Title Length-based assessment for mackerel icefish (Champsocephalus gunnari) at South Georgia
Author Hillary, R.M.; Edwards, C.T.T.; Mitchell, R.E.; Agnew, D.J.
Author Affil Hillary, R.M., Imperial College London, Division of Biology, London, United Kingdom. Other: MRAG, Marine Resources and Fisheries Consultants, United Kingdom
Source CCAMLR Science, Vol.17, p.129-137. Publisher: Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), International. ISSN: 1023- 4063
Publication Date 2010
Notes In English GeoRef Acc. No: 309662
Index Terms Atlantic Ocean Islands--South Georgia; Southern Ocean; age determination; Atlantic Ocean Islands; biomass; Champsocephalus gunnari; Channichthyidae; Chordata; fisheries; models; Pisces; population dynamics; Scotia Sea Islands; size; South Atlantic Ocean; South Georgia; surveys; Vertebrata
Abstract Discusses CCAMLR mixture analysis program (CMIX) and generalized yield model (GYM) packages used by current CCAMLR assessment method, with particular reference to accurate identification of age cohorts from survey data. Describes length-based approach to cohort determination which uses bootstrap technique to estimate length distribution of population from survey data in conjunction with bootstrapped survey biomass data to yield estimate of population numbers-at-length. Comparison of this method and existing age-based CMIX/GYM methodology showed very good agreement in calculated yields for 2006, 2007 and 2009. Differences for 2008 were explained by unusual length distribution from which it was difficult to reliably estimate age composition in CMIX. Using 2009 survey data and new methodology, total allowable catch (TAC) was calculated according to CCAMLR decision rules of 1,577 and 933 tons for 2009-10 and 2010-11 fishing seasons respectively. Respective estimates using existing CMIX/GYM methodology were 1,590 and 968 tons respectively.
Publication Type journal article
Record ID 91394