Some methods used by observers to record by-catch data in the longline toothfish fishery are discussed. Proposals on implementation of a uniform process reporting accurate by-catch data in the CCAMLR Convention Area are shown.

Closed mostly within the Weddell Sea Subarea 48.5 is one of the closed data-poor CCAMLR subareas, where stock assessment should be carried out. In spite of hard ice conditions at most part of the Sea during mostly all the year, this large water area is very similar to the Ross Sea. This similarity could be found in geographical location, bathymetric profile, currents system and follows from results of the first and the second stage of this program. It highlights the Weddell Sea as one of the most promising area for exploratory fishery of Dissostichus sp. However, fishery in Subarea 48.5 is closed on the basis data on stock assessment absence. The main objective of the present program is collecting data for reliable stock assessment and following estimation of precautionary limits in accordance with CCAMLR decision rules. The program contains schedule and research program of the third stage of the Russian multi-year research program in the Weddell Sea that is prospected for 3-5 years. Detailed plan of fishing operations, data collecting and analysis will be provided for the Scientific Committee and Commission consideration.

Russian Federation is going to continue investigation for toothfish in Ross Sea in fishing seasons 2016-2019. The present program aims to recapture tagged fishes released during the implementation of the previous research program took place in 2010-2012 fishing seasons and investigate resource potential and life cycle of Dissostichus species within the eastern part of the Ross Sea over shelf and continental slope within the Subarea 88.2 A.

This document proposes multinational research in Subarea 88.2 A by  Russian vessel and vessels from another CCAMLR country-members participating  the proposed survey together.

At the 2015 meetings of WG-FSA and the Scientific Committee, the UK, New Zealand and Norway noted that they would perform an analysis of CPUE variability, haul duration and haul speed from the 2015 survey of the northern region of SSRUs 88.2A–B, including a comparison with all exploratory fisheries and closed areas. The analysis showed that overall, the CPUE rates observed in the survey were within the range of that observed in other exploratory fisheries and similar to those typically observed in the north area of Subarea 88.1, the nearest comparable area. Hauling speeds (number of hooks hauled per hour) during the survey were generally lower than those observed elsewhere and showed a decreasing trend with increasing CPUE. This is consistent with the time required to land and process sets with a larger number of fish per 1000 hooks, especially in seamount habitats where the fish are large and during research surveys that have increased tagging rates. The distributions of CPUE observed, haul duration, and haul speed during the survey were within the range observed for other comparable areas, and most importantly, showed the same pattern of both high and low catch rates, along with a pattern of lower hauling rates for lines when high CPUE areas were encountered.

We propose the continuation of a multi-member research project using standardised longline gear to sample the toothfish populations in the northern areas (61°‑ 66° S) of SSRUs 88.2A–B. The purpose of the research as requested by the Scientific Committee (SC-CAMLR XXXII, paragraph 3.76) is to characterise the local toothfish populations found there to better understand stock structure, movement patterns and improve estimation of population characteristics by Ross Sea spatial population models. Four of the eleven research blocks were sampled in 2015. Additional outcomes of the research relate to mapping the bathymetry of fishable areas, documenting relative abundance of Patagonian and Antarctic toothfish, tagging toothfish for biomass estimation and for stock linkage studies, and collecting information on distribution, relative abundance, and life history of bycatch species.

At its 2011 meeting, the Scientific Committee agreed that a time series of relative abundance from a well-designed survey could be a useful input into the Ross Sea stock assessment model. The first four surveys were completed in February 2012, 2013, 2014, and 2015. In this paper we provide results of the fifth survey in the time series. The objectives of this survey were: (1) to continue a time series of longline surveys to monitor sub-adult (≤ 110 cm TL) toothfish in the south of SSRUs 881.J and 881.L in the southern Ross Sea (Strata A–C) using standardised gear in a standardised manner; and (2) to monitor trends in larger (large sub-adult and adult) toothfish abundance in two areas (both situated in SSRU 881.M) of importance to predators: McMurdo Sound in 2016 and Terra Nova Bay in 2017.

The 2016 survey was successful in completing all of the planned stations and objectives. Standardised catch rates of sub-adult (<110 cm) toothfish for the core strata showed an increase to the highest point observed in the time series. Age frequency data from the surveys have shown the progression of a cohort from age seven in 2012 to age nine in 2014 and to age ten for females in 2015. In 2016, the survey length frequency distributions indicate than another stronger year class has entered the population with a mode at 75 cm, and that the older year class has 100 cm. The decline in the catch rates from 2012–2015 was correlated with the decline in the abundance of the older cohort over time through mortality and the movement of older fish out of the core survey area, as well as the relatively weaker subsequent year classes. The increase in 2016 is also reflective of the introduction of a new, stronger year class into the population. These results suggest that the surveys are indexing local abundance and are providing a method for monitoring recruitment and estimating recruitment variability. We notify here that the survey will be conducted in 2016-17 as endorsed by the Commission.

Understanding the spatial distribution of the release of tagged fish and the subsequent spatial coverage of fishing effort to recapture tagged fish is an important consideration when interpreting the biomass estimated from mark recapture data. In 2015, the Scientific Committee identified that measures of spatial overlap and potential bias in the development of tag-based biomass estimates are an important focus topic for WG-SAM (SC-CAMLR-XXXIV, 2015, para 3.83). This paper outlines developments towards new biomass-weighted spatial overlap summary statistics for tagging data. The method calculates two statistics: (i) a single measure of the degree of spatial overlap between the release of tagged fish and subsequent fishing effort for tag recovery, labelled the tag spatial overlap (TSO) statistic and (ii) a measure of the potential bias in the biomass estimate calculated from non-homogenous spatial mark-recapture data, labelled the tag spatial bias (TSB) statistic.

We apply the method to a single case study area, SSRUs 88.2H to illustrate its use. We found that the median tag spatial overlap statistic in 2012 was 70% (95% CIs 53–80%), and the median tag overlap bias was 88% (95% CIs 64–114%). In 2014 the median tag spatial overlap statistic 60% (95% CIs 50-69%), and the median tag overlap bias was 192% (95% CIs 141-268%).

The TSO statistic and TSB statistic provide a simple; and intuitive approach to indexing the degree of spatial overlap and potential bias from mark recapture data, with few assumptions required on the distribution of fish, movement, or catch history. Potential uses of these statistics could include a measure of the total spatial distribution of effort through time in research or developing fisheries, and a measure of the change in bias of mark-recapture estimates through time.

This paper evaluates present regulation of cabled net monitoring instrumentation and suggests an adjustment in the CCAMLR requirements that enable the industry and researches onboard the krill vessel to collect more and better monitoring and research data.

This paper evaluates present reporting procedures for the continuous fishing method and proposes a change in the CCAMLR requirements that produces more robust and correct catch statistics.