Terms of Reference

Review of the Beginning of the Year Weight-at-Age of Cod Used in Calculating the Spawning Stock Biomass (SSB)

Quebec Region Science Workshop

October 15, 2010 - Mont-Joli, Qc

Chairperson: Martin Castonguay

Background

Assessments of cod stocks in the northern Gulf have always used the mean weights from the commercial fishery in the analyses. Considering this does not affect population abundance estimates by SPA (Sequential Population Analysis) which is based strictly on numbers, biomass estimates made at a later time will be overestimated, which will influence the perception of the stock and its productivity. The use of the mean weight-at-age from the commercial fishery generates an overestimation of the SSB because the commercial fishery selects the youngest ages of fish whose growth is fastest and which are not representative of the population at this age. To correct this situation, the DFO Science Branch has requested that various approaches to calculate the weight-at-age for use in the SPA be reviewed and that a recommendation be issued on the best approach to use.

Objectives

Review the various data sources and possible approaches for calculating beginning of the year weight at age for cod for use in the SPA:

• Mature biomass, risk analysis, projections, and reference points.

Products

A CSAS Research Document
CSAS Proceedings with a summary of discussions

Participants

DFO Science Branch