CCAMLR

During the Antarctic krill fishing in the area off the North-Western slope of the South Orkney Islands shelf were caught 5000 kg of Champsocephalus gunnari.
 

This article reviews the adequacy of data and models currently being used to estimate the present and future population sizes of the Antarctic toothfish (Dissostichus mawsoni Norman) in the Ross Sea regional ecosystem. It argues that the current tagging program is unlikely to provide an accurate picture of total population size, and that estimates of both the pre-exploitation spawning stock biomass and the ratio of current to pre-exploitation biomass are unreliable. Many parameters necessary for estimating future population growth or decline have not been measured, and the current objective of a 50% reduction in biomass relative to unexploited biomass may easily fail to prevent a much larger reduction from taking place. The need to guess values of important parameters makes it impossible to set bounds on the potential errors of population forecasts. Current scientific knowledge is far from what is needed to predict the likely effects of food web responses to harvesting of toothfish in the Ross Sea, or to predict the feedback effects of those food web changes on toothfish populations.

In the fishing season 2012/2013 Russian vessel “Yantar-35” worked in the Weddell Sea for the first time since fishery of Dissostichus mawsoni began. It has allowed extending a sampling area on biology of this species. In particular, size-age and growth samples of the Antarctic toothfish were collected in this sea.

According to the stock assessment survey, as well as using CPUE data collected by Russian and South Korean vessels in three Antarctic sectors in 2003-2010, it has been shown that fishery of the Antarctic toothfish is commercially viable not only for countries which are close to the fishing areas. The assessment study was conducted by several researchers using various models designed for the Pacific and Indian sectors of the Antarctic. According to lack of data on the Antarctic toothfish from “zero” SSRUs, it follows that current TAC values are underestimated in all studied areas. Correct estimation of toothfish stock and TAC values in all high-latitude Antarctic seas is necessary.

From data available we suggest that factual stock values of the Antarctic toothfish are considerably underestimated in the Pacific (the Ross Sea) and the Indian sectors (the Dumont d'Urville Sea (SSRU G), the Mawson Sea (SSRU E), the Davis Sea (SSRU C)) resulting in restrictive policy of the Antarctic toothfish fishery.

The Scientific Committee (SC -XXXI, par. 9.30)  focused on distribution pattern of toothfish in SSRU 88.2 A and adjacent SSRUs 88.1 K and L, and discussed a need to carry out background investigations considering insufficient information on this area, and how catch limits used in the Ross Sea can be applied for this SSRU.

Investigations conducted by Russian scientists in SSRU 88.2A in 2010-2012 showed that this unit should be open for shared environmental management. We propose agreement on SSRU 88.2A opened within the scope of the Conservation Measure 41-10.

In 2011 and 2012 in Subarea 88.3 research fishing for toothfish has been conducted by Russia. In 2011 fishing was carried out by Russian longliner “Sparta” out and in 2012 it was longliner “Chio Maru 3”. Totally, during the work period 44 longlines were set at a depth from 625 to 2336 m. Collected in research fishing data contributes to the achievement of the main objectives of research for the data-poor area: estimate of number index, evaluation of fishing capacity of Subarea 88.3, preparation of hypotheses about the ratio of fish in the area and the total stock as well as studying of biological parameters associated with productivity (SC-CCAMLR-XXX/5, par. 2.26-2.29). Toothfish`s biomass was calculated by the accepted in SC-CCAMLR-XXX/5 p.2.40 (ii) formula. Value of toothfish`s stock by SSRUs and all details of stock assessment methods are described in the present work.

Research program in data-poor Subarea 48.5 (Weddell Sea) have been carried out for the first time. New commercial and biological data on the target (Dissostichus mawsoni Norman, 1937) and by-catch species have been collected. Toothfish tagging program have been executed. Distribution of Antarctic toothfish and by-catch species by depth ranges has been investigated. Data on CPUE and commercial density have been collected. Calculation of stock assessment has been done by areal method that is recommended by CCAMLR (SC-CCAMLR-XXX/5 п. 2.40 (ii)). Calculated stock of toothfish in Subarea 48.5 equal 428 thousand tons.