CCAMLR

One indicator that has been proposed for use in a feedback management system for the krill fishery is an estimate of predator productivity attributable to consumption of harvested species. We illustrate some of the data and methods that could be used for measuring and evaluating this indicator and for designing a monitoring program for a feedback management system.

We analysed the available data from vessel and scientific observer logbooks from the exploratory fishery for Antarctic toothfish (Dissostichus mawsoni) and Patagonian toothfish (D. eleginoides) in CCAMLR subarea 48.6 (South East Atlantic). This report summarises the catch, effort, timing, depth, location, size structure and maturity of Dissostichus spp.  Information on the composition of  bycatch species caught in the fishery over the period 2003-4 to 2011-12 are also presented. For the Antarctic toothfish, accumulated catch across years yielded 1,353 tons with the majority of the catch coming from SSRUs 48.6G and 48.6E. For the Patagonian toothfish the accumulated catch was 349 tons and almost all was reported exclusively in the SSRUs 48.6A and 48.6G. Most of the catches were reported by vessels from Japan (58%) and Rep. of Korea (31%) and to a lesser extent, from South Africa (7%) and Norway (4%).

Unstandardized raw catch and effort data suggested that the median catch per unit of effort in Antarctic toothfish has generally increased over the course of the fishery whilst it has decreased over time for Patagonian toothfish. In both species average length of catches is larger in females. Antarctic toothfish is caught at deeper waters and have a larger mean length than Patagonian toothfish. There is not evidence of truncation in the overall length frequency distribution of both species, although some evidence of reduction in the mean fish length has been observed in the last three fishing seasons. In both sexes, high frequencies of maturity stages 2 and 3 were observed in Antarctic toothfish whereas for Patagonian toothfish immature (stage 1) fish were  most frequently observed. The bycatch for both toothfish species is composed of few species. In term of biomass, the most important bycatch species are grenadiers and blue antimora. A total of 3,828 individuals of toothfish have been tagged in this area but only 19 have been recaptured. We concluded that from the data examined from the fishery to date there is not evidence for substantial changes in the population structure of both species in this subarea.

Errors in the growth model used in stock assessments of Antarctic krill, specifically higher rates of growth than occur in reality, could inadvertantly lead to over-exploitation of the krill population and cause impacts on krill predators.  We review the three classes of models available for modelling krill growth – the von Bertalanffy class, the moult-cycle class based on measures of the duration of the intermoult period and the instantaneous growth rate at moult, and the energetics class, based on the energetics of growth.  We present a new model which is a combined energetics moult-cycle model that can flexibly take account of regional and interannual variation, including time trends, of temperature and food supply.  The parameterisation for the energetic-moult-cycle model provides results consistent with the general expectations for krill growth models as well as having the flexibility to be generally applied under spatially and temporally varying conditions.  In the context of assessments of precautionary yield for krill in CCAMLR, we recommend that this new model be incorporated into those assessments.  The current uncertainty in many of the parameter values could be included in the Monte Carlo population projections that are used to determine yield, particularly in relation to the future trends in food supply of krill.

We present a synopsis of the US AMLR satellite telemetry data, including both ARGOS and GPS positions estimates, to inform spatial planning efforts in the Antarctic Peninsula and Scotia Sea region. Identifying the patterns of habitat utilization by marine organisms is critical for proper spatial planning. Moreover, the timing and extent of habitat use by multiple species must be considered to correctly identify the location and overlap of critical habitat for multiple species.

The US AMLR program has collected satellite telemetry data from summer foraging trips and overwinter migratory routes of penguins and pinnipeds tagged at Cape Shirreff, Livingston Island and at Admiralty Bay, King George Island since 1997/98 for penguins and 2000/01 for pinnipeds. Species tracked include Adélie, chinstrap, and gentoo penguins, and Antarctic fur, Weddell, and leopard seals. The data from 14 years of tracking are presented to highlight patterns of local habitat use and long-range migration of these six species.

Krill consumption by natural predators represents a critical link between surveys and models of standing krill biomass and the design of a sustainable krill fishery for the Scotia Sea. Antarctic krill (Euphausia superba) is a significant component of diet for penguins breeding in this region and, consequently, uncertainties regarding penguin population abundances contribute to uncertainties in krill predation estimates. We use a comprehensive database of Antarctic penguin abundances to identify 14 breeding colonies that contribute most significantly to uncertainty regarding the total number of pygoscelid penguins breeding in this region. We find that a high quality survey of Zavodovski Island alone would decrease uncertainty in total population by 24.8%, whereas high quality surveys of all 14 “high-influence” locations would decrease uncertainty by almost 72%. Updated population estimates at these sites should be considered top priority for future field work in the region. Our results are based on a robust quantitative method for assessing data priorities in estimating krill consumption that is easily extended to other groups of krill predators.

Recent, rapid climate change is now well documented in the Antarctic, particularly in the Antarctic Peninsula region. One of the most evident signs of climate change has been ice shelf collapse; overall, 87% of the Peninsula’s glaciers have retreated in recent decades. Ice shelf collapse will lead to the loss of existing marine habitats and the creation of new habitats. In general, fauna under ice shelves exist in oligotrophic conditions, and because ice shelf collapse may lead to greater nutrient input, there may be consequent loss of some species or communities. Colonisation of new habitats after ice shelf collapse may simply include species from areas that are immediately adjacent to the collapsed ice shelf; however, other complex processes may also take place as warmer waters may create opportunities for species to return that were last present during the last interglacial, a warmer period than at present. In addition, altered ecosystem dynamics may allow new species to invade as ocean warming potentially removes physiological barriers that have previously led to the isolation of the Antarctic fauna. Habitats revealed by collapsed ice shelves offer unique scientific opportunities. Given the complexity of the possible interactions and the need to study these in the absence of any other human induced perturbation, we recommend that commercial fishing activities should not be permitted in these habitats. We suggest that in Subareas 48.1, 48.5 and 88.3, areas under existing ice shelves should be preserved for scientific study as Marine Protected Areas (MPAs). We recommend that the boundaries of these areas should henceforth remain fixed, even if the ice shelves recede or collapse in the future. Designation of areas under ice shelves as MPAs for scientific study would fulfil one of the recommendations made by the Antarctic Treaty Meeting of Experts in 2010.

Annually (from 1973 to 1991) 1-4 fishing vessels carried out research and scouting operations in the Indian sector of the Southern Ocean (statistical divisions 58.4.1 and 58.4.2) for the purposes of the searching of fishable aggregations of Antarctic krill (Euphausia superba). Commercial fishing for the Antarctic krill in the Indian sector of the Southern Ocean was carried out from 1977 to 1984. The main peculiarity of fishable aggregations in the Cooperation Sea as a rule out of shelf water (over the depths more than 1000 m).

This document analyses and relates long term information on population trends of inshore demersal fish and Antarctic shags of the South Shetland Islands. The analysis is complemented with comparable information on diet, foraging patterns and breeding output of shags from the Danco Coast, western Antarctic Peninsula, an area that has remained out of the influence of the commercial fishery. Instead of climate change processes, indicated as responsible for the diminution of other bird populations, the most reliable cause of the declining trend observed in shag colonies at the South Shetland Islands is the concomitant decrease in the abundance of two of their main preys, the nototheniids Notothenia rossii and Gobionotothen gibberifrons, owed to the intensive industrial fishing in the area in the late 1970s.