Research Document 1998/08

Assessment of cod in the southern Gulf of St. Lawrence, January 1998

By A.F. Sinclair, G.A. Chouinard, and L. Currie

Abstract

The southern Gulf of St. Lawrence cod stock was in a state of rapid decline in abundance and biomass in the early 1990s, and this decline was halted by the closure of the commercial fishery in September 1993. Since then, population biomass has remained low, close to the lowest seen since 1950. Recruitment has been well below the historical average and there is no sign of improvement. While there is a significant standing stock, its rate of production is very low due mainly to the paucity of recruitment. Post moratorium estimates of total mortality from research survey results indicate that the natural mortality rate of this stock is in the range of 0.4 - 0.5, more than twice that traditionally assumed. Goodness of fit tests of an SPA calibration and changes in size at age indicate that M may have increased in the mid-1980s. Catch projections based on population estimates assuming the traditional value of natural mortality (0.2) indicate that the spawning stock biomass may increase by about 5% if there is no catch in 1998. However, if natural mortality is as high as the survey results suggest, the stock may decline even if there is no catch in 1998. Improved recruitment is essential for this stock to recover. At present there is no evidence to suggest that this is happening. Given that recruitment estimates are available for age 2 cod, that they recruit to the fishable population at age 5, and that it will take a few good year-classes to fuel a recovery, the indications are that commercial stock abundance (age 5+) will not recover for several years.

Complete document (PDF, 3021 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.