CCAMLR

Ce rapport synthétise les observations faites en matière de pêche illicite du 15 juillet 2017 au 15 juillet 2018 concernant les sous-zones statistiques 58.6, 58.5.1, 58.5.2 incluant les zones sous juridiction françaises de Crozet et des Kerguelen. Il comprend également  des informations d’intérêt général sur les activités de pêche dans les sous-zones statistiques 58.4.3 et 58.4.4, eaux internationales comprenant les bancs Banzare, Elan, Lena et Ob.

Dans les ZEE françaises, où le dispositif de surveillance s’est maintenu sur toute la période, aucune observation d’activité de pêche INN n’a été constatée ou signalée, cependant du matériel de pêche non conforme a été trouvé.

The stock of Antarctic toothfish (D. mawsoni) in CCAMLR subarea 48.4 is estimated from tagging returns to be 982 tonnes in 2018. Applying the CCAMLR agreed precautionary assumption of average biomass across the time series and harvest rate of γ = 0.038, implies a 2018/19 yield of 37 tonnes, unchanged from the 2017/18 catch limit.

Historically, a precautionary approach has been applied in treating the 48.4 Antarctic toothfish as a separate stock. Based on the biological characteristics of the catches in Subarea 48.4, and the surrounding regions, the Antarctic toothfish around the southern South Sandwich Islands are now hypothesised as being part of a much larger stock that extends south into Subarea 48.2, 48.6 and possibly 48.5. The current method of assessment, based on tag returns, consequently, is considered to provide an estimate of the local biomass.

A first Marine Ecosystem Assessment for the Southern Ocean (MEASO) is under development. MEASO aims to provide a forward-looking assessment of what trends in Southern Ocean ecosystems are happening now and into the future, and what may need to be planned for, in terms of research and management. The aim is to have a quantitative assessment that enables managers to achieve consensus in adapting their management strategies to ecosystem change.  MEASO officially began at an international conference held in Hobart in early April 2018 (http://www.measo2018.aq/). The conference provided an opportunity to share relevant science, enhance community input into the design and planning of the MEASO, and to develop a work plan.  Since the conference, summaries of information available for a MEASO have been compiled in order to determine what can be used to assess status and trends within the Southern Ocean on regional and circumpolar scales. This review includes a record of field programmes and ecological surveys, current Southern Ocean syntheses, model coverage and assessments. The types of biological data collected from the field programmes are also being summarised, based on an open, international survey of researchers.  For this survey, an indication of where and when national research programmes have conducted field work were requested, particularly for measures of density (abundance) for different taxonomic and functional groups within the benthos, pelagos and plankton as well as birds and marine mammals. To date 12 countries have contributed to the data survey, coverage of which can be viewed on the Southern Ocean Knowledge and Information wiki: http://soki.aq/display/MEASO/MEASO+Data+Availability.  The work program for the first assessment is detailed in the paper.

The stocks of Antarctic toothfish, Dissostichus mawsoni were a relatively economically and ecologically important fishery resource in the waters of Antarctic. However, there is not enough data and information to assess the robust stocks and deliberate proper measurements for sustainable utilize, especially relate to diet and feeding strategy which may lead to think about ecosystem based stock assessments and fishery managements. Therefore, the Korean scientists analyze diet composition and feeding strategy of D. mawsoni in the research blocks 58 and 88 as a part of Korean research plan for the exploratory longline fishery for Dissostichus spp. during 2014/2018 season. This study was carried out based on the results of stomach content identification of the D. mawsoni caught in the research blocks 58 and 88 in CCAMLR Conversion Area during season (December-March) per year from 2014 to 2018. The diet composition and feeding strategy of D.  mawsoni were studied using 1,786 specimens and 1,062 in the research blocks 58 and 88, respectively. D. mawsoni is a carnivore and piscivorous fish that mainly consumed fishes. Its diet also included small quantities of mollusks, crustaceans, stones, anthozoans, echinoderms, eggs, birds, and mammals. In this study, fishes were the dominant prey item in all size classes (<100 cm, 100-120 cm, 120-140 cm, 140-160 cm, 160< cm). The graphical method for feeding strategy revealed that D. mawsoni is an opportunistic and specialized predator on fishes, and showed narrow niche width.

Data retrieved from five popup satellite-tagged Antarctic toothfish (Dissostichus mawsoni) released in the Mawson Sea were analyzed. Toothfish were at liberty for 36-366 days, and yielding yearlong, 15-second data records from a single, recaptured individual.  These fish occupied an overall depth range of 326 to 1824 m and a temperature range of -1.95 to 0.7°C.  Through available depth and temperature data, and albeit limited ability to accurately geolocate deep-diving toothfish, all tagged fish appeared to have remained in the Mawson Sea area for the majority of time at liberty. The recaptured individual exhibited distinctive vertical ascents only in September, during the presumed spawning season, and was estimated to be near shore in the Mawson Sea. These ascents could represent characteristic spawning behavior and suggested Mawson Sea is a potential spawning ground. Future investigation is warranted to observe similar ascents in other individuals, and be analyzed in the greater context of reproductive ecology of Antarctic toothfish. To this end, a tagging configuration is proposed to target logging of putative spawning behavior, and is recommended to put forward to the greater CCAMLR community as standard protocol for popup satellite tagging studies

To highlight ontogenetic and geographical variability in resource utilization of Antarctic toothfish, we investigated neutral fatty acid (NFA) profiles and stable isotopes (SIs) in muscles of toothfish and their potential prey (bycatch and stomach contents), captured in fisheries in the Small Scale Research Units (SSRUs) 88.3 (the Pacific Ocean sector, POS) in austral summer during 2016–2018, making comparisons with previous dataset obtained from the Ross Sea shelf (RSS) and the Indian Ocean sector of the Antarctica during 2012–2017. We found significant differences in size distributions of regional toothfish stocks, demonstrating an ontogenetic movement into deeper water from shelf water. The relative proportions of NFAs of the IOS and POS stocks were similar to each other but differed from those of the shelf (RSS) counterpart. Although not great, isotopic differences between the shelf and slope stocks were detectable in both δ13C and δ15N values. The NFA and SI profiles show a pattern of differences between regional stocks. The NFA profiles of the RSS stock displays a considerable overlap between adults and subadults but also shows a size effect. The IOS and POS stocks showed quite large trophic overlaps, but shared very limited or no space with RSS. Adults and subadults of the RSS had overlapped trophic spaces. Sampling region, depths, and toothfish length serve as strong descriptors for most trophic markers in toothfish, emphasizing both ontogenetic and geographical variability. Finally, the regional variation in trophic niche is explained by different patterns in resource utilization, which are partitioned into two prey groups (i.e. feeding on bathypelagic vs. bathydemersal organisms), between regions and toothfish size, reflecting diet shift during ontogenetic migration across the geographic range of Antarctic waters as confirmed by the combined mixing-model calculations of both trophic markers.

Important catches of sea pens (Pennatulacea, NTW) in the 58.4.4b sector (Lena bank) have been reported during the CCAMLR SAM Working Group 2018 (see WG-SAM-18/31 "Annual report of research fishing operations at Division 58.4.4b in 2016/17 fishing season" by Japanese and French delegations).

Detail of French catches, with abundances and weights are provided here (Tab.1). Data and specimens have been collected according to the French protocol for benthic invertebrate survey, which includes the exhaustive collection of the organisms caught by the longlines (see WG-EMM-17/09). This report does not include the latest data collected.

Marine debris data were collected at Bird Island and King Edward Point, South Georgia, at Signy Island, South Orkneys and at Goudier Island, Antarctic Peninsula for the period April 2017 to March 2018. Surveys of beached marine debris at Bird Island recorded a total of 371 items during austral winter (April to September 2017) and 111 items during summer (October 2017 to March 2018). Thirteen items of beached debris were recorded at Signy Island (operational during summer only; 6 November 2017 to 31 March 2018). Twenty-seven items of beached marine debris were recorded at Goudier Island (operational 16 November 2017 to 6 March 2018). Entanglements of seven Antarctic fur seals were observed at Bird Island and two at King Edward Point with no marine mammal entanglements recorded at Signy Island or Goudier Island. In total, 70 items of marine debris were found in association with seabird colonies at Bird Island, most commonly in association with wandering albatrosses (36 items; 51 %). One incidence of an entangled wandering albatross was reported; a bird with a white cable tie around its leg - this was removed successfully. There were no observed incidences of hydrocarbon soiling at any site during the reporting period. Overall, the occurrence of beached marine debris was above the long-term mean at both Bird Island and Goudier Island but below the mean at Signy Island. The incidence of marine mammal entanglements was below the long-term mean at all sites surveyed. Debris associated with seabird colonies was above the mean level for black-browed albatrosses, but below the mean for wandering albatrosses, grey-headed albatrosses and giant petrels.