Research Document - 2000/106

The northern Gulf of St. Lawrence cod stock -background information on recruitment.

By M. Castonguay

Abstract

As part of a Workshop on cod recruitment, the FOC (Fisheries Oceanography Committee) reviewed recent trends in recruitment for all Canadian cod stocks to determine if poor recruitment could account for the slow recovery of stocks. Spawning stock biomass of northern Gulf of St. Lawrence cod (3Pn4RS) gradually declined to a minimum in 1994 and has slowly recovered since. Recruitment has been weak through the 1990s. There appears to be a fairly good stock/recruitment relationship in this stock. Recruitment rate (i.e., recruitment given the observed level of spawning stock biomass) has risen in the 1990s, which could indicate a compensatory response of the stock to low abundance levels. Hence the slow recovery of the stock cannot be accounted for by low recruitment given the observed level of spawning stock biomass. Total mortality of adult cod calculated from survey data has been around 0.5 from 1994 to 1997. Taking fishing mortality into account suggests that natural mortality has been between 0.3 and 0.4, which supports the current natural mortality value of 0.4 assumed for the stock in sequential population analysis. There has been a pronounced decline in size-at-age of cod in the late 1980s, early 1990s, indicative of a decline in surplus production.

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