CCAMLR

We present initial findings from a multi-site, multi-species ecological study of pygoscelis penguins in the Bransfield Strait through the austral summer 2018-2019. Using high resolution GPS movement data in conjunction with C1 Catch and Effort data for the Antarctic krill fishery, we identify the home range distribution of chinstrap, gentoo and Adélie penguins at Baily Head (Deception Island), Harmony Point (Nelson Island) and Kopaitic Islands and estimate the amount of direct competition with the fishery over time. We further integrate information on humpback whale (Megaptera novaeangliae) abundance and distribution in the Bransfield Strait collected during the 2019-2020 summer in the same area, to provide an estimate of the potential competitive implications that recovering whale populations may have on constrained, breeding pygoscelid penguins. During the period in which these data were collected, there was no competitive overlap with the fishery during the brood-crèche phase, only 107 tonnes of krill caught during incubation within the foraging ranges of all three species, and a total of ~10,000 tonnes of krill fished in areas occupied by chinstrap penguins during brood-crèche over the preceding thirty years. We summarise the amount of krill fishing conducted during the penguin breeding season at the Subarea 48.1 scale, which has never exceeded 35% of the trigger level and most seasons were under 10%. We also highlight that in the past 10 years the fishery has begun to increase fishing efforts throughout March, resulting in increased spatiotemporal segregation with breeding pygoscelid penguins. Population abundance of chinstrap penguins at Deception and Nelson Islands have declined precipitously over the preceding three decades, and while the marginal levels of direct competition with the fishery cannot be ruled out, it is prudent to actively consider other mechanisms that are contributing to the decline of this species throughout the western Antarctic Peninsula. The movement data of penguins from the three colonies (when considered alongside other species that are not constrained by offspring provisioning) also suggests a structuring of foraging habitat within the Bransfield Strait, that may be linked to hydrographic variability driven by larger scale climactic processes such as the Amundsen Sea Low and its interactions with the El Niño Southern Oscillation and the Southern Annular Mode. As our data represent foraging behaviour of breeding penguins from three sites across the Bransfield Strait which are under no direct competitive pressure from the Antarctic krill fishery, they are amenable for use when comparing similar data to be collected off the western coastline of the South Orkney Islands over the coming two years.

Based on the direction of WG-ASAM during 2021, an e-group was established to develop a method to provide estimates of krill biomass for use in the GRYM and for development of a management strategy for krill. Krill biomass densities at a variety of spatial scales are presented for consideration by WG-EMM in 2021. The mean biomass density ranges from a low of 45.54 gm m^-2 for the time series averaged over the time since adoption of CM5107 to a high of 64.34 gm m^-2 when the time series is averaged over just the last 3 yrs of sampling. Importantly embedded within this time series is a low frequency quasi-decadal variability with several periods when krill biomass density is much lower than the longterm mean of ~52 gm m^-2.

A collaborative research program has been undertaken by Japan and South Africa since 2013 to enhance data collection and analysis in the subarea 48.6 under CM 21-02. Spain joined the proposal starting from 2018/19 fishing season in order to contribute to the data acquisition and to speed up the integrated assessments of the Antarctic toothfish (Dissostichus mawsoni) stock in this subarea (WG-FSA-18/34).

The continuation of the three-member research proposal for 2021/22 season is presented to ensure continuity of previous research activities. Data and investigations about the population structure and various demographic parameters of D. mawsoni using trotline (JPN and ZAF) and Spanish longline (ESP) gears, established tagging techniques, pop-up tags and genetic analysis will provide the basis for the development of spatial population models and assessments in support of management advice. An Integrated Stock Assessment (ISA) which takes into account the tag time series from southern research areas of Subarea 48.6 D. mawsoni is going to be continually developed until the end of the 2023/24 season.

The updated CCAMLR Research Plan – Research Proponent Self-Assessment can be found in Appendix 1.

To aid the development of a simple first step management approach for the Antarctic krill in Subarea 48.1, the suitable spatial scale for biomass estimate, the choice of recruitment index for the GrYM model and some considerations for the risk assessment are discussed.  

Parasitological study was conducted onboard the Ukrainian trawler “MORE SODRUZHESTVA”, which fished Antarctic krill during the cruise from the end of December 2020 till the end of March 2021. All fish specimens collected and examined were infected with helminths of five taxonomic groups (Nematoda, Cestoda, Trematoda, Acanthocephala or Monogeneans). Two groups of helminths dominated in the helminth communities – nematodes (consists from 28 to 61% of the total parasite number) and cestodes (from 15 to 22%); trematodes and acanthocephalans accounted for 3 to 8% of the total number of helminths found in different species of fish.

Cetacean observations were conducted onboard the Ukrainian trawler “MORE SODRUZHESTVA”, which fished Antarctic krill and was used as a platform of opportunistic research during the cruise from December 2020 till March 2021. During the Australian summer the fishing grounds were in the CCAMLR Statistical Area 48.2 (South Orkney Islands). Visual observations of marine mammals were conducted.