ALBERT

Description: Inferring feeding activities from undulations in diving depth profiles is widespread in studies of foraging marine predators. This idea, however, has rarely been tested because of practical difficulties in obtaining an independent estimate of feeding activities at a time scale corresponding to depth changes within a dive. In this study we attempted to relate depth profile undulations and feeding activities during diving in a single Chinstrap Penguin Pygoscelis antarctica, by simultaneously using a conventional time-depth recorder and a recently developed beak-angle sensor. Although failure in device attachments meant that data were obtained successfully from just a part of a single foraging trip, our preliminary results show a linear relationship between the number of depth wiggles and the number of underwater beakopening events during a dive, suggesting that the relative feeding intensity of each dive could be represented by depth-profile data. Underwater beak-opening patterns of this krill-feeding penguin species are compared with recent data from three fish- and squid-feeding Magellanic Penguins Spheniscus magellanicus.

Description: Interannual variability in the mesoscale oceanography of the inferred hatching area of winter-spawned Illex argentinus (i.e. those belonging to the Southern Patagonic Stock) was examined during the hatching months of June and July. The hatching area was defined as the region 32°–39°S, 49°–61° W, and indicators of the surface oceanography in this area were derived from remotely sensed advanced very high resolution radiometer (AVHRR) sea-surface temperature (SST) data. Interannual variability in the mesoscale oceanic circulation in the inferred hatching area was examined in terms of (1) the area occupied by "frontal" waters (defined as areas with SST gradients of ≥3°C over an area of 15 km by 15 km), and (2) the area occupied by waters of "favourable" SST (defined as those with temperatures in the range 16–18°C). Oceanographic indicators were compared with an index of I. argentinus recruitment to the Falkland Islands (Malvinas) fishery (catch per licensed vessel) for the period 1987 to 1999. The two oceanographic indicators were seen to co-vary, with a decrease in the proportion of the inferred hatching area occupied by frontal waters corresponding to an increase in the proportion of water of favourable SST. High squid abundance was found to be associated with a lower proportion of frontal waters or a higher proportion of favourable-SST waters within the inferred hatching area in the year preceding the fishery. Interannual variability in the interaction of the Brazil and Falkland Currents in the inferred hatching area during the early life stages is shown to be important in influencing the population size of I, argentinus, and mechanisms influencing squid recruitment in this highly dynamic region are discussed.

Description: Adélie (Pygoscelis adeliae) and chinstrap penguins (P. antarctica) are morphologically and ecologically very similar, have very similar diet and breed sympatrically in the Scotia Arc from the South Sandwich Islands to the Antarctic Peninsula. To investigate how these two species co-exist, their foraging distribution and diet were studied during the chick-rearing period at Signy Island, South Orkney Islands, during the breeding seasons of 2000 and 2001. Satellite tracking data from of 19 Adélie penguins and 24 chinstrap penguins were used to compare foraging distributions. In both years the diet of both species was exclusively Antarctic krill (Euphausia superba) of the same size range. In a year of low prey availability (2000), there was a statistically significant segregation of foraging areas between the two species, however, in a year of normal resource availability (2001) there was no such segregation. There was a significant difference in the foraging areas used by Adélie penguins between years but not for chinstrap penguins. Adélie penguins foraged significantly farther (mean 100 km) from the colony than chinstrap penguins (mean 58 km) in 2000 but not in 2001 (mean 58 km and 35 km respectively). In 2000, the breeding success of Adélie penguins was 51% lower than the long-term mean compared to 15% lower in chinstrap penguins. Both species achieved above average breeding success in 2001. The changes in foraging distribution and breeding success suggest that in years of low resource availability, chinstrap penguins may be able to competitively exclude Adélie penguins from potential inshore foraging areas. Current trends in climatic change and possible effects on ice distribution and krill abundance suggest that conditions could become less favourable for Adélie penguins than chinstrap penguins in areas where both species occur.

Description: In this study, we consider the influence of mesoscale oceanographic processes around the Falkland Islands (Islas Malvinas) in the South-west Atlantic, during the period in which the commercial squid fishery for Illex argentinus operates. Spatially referenced fishery data and satellite-derived advanced very high resolution radiometry (AVHRR) sea surface temperature (SST) data were examined using geographic information system (GIS) techniques. The distribution and relative abundance of I. argentinus in the Falkland Islands fishery was examined for the period 1989–96. Three consistent areas of high abundance were observed to the north-east (shelf-break region) and north-west (shelf region) of the islands, and close to the northern coast of East Falkland. Areas of high sea surface temperature gradients (thermal gradients) extracted from remotely sensed satellite images were used as an indicator of mesoscale oceanographic activity and compared with the location of the fishery. I. argentinus were found to be associated with areas of thermal gradients, commonly seen at the interface of Falkland Current and Patagonian shelf waters. The techniques used in this analysis allow the overlay and analysis of physical oceanographic and fishery data with potential applications in fisheries management and operational fisheries oceanography.

Description: To investigate the role of sea ice cover on penguin populations we used principal component analysis to compare population variables of Adélie (Pygoscelis adeliae) and chinstrap (Pygoscelis antarctica) penguins breeding on Signy Island, South Orkney Islands with local (from direct observations) and regional (from remote sensing data) sea ice variables. Throughout the study period, the Adélie penguin population size remained stable, whereas that of chinstrap penguins decreased slightly. For neither species were there significant relationships between population size and breeding success, except for an apparent inverse density-dependent relationship between the number of Adélie breeding pairs and the number of eggs hatching. For both species, no general relationship was found between either population size or breeding success and the local sea ice conditions. However, the regional sea ice extent at a particular time prior to the start of the breeding season was related to the number of birds that arrived to breed. For both species, this period occurred before the sea ice reached its maximum extent and was slightly earlier for Adélie than for chinstrap penguins. These results suggest that sea ice conditions outside the breeding season may play an important role in penguin population processes.

Description: The fishery for Illex argentinus in the Southwest Atlantic is subject to large inter-annual variability in recruitment strength. In this paper we attempt to build a predictive model using sea surface temperature (SST) to examine links between recruitment to the Falkland Islands fishery and environmental variability during the juvenile and adult life history stages. SST data from the National Center for Atmospheric Research (NCAR) were found to be comparable with near-surface data derived from in situ expendable bathy-thermograph (XBT) profiles in the southern Patagonian shelf. Variation in SST during the early life stages appears to be important in determining recruitment of I. argentinus. SST in the hatching grounds of the northern Patagonian shelf during the period of hatching (particularly June and July) was negatively correlated with catches in the fishery in the following season. SST anomaly data from positions in the Pacific and Southwest Atlantic were used to examine teleconnections between these areas. Links were seen at a lag of 2 yr between the Pacific and southern Patagonian shelf, and at about 5 yr between the Pacific and northern Patagonian shelf. This is consistent with SST anomalies associated with El Niño in the Pacific propagating around the globe via the Antarctic Circumpolar Wave (ACW). Predicting cold events via teleconnections between SST anomalies in the Pacific and Atlantic would appear to have the potential to predict the recruitment strength of I. argentinus in the Southwest Atlantic.

Description: The use of United States Defense Meteorological Satellite Program Operational Linescan System (DMSP-OLS) data has enabled the precise location of the distribution of the global light-fishing fleet over a six month period in relation to the large and general mesoscale oceanography of the ecological provinces where they occur. The squid catch in these light fisheries can be identified to genera or species in seven ecological provinces where DMSP-OLS imagery reveals light-fishing activities. The DMSP-OLS data provide the information needed to review the relationship between the squid fisheries using lights and other fisheries for finfish with better spatial resolution than has been previously possible using data for FAO statistical areas alone. This chapter demonstrates that 62–70%, and possibly up to something 〈96, of the world squid catch can be accounted for in the light fisheries identified in the images. This provides the opportunity of being more specific about possible interactions between cephalopod fisheries and declining groundfish stocks and allows the hypothesis about the inverse relationship between the trends in these fisheries. The ability to visualize the spatial distribution of fishing fleets and their movements over time with DMSP-OLS data has implications for the assessment and management of the exploited squid stocks.

Description: Cephalopods play an important role in the diet of many predators of the Southern Ocean. We investigated the cephalopod component of the diet of the wandering albatross, during breeding at South Georgia, from 269 boluses containing more than 34,000 beaks (corresponding to 19,452 individual cephalopods), collected between 1989 and 1999, and assessed the inter-annual variability of the cephalopod species, the level of scavenging on cephalopods by wandering albatrosses and the relationships between cephalopod availability and wandering albatross breeding parameters (breeding period, breeding success, fledging period, fledging success, egg mass and chick mass). We also proposed possible foraging areas of wandering albatrosses based on the cephalopods eaten. The cephalopod component of the diet of wandering albatrosses was relatively stable over the 11 years of the study. By number of lower beaks, three species predominated in the cephalopod component of the diet: Kondakovia longimana (29.5% of the total number of lower beaks; family Onychoteuthidae), Taonius sp. (20.4%; family Cranchiidae) and Histioteuthis sp. B (19.5%; family Histioteuthidae). K. longimana was consistently the predominant cephalopod species by mass in every year of the study (range 60.2–88.7% of mass contribution to diet). A minimum estimate of 30% of the number of cephalopods scavenged corresponded to 85% of the total mass of the cephalopods that contributed to the diet. Wandering albatrosses fed consistently more on "Antarctic" cephalopods than on "sub-Antarctic" or "subtropical" cephalopods in all years of the study, suggesting that Antarctic waters are an important foraging area for wandering albatrosses. Although some significant correlations between cephalopod abundance and wandering albatross breeding parameters existed (e.g. correlation between Taonius sp. by number and fledging success), none included K. longimana. When comparing groups of variables (using canonical analysis), no correlations were found between the most important cephalopod species (by number and by mass), total mass of squid consumed, cephalopod diversity index (H) for each year, and wandering albatross breeding parameters. This may reflect the possibility that other components in the diet (e.g. fish and carrion) are more important or, more likely, that the consistency across years of the wandering albatross breeding performance indicates that it is well buffered against fluctuations in prey availability.