Research Document - 1999/161
An assessment of the cod stock in NAFO Subdivision 3Ps in October 1999.
By J. Brattey, N.G. Cadigan, G.R. Lilly, E.F. Murphy, P.A. Shelton, and D.E. Stansbury
Abstract
Two assessments of the cod stock in NAFO Subdiv. 3Ps were conducted in 1999. The first assessment was conducted in March. The second assessment, the results of which are documented here, was conducted during 18-22 October 1999, i.e. mid-way through the commercial fishing season. In this assessment it was assumed that the entire TAC allocated for 1999 would be taken as indicated in the management plan announced prior to the opening of the 1999 fishery. The current assessment incorporates new information from the most recent research vessel survey (April 1999) as well as sampling of a portion of the 1999 commercial fishery. Other sources of information included oceanographic data, sentinel surveys, science logbooks, and mark-recapture (tagging) experiments. A comparison of various methods of sequential population analysis (QLSPA, ADAPT, XSA, ICA) was undertaken using the commercial catch data together with Canadian winter and spring research vessel indices and an index derived from the sentinel gillnet catch rate index. The current population biomass is estimated to be 198,000 t, approximately 50,000 t lower than the estimate from the March 1999 assessment. This is primarily because the strengths of the 1993-1999 year classes have been revised downward due to low numbers of young fish in the April 1999 survey. Spawner biomass is currently estimated to be 147,000 t, approximately the same as the March 1999 assessment; however, spawner biomass is not being sustained by more recent recruitment and the present assessment predicts that the spawner biomass will decline in 1999 assuming the 30,000 t TAC is caught. It was estimated that TAC's above 25,000 t would have a risk of greater than 10% of exceeding F0.1 and that even at 15,000 t there was a greater than 10% risk of the spawner biomass declining.
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