CCAMLR

This document summarises the items addressed in the Fifth Session of the United Nations Environment Assembly of the United Nations Environment Programme, which was held online on February 2021, with an agenda that focused on administrative and budgetary matters. As agreed, sessions will resume in-person in February 2022 to focus on core items on the agenda.

Marine mammal depredation on fisheries is a worldwide issue involving socio-economic and ecological consequences. The bottom longline fisheries directed to toothfish are among them, where Sperm and Killer whales star the depredation events. The SAGO Extreme System is an innovative technology developed to prevent this interaction. Based on the Autoline System and with the addition of the SAGO Extreme device and other accessories, this system implies mayor changes in the vessel and gear. On this paper the system, setting and hauling maneuvers implemented on the Uruguayan FV Ocean Azul are described. The performance of the Sago Extreme System is discussed and an intrinsic mitigation measure for preventing seabird incidental catch is presented. Marine mammal depredation on fisheries is a worldwide issue involving socio-economic and ecological consequences. The bottom longline fisheries directed to toothfish are among them, where Sperm and Killer whales star the depredation events. The SAGO Extreme System is an innovative technology developed to prevent this interaction. Based on the Autoline System and with the addition of the SAGO Extreme device and other accessories, this system implies mayor changes in the vessel and gear. On this paper the system, setting and hauling maneuvers implemented on the Uruguayan FV Ocean Azul are described. The performance of the Sago Extreme System is discussed and an intrinsic mitigation measure for preventing seabird incidental catch is presented.

The Gradual contraction of Antarctic krill fishery toward islands or concentration in some localized area has caused increased concerns. To examine the potential impact of the concentration of krill fishery, acoustic data and fishery statistics were analyzed to reveal the relationship between the actual fishing sites and the underlying krill distribution; sea ice concentration is also used to explain the movement of the krill fishery into the Bransfield Strait. The analyses demonstrated again that the krill distribution is highly patchy and dynamic; and that the contraction or concentration of the krill fishery were most likely to be a natural response of the fishery to the characteristics of Antarctic krill distribution as knowledge accumulates, and to the suitability of emerging fishing ground as sea ice concentration decreases. The analyses also showed that the krill fishery will only concentrated in areas in which there was ample krill resources, and the potential impact of the concentration of krill fishery need to be assessed against the highly patchy and dynamic nature of krill distribution, not merely by its presence. The results of the analyses further implied that when progressing the Risk Assessment Framework for allocating the Precautionary Catch Limit into smaller management units, the spatial size of the candidate management unit need to be large enough to accommodate the highly patchy and dynamic nature of krill distribution to avoid the potential to create inadvertent risks to the local krill stock or predators depending on it.

Otolith shape analysis has been often widely used for stock discrimination. Controversial results are concluded on geographical stocks between the Crozet Islands and the Kerguelen Islands, East Antarctic. In this study, six otolith shape indices (form factor, roundness, circularity, rectangularity, ellipticity, and aspect ratio) and elliptical Fourier coefficients were used to analyze the otoliths shape of Patagonian toothfish Dissostichus eleginoides (TOP) from those two regions to try to supplement the information about the stocks. Prior to analysis, the allometric effect of fish growth on the otolith morphology was examined. The principal component analysis (PCA) was used for analyzing the shape indices (SIs), the Ellipse Fourier coefficients (EFCs), and the combination of SIs and EFCs, and the success rate of classification is 51.00 %, 74.00 %, and 80.00 % for those three treatments, respectively. The overall otolith shapes of D. eleginoides from the Kerguelen Islands and the Crozet Islands are similar, although fine differences occur in the outer contours of otolith. Combined with the tagging and genetic data, the present study concluded that stock connectivity occurs for TOP between the Crozet Islands and the Kerguelen Islands. Multiple approaches, including otolith chemistry, may help elucidate the proportion and mechanism of exchange between two regions.

The otolith morphology of fish species varies ontogenetically. In this study, 120 otoliths collected from the Ross Sea, the Amundsen Sea, the Weddell Sea, and the Lazarev Sea were used to analyze the morphological differences in otolith of Antarctic toothfish (Dissostichus mawsoni, TOA) across life stages by conventional measurement analysis, elliptical Fourier analysis and landmark method. The results showed that there were differences ontogenetically in otolith morphology. The shape of otolith changes from smooth and low complexity to intricate and high complexity, and the growth rate of otolith along the longitudinal axis is lower than that along the transverse axis. The characteristic parts, such as antirostrum, change significantly across life stages. Linear discriminant analysis showed the highest correct rate of classification is 85.417% from elliptical Fourier analysis, and followed by 79.167% from landmark method and 71.875% from geometric morphometrics, respectively.

In order to achieve the milestone “1.5 Update CASAL model” (SC-CAMLR-37 Report, Annex12), the CASAL models for Dissostichus eleginoides at Division 58.4.4b were revised.

We updated CASAL model with data up to 2019/20 fishing season. In this report, the base model (M1 model) is derived from the M4 model of previous report (SC-CAMLR-39/BG/51). We estimated the harvest rate (CAY and MAY) as defined in CASAL manual using each CASAL runs.

A single-sex age structured CASAL model using 5 cm bin for length distribution (M2 model) was built to assess the stock of constructed for D. eleginoides of the research block 1 of Division 58.4.4b. We updated data weighting values with latest data. Similar to the CASAL results reported previously (WG-FSA-2019/62, SC-CAMLR-39/BG/51), the MPD profile look good under both scenarios. It is noted that he MPD estimate values of B0 (M1: 870.54 tonnes, M2: 751.90 tonnes) are smaller than previously estimated in SC-CAMLR-39/BG/51 (ranging from 854 to 940 tonnes).

In both scenarios, estimated MCYs for D. eleginoides are higher than current catch limit 18 tonnes in block 1 at Division 58.4.4b. Harvest rates to achieve CCAMLR management target (50% B0), FCAY, were estimated to be close to 7%, which is higher than current precautionary harvest rate for explanatory fisheries where there is no estimate of B0.

This paper represents the final report of the multi-member longline survey on Patagonian toothfish (Dissostichus eleginoides) at Division 58.4.4b between 2016/17 and 2020/21 fishing seasons by Japan and France. The C2 and Observer data sets were provided by the CCAMLR Secretariat on July the 12th, 2021. In 2020/21 fishing season, both Japanese and French vessel could not conduct survey at Division 58.4.4b due to operational restrictions by COVID-19. This report mainly summarizes fishing activity and collected data. Although progress and achievements of each objective are reported, it is noted that there are ongoing studies that will be presented later in separate documents for future meetings.