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  • 38
    Publication Date: 2011-11-24
    Description: Magnussen, E. 2011. Food and feeding habits of cod ( Gadus morhua ) on the Faroe Bank. – ICES Journal of Marine Science, 68: 1909–1917. Data from ten bottom surveys on the Faroe Bank during the years 1994–1998 are used to describe the feeding habits of cod on the Faroe Bank. Cod are clearly omnivorous in their diet. Overall, fish were found in 82% of the stomachs, accounting for 59% of the food by weight, but just 35% of the food items by number. Of the fish, lesser sandeel was the most common, making up 78% of the fish biomass consumed. Cannibalism was practically non-existent. In some years, the squid Loligo forbesi formed an important component of the diet, was the main food and identified in up to 64% of the stomachs, and constituting 60% by weight of the diet; in other years, it was a negligible part. Crustaceans were found in 48% of the stomachs, accounting for 16% by weight but as much as 44% by numbers. The diet of cod shifts ontogenetically, with stomach fullness greater and nutrient quality of prey higher for cod 〈70 cm.
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  • 39
    Publication Date: 2011-11-24
    Description: Uglem, I., Berg, M., Varne, R., Nilsen, R., Mork, J., and Bjørn, P. A. 2011. Discrimination of wild and farmed Atlantic cod ( Gadus morhua ) based on morphology and scale-circuli pattern. – ICES Journal of Marine Science, 68: 1928–1936. To evaluate the spatio–temporal distribution and ecological impacts of escaped farmed Atlantic cod ( Gadus morhua ), it is necessary that escapees can be traced in the wild. To do this, simple, reliable, and fast methods for determining the origin of cod are required. The aim of this proof-of-concept study was to evaluate whether simple analyses of scales and body morphology can distinguish between wild and farmed cod. Digital images of fish and scales from adult cod from two farms, and wild cod caught near these farms, were analysed by computer-based image analyses. By combining mean breadth of circuli and length-adjusted scale radius in a discriminant analysis, 86 and 80% of wild and farmed fish, respectively, were correctly classified. Moreover, using three simple morphometric measures representing dorsal fin size, neck curvature, and length of lower jaw, 100 and 95% of wild and farmed cod, respectively, were classified correctly. To validate these discrimination methods further, an expanded analysis of additional farmed and wild cod populations is required. The results pave the way for the development of a reliable and standardized methodology for classification of the origin of cod caught in the wild.
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  • 40
    Publication Date: 2011-11-24
    Description: Przeslawski, R., Currie, D. R., Sorokin, S. J., Ward. T. M., Althaus, F., and Williams, A. 2011. Utility of a spatial habitat classification system as a surrogate of marine benthic community structure for the Australian margin. – ICES Journal of Marine Science, 68: 1954–1962. This study tests whether a continental-scale classification of Australian benthic habitats (termed "seascapes") and the interpolated environmental data from which they are derived are useful as abiotic surrogates of biodiversity at a local [tens of kilometres, Great Australian Bight (GAB)] and regional scale [hundreds of kilometres, Western Australian (WA) margin]. Benthic invertebrate community structure is moderately associated with specific seascapes in both the GAB ( R = 0.418) and WA margin (excluding hard substrata, R = 0.375; all substrata, R = 0.313). Mud content, seafloor slope, and seafloor temperature are significantly correlated with invertebrate communities at both scales, with disturbance and primary production correlated with GAB communities. Seascapes are not consistently useful surrogates because the strength and significance of relationships between seascapes and community structure differs among seascapes, regions, and spatial scales. Nevertheless, a national system of seascapes is an appropriate surrogate for broad-scale benthic invertebrate community patterns when biological data are limited, provided the uncertainty is acknowledged and, where possible, an assessment made of each seascape's ability to differentiate biological communities. Further refinement of seascape derivations may include updated and additional environmental data (particularly for hard vs. soft substrata) and validation among biological datasets from a range of habitats and scales.
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  • 41
    Publication Date: 2011-11-24
    Description: Frie, A. K., Fagerheim, K-A., Hammill, M. O., Kapel, F. O., Lockyer, C., Stenson, G. B., Rosing-Asvid, A., and Svetochev, V. 2011. Error patterns in age estimation of harp seals ( Pagophilus groenlandicus ): results from a transatlantic, image-based, blind-reading experiment using known-age teeth. – ICES Journal of Marine Science, 68: 1942–1953. Blind readings of known-age samples are the ultimate quality control method for age estimates based on hard tissues. Unfortunately, this is often not feasible for many species because of the scarcity of known-age samples. Based on a unique collection of known-age teeth of harp seals (age range: 1–18 years), ageing errors were evaluated in relation to true age, reader experience, sex, and tooth format (images vs. originals). Bias was estimated by linear models fitted to deviations from true age, and precision was estimated as their residual standard error. Image-based blind readings of 98 tooth sections by 14 readers, representing different levels of experience, generally showed high accuracy and precision up to a seal age of ~8 years, followed by an increasingly negative bias and increased variance. Separate analyses were therefore conducted for young seals (1–7 years) and older seals. For young seals, moderate associations were found between reader experience and levels of bias, precision, and proportions of correct readings. For older seals, only precision levels showed a significant association with reader experience. Minor effects of sex and tooth format are unlikely to affect these main patterns. Observed errors, even for highly experienced readers, may affect important age-related parameters, emphasizing the importance of known-age calibration of the output from all readers.
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  • 42
    Publication Date: 2011-11-24
    Description: van der Kooij, J., Kupschus, S., and Scott, B. E. 2011. Delineating the habitat of demersal fish assemblages with acoustic seabed technologies. – ICES Journal of Marine Science, 68: 1973–1985. Habitats influence species distribution and, although the seabed is an important habitat factor for demersal species, traditional sampling methods often provide no practical solution to investigating the seabed over large areas. The ability of a multivariate method that utilizes single-beam acoustic seabed data combined with species composition data to define demersal fish habitats was tested. The best model explained 19.4% of the variance observed in the species data and was robust between years. Ten biotopes were identified, each containing species that, either alone or in combination with others, were indicative of that biotope. Using unclassified acoustic seabed data as explanatory variables, discrepancies between the numbers of acoustically distinct classes and species assemblages, as previously reported in the literature, were avoided, while utilizing their relationship with community structure. The study focused on the relationship between simultaneously recorded species composition and seabed data from fishing stations, but because continuous acoustic data along the survey tracks were available between stations, the model could be used to predict the spatial extent of the biotopes. Although the method was developed with the eventual aim of providing a meaningful foundation to the spatial management of mixed fisheries, it could also contribute to applications in spatial planning.
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  • 43
    Publication Date: 2011-11-24
    Description: Faunce, C. H., and Barbeaux, S. J. 2011. The frequency and quantity of Alaskan groundfish catcher-vessel landings made with and without an observer. – ICES Journal of Marine Science, 68: 1757–1763. The North Pacific Groundfish Observer Programme (NPGOP) is one of the largest on-board fishery-monitoring programmes in the world, and the data are used extensively for both in- and post-season management of fisheries. Within certain limits, Alaskan fishers determine when and where to carry observers. There may be an incentive to fish differently during observed trips because (i) observed trips carry higher costs than unobserved trips, and (ii) bycatch quanta for quota deduction are estimated by applying bycatch rates from observed trips to retained catches on unobserved trips. Such differences may be manifest through the skewed deployment of observers among fisheries, i.e. a deployment effect, and through unrepresentative activities by fishers when an observer is on board, i.e. an observer effect. Despite long-standing concerns expressed over the NPGOP's 40-year history, evidence of deployment and observer effects have been based largely on anecdotal information. In 2008, database changes allowed a comparison of industry landing reports for trips with and without an observer. A deployment effect was evidenced by significant deviations from the expected landing ratios between observed and unobserved trips, and linear mixed-effect models revealed differences in the landed weight and evidence for an observer effect within two of five fisheries examined.
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  • 44
    Publication Date: 2011-11-24
    Description: Kloser, R. J., Ryan, T. E., Macaulay, G. J., and Lewis, M. E. 2011. In situ measurements of target strength with optical and model verification: a case study for blue grenadier, Macruronus novaezelandiae . – ICES Journal of Marine Science, 68: 1986–1995. In situ measurements of target strength ( TS ) of isolated fish surrounding dense schools need to be representative of the schooling fish to calculate their echo-integrated biomass. Using synchronous optical and acoustic measurements from a pelagic fishing net, the standard length (81 cm, n = 128), tilt-angle (–9°), and net-disturbed in situ TS (–34.4 dB) of Australian Macruronus novaezelandiae (blue grenadier) were confirmed at depth. In situ drift experiments of assumed undisturbed but dispersed blue grenadier recorded a mean TS of –31.8 dB ( CI –33.1 to –30.9 dB) with attributed fish standard lengths of 83 cm (s.d. 7.5 cm) and weight 2.5 kg. Modelling the gasbladder showed that uncertainties in fish length, orientation, and gasbladder size could explain the differences observed. Blue grenadiers have negative buoyancy because the cavity size of their gasbladder is smaller than the volume of gas required for neutral buoyancy at depth. For the same species and length, New Zealand hoki weigh less and have smaller gasbladders than Australian blue grenadier, suggesting a conversion factor of 1.10 in length for comparative measurements. Net-attached acoustic and optical measurements indicate that model and drift in situ measurements are biased high by 2.9 and 1.0 dB, respectively. Net-attached acoustic and optical measurements are a cost-effective method of monitoring TS routinely at depth for changes in species length and weight.
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  • 45
    Publication Date: 2011-11-24
    Description: Garcia, S. M. 2011. Potential contribution of the Internet to a global community of practice for fishery management. – ICES Journal of Marine Science, 68: 1800–1804. Managing complex socio-ecological fishery systems, following an Ecosystem Approach to Fisheries, calls for a broad range of information covering many components of the system, intensified sharing of data and knowledge (to accelerate social learning and adaptive management), and a much tighter collaboration between disciplines and stakeholders. I argue that the time has come to establish one or more communities of practice ( sensu Wenger) and that the Internet could be used efficiently for this purpose, enhancing the co-evolution of science and decision-making. Important Internet resources exist and can be mobilized, but the contribution of fishery science is still too fragmented and that of the fishing industry is embryonic. This paper suggests a web infrastructure that would facilitate the needed change.
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  • 46
    Publication Date: 2011-11-24
    Description: Rihan, D., Graham, N., Reid, D. G., and Lordan, C. 2011. The provision of fishery information by ICES–WGFTFB to assessment working groups: use of information and lessons learned. – ICES Journal of Marine Science, 68: 1809–1814. ICES is now asked to provide advice that is more holistic in nature, including information on the influence and effects of human activities on the marine ecosystem. From a fishing-technology perspective, this includes information on how fishers respond and adapt to changes in regulatory frameworks, the impact of technology creep, ecosystem impacts, and changes in fleet dynamics. Recognizing the importance of this, in 2005, the ICES–Food and Agriculture Organization (FAO) Working Group on Fish Technology and Fish Behaviour (WGFTFB) began to collect data and information to support scientific advice on fisheries and ecosystem issues through a questionnaire circulated to its members. The information from the questionnaires was collated by the WGFTFB and submitted in the form of summary documents to various ICES assessment working groups. This paper describes the background to this initiative, the questionnaire structure, the type of information provided, and its utility.
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  • 47
    Publication Date: 2011-11-24
    Description: Lorance, P., Agnarsson, S., Damalas, D., des Clers, S., Figueiredo, I., Gil, J., and Trenkel, V. M. 2011. Using qualitative and quantitative stakeholder knowledge: examples from European deep-water fisheries. – ICES Journal of Marine Science, 68: 1815–1824. Stakeholder knowledge was collected through questionnaires and cognitive maps and used to summarize biological, environmental, technical, management, and socio-economic factors for several deep-water fisheries, identifying regional management issues and solutions. The questionnaires and cognitive maps revealed different technical, environmental, and management concerns in these fisheries. Dissatisfaction with management was more at an implementation than a conceptual level, because the existing management measures were mostly considered fit for purpose. Further, catch-and-effort data provided by the fishing industry were used to calculate standardized landings per unit effort. The results suggested different trends over time for three deep-water stocks exploited by the same fleet. The examples demonstrate how stakeholder involvement and use of qualitative knowledge and quantitative data might improve the management process and stock assessments when data are limited.
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  • 48
    Publication Date: 2011-11-24
    Description: Chandrapavan, A., Gardner, C., Green, B. S., Linnane, A., and Hobday, D. 2011. Improving marketability through translocation: a lobster case study from southern Australia. – ICES Journal of Marine Science, 68: 1842–1851. Translocation as a method to increase the value of less-marketable, deep-water southern rock lobster Jasus edwardsii was explored. First, variation in the commercially important shell colouration and body shape between deep- and shallow-water Tasmanian populations and among South Australian and Victorian populations was quantified. Deep-water J. edwardsii were pale in colour, with longer walking legs but less meat content than shallow-water, red-coloured J. edwardsii . Traits in body shape were variable among deep-water populations across the three states and between sexes in each population. Deep-water lobsters were then translocated to a shallow-water inshore reef to determine whether the observed variation in traits was plastic and whether translocation could be used to improve the quality of deep-water lobsters. Translocated lobsters were then monitored over a 14-month post-release period, and during this time, they changed from a pale/white colour to the more marketable red colour within a single moult. Plasticity was observed in tail morphology, but not in leg morphology. The translocation experiment was successful in transforming pale/white deep-water lobsters into red lobsters with higher market value in a phenotypic response to habitat manipulation. Translocation appears to have commercial application for exploiting natural plasticity in the market traits of lobsters to increase price.
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  • 49
    Publication Date: 2011-11-24
    Description: Xavier, J. C., Phillips, R. A., and Cherel, Y. 2011. Cephalopods in marine predator diet assessments: why identifying upper and lower beaks is important. – ICES Journal of Marine Science, 68: 1857–1864. Cephalopods are components of the diet of many predators worldwide. They are identified mainly using their chitinized upper and lower beaks, but because it has been assumed that the number of upper and lower beaks would be the same in predator diet samples, more effort has been put into creating keys for the lower beaks, which are more easily identifiable from morphology. A test is made of whether the number of upper and lower beaks differs in diet samples collected from a major cephalopod predator, the wandering albatross ( Diomedea exulans ), potential biases in the estimation of predator diets are assessed, and upper:lower beak ratios in published studies of other seabirds, seals, whales, and fish from different parts of the world reviewed. The ratio of upper to lower beaks in diet samples from wandering albatrosses varied greatly in a single year (from 69.6% more lower beaks to 59% more upper beaks), and between years (from 0.5 to 32.1% more upper beaks), and biases were greater for certain cephalopod species, resulting in underestimation of their relative importance. Future studies need to consider using both upper and lower beaks to improve the assessment of the contribution of different cephalopods to predator diets.
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  • 50
    Publication Date: 2011-11-24
    Description: Burt, J. A., Feary, D. A., Bauman, A. G., Usseglio, P., Cavalcante, G. H., and Sale, P. F. 2011. Biogeographic patterns of reef fish community structure in the northeastern Arabian Peninsula. – ICES Journal of Marine Science, 68: 1875–1883. This study provides the first large-scale comparison of reef-associated fish communities in the northeastern Arabian Peninsula, with 24 sites spanning 〉3000 km of coastline in the southern Persian Gulf, the western Gulf of Oman, and the northwestern Arabian Sea, each with its own unique environmental conditions. Multivariate analyses revealed three distinct community types that were represented mainly by sites within each major water body, with 〉70% dissimilarity in community structure between each. Persian Gulf communities had low species richness, abundance, and biomass of reef fish compared with the other subregions, with communities dominated by herbivores and generalist predators that had little association with live coral. Reef fish biomass in the Gulf of Oman and Arabian Sea was comparable, and communities were dominated by fish with moderate coral association. However, there were relatively more herbivores and larger fish in the Arabian Sea than in the Gulf of Oman, where communities were dominated by planktivores. Species richness was highest in the Arabian Sea when differences in abundance among regions were accounted for. The influence of distinct environmental and oceanographic conditions on reef fish community structure in each of these areas is discussed.
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  • 51
    Publication Date: 2011-11-24
    Description: Chouinard, P-M., and Dutil, J-D. 2011. The structure of demersal fish assemblages in a cold, highly stratified environment. – ICES Journal of Marine Science, 68: 1896–1908. Fish are a major component of marine ecosystems, with many species co-occuring in the same habitats. Potential interactions among species and with the environment can be studied through the identification of species assemblages. Data from bottom trawl surveys (2004–2008) conducted in the estuary and northern Gulf of St Lawrence were analysed using multivariate methods (cluster, multidimensional scaling, and detrended canonical correspondence analysis) to describe the structure and composition of demersal fish assemblages, including rare and smaller non-commercial species. The spatial variability in environmental conditions that characterizes the study area has a significant impact on the composition of fish assemblages in the region. In all, 35 taxa were classified as key, and 6 main fish assemblages were described, based on catch in numbers. These assemblages had a coherent spatial distribution in the study area, associated with either depth, salinity and temperature, or dissolved oxygen. The analyses showed overall strong correlations between species abundance and prevalent environmental conditions and explained 18.4% of the variance in species abundance data and 79.2% of the variance in the species–environment relationship.
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  • 52
    Publication Date: 2011-11-24
    Description: Wright, P. J., Millar, C. P., and Gibb, F. M. 2011. Intrastock differences in maturation schedules of Atlantic cod, Gadus morhua . – ICES Journal of Marine Science, 68: 1918–1927. Differences in maturation schedules from three subpopulations of North Sea cod ( Gadus morhua ) were examined using the demographic probabilistic maturation reaction norm (PMRN) approach. Declines in maturation probability with size and age were evident within the North Sea cod stock, but the magnitude of decline differed among subpopulations. The difference in the rate of decline led to significant spatial differences in recent times. Changes in maturation probability could not be explained by colonization from adjacent regions indicating a local response to conditions. The greatest decline in maturation probability followed the near collapse of regional spawning biomass during the 1980s and 1990s. A new methodology was developed to integrate the effects of temperature and competitive biomass into the estimation of the PMRN. Temperature had a positive effect on maturation probability, but could only partially explain the decreasing trend in PMRN midpoints. Consequently, regional selection for early maturing genotypes provides the most parsimonious explanation for the declines in maturation probability observed. The difference in maturation probability among North Sea cod subpopulations, and the additive contribution of temperature to the estimation of change, underscores the need to account for population structuring and to incorporate temperature as a covariate in future applications of the PMRN.
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  • 53
    Publication Date: 2011-11-24
    Description: Da Rocha, J-M., and Gutiérrez, M-J. 2011. Lessons from the long-term management plan for northern hake: could the economic assessment have accepted it? – ICES Journal of Marine Science, 68: 1937–1941. An economic working group was convened by the EU's Scientific, Technical and Economic Committee for Fisheries (STECF) in 2007 to evaluate the potential economic consequences of the long-term management plan for the northern hake ( Merluccius merluccius ) stock. An analysis of all the scenarios proposed by the biological assessment using the Economic Interpretation of ACFM Advice (EIAA) model showed that F at the status quo level was the best policy for both yield and profits, in terms of net present values. This result is counter-intuitive because it seems to suggest that effort costs do not influence economic indicators, whereas it is widely accepted that including costs negatively affects economic indicators. A dynamic age-structured model is applied to northern hake and shows that the optimal fishing mortality that maximizes the net present value of profits is 〈 F max . The reason why the EIAA analysis was biased towards scenarios with F 〉 F max is also shown.
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  • 54
    Publication Date: 2011-11-24
    Description: Shephard, S., Reid, D. G., and Greenstreet, S. P. R. 2011. Interpreting the large fish indicator for the Celtic Sea. – ICES Journal of Marine Science, 68: 1963–1972. The large fish indicator (LFI) was developed in the North Sea as a size-based indicator of fish community state. It is now established as OSPAR's fish community Ecological Quality Objective (EcoQO) metric and will be applied across all OSPAR regions. To produce a protocol for use when developing regional LFIs, the North Sea experience is interpreted using data from the Celtic Sea. Differences in fish community species composition and size distribution were reflected in a different species complex and large fish threshold (50 cm) for the Celtic Sea LFI. However, a lag of 12–14 years in the relationship between assemblage-averaged fishing mortality F com, y and the LFI suggested similar underlying ecological mechanisms to the North Sea. The indicator responded to changes in small fish biomass that follow fishing-induced changes in the level of predation by large demersal piscivores. The Celtic Sea LFI showed maximum observed values 〉0.40 before 1990, and 0.40 is here proposed as an EcoQO. Development of regional LFIs demands a flexible process rather than a strictly prescriptive protocol.
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  • 55
    Publication Date: 2011-11-24
    Description: Welcomme, R. L. 2011. An overview of global catch statistics for inland fish. – ICES Journal of Marine Science, 68: 1751–1756. The reported global inland fish catch passed 10 million tonnes in 2008, after almost linear growth from the early 1950s. The rise coincides with an increasing number of reports of falling catches resulting from environmental degradation. It is thought that catches from inland waters were underreported in the past because of constraints on collecting the relevant data. National approaches to data collection are not generally comparable and their accuracy not usually assessed. National data processing and reporting should be audited, and training undertaken to harmonize these activities. The apparently bigger catches probably result from better reporting of actual catches rather than any increase in the amount of fish landed. Current data are sufficient only for a general overview of global inland catches of fish, rather than for the detailed analysis needed for management, policy formulation, and the valuation of inland fisheries. There is a need for improved approaches to data collection and for historical catches to be corrected to account for changes in methodologies and reporting procedures.
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  • 56
    Publication Date: 2011-11-24
    Description: Lam, V. W. Y., Sumaila, U. R., Dyck, A., Pauly, D., and Watson, R. 2011. Construction and first applications of a global cost of fishing database. – ICES Journal of Marine Science, 68: 1996–2004. The development of a new global database of fishing cost is described, and an overview of fishing cost patterns at national, regional, and global scales is provided. This fishing cost database provides economic information required for assessing the economics of fisheries at various scales. It covers variable and fixed costs of maritime countries, representing ~98% of global landings in 2005. Linked to country and gear-type combinations, cost estimates can be mapped to a database of spatially allocated fisheries catches for future analysis in both spatial and temporal dimensions. The global average variable cost per tonne of catch in 2005 is estimated to range between US$639 and $1217, and the total cost per tonne from $763 to $1477, with mean values of $928 and $1120, respectively. The total global variable fishing cost is estimated to be in the range US$50–96 billion per year, with a mean of $73 billion per annum in 2005 dollar equivalents.
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  • 57
    Publication Date: 2011-11-24
    Description: Faunce, C. H. A 2011. comparison between industry and observer catch compositions within the Gulf of Alaska rockfish fishery. – ICES Journal of Marine Science, 68: 1769–1777. Stock assessment scientists and fishery managers operate under the necessary assumption that the identities of species in official catch reports are known without error. To test this assumption, the incidence, magnitude, and possible causes of species misidentification between industry and fishery-observer data sources were investigated for 29 rockfish landings made in Kodiak, AK. Rockfish species were misidentified in nearly all these landings, and the incidence of misidentification between data sources differed among species rather than the processing plant examined. Although observers failed to identify species recorded by processing plant staff as a result of small sampling fractions, the industry missed species that were identified by observers in more than half the offloads examined. The presence of management species complexes did not reduce the likelihood of erroneous quota debiting as a result of species misidentification. In one landing, the misidentification of the main rockfish species corresponded to the release of a weekly report on total allowable catch and resulted in a delayed fishery closure. Efforts to improve the accuracy of species identifications reported by industry in landing reports are warranted in Alaska, and methods to accomplish this through efficient deployment of observers are discussed.
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  • 58
    Publication Date: 2011-11-24
    Description: Dynamically typed languages are becoming increasingly popular for different software development scenarios such as Web engineering, rapid prototyping or the construction of applications that require runtime adaptiveness. In contrast, statically typed languages have undeniable advantages such as early type error detection and more opportunities for compiler optimizations. Since both approaches offer different benefits, hybrid statically and dynamically typed programming languages have emerged, and some statically typed languages have also incorporated dynamic typing capabilities. In this paper, we present the minimal core of StaDyn , a hybrid typing language that performs static type inference of both statically and dynamically typed references. The type information gathered by the compiler is used to generate efficient .NET code, obtaining a significant runtime performance improvement compared with C# 4.0 and Visual Basic 10.
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  • 59
    Publication Date: 2011-11-24
    Description: Readahead is an important technique to deal with the huge gap between disk drives and applications. It has become a standard in modern operating systems and advanced storage systems. However, it is difficult to develop the common kernel readahead and to achieve full testing coverage of all cases. In this paper, we formulate the kernel read handling, caching and readahead behavior as an absorbing Markov decision process, and present performance evaluations to compare or verify various readaheads. We also introduce algorithms to find optimal prefetching policies for specific read pattern and present the convergence analysis. By exploiting sample-path-based methods, it becomes much easier to evaluate and optimize prefetching policies, which can provide valuable informations to help the design and improvement of practical readaheads. For illustration and verification, we present two examples and some experiments on the readaheads in Linux kernel. The results show that the model-based evaluations agree with the practice and the improved prefetching policy significantly outperforms the original one in Linux kernel for the specified workloads.
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  • 60
    Publication Date: 2011-11-24
    Description: Crowds must be simulated believable in terms of their appearance and behavior to improve a virtual environment's realism. Due to the complex nature of human behavior, realistic behavior of agents in crowd simulations is still a challenging problem. In this paper, we propose a novel behavioral model which builds analytical maps to control agents’ behavior adaptively with agent–crowd interaction formulations. We introduce information theoretical concepts to construct analytical maps automatically. Our model can be integrated into crowd simulators and enhance their behavioral complexity. We made comparative analyses of the presented behavior model with measured crowd data and two agent-based crowd simulators.
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  • 61
    Publication Date: 2011-11-24
    Description: Inspired by the swarm behaviours of social insects, research into the self-assembly of swarm robots has become an attractive issue in the robotic community. Unfortunately, there are very few platforms for self-assembly and locomotion in the field of swarm robotics. The Sambot is a novel self-assembling modular robot that shares characteristics with swarm robots and self-reconfigurable robots. Each Sambot can move autonomously and connect with the other. This paper discusses the concept of combining self-assembly and locomotion for swarm robots. Distributed control algorithms for self-assembly and locomotion are proposed. Using five physical Sambots, experiments were carried out on autonomous docking, self-assembly and locomotion. Our control algorithm for self-assembly can also be used to realize the autonomous construction and self-repair of robotic structures consisting of a large number of Sambots.
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  • 62
    Publication Date: 2011-11-24
    Description: Scanning of ports on a computer occurs frequently on the Internet. An attacker performs port scans of Internet protocol addresses to find vulnerable hosts to compromise. However, it is also useful for system administrators and other network defenders to detect port scans as possible preliminaries to more serious attacks. It is a very difficult task to recognize instances of malicious port scanning. In general, a port scan may be an instance of a scan by attackers or an instance of a scan by network defenders. In this survey, we present research and development trends in this area. Our presentation includes a discussion of common port scan attacks. We provide a comparison of port scan methods based on type, mode of detection, mechanism used for detection and other characteristics. This survey also reports on the available data sets and evaluation criteria for port scan detection approaches.
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  • 63
    Publication Date: 2011-11-24
    Description: Proxy blind signature is an important cryptographic primitive and plays an essential role in construction of the electronic cash (e-cash). Recently, Tan (2001, An offline electronic cash scheme based on proxy blind signature. Comput. J. , 54, 505–512) proposed a new proxy blind signature scheme and applied it to electronic cash. The scheme was claimed as being provably secure under the Discrete Log assumption, DBDH assumption and Chosen–Target CDH assumption in the random oracle model. In this paper, we show that Tan's proxy blind signature scheme is insecure by demonstrating several attacks in which a malicious original signer can forge both valid proxy signature keys of arbitrary proxy signers and a proxy blind signature on an arbitrary message with respect to any proxy signer directly. We also discuss some weaknesses in the e-cash scheme proposed by Tan.
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  • 64
    Publication Date: 2011-11-24
    Description: In recent times, there has been increasing interest in storing data securely in the cloud environment. To provide owners of data stored in the cloud with flexible control over access to their data by other users, we propose a role-based encryption (RBE) scheme for secure cloud storage. Our scheme allows the owner of data to store it in an encrypted form in the cloud and to grant access to that data for users with specific roles. The scheme specifies a set of roles to which the users are assigned, with each role having a set of permissions. The data owner can encrypt the data and store it in the cloud in such a way that only users with specific roles can decrypt the data. Anyone else, including the cloud providers themselves, will not be able to decrypt the data. We describe such an RBE scheme using a broadcast encryption algorithm. The paper describes the security analysis of the proposed scheme and gives proofs showing that the proposed scheme is secure against attacks. We also analyse the efficiency and performance of our scheme and show that it has superior characteristics compared with other previously published schemes.
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  • 65
    Publication Date: 2011-11-24
    Description: Although the objective of secure communication can be achieved by using cryptographic tools, the undeniability that results from cryptographic properties may create a potential threat to the sender of the message. Unfortunately, most existing deniable protocols only provide 1-out-of-2 deniability. When both parties (the sender and the receiver) are allowed to deny generating the message, a dispute might occur between these two parties. The 1-out-of-2 deniable protocol can result in an unfair resolution of the dispute. Therefore, we propose a new model of deniability, called 1-out-of- deniability, that can provide full deniability. The 1-out-of- deniability protocol allows the originator of the message to deny that he or she generated the message, since there are an infinite number of possible message generators; at the same time, all transmitted messages can be protected and authenticated between the sender and the intended receiver. Our design can be implemented by using any public-key cryptography technique. We also analyze the correctness of the proposed protocols based on logical rules, and two practical examples are given to illustrate our design.
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  • 66
    Publication Date: 2011-11-24
    Description: Each year, large amounts of money and labor are spent on patching the vulnerabilities in operating systems and various popular software to prevent exploitation by worms. Modeling the propagation process can help us to devise effective strategies against those worms’ spreading. This paper presents a microcosmic analysis of worm propagation procedures. Our proposed model is different from traditional methods and examines deep inside the propagation procedure among nodes in the network by concentrating on the propagation probability and time delay described by a complex matrix. Moreover, since the analysis gives a microcosmic insight into a worm's propagation, the proposed model can avoid errors that are usually concealed in the traditional macroscopic analytical models. The objectives of this paper are to address three practical aspects of preventing worm propagation: (i) where do we patch? (ii) how many nodes do we need to patch? (iii) when do we patch? We implement a series of experiments to evaluate the effects of each major component in our microcosmic model. Based on the results drawn from the experiments, for high-risk vulnerabilities, it is critical that networks reduce the number of vulnerable nodes to below 80%. We believe our microcosmic model can benefit the security industry by allowing them to save significant money in the deployment of their security patching schemes.
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  • 67
    Publication Date: 2011-11-24
    Description: Although analyzing complex systems could be a complicated process, current approaches to quantify system security or vulnerability usually consider the whole system as a single component. In this paper, we propose a new compositional method to evaluate the vulnerability measure of complex systems. By the word composition we mean that the vulnerability measure of a complex system can be computed using pre-calculated vulnerability measures of its components. We define compatible systems to demonstrate which components could combine. Moreover, choice, sequential, parallel and synchronized parallel composition methods are defined and the measurement of the vulnerability in each case is presented. Our method uses a state machine to model the system. The model considers unauthorized states and attacker capabilities. Furthermore, both the probability of attack and delay time to reach the target state are used to quantify vulnerability. The proposed approach would be useful to analyze complex systems which may have complicated models. This approach reduces the state space and complexity of computation. On the other hand, if a component is replaced by another one, the vulnerability measures of other components do not change. Thus, these quantities are reused in new computation. Therefore, the calculation of the vulnerability measure for a new system is simplified.
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  • 68
    Publication Date: 2011-11-24
    Description: The construction of gene regulatory networks from expression data is one of the most important issues in systems biology research. However, building such networks is a tedious task, especially when both the number of genes and the complexity of gene regulation increase. In this work, we adopt the S-system model to represent the gene network and establish a methodology to infer the model. Our work mainly includes an adaptive genetic algorithm-particle swarm optimization hybrid method to infer appropriate network parameters, and a gene clustering method to decompose a large network into several smaller networks for dimension reduction. To validate the proposed methods, different series of experiments have been conducted and the results show that the proposed methods can be used to infer S-system models of gene networks efficiently and successfully.
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  • 69
    Publication Date: 2011-11-24
    Description: We present a content-based image retrieval system for plant image retrieval, intended especially for the house plant identification problem. A plant image consists of a collection of overlapping leaves and possibly flowers, which makes the problem challenging. We studied the suitability of various well-known color, shape and texture features for this problem, as well as introducing some new texture matching techniques and shape features. Feature extraction is applied after segmenting the plant region from the background using the max-flow min-cut technique. Results on a database of 380 plant images belonging to 78 different types of plants show promise of the proposed new techniques and the overall system: in 55% of the queries, the correct plant image is retrieved among the top-15 results. Furthermore, the accuracy goes up to 73% when a 132-image subset of well-segmented plant images are considered.
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  • 70
    Publication Date: 2011-11-24
    Description: We investigate the assignment of assets to tasks where each asset can potentially execute any of the tasks, but assets execute tasks with a probabilistic outcome of success. There is a cost associated with each possible assignment of an asset to a task, and if a task is not executed there is also a cost associated with the non-execution of the task. As we proposed in [Gelenbe, E., Timotheou, S., and Nicholson, D. (2010). Fast distributed near optimum assignment of assets to tasks. Comput. J., doi:10.1093/comjnl/bxq010], we formulate the allocation of assets to tasks in order to minimize the overall expected cost, as a nonlinear combinatorial optimization problem. We propose the use of network flow algorithms which are based on solving a sequence of minimum cost flow problems on appropriately constructed networks with estimated arc costs. We introduce three different schemes for the estimation of the arc costs and we investigate their performance compared with a random neural network algorithm and a greedy algorithm. We also develop an approach for obtaining tight lower bounds to the optimal solution based on a piecewise linear approximation of the considered problem.
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  • 71
    Publication Date: 2011-11-24
    Description: Building trust is a major concern in Peer-to-Peer networks as several kinds of applications rely on the presence of trusted services. Traditional techniques do not scale, produce very high overheads or rely on unrealistic assumptions. In this paper, we propose a new membership algorithm (Community Of Reputable PeerS, CORPS) for Distributed Hash Tables which builds a community of reputable nodes and thus enables the implementation of pseudo-trusted services. CORPS uses a reputation-based approach to decide whether a node can be a member of the group or not. We demonstrate the benefits of this approach and evaluate how much it improves the reliability of a trusted routing service.
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  • 72
    Publication Date: 2011-11-24
    Description: Many data sets exhibit skewed class distributions in which most cases are allocated to a class and far fewer cases to a smaller one. A classifier induced from an imbalanced data set has usually a low error rate for the majority class and an unacceptable error rate for the minority class. This paper provides a review on various methodologies that have tried to handle this problem. Afterwards, it presents an experimental study of these methodologies with a proposed cascade generalization ensemble that is applied in reweighted data and it concludes that such a framework can be a more effective solution to the problem. Our method improves the identification of a difficult small class, while keeping the classification ability of the other class in an acceptable level.
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  • 73
    Publication Date: 2011-11-24
    Description: Ants are generally believed to follow an intensive work routine. Numerous tales and fables refer to ants as conscientious workers. Nevertheless, biologists have discovered that ants also rest for extended periods of time. This does not only hold for individual ants. Interestingly, ant colonies exhibit synchronized activity phases that result from self-organization. In this work, self-synchronization in ant colonies is taken as the inspiring source for a new mechanism of self-synchronized duty-cycling in mobile sensor networks. Hereby, we assume that sensor nodes are equipped with energy harvesting capabilities such as, for example, solar cells. We show that the proposed self-synchronization mechanism can be made adaptive depending on variable energy resources. The main objective of this paper is to study and explore the swarm intelligence foundations of self-synchronized duty-cycling. With this purpose in mind, physical constraints such as packet collisions and packet loss are generally not considered.
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  • 74
    facet.materialart.
    Unknown
    Oxford University Press
    Publication Date: 2011-11-24
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  • 75
    Publication Date: 2011-11-24
    Description: Vector field tomography is a field that has received considerable attention in recent decades. It deals with the problem of the determination of a vector field from non-invasive integral data. These data are modelled by the vectorial Radon transform. Previous attempts at solving this reconstruction problem showed that tomographic data alone are insufficient for determining a 2D band-limited vector field completely and uniquely. This paper describes a method that allows one to recover both components of a 2D vector field based only on integral data, by solving a system of linear equations. We carry out the analysis in the digital domain and we take advantage of the redundancy in the projection data, since these may be viewed as weighted sums of the local vector field's Cartesian components. The potential of the introduced method is demonstrated by presenting examples of vector field reconstruction.
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  • 76
    Publication Date: 2011-11-24
    Description: Historically, at the beginning of natural language processing, applications with industrial objectives were preferred, e.g. for a fully automated translation. Soon, during the 1960s, there were attempts to separate applications from basic theoretical research. Since this theoretical research encounters difficulties regarding its status as a separate discipline, and considering the constraints necessary to clarify the concept of ‘good application’, impossible to satisfy simultaneously (a real problem to solve, in response to a social demand, and a viable solution in terms of reliability, robustness, speed and cost), two main streams have emerged. The first one, as a computer technique, is intended to build applications based on a strict logic, using natural language to facilitate interaction with the computer, but not directly related to the human way of using language (this approach is designated as natural language processing ). Such pragmatic research accepts certain kinds of errors, but must lead to concrete results in limited time. The goal is to provide effective systems for real applications, able to respond effectively to requests addressed to them in fairly large areas; these systems are directly related to social and industrial productivity, which is the essential criterion of evaluation. Some technological developments, such as microcomputers, have made available to people specific applications of natural language processing and have enabled the emergence of small specialized firms. This produced, in the second half of the 1980s, the emergence of a ‘language industry’ and of the field of ‘linguistic engineering’. On the other hand, during the late 1960s, the gap between the social demand, the resources invested and the poor performance obtained led to the emergence of theoretical studies intended to formalize languages (as opposed to the more empirical machine translation). This leads to ‘pilot systems’, aimed at demonstrating the feasibility of complex theoretical approaches, but unable to operate outside a set of rather limited examples. The limits may be at different levels: more or less limited vocabulary or accepted sentences, knowledge about the field more or less complete, more or less developed reasoning and so on. These limits have a significant impact on communication itself. For natural language processing systems to be effective, they must make appropriate inferences from what is said and, conversely their behavior should allow the inferences that the users usually do when using their language. Thus, this position paper stresses that understanding the surface meaning of a natural language is not sufficient but that the goals, intentions and strategies of the participants in a dialogue must be understood.
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  • 77
    Publication Date: 2011-12-01
    Description: Ubiquitous smart environments equipped with low-cost and easily-deployable wireless sensor networks (WSNs) and ever-increasing widespread Mobile Ad hoc NETworks (MANETs) are opening brand new opportunities in environmental monitoring. This paper proposes an original solution for WSN/MANET integration based on the primary design guideline of opportunistically exploiting MANET overlays impromptu formed over the WSN to improve and boost the data collection task of a typical WSN. On the one hand, we adopt a cross-layer approach that exploits MANET connections to differentiate and fasten the delivery of sensed urgent data by pushing them over low-latency MANET paths. On the other hand, we take advantage of local cross-layer visibility of the WSN data collection procedures and protocols to carefully control and limit WSN–MANET coordination overhead. We claim that our proposed solution can obtain significant quality of service improvements via differentiation, by granting faster delivery times to urgent data with a very limited cost in most common execution scenarios.
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  • 78
    Publication Date: 2011-12-01
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  • 79
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    Unknown
    Oxford University Press
    Publication Date: 2011-12-01
    Description: The Capsule Reviews are intended to provide a short succinct review of each paper in the issue in order to bring it to a wider readership. The Capsule Reviews were compiled by Fairouz Kamareddine. Professor Kamareddine is an Associate Editor of The Computer Journal and is based in the Department of Mathematical and Computer Sciences at Heriot-Watt University, Edinburgh, UK.
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  • 80
    Publication Date: 2011-12-01
    Description: Cache sharing has been a popular technique used to facilitate data access in mobile network environments. The key to this technique is to allow an efficient sharing of cache contents between neighboring nodes without introducing excessive amount of communication overhead. In this paper, we propose a cache-sharing protocol, called ‘Pull with Piggybacked Push (PPP)’, which exploits data request broadcasts by performing data pull and index push operations together. Taking advantage of both push- and pull-based approaches, PPP gains benefits from both ends: performance and communication overhead. PPP is unique in that it yields good performance over diverse operating environments, while accomplishing it with lower communication overhead than the previous methods. In addition, it adapts well to different data access patterns. As a result, better scalability is achieved by the proposed protocol.
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  • 81
    Publication Date: 2011-12-01
    Description: With recent advances in technologies such as radio-frequency identification and new standards such as the electronic product code, large-scale traceability is emerging as a key differentiator in a wide range of enterprise applications (e.g. counterfeit prevention, product recalls and pilferage reduction). Such traceability applications often need to access data collected by individual enterprises in a distributed environment. Traditional centralized approaches (e.g. data warehousing) are not feasible for these applications due to their unique characteristics such as large volume of data and sovereignty of the participants. In this paper, we describe an approach that enables applications to share traceability data across independent enterprises in a pure peer-to-peer (P2P) fashion. Data are stored in local repositories of participants and indexed in the network based on structured P2P overlays. In particular, we present a generic approach for efficiently indexing and locating individual objects in large, distributed traceable networks, most notably, in the emerging environment of the internet of things. The results from extensive experiments show that our approach scales well in both data volume and network size. A real-world returnable assets management system is also developed using the proposed techniques to demonstrate its feasibility.
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  • 82
    Publication Date: 2011-12-01
    Description: Detecting motion-based video change, such as different types of motion video or applications using different change detection algorithms in a Web system, is difficult. This paper designs and implements architecture for a real-time or near real-time on-demand motion video change detection system using the Sensor Observation Service (SOS) and the Web Processing Service (WPS) in the Sensor Web environment. Real-time or near real-time includes sensors that obtain motion video data, SOS provides motion video data to WPS and WPS processes this data. Three solution methods are introduced: the GetObservation operation of SOS by transaction, dynamical interaction between SOS and WPS, and WPS real-time or near real-time processing. On-demand means that a developer can choose different motion video change detection algorithms under different applications or different conditions. For this purpose, a flexible, standards-based and service-oriented WPS architecture is designed, which consists of three layers: the WPS interface layer, the field interface layer and the implementation layer. To test the proposed approach, a video change detection case of monitoring a road situation is shown, which was a demonstration for Open Geospatial Consortium Web Service phase 7. The results demonstrate that the proposed approach is feasible.
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  • 83
    Publication Date: 2011-11-24
    Description: Most traditional recommender systems lack accuracy in the case where data used in the recommendation process is sparse. This study addresses the sparsity problem and aims to get rid of it by means of a content-boosted collaborative filtering approach applied to a web-based movie recommendation system. The main motivation is to investigate whether further success can be obtained by combining ‘local and global user similarity’ and ‘effective missing data prediction’ approaches, which were previously introduced and proved to be successful separately. The present work improves these approaches by taking the content information of the movies into account during the item similarity calculations. The comparison of the proposed approach with the original methods was carried out using mean absolute error, and more accurate predictions were achieved.
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  • 84
    Publication Date: 2011-12-01
    Description: How do animals use their habitat? Where do they go and what do they do? These basic questions are key not only to understanding a species’ ecology and evolution, but also for addressing many of the environmental challenges we currently face, including problems posed by invasive species, the spread of zoonotic diseases and declines in wildlife populations due to anthropogenic climate and land-use changes. Monitoring the movements and activities of wild animals can be difficult, especially when the species in question are small, cryptic or move over large areas. In this paper, we describe an Automated Radio-Telemetry System (ARTS) that we designed and built on Barro Colorado Island (BCI), Panama to overcome these challenges. We describe the hardware and software we used to implement the ARTS, and discuss the scientific successes we have had using the system, as well as the logistical challenges we faced in maintaining the system in real-world, rainforest conditions. The ARTS uses automated radio-telemetry receivers mounted on 40-m towers topped with arrays of directional antennas to track the activity and location of radio-collared study animals, 24 h a day, 7 days a week. These receiving units are connected by a wireless network to a server housed in the laboratory on BCI, making these data available in real time to researchers via a web-accessible database. As long as study animals are within the range of the towers, the ARTS system collects data more frequently than typical animal-borne global positioning system collars (~12 locations/h) with lower accuracy (approximately 50 m) but at much reduced cost per tag (~10X less expensive). The geographic range of ARTS, like all VHF telemetry, is affected by the size of the radio-tag as well as its position in the forest (e.g. tags in the canopy transmit farther than those on the forest floor). We present a model of signal propagation based on landscape conditions, which quantifies these effects and identifies sources of interference, including weather events and human activity. ARTS has been used to track 374 individual animals from 38 species, including 17 mammal species, 12 birds, 7 reptiles or amphibians, as well as two species of plant seeds. These data elucidate the spatio-temporal dynamics of animal activity and movement at the site and have produced numerous peer-reviewed publications, student theses, magazine articles, educational programs and film documentaries. These data are also relevant to long-term population monitoring and conservation plans. Both the successes and the failures of the ARTS system are applicable to broader sensor network applications and are valuable for advancing sensor network research.
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  • 85
    Publication Date: 2011-12-01
    Description: Energy efficiency is a key characteristic of modern wireless sensors. Assuming that the transceiver is the most power-consuming component of a typical sensor node, then a large advantage can be achieved at the data link layer where the medium access control (MAC) protocol controls the usage of the radio unit. Many MAC protocols have been developed for traditional wireless networks. Given that the sensor network is different from the traditional wireless network in many places, researchers are looking for a MAC protocol that is specifically designed and adapted to the sensor network. Moreover, most of the contributions in the wireless sensor network have assumed static nodes. However, some applications in the area of medical care and disaster response make use of the mobile sensor network. Thus, the present paper studies and simulates the sensor MAC (S-MAC), timeout MAC and mobility-aware S-MAC (MS-MAC) protocols in terms of their energy efficiency in different mobility situations. Furthermore, an enhancement of the MS-MAC protocol, named as enhanced MS-MAC, is introduced and simulated. The results show that this enhancement can significantly improve the energy efficiency when there is a reasonable packet delivery rate.
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  • 86
    facet.materialart.
    Unknown
    Oxford University Press
    Publication Date: 2011-11-24
    Description: Rice, J. C. 2011. Advocacy science and fisheries decision-making. – ICES Journal of Marine Science, 68: 2007–2012. Science advice is supposed to meet idealistic standards for objectivity, impartiality, and lack of bias. Acknowledging that science advisors are imperfect at meeting those standards, they nonetheless need to strive to produce sound, non-partisan advice, because of the privileged accountability given to science advice in decision-making. When science advisors cease to strive for those ideals and promote advocacy science, such advice loses the right to that privileged position. There are temptations to shape science advice by using information that "strengthens" the conservation case selectively. Giving in to such temptation, however, dooms the advice; science advice becomes viewed as expressions of the biases of those who provide it rather than reflecting the information on which the advice is based. Everyone, including the ecosystems, loses. There are ways to increase the impact of science advice on decision-making that do not involve perverting science advice into advocacy: peer review by diverse experts, integrating advice on ecological, economic, and social information and outcomes, and focusing advisory approaches on risks, costs, and trade-offs of different types of management error. These approaches allow the science experts to be active, informed participants in the governance processes to aid sound decision-making, not to press for preselected outcomes. Everyone, including the ecosystems, wins.
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  • 87
    Publication Date: 2011-11-24
    Description: Doubleday, Z. A., White, J., Pecl, G. T., and Semmens, J. M. 2011. Age determination in merobenthic octopuses using stylet increment analysis: assessing future challenges using Macroctopus maorum as a model. – ICES Journal of Marine Science, 68: 2059–2063. Stylet increment analysis (SIA) is a method recently developed to age octopuses; it involves the enumeration of daily growth increments within stylets (an internal shell). To examine the potential of SIA in a merobenthic octopus species, SIA was applied to Macroctopus maorum collected from southeast Australia and New Zealand ( n = 147). The stylets had clear concentric growth increments and a core-like region. However, low increment counts (≤224 d) produced non-feasibly high (≤21.7% body weight per day) instantaneous growth rates, based on the assumption that increment number relates to age (d). In the light of these results, the issues surrounding the application of SIA to merobenthic octopuses is discussed, particularly in relation to the lack of understanding in regard to stylet development in the early life history stages and the importance of validating age at first increment formation.
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  • 88
    Publication Date: 2011-11-24
    Description: de Moor, C. L., Butterworth, D. S., and De Oliveira, J. A. A. 2011. Is the management procedure approach equipped to handle short-lived pelagic species with their boom and bust dynamics? The case of the South African fishery for sardine and anchovy. – ICES Journal of Marine Science, 68: 2075–2085. Worldwide, small shoaling pelagic fish manifest rapid and substantial natural changes in abundance. Is the application of a management procedure (MP), evaluated using simulation tests [i.e. a MP approach otherwise known as management strategy evaluation (MSE)], to recommend total allowable catches (TACs) with constraints desired by industry on the extent of interannual changes viable for such resources, particularly given the customarily lengthy MP evaluation process? This question is examined by considering the rapid boom and then bust situation that arose for the South African fishery for sardine ( Sardinops sagax ) and anchovy ( Engraulis encrasicolus ) across the turn of the century. Novel adaptations to the MP in place at the time of the boom allowed enhanced resource use during the boom period without compromising the risk of unintended depletion of the populations. Importantly a two-tier threshold system allowed the normal constraints on the maximum extent of interannual TAC reduction to be modified when TACs rose above the specified thresholds. The general protocol underlying the application of MPs for South African fisheries proved sufficiently flexible for the approach to continue to be applied, despite the unanticipated rapid fish population boom and then bust experienced.
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  • 89
    Publication Date: 2011-11-24
    Description: Hinrichsen, H-H., Huwer, B., Makarchouk, A., Petereit, C., Schaber, M., and Voss, R. 2011. Climate-driven long-term trends in Baltic Sea oxygen concentrations and the potential consequences for eastern Baltic cod ( Gadus morhua ). – ICES Journal of Marine Science, 68: 2019–2028. Variations in oxygen conditions in the Baltic are influenced by several mechanisms. Generally, the frequency and magnitude of major inflows have been identified as the most crucial process for the renewal of oxygen-depleted water masses in the Baltic Sea. Furthermore, enhanced degradation of suspended organic matter by bacteria over the past few decades has increased oxygen consumption. Finally, the effects of large-scale climate warming are causing long-term variations in oxygen content and saturation as an observed increase in temperature has led to a general decrease in oxygen solubility of water masses. Oxygen-dependent relationships based on field data and laboratory experiments were used to analyse the impact of the observed decrease in oxygen content on eastern Baltic cod ( Gadus morhua ) stock-specific processes (e.g. survival rates of eggs, settlement probability of juveniles, habitat utilization of spawning fish, age structure of successful spawners, food consumption rates of adult fish). The observed long-term decline in oxygen conditions in the Baltic Sea has had a seemingly generally negative impact on oxygen-related processes for the different life stages of eastern Baltic cod. Experimentally derived results of oxygen-driven processes were validated by field data.
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  • 90
    Publication Date: 2011-11-24
    Description: Fisher, J. A. D., Frank, K. T., Kostylev, V. E., Shackell, N. L., Horsman, T., and Hannah, C. G. 2011. Evaluating a habitat template model's predictions of marine fish diversity on the Scotian Shelf and Bay of Fundy, Northwest Atlantic. – ICES Journal of Marine Science, 68: 2096–2105. Habitat template models that integrate physical, chemical, and biological data have the potential to explain geographic variation in life-history traits within assemblages and to predict locations where species will be most vulnerable to anthropogenic impact. A previously developed model based on spatial variations in scope for growth (SG) and natural disturbance (ND) for the Scotian Shelf/Bay of Fundy was tested for its ability to predict fish life-history traits, species diversity, and community composition using trawl survey data. Of 30 dominant fish species, large, slow-growing ones most vulnerable to overexploitation tended to be found in naturally stable habitats. Among consistently co-occurring groups, functional differentiation, rather than similarity of life history, characterized assemblages, whereas among survey strata, species richness peaked at intermediate levels of ND and species evenness increased with average SG. Community composition was significantly correlated with both habitat variables, declined by 40% through time preceding structural changes on the eastern Scotian Shelf, but geographic distance, depth, and bottom temperature remained more strongly related to composition. The results revealed compelling matches between template predictions and patterns of fish species diversity, but low variation in diversity of life history, and mobility of fish may account for some of the weaker matches to model predictions.
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  • 91
    Publication Date: 2011-11-24
    Description: Lefebvre, A., Guiselin, N., Barbet, F., and Artigas, F. L. 2011. Long-term hydrological and phytoplankton monitoring (1992–2007) of three potentially eutrophic systems in the eastern English Channel and the Southern Bight of the North Sea. – ICES Journal of Marine Science, 68: 2029–2043. The spatial and main temporal variations in nutrient concentrations and phytoplankton abundance were investigated between 1992 and 2007 in the eastern English Channel and the Southern Bight of the North Sea, zones of consistent presence of Phaeocystis globosa and diatom blooms. Silicate and phosphate were the main nutrients potentially limiting phytoplankton growth, but the dynamics of the limitation seemingly differ between sites. Phosphate concentration showed a clear monotonic decreasing trend, whereas dissolved inorganic nitrogen and silicate trends were more complex. Nitrate was rarely or never a limiting factor. Results highlight three main periods with a Phaeocystis - or diatom-dominated system in the 1990s, and a more complex pattern in the 2000s. The composition of the phytoplanktonic community is described and an attempt made to establish a link between the community and its environment in terms of variability, shifts, and trends. The effects of larger- vs. regional-scale controlling factors are also discussed.
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  • 92
    Publication Date: 2011-11-24
    Description: Portman, M. E. 2011. Marine spatial planning: achieving and evaluating integration. – ICES Journal of Marine Science, 68: 2191–2200. Coastal states and nations are conducting marine spatial planning (MSP) at an ever-increasing pace. Some MSP efforts are aimed at planning areas at a subnational level, whereas others extend as far as 200 nautical miles from shore, within national exclusive economic zones. For planning of all types, but especially for planning in the marine realm, integration has become a sought-after norm now that traditional sectoral, single-issue management has not succeeded. Fisheries collapse, threats to marine biodiversity, and global climate change all support the case for greater integration in marine resource management and policy. The designation of boundaries can be related to the level of cross-sector and cross-jurisdictional integration achieved by MSP. The importance of scale and scope for MSP initiatives is examined, relating these aspects of plans and/or programmes to the levels of integration achieved, and a framework is suggested for evaluation. MSP initiatives in Portugal, the UK, and the USA serve as potential case studies for use of the framework.
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  • 93
    Publication Date: 2011-11-24
    Description: Makhrov, A. A., Artamonova, V. S., Popov, V. I., Rolskiy, A. Yu., and Bakay, Y. I. Comment on: Cadrin et al . 2011. "Population structure of beaked redfish, Sebastes mentella : evidence of divergence associated with different habitats. ICES Journal of Marine Science, 67: 1617–1630" – ICES Journal of Marine Science, 68: 2013–2015. An analysis of the genetic data used in the paper by Cadrin et al. (2010) indicates that they do not disprove the hypothesis of the existence of a single population of S. mentella in the Irminger Sea.
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  • 94
    Publication Date: 2011-11-24
    Description: Bateman, K. S., Hicks, R. J., and Stentiford, G. D. 2011. Disease profiles differ between non-fished and fished populations of edible crab ( Cancer pagurus ) from a major commercial fishery. – ICES Journal of Marine Science, 68: 2044–2052. Despite their significant contribution to global marine fisheries, relatively little information is available on the pathogen profile of commercially exploited decapod crustacean populations. Most of the information published relates to adult (fished) subpopulations, with almost nothing known about disease processes and mortality drivers in juveniles. The seasonal profile of pathogens in non-fished (prerecruit) and fished (recruit) subpopulations of Cancer pagurus , a major target fishery target in European waters, is investigated. Histopathology and ultrastructural assessment of tissues demonstrated a distinct pathogen profile in the two subpopulations, the apparent prevalence of specific pathogens varying with both season and life stage of the host. In some cases, highly prevalent pathogens in the prerecruit subpopulation were not observed in the recruit subpopulation. In this context, the discovery of a novel and highly prevalent haplosporidian-like parasite infecting the antennal gland and bladder of prerecruit life stages of C. pagurus is reported. Co-infections with pathogens described previously, such as Hematodinium sp. and C. pagurus bacilliform virus, were also observed. Disease assessments in the prerecruit subpopulation of commercial decapod fishery targets could perhaps be utilized to improve the estimation of cohort success and, therefore, forecasts of future recruitment to the fishery.
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  • 95
    Publication Date: 2011-11-24
    Description: Godwin, R. M., Frusher, S., Montgomery, S. S., and Ovenden, J. 2011. Telomere length analysis in crustacean species: Metapenaeus macleayi , Sagmariasus verreauxi , and Jasus edwardsii . – ICES Journal of Marine Science, 68: 2053–2058. Estimates of age and growth in crustaceans have been historically problematic and presented significant challenges to researchers. Current techniques of age determination provide valuable data, but also suffer from disadvantages. Telomeric DNA has been proposed as an age biomarker because it shortens with age in some species. In this study, the feasibility of using telomere length (TL) to estimate age was examined in the school prawn Metapenaeus macleayi and the spiny lobsters Sagmariasus verreauxi and Jasus edwardsii . Carapace length (CL) was used as a surrogate for age, and terminal restriction fragment assays were used to test the relationship between TL and size. Degradation of telomeric DNA with time during storage significantly influenced TL estimates, particularly for M. macleayi . TLs obtained from species in this study were 10–20 kb. No relationship between CL and TL was detected for any of the test species, and TL did not differ between male and female M. macleayi. TLs of J. edwardsii pueruli were unexpectedly shorter than those of J. edwardsii adults. The suitability of TL as an age biomarker in crustaceans may be limited, but further research is needed to elucidate telomere dynamics in these species with their different life histories and lifespans.
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  • 96
    Publication Date: 2011-11-24
    Description: Davison, P. 2011. The specific gravity of mesopelagic fish from the northeastern Pacific Ocean and its implications for acoustic backscatter. – ICES Journal of Marine Science, 68: . Knowledge of the species present, their morphology, and their size distribution is required to infer biomass from acoustic surveys of fish. The gas content and specific gravity of the body (with gas removed), f , was measured for 71 species of mesopelagic fish in the NE Pacific Ocean. Those species that have functional swimbladders when large maintain constant f with increasing body size. Species without functional swimbladders as adults show decreased f with increasing body size. The acoustic-backscattering cross-section, bs , was modelled for all individuals collected from three fish species that differed in the presence of a gas-filled swimbladder. The change in bs with increasing body size was markedly different between the three. The low body density of those mesopelagic fish without gas-filled swimbladders greatly reduces their bs . In species of fish that possess a functional swimbladder as juveniles and in which the swimbladder regresses with growth, the bs first decreases, then increases with increased body size. Knowledge of the ontogenetic changes in swimbladder inflation and body density in mesopelagic fish is critical for the construction of the backscattering models used to interpret acoustic surveys.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 97
    Publication Date: 2011-11-24
    Description: Cadrin, S. X., Mariani, S., Pampoulie, C., Bernreuther, M., Daníelsdóttir, A. K., Johansen, T., Kerr, L., Nedreaas, K., Reinert, J., Sigurðsson, Þ., and Stransky, C. 2011. Counter-comment on: Cadrin et al. (2010) "Population structure of beaked redfish, Sebastes mentella : evidence of divergence associated with different habitats. ICES Journal of Marine Science, 67: 1617–1630." – ICES Journal of Marine Science, 68: 2016–2018. A one-stock hypothesis for S. mentella in the Irminger Sea was rejected in favour of one involving depth-segregated stock structure based on the best scientific information available, including recent genetic results. The depth-based hypothesis is maintained and supported, despite the criticisms by Makhrov et al. (2011) , which can all be explained and refuted.
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    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 98
    Publication Date: 2011-11-24
    Description: Tuck, G. N., Phillips, R. A., Small, C., Thomson, R. B., Klaer, N. L., Taylor, F., Wanless, R. M., and Arrizabalaga, H. 2011. An assessment of seabird–fishery interactions in the Atlantic Ocean. – ICES Journal of Marine Science, 68: 1628–1637. Currently, 17 of 22 albatross species are listed as Vulnerable, Endangered, or Critically endangered by the International Union for the Conservation of Nature (IUCN). Incidental mortality in fisheries is by far the most widespread cause of the population declines observed for these and other closely related species. In 2006, the International Commission for the Conservation of Atlantic Tunas (ICCAT) requested an assessment of the threat from their fisheries to all seabirds that breed or forage within their jurisdiction. Methods were developed to assess the potential consequences of fishing for more than 60 populations of seabird. The assessment framework involved the identification of at-risk populations, overlap analyses, estimation of total bycatch, and an evaluation of the impact of the bycatch on key selected populations for which there were sufficient data on bird distribution and demography. These were the wandering and black-browed albatrosses of South Georgia and the Atlantic yellow-nosed and Tristan albatrosses of Gough Island. Summary results from the seabird assessment are presented, revealing that ICCAT longline fisheries catch substantial numbers of seabirds, with potentially significant conservation implications. If this mortality is not reduced, the numbers of breeding birds in some populations will continue to decline, threatening their long-term viability.
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    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 99
    Publication Date: 2011-11-24
    Description: De Robertis, A., and Wilson, C. D. 2011. Silent ships do not always encounter more fish (revisited): comparison of acoustic backscatter from walleye pollock recorded by a noise-reduced and a conventional research vessel in the eastern Bering Sea. – ICES Journal of Marine Science, 68: 2229–2239. Vessel-induced avoidance behaviour is potentially a major source of error in surveys of fish populations. Noise-reduced research vessels have been constructed in an effort to minimize fish reactions to auditory stimuli produced by survey vessels. Here, measurements of acoustic backscatter from walleye pollock ( Theragra chalcogramma ) made on the eastern Bering Sea Shelf from the conventional NOAA ship "Miller Freeman" (MF) are compared with similar measurements made on the noise-reduced NOAA ship "Oscar Dyson" (OD). As in a previous study, acoustic abundance measurements from these vessels were equivalent during daylight, when large-scale acoustic surveying is conducted. However, significant differences were observed at night: on average, 44% more pollock backscatter was observed from OD than MF. Observations with a free-drifting echosounder buoy suggest that the night-time discrepancy is attributable to a stronger behavioural response to the passage of the louder MF, and a resulting decrease in pollock target strength. Pollock did not exhibit a strong reaction to the passage of OD. These observations are consistent with previous comparisons of these vessels, which show that with vessel differences, the noise-reduced OD detects more pollock.
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    Electronic ISSN: 1095-9289
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  • 100
    Publication Date: 2011-11-24
    Description: Fitzpatrick, M., Graham, N., Rihan, D. J., and Reid, D. G. 2011. The burden of proof in co-management and results-based management: the elephant on the deck! – ICES Journal of Marine Science, 68: 1656–1662. Results-based management requires that outcomes can be demonstrated by industry and verified by managers on behalf of society. The core questions are: what outcomes, and how can they be proved? Existing fishery approaches to reversing the burden of proof are examined with focus on how proof is demonstrated. Outcomes can be measured in situ (on the vessel) or ex situ (at the stock or ecosystem level). In situ measures are preferable because they give direct measurements, although they can be invasive and costly. Ex situ results are only observable on scales that make it difficult to attribute them to specific management measures, or they may be influenced by external factors. Three main environmental impacts caused by fishing are assessed with respect to how industry can assume the burden of proof. The combined use of vessel-monitoring systems and benthic-impact models may offer a practical solution to the problem of managing fishery impacts on the benthos. Three Irish fisheries are assessed in terms of the feasibility of reversing the burden of proof. There are limits to the extent to which industry can assume the burden of proof, and the concept of sharing the burden of proof could be more realistic.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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