CCAMLR

Depredation caused by killer whales and sperm whales on the Patagonian toothfish (Dissostichus eleginoides) fishery off Kerguelen and Crozet EZs are amongst the most important in the Southern Ocean. This paper presents the first results of depredation rates calculated on a yearly basis using the CPUE method.

Being able to correctly identify species is crucial in observer’s tasks and data quality implies very good knowledge from observers. Identification quality is related to observer’s training and resources provided by technical coordinators.

This document is updating the original tool described in WG-FSA-15/75, developed as  a “serious game” for observers to more easily learn species names before to go at sea or when steaming for example.

Preliminary results of a pop-up satellite tag (PSAT) on large Antarctic toothfish are described in this report. The toothfish was caught in the Mawson Sea in Feb 2015 and released with a PSAT by a Korean scientific observer. The same observer recovered the fish a year later. The days of liberty were over a year (366 days). The vertical movement of the fish shows strong and contrasting patterns. The most significant pattern was the fish staying at the same depth for a couple months. The vigorous diel vertical movement period followed after. It occurred during winter to early spring that it may be indicating the possibility of a spawning behavior.

We measured concentrations of 15 perfluorinated compounds (PFCs) in muscle tissues of Antarctic toothfish (n=113), and investigated accumulation patterns of PFCs in female and male muscles. The total PFCs (Σ₁₅PFCs) were ND (not detected) to 2.98 ng/g wet weight (ww) in muscle tissues with 0.32 ng/g ww of median concentration. The main compounds among PFCs were perfluoro-n-hexanoic acid and perfluoro-n-pentanoic acid. PFCs concentrations and compositions were significantly different between male and female. The levels of PFCs in the present study are comparable to those reported in 31 fish species from Korean coastal waters (0.27-4.81 ng/g ww). The concentrations of Perfluoro-1-octanesulfonate in the present study were much lower than environmental quality standard for biota (9.1 ng/g ww) by EU Water Framework Directive.

To identify the important prey items for pre-recruit Antarctic toothfish in the SSRUs 58.4.1.C, 58.4.1.G, 58.4.1.E, and 58.4.2.E, their stable carbon and nitrogen isotope ratios were determined. Sampling efforts were made during a longline survey of pre-recruit toothfish from commercial fishing vessel. In the previous studies, similarities in total FA compositions and the FA profiles in muscle tissue of Antarctic toothfish, bycatch specimen and icefish in the stomachs indicated a trophic connection between the toothfish and icefish. In this study, similarities in the δ13C values δ15N values of Antarctic toothfish indicate they occupy same trophic position irrespective of the area, body size, sex, and gonadal maturity. The combination of stable isotope ratios and fatty acid profiles can be effectively used to trace the trophic transfer from organic matter sources to higher trophic levels through food chains. Further studies on the trophic relationship between Antarctic toothfish and other animals by collection and subsequent biomarker analyses such as stable isotope analysis after lipid extraction, stomach contents analysis, and fatty acid analysis are needed to better understand the carbon flow through the Antarctic ecosystems.

This paper presents an update of the metrics of capacity and capacity utilisation presented in WG-SAM-14/19 and WG-FSA-15/09 in order to monitor trends in capacity in exploratory toothfish fisheries in Subareas 88.1 and 88.2. The updated metrics show the same pattern as the metrics based on the data up 2016 and do not indicate an excess capacity in the fishery. As indicated previously, based on a measure of potential daily fishing capacity and the catch limit for an area the notified fishing capacity in some management areas is in excess of the level that would allow the Secretariat to forecast and issue a timely closure notice using the current fishery forecasting procedure.

Data on fish bycatch in the krill from Commercial catch data (95 513 hauls) and CCAMLR SISO data (11875 hauls) was used to examine the frequency of occurrence, proportion by mass, length-frequency distribution and geographic provenance of the key fish taxa reported. There was a high degree of overlap in the most frequently reported taxa in the C1 data and SISO data, with Lepidonothen larseni and Chaenodraco wilsoni the most frequently reported in both datasets. The estimated total annual mass of fish by-catch in a 300 000 t krill fishery would be 370 t, comprising 40% Champsocephalus gunnari and 30% Lepidonotothen larseni. The length-frequency distribution of all taxa for which >100 fish were measured had modal size class of <10 cm. The fish species taken as by-catch in the krill fishery are the same species (and size classes) as those reported in the diet of ‘krill-dependent’ predators. There is evidence of both an increase in the data quality from the observer scheme, as reflected in the reduced confidence intervals around the frequency of occurrence data, as well as an increase in the fish by-catch reported in the commercial krill catch data. A systematic method for observers to record fish by-catch and increases in observer coverage in the krill fishery has provided an increase in the data available with which to examine the magnitude of fish by-catch in the krill fishery.

ASOC strongly supports the recommendation of WG-EMM-16 that Conservation Measure 51-07 should be retained while alternative strategies and feedback management (FBM) are under evaluation. Discussions at WG-EMM-16 provided further evidence that concentrating krill fishing operations in areas being used by land-based predators puts predators at risk from localized depletion. Consequently, ASOC expects CCAMLR to endorse the scientific advice from its working group. Although it has some weaknesses, CM 51-07 has minimized the risks of localized krill depletion and therefore should not be allowed to lapse. ASOC also urges SC-CAMLR and the Commission to develop additional means of preventing overlap between fishing locations and predator foraging areas to minimize the risk of fishery impacts on krill predators.

A project is proposed to provide CCAMLR with a detailed description of all species which are or have been subject to exploitation at one time in the Southern Ocean. It is envisaged that CCAMLR will benefit considerably from the project both in terms of its publicity and perception in the context of international organisations.  This paper provides a brief outline of the work proposed, work priorities, possible participation, length of the project and costs incurred.