CCAMLR

Most things related to Dissostichus spp. in the eastern side of Antarctic has not been known well as namely the area is data poor areas. In the Division 58.4.1 there are two stocks; one extends from the SSRU 58.4.1C to the SSRU 58.4.2A, and the other one to the SSRU 58.4.1H. The population sizes would be vulnerable like the neighbour divisions if there is the same population. During the 2004-2014 fishing seasons in Subarea 48.6, 3,589 Dissostichus spp. were tagged and released, but only 4 fishes among them have been recaptured which were not enough data to estimate stock biomass for considering the precautionary catch limit. Therefore, the catch limits that the meeting got in 2013 meetings increased to get more recapture. The food-web of Dissostichus spp. has started to be studied in the southern Ross Sea and 58.4.1. Some studies on biology of the fish have been evaluated, but those are not enough to assess the stocks and consider proper management measures. Based on CCAMLR’s fishery report, the eastern area is still data-poor area showing low recapture rate. Consequently, providing catch and effort data from the area, analysing biological samples, and collecting recapture data focusing on SSRUs in Subarea 48.6 is very important.

Therefore, Korea notifies the participation in exploratory fishery for Dissostichus spp. in the SSRUs in Subarea 48.6 from 2014/2015 season to 2018/2019 using Korean commercial bottom longline vessel, KINGSTAR belonged to Sunwoo Company in accordance with paragraph of CM 24-01 and paragraph 6 (iii) of CM 21-02 to collect the catch and effort, CTD, tagged and released, recaptured data including archival tag, biological data for estimating biomass for Dissostichus spp. using CASAL and evaluating migration and distribution pattern by developmental maturity and size stages.
 

An updated and revised assessment of the Patagonian toothfish (Dissostichus eleginoides) stocks in Kerguelen and Crozet areas is presented. This study is based on a CASAL (C++ Algorithmic Stock Assessment Laboratory) model. Different statistical and biological datasets are used: catches, tag releases/recaptures data, commercial catch-at-length data and data from the recent POKER survey (2013). Preliminary results show stable estimates of biomass and SSB never fall below 60% of the initial biomass considering the actual level of catches (5100t in Kerguelen and 700t in Crozet).
 

We addressed the revisions requested by the WG-SAM-14 regarding the results of the second year of Spanish research experience and ongoing research plan presented in WG-SAM- 14/12 and WG-SAM-14/09. 

A summary of the results of the Spanish research that took place in the 58.4.1 division during the last two fishing seasons is presented.   

A prospective estimation of the local biomass (B_LOC) of three SSRUs visited using the local depletion method, together with the extrapolation to the total Biomass in the entire SSRUs, as well as an estimation of the Biomass in SSRU 58.4.1H using the mark-recapture Petersen model is made.

Current CCAMLR maturity stages for skates (Rajiformes) use a three-stage key. As such, important elements of the reproductive cycle may go unrecorded, including females in the process of egg-laying. Additionally, the current description of females at stage 2 (maturing) in the CCAMLR observer manual could lead to some confusion between fish at stage 2 and stage 3 (mature). Suggestions for updating the descriptions of the maturity stages for skates are provided, as is a rationale for considering a four-stage key that allows for the collection of data for fish that are at active stages of the reproductive cycle.

This paper presents an updated assessment for Patagonian toothfish (Dissostichus eleginoides) at the Heard and the McDonald Islands (Division 58.5.2) with data until mid August 2014. This paper presents a bridging analysis and proposes a new base case assessment model which is based on the best available estimates of model parameters, the use of abundance estimates from a random stratified trawl survey (RSTS), an estimated survey catchability coefficient q, and auxiliary commercial composition data to aid with the estimation of year class strength and selectivity functions of sub-fisheries.

Compared to the 2013 assessment, this assessment takes into account the recommendations of WG-FSA-2013, SC-CAMLR-2013 and WG-SAM-2014, and incorporates (a) new fishery observations up to 2014 including new ageing data from the 2012, 2013 and 2014 random stratified trawl surveys (RSTS) and commercial ageing data from 2013, (b) a Beverton-Holt stock-recruitment relationship, (c) a simplified model structure, (d) an updated ageing error matrix, (e) an updated growth model, and (f) a prior for the survey catchability q which has been estimated from the ratio of survey fish abundance using the swept area method and the proportion of tag-recaptures in survey catch on the main trawl ground. All model runs were conducted with the CASAL version that was agreed on by WG-SAM-14. These changes substantially improved the internal consistency and stability of the assessment model.

The new base case assessment model indicates that the virgin spawning stock biomass (SSB₀) is higher than that estimated in 2013, with an MCMC estimate of 136 714 tonnes (95% CI: 96 982-186 401 tonnes). Estimated SSB status in 2014 was 0.72 (95% CI: 0.63-0.81), and survey q was estimated at 0.32 (95% CI: 0.23-0.47). Using this model, a catch limit of 6110 tonnes satisfies the CCAMLR decision rules. The projected stock remains above the target level for the entire projection period.

Current CCAMLR maturity stages for skates (Rajiformes) use a three-stage key. As such, important elements of the reproductive cycle may go unrecorded, including females in the process of egg-laying. Additionally, the current description of females at stage 2 (maturing) in the CCAMLR observer manual could lead to some confusion between fish at stage 2 and stage 3 (mature). Suggestions for updating the descriptions of the maturity stages for skates are provided, as is a rationale for considering a four-stage key that allows for the collection of data for fish that are at active stages of the reproductive cycle.

Although steepness is typically considered a convenient re-parametrization of a stock-recruitment relationship, it is deeply rooted in the biology of each species.  Furthermore, specifying steepness and other life-history parameters such as natural mortality and growth rates fixes reference points that are commonly used in fisheries management.  Thus, one cannot pick an arbitrary value of steepness in a stock assessment.  We take the first step towards a consistent treatment of steepness for Antarctic toothfish by showing how to compute a frequency distribution of steepness based on life-history parameters.  We also highlight what the next steps should be – both theoretical and empirical – for improving estimates of steepness and their use in stock assessments.

The draft CCAMLR compliance report has recorded that when fishing in Subarea 88.2 in 2013/14 the vessel Argos Georgia achieved a tag overlap statistic of 52% rather than the required minimum of 60% as specified in CM 41-01. A review of the data indicates that the number of fish tagged was above the rate per tonne required by CM 41-10, but due to sampling noise the distribution of the length of fish tagged did not match closely with that of the catch resulting in a the overlap statistic, as required by CM 41-01. The overall length range of the two data sets was similar indicating that this was not a case of only small fish being tagged. The low tag overlap statistic is shown to be a sampling artefact and not a compliance issue. WG-FSA 2014 and CCAMLR SC 2014 should consider and discuss cases such as this and others if they have arisen, to determine how to provide advice to the Commission in cases where the noise associated with such low numbers of fish triggers false positives in the tag statistic. It is considered that such events will become more frequent as capacity increases in the Olympic exploratory fisheries and small catches with a consequent low total tag number increase in frequency.

We provide a perspective on steepness, reference points for fishery management, and stock assessment. We first review published data and give new results showing that key reference points are fixed when steepness and other life history parameters are fixed in stock assessments using a Beverton–Holt stock–recruitment relationship. We use both production and age-structured models to explore these patterns. For the production model, we derive explicit relationships for steepness and life history parameters and then for steepness and major reference points. For the age-structured model, we are required to generally use numerical computation, and so we provide an example that complements the analytical results of the production model. We discuss what it means to set steepness equal to 1 and how to construct a prior for steepness. Ways out of the difficult situation raised by fixing steepness and life history parameters include not fixing them, using a more complicated stock–recruitment relationship, and being more explicit about the information content of the data and what that means for policy makers. We discuss the strengths and limitations of each approach.

For several years, ASOC has been calling for improved management of Antarctic krill fisheries. In this paper, ASOC urges CCAMLR to continue to work towards requiring 100% scientific observer coverage on board krill vessels, identifying priority objectives for research and development in support of the management of the krill fishery, conducting a new krill synoptic survey, keeping the trigger level as the enforceable catch limit, improving monitoring through a strengthened CEMP program, continuing efforts towards estimating green weight and krill escape mortality, reviewing krill notifications procedures with the aim of reducing speculative notifications, and requiring mandatory ice-strengthening for krill fishing vessels.