CCAMLR

An observation on the interaction between marine mammal and krill midwater trawl was carried out onboard the Chinese krill fishing vessel Fu Rong Hai during the 2018/19 fishing season. The underwater and on sea surface observations were both deployed. Although large numbers of Antarctic fur seal Arctocephalus gazella were observed around the vessel during the vessel fishing in the Subarea 48.3, no identified marine mammal was observed in the main body of trawl net. There was no marine mammal by-catch observed either. The observation found the Antarctic fur seals would be attracted by the codend of krill trawl net, especially during the periods difficult to get foods. The observation also indirectly implied that well designed seal escaping devices might reduce the risk of accidently by-catch of Antarctic fur seals. Future researches on the interaction between marine mammals and krill fishing gears would be helpful to understand the relationships between krill fishing and krill predators.

We invite Members to collaborate with the U.S. AMLR Program to conduct a multi-national, empirical study of krill flux through the Bransfield Strait and across the continental shelf surrounding Astrolabe Island. We propose to conduct this study with 20+ acoustically instrumented moorings. Collaboration could include refining study design, deploying and recovering moorings, conducting separate acoustic surveys to estimate krill standing stock within the study area, and, ultimately, data analysis and synthesis.

The UK undertook a bottom trawl survey of CCAMLR sub-Area 48.3 on the FV Sil between the 27thth January and 5th February 2019. A total of 73 random and representative hauls were completed covering depths of between 108 and 352m. Overall biomass of mackerel icefish, Chamsocephalus gunnari, was calculated at 50,897 tonnes with a lower 1-sided 95% interval estimate of 30,288 tonnes. This is lower than in 2017, but is comparable with the long term average. The highest catches were on the moraine banks of the two northern strata and at the western end of Shag Rocks, with one high catch recorded in the South West stratum.

Clear regional differences in C. gunnari diet composition were observed. At Shag Rocks Euphausid spp. made the largest contribution to icefish diet, however the amphipod Themisto sp. dominated the diet around South Georgia. Based on the Index of Relative Importance, the importance of E. superba as a prey species varied across the four regions at South Georgia, ranging from 10.48% IRI in the South West to 33.49% IRI in the South East.

Catches of juvenile Dissostichus eleginoides were small and dominated by fish of 18-26cm (TL) indicating the presence of a cohort of age 1+ fish. Estimated biomass for the other icefish species, Pseudochaenichtys georgianus and Chaenocephalus aceratus, were higher than results obtained in 2017. The estimated biomass of Notothenia rossi was higher than observed in 2017 and is the second highest seen in the survey time series. The estimated biomass of Patogonotothen guntheri was also higher than observed in 2017, and was the third highest in the survey time series.

Reliable species identification and population assessments of skates are crucial for the sustainable management of their vulnerable stocks. However, species identification is a major challenge in skate studies due to convergent morphology within and between genera. In this study, we applied molecular tools to identify specimens of softnose skates (Bathyraja spp.) caught as bycatch from the longline fishery around South Georgia. Mitochondrial DNA Control Region sequence analyses highlighted a discrepancy between previous genetic studies of B. meridionalis and B. maccaini that challenged the identification of our putative B. meridionalis samples. Detailed analyses of Bathyraja data submitted in Genbank lead to the conclusion that our South Georgia samples were likely to be B. meridionalis but further mitochondrial markers are being sequenced to confirm species identity. Genetic diversity of these putative B. meridionalis was low and indicated a single population around South Georgia. We are currently developing faster-evolving microsatellite markers to more robustly assess genetic diversity and population structure in this species.

This update by SCAR on recent advances in our understanding of climate change across the Antarctica and the Southern Ocean, and the impacts on the terrestrial and marine biota and ecosystems, builds on the material included in the Antarctic Climate Change and the Environment (ACCE) report, published by SCAR in 2009 (Turner et al. 2009), with an update of the key points in 2013 (Turner et al. 2014).

At the request of the ATCM, SCAR agreed to provide regular updates on the original report (e.g. ATCM Resolution 4 (2010)). This activity is coordinated by the SCAR ACCE Expert Group (see http://www.scar.org/ssg/physical-sciences/acce), which provides annual updates to the ATCM.  The remit of the ACCE group is to keep abreast of recent advances in climate science, with a particular focus on Antarctic climate change and the environmental implications of such changes.

The original ACCE report and an overview of significant updates are available online as a wiki at http://acce.scar.org/wiki/Antarctic_Climate_Change_and_the_Environment. The online version is progressively updated by a number of editors with input from many active scientists.