The exploratory longline fishery for Dissostichus spp. has now been operating for 14 years in Subarea 88.1 and for nine years in Subarea 88.2. The research and assessment work in these areas on the distribution, abundance and demography of Antarctic toothfish (D. mawsoni) has led to an estimate of the fisheries potential yield. However, one source of ongoing uncertainty in the stock assessment concerns recruitment dynamics.
Pre-recruit Antarctic toothfish fish are caught in various locations during fishing operations. However, different vessels catch different length classes in different locations in different years, making it impossible to develop a consistent time series that would monitor trends in recruitment over time from the fishery. At its 2010 meeting, the Scientific Committee agreed that a time series of recruitments from a well designed longline survey could be a useful input into a stock assessment model and requested members develop a pre-recruit survey design (SC-CAMLR-XXIX, para. 3.185). This paper presents a proposal for a CCAMLR sponsored research survey in response to the Scientific Committee request.
We propose that the first survey be a pilot, with two main objectives:
(i) To establish the feasibility of developing a time series of longline surveys to monitor pre-recruit (<100 cm TL) toothfish in the south of SSRUs 881.J and 881.L in the southern Ross Sea using standardised gear in a standardised manner; and
(ii) To carry out experimental depth stratified fishing in 400–600 m depth adjacent to the survey boundaries to establish the most appropriate depth strata for future surveys.