CCAMLR

Following Operation Sparrow 2, WG-FSA-17 noted the unprecedented availability of catch data from four IUU vessels including reported removals, video footage, and catch in gillnets recovered by an NGO vessel. As requested in WG-FSA-17 paragraph 2.16, this document provides an analysis of the spatio-temporal distributions of catch and effort by the Chang Bai, Nihewan and Jiangfeng in Division 58.4.1 during the 2013/14 season, as well as the Thunder in Division 58.4.3b during the 2014/15 season. During the 2013/14 season the Chang Bai, Nihewan and Jiangfeng operated across SSRUs 58.4.1C, 58.4.1D and 58.4.1E and caught a total of 792 tonnes of toothfish. Daily catch rates were similar between IUU and authorised vessels. Based on data from 2013/14, total removals by IUU vessels fishing with gillnets were higher than authorised vessels fishing with longlines, and the presence of an authorised vessel in the region of IUU activity did not appear to deter the IUU fleet. Hence there have been substantial and unaccounted for IUU removals, which may have impacted on research activities in Division 58.4.1.

Exploratory fishing for toothfish (Dissostichus mawsoni) in East Antarctica (Divisions 58.4.1 and 58.4.2) began in 2003. Robust stock assessments and catch limits according to CCAMLR decision rules remain to be determined for these Divisions. WG-FSA-16/29 outlined the first multi-member toothfish exploratory fishery research plan up to 2017/18 for East Antarctica, which the Scientific Committee agreed was appropriate to achieve the research objectives (SC-CAMLR-XXXV, para. 3.244). Subsequent research progress including evaluation of standard approaches to identify precautionary catch limits (WG-FSA-17 para. 4.28-4.38) and bycatch mitigation (Maschette et al. 2017), suggests a low risk profile for this fishery. Furthermore, examination of bycatch data and underwater video footage have not led to the identification of vulnerable marine ecosystem (VME) indicator species (Maschette et al. 2017). Here, we present a succeeding research proposal with updated research objectives for 2018/19 to 2021/22, in accordance with Annex 24-01/A, Format 2. This succeeding plan has been designed as a 4-year plan, based on the low risk profile of this fishery and to allow more time for review by Working Groups of major reporting and review years in non-stock-assessment years. Based on the outcomes of the approach to review the locations of research blocks presented in WG-SAM-18/17, research blocks will be retained in their current locations.

CCAMLR-XXXIV (para. 5.68) endorsed new pre-season (1–14 April) and post-season (15–30 November) trial season extensions, in addition to an existing pre-season (15–30 April) and trial post-season (1–14 November) extension in the Patagonian toothfish longline fishery in Statistical Division 58.5.2 (WG-FSA-15/48).

Australia undertook to report annually on the results of all the trials. This paper presents information on fishing effort and seabird interactions with fishing gear collected during the periods 1–14 November 2017, 15–30 November 2017, 1–14 April 2018 and 15–30 April 2018. This report complements the fishing effort and interaction data reported in 2015 (WG-FSA-15/48), 2016 (WG-FSA-16/28 Rev. 1), and 2017 (WG-FSA-17/20).

The annual random stratified trawl survey was undertaken in Division 58.5.2 in the vicinity of Heard Island and McDonald Islands during April 2018. This paper provides an updated growth model and a preliminary assessment for mackerel icefish (Champsocephalus gunnari) population structure, abundance and yield in Division 58.5.2 to the west of 79^o 20’ E using standard CCAMLR methods (CMIX and Generalized Yield Model).

The 2018 survey showed a large 2+ cohort in the population. Catches of 443 t in the 2018/19 season and 320 t in the 2019/20 season respectively satisfied the CCAMLR decision rules.

The annual random stratified trawl survey (RSTS) of 2018 around Heard Island and McDonald Island (HIMI) in Division 58.5.2 took place from the end of March to the end of April, with the completion of 163 stations plus eight extra fine mesh hauls. The survey was conducted on the FV Atlas Cove. Sampling protocols such as the design and the duration of the hauls were similar to recent surveys, but with a new set of randomly selected station points.

The catch of Dissostichus eleginoides (Patagonian toothfish) was twice that of 2017 while the catch of Champsocephalus gunnari (mackerel icefish) was two thirds of the 2017 survey catches. The catches of the other managed bycatch species, Channichthys rhinoceratus (unicorn icefish), Lepidonotothen squamifrons (grey rockcod) and Macrourus spp. (macrourids combined) were also two to three times greater than those of last year. Catches of skates were similar to those of 2017. Invertebrate catch (including jellyfish) in the 2018 survey was 1.5 times the low value of 2017.

The calculated biomass for 2018 of the target species D. eleginoides and C. gunnari in the survey area were close to the highest estimates for the past 10 years. For the managed by-catch species C. rhinoceratus and Macrourus spp. the biomass estimate was similarly high. Conversely, the estimate for L. squamifrons has been low for the past 4 years. The 2018 biomass estimates for each of the three Bathyraja spp. (skates) were the highest in the last 10 years.

Length measurements and sex were taken for nearly 22 000 fish and for more than half of those biological measurements were also recorded. Otoliths were collected from 656 D. eleginoides and 609 individuals were tagged and released.

During the 2017/18 season the Spanish F/V Tronio fished in Statistical Subarea 88.1 and Division 58.4.1 where the latter area required a tag rate of five fish per ton greenweight caught and also where the overall size of the fish exceeds 115cm. The tagging station on the FV Tronio is on the upper deck above the hauling station providing easy access to retrieve smaller fish directly from the hauling station and to operate the cradle over the side for landing larger fish. To optimise the use of the cradle a series of modifications were trialed to optimize the handling of the cradle, achieve rapid retrieval to minimize hauling downtime, minimize handling and time out of the water of the fish and use the cradle to release the fish. The modification achieved most of these objectives, with room for some further suggested alteration to further improve the system.

In the present study a comparative morphometric analysis of sagittal otoliths was performed in three Channichthyids (Pseudochaenichthys georgianus, Chaenocephalus aceratus and Chaenocephalus gunnari) collected during a research survey carried out between January 23 and February 13, 2016, along the continental shelf and slope around Elephant Island (Subarea 48.1) and the South Orkney Islands (Subarea 48.2). Morphometric analysis was addressed using Basic size descriptors (BSD; area & perimeter), shape indices (SI; circularity, squareness and roundness) and elliptical Fourier Descriptors (EFD) on 2D binarized images of left and right otoliths for fish ranging from 20 to 67 cm TL. To test for significant differences between the left and right sagittae in BSDs, a univariate and multivariate ANOVA and MANOVA were used, with BDSs as dependent variables and otolith type as fixed factor. ANOVA and MANOVA showed all standardized BSDs did not varied significantly between right and left sagittae (P>0.05). All EFDs derived from the 20 harmonics analyzed were homoscedastic and normal, and showed very low level of correlation among them. Hence, all coefficients were used in MANOVA and LFDA. MANOVA showed significant differences in the contour between both otolith pairs for each species (p<0.001). Similarly, EFS coefficients showed a high discriminatory power to distinguish the left and right otoliths, with a total percentage of correct classification of 76, 96, and 89% for P. georgeanus, C. gunnari and C. aceratus. A link between the extreme environmental conditions of Antarctic waters and the occurrence of the unusual high asymmetry in the otolith contour is proposed for Channichthyids and its implications are discussed.

In the present study we provide new insights on the spatial distribution and population structure of juvenile D. mawsoni caught during bottom trawl survey on the shelves around the South Shetland Islands (CCAMLR Subarea 48.1). Fish samples were collected during five summer cruises conducted from 2001 to 2007. Juveniles were relatively evenly distributed on the shelves around Elephant Island and northern lower South Shetland Islands. Although they were caught in all depth strata, they were most abundant between 100 and 300 m depth. The sampled population was composed of 150 specimens measuring between 22 and 78 cm TL, equally distributed between sexes, most of them with gonads at immature stage of maturity. Both males and females showed a positive allometric body growth, suggesting a good condition factor. Based on counts of annual growth increments from sagittal otolith sections, age estimates ranged between 2 and 7 years in males and between 2 and 8 years in females, respectively. Annual growth rate was estimated from the age-length keys, spanning from 10 to 5 cm TL. Present data have been discussed in comparison with the biological traits of adults reported elsewhere.

A research plan for this subarea was commenced by Korea in 2016 and a revised collaborative proposal was submitted to WG-FSA-17 by Korea and New Zealand. This joint research proposal was for an additional 3 years covering the period 2018, 2019 and 2020. It was designed to build on Korea’s previous research by continuing to focus on those research blocks where tagged fish have previously been released on the slope, whilst also prospecting two of the northern seamount complexes and two boxes on the southern shelf, where little or no fishing has occurred. The main objective of the proposal is to determine the abundance of Antarctic toothfish in Subarea 88.3. Secondary objectives are to improve understanding of stock structure of toothfish in this area, to carry out calibration trials between the two vessels, to collect data on the spatial and depth distributions of bycatch species, and to trial electronic monitoring using video cameras. This paper updates the proposal with an amendment to include a catch redistribution mechanism and to incorporate a milestone table as recommended by WG-SAM-18.

This paper proposes to continue the Ross Sea shelf toothfish survey for the next five years, 2018–2022. The first objective of the survey is to monitor toothfish recruitment in the southern Ross Sea (core strata). This is a continuation of the yearly time series of research surveys of these strata carried out since 2012. It is important to continue the time series as the data collected provide essential input to the stock assessment to estimate year class strength which is used to inform management decisions. The second objective is to monitor trends in larger (large sub-adult and adult) toothfish abundance in alternate years in McMurdo Sound and Terra Nova Bay where toothfish may form an important part of the diet of Type C killer whales and Weddell seals. The third objective is to collect and analyse a wide range of data and samples from these areas (e.g. benthic invertebrates, stomach and tissue samples, and acoustic data). Both objectives two and three are specified as high priority research topics in the research and monitoring plan for the Ross Sea region MPA. The survey design will remain consistent with previous years. Different catch limits are requested on alternate year to account for the different catch rates in McMurdo Sound and Terra Nova Bay. The results of each survey and trends in the time series will be presented to WG-FSA for review each year and the results included in the stock assessment. A full review will be completed and presented to WG-SAM, WG-EMM, and WG-FSA in 2022. This revised proposal incorporates the milestone tracking table recommended by WG-SAM-18.