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  • 1
    Publication Date: 2012-04-10
    Description: Probst, W. N., Stelzenmüller, V., and Fock, H. 2012. Using cross-correlations to assess the relationship between time-lagged pressure and state indicators: an exemplary analysis of North Sea fish population indicators. – ICES Journal of Marine Science, 69: 670–681. A sustainable ecosystem-based management, as postulated by the European Union-Marine Strategy Framework Directive (MSFD), requires a sound understanding of the cause–effect relationships between human pressures and ecosystem states. In this study, cross-correlations are used to introduce a protocol for the analysis of time-lagged relationships between pressure and state indicators. To perform meaningful cross-correlations, the time-series of the pressure and the state indicator should be prewhitened by fitting autoregressive integrated moving average models to the pressure indicator time-series. This study provides some theoretical examples on the implications of non-prewhitened and prewhitened cross-correlations and exemplifies the use of prewhitened cross-correlations to compare the pressure–state relationship of a well-established indicator suite vs. the relationship of a new indicator proposed under the MSFD. The established indicator suite is fishing mortality ( F ) vs. spawning-stock biomass ( SSB ), the new indicator suite is F vs. the 95% percentile of the length frequency distribution ( L 95 ). The L 95 aims to characterize the proportion of large individuals within a population. The prewhitened cross-correlations for F and SSB are significant for all four analysed species (cod, haddock, saithe, and plaice), the L 95 is correlated with F for cod, haddock, and saithe. However, the L 95 was also influenced by the annual survey catch and recruitment.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 2
    Publication Date: 2012-04-10
    Description: Sonntag, N., Schwemmer, H., Fock, H.O., Bellebaum, J., and Garthe, S. 2012. Seabirds, set-nets, and conservation management: assessment of conflict potential and vulnerability of birds to bycatch in gillnets. – ICES Journal of Marine Science, 69: 578–589. We addressed the issue of bird bycatch in set-nets in the southern Baltic Sea by (i) assessing the vulnerability of diving birds to drowning by developing a vulnerability index based on weighted bird abundance, (ii) providing information on set-net fishing activities, and (iii) using a spatial overlap approach to indicate the potential conflicts between diving birds and fishing activities. Birds and fisheries concentrated in the same areas. Vulnerability and potential conflict were highest during winter and spring in coastal waters and around shallow offshore grounds. Local bycatch studies validated the usefulness of our approach, which can provide a valuable tool for conservation purposes. Although the conflict analysis outlined the current extent of overlap between birds and fisheries, the vulnerability index indicated important areas and periods in terms of diving bird abundance, irrespective of fisheries, and enabled the development of appropriate conservation and management options. A suite of measures including temporal or spatial restrictions can be derived, despite a scarcity of real data for bycatch rates. This approach is particularly useful for assessing impacts that are difficult to monitor and where mortality cannot be properly addressed, as in artisanal gillnet fisheries. It is also generally applicable to any marine area or species worldwide.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 3
    Publication Date: 2015-03-07
    Description: Maritime spatial planning (MSP) and fishery management may generate extra costs for fisheries by constraining fishers activity with conservation areas and new utilizations of the sea. More energy-efficient fisheries are also likely to alter existing fishing patterns, which already vary from fishery to fishery and from vessel to vessel. The impact assessment of new spatial plans involving fisheries should be based on quantitative bioeconomic analyses that take into account individual vessel decisions, and trade-offs in cross-sector conflicting interests. We use a vessel-oriented decision-support tool (the DISPLACE model) to combine stochastic variations in spatial fishing activities with harvested resource dynamics in scenario projections. The assessment computes economic and stock status indicators by modelling the activity of Danish, Swedish, and German vessels (〉12 m) in the international western Baltic Sea commercial fishery, together with the underlying size-based distribution dynamics of the main fishery resources of sprat, herring, and cod. The outcomes of alternative scenarios for spatial effort displacement are exemplified by evaluating the fishers's abilities to adapt to spatial plans under various constraints. Interlinked spatial, technical, and biological dynamics of vessels and stocks in the scenarios result in stable profits, which compensate for the additional costs from effort displacement and release pressure on the fish stocks. The effort is further redirected away from sensitive benthic habitats, enhancing the ecological positive effects. The energy efficiency of some of the vessels, however, is strongly reduced with the new zonation, and some of the vessels suffer decreased profits. The DISPLACE model serves as a spatially explicit bioeconomic benchmark tool for management strategy evaluations for capturing tactical decision-making in reaction to MSP.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 4
    Publication Date: 2015-03-07
    Description: Marine spatial planning (MSP) requires spatially explicit environmental risk assessment (ERA) frameworks with quantitative or probabilistic measures of risk, enabling an evaluation of spatial management scenarios. ERAs comprise the steps of risk identification, risk analysis, and risk evaluation. A review of ERAs in in the context of spatial management revealed a synonymous use of the concepts of risk, vulnerability and impact, a need to account for uncertainty and a lack of a clear link between risk analysis and risk evaluation. In a case study, we addressed some of the identified gaps and predicted the risk of changing the current state of benthic disturbance by bottom trawling due to future MSP measures in the German EEZ of the North Sea. We used a quantitative, dynamic, and spatially explicit approach where we combined a Bayesian belief network with GIS to showcase the steps of risk characterization, risk analysis, and risk evaluation. We distinguished 10 benthic communities and 6 international fishing fleets. The risk analysis produced spatially explicit estimates of benthic disturbance, which was computed as a ratio between relative local mortality by benthic trawling and the recovery potential after a trawl event. Results showed great differences in spatial patterns of benthic disturbance when accounting for different environmental impacts of the respective fleets. To illustrate a risk evaluation process, we simulated a spatial shift of the international effort of two beam trawl fleets, which are affected the most by future offshore wind development. The Bayesian belief network (BN) model was able to predict the proportion of the area where benthic disturbance likely increases. In conclusion, MSP processes should embed ERA frameworks which allow for the integration of multiple risk assessments and the quantification of related risks as well as uncertainties at a common spatial scale.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 5
  • 6
    Publication Date: 2014-12-01
    Description: Maritime spatial planning (MSP) and fishery management may generate extra costs for fisheries by constraining fishers activity with conservation areas and new utilizations of the sea. More energy-efficient fisheries are also likely to alter existing fishing patterns, which already vary from fishery to fishery and from vessel to vessel. The impact assessment of new spatial plans involving fisheries should be based on quantitative bioeconomic analyses that take into account individual vessel decisions, and trade-offs in cross-sector conflicting interests. We use a vessel-oriented decision-support tool (the DISPLACE model) to combine stochastic variations in spatial fishing activities with harvested resource dynamics in scenario projections. The assessment computes economic and stock status indicators by modelling the activity of Danish, Swedish, and German vessels (〉12 m) in the international western Baltic Sea commercial fishery, together with the underlying size-based distribution dynamics of the main fishery resources of sprat, herring, and cod. The outcomes of alternative scenarios for spatial effort displacement are exemplified by evaluating the fishers's abilities to adapt to spatial plans under various constraints. Interlinked spatial, technical, and biological dynamics of vessels and stocks in the scenarios result in stable profits, which compensate for the additional costs from effort displacement and release pressure on the fish stocks. The effort is further redirected away from sensitive benthic habitats, enhancing the ecological positive effects. The energy efficiency of some of the vessels, however, is strongly reduced with the new zonation, and some of the vessels suffer decreased profits. The DISPLACE model serves as a spatially explicit bioeconomic benchmark tool for management strategy evaluations for capturing tactical decision-making in reaction to MSP.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 7
    Publication Date: 2016-05-26
    Description: Macroramphosus spp. (Centriscidae, Macroramphosinae) are the most abundant demersal fishes on the Great Meteor Seamount (GMR, subtropical NE Atlantic, 30degrees N, 28.5degrees W). Previous investigations evidenced the existence of two species that differed in morphology and diet. A deep-bodied benthos feeding type (b-type), M. scolopax, could be significantly distinguished from a slender planktivorous type (p-type), M. gracilis. In this study we investigate whether dietary differences are also significant. Based on a novel null model termed ortho-RA3 in accordance with Lawlor (1980), the analysis of dietary overlap revealed significant differences between feeding types for two of three hypotheses that were tested, i.e., between-group differences and within-group differences for M. gracilis. Reasons for the failure of the third hypothesis (within-group differences for M scolopax) are discussed. Our results 4 reinforce the hypothesis of two competing species of snipefishes at GMR
    Type: Article , NonPeerReviewed
    Format: text
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  • 8
    Publication Date: 2024-01-07
    Description: The southern African subcontinent and its surrounding oceans accommodate globally unique ecoregions, characterized by exceptional biodiversity and endemism. This diversity is shaped by extended and steep physical gradients or environmental discontinuities found in both ocean and terrestrial biomes. The region’s biodiversity has historically been the basis of life for indigenous cultures and continues to support countless economic activities, many of them unsustainable, ranging from natural resource exploitation, an extensive fisheries industry and various forms of land use to nature-based tourism. Being at the continent’s southern tip, terrestrial species have limited opportunities for adaptive range shifts under climate change, while warming is occurring at an unprecedented rate. Marine climate change effects are complex, as warming may strengthen thermal stratification, while shifts in regional wind regimes influence ocean currents and the intensity of nutrient-enriching upwelling. The flora and fauna of marine and terrestrial southern African biomes are of vital importance for global biodiversity conservation and carbon sequestration. They thus deserve special attention in further research on the impacts of anthropogenic pressures including climate change. Excellent preconditions exist in the form of long-term data sets of high quality to support scientific advice for future sustainable management of these vulnerable biomes.
    Type: Book chapter , NonPeerReviewed
    Format: text
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden , USA : Blackwell Science Ltd
    Journal of fish biology 64 (2004), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: One specimen of the largetooth cookiecutter shark Isistius plutodus was caught in the north-eastern Atlantic at 43°58′ N; 28°32′ W. This is the first record of this rare species in the north-eastern Atlantic and the northernmost point of its known distribution.
    Type of Medium: Electronic Resource
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  • 10
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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