Research Document - 2002/021

Updated estimates of exploitation rates and biomass for cod (Gadus morhua) in NAFO Divisions 3KL and Subdivision 3Ps during 1997-2000 from tagging experiments in these years

By Noel Cadigan and John Brattey

Abstract

We update the analyses in Cadigan and Brattey (2001a) using additional recaptures from tagging experiments conducted in NAFO Divisions 3K and 3L (3KL) and Subdivision 3Ps during 1997-2001. The additional recaptures we consider occurred up to April 1, 2001. The methods of analysis we use are identical to those in Cadigan and Brattey (2001a), with a few exceptions.

We estimate exploitable biomass for three regions in 3KL and 3Ps for weeks in which sufficient landings (>100 tonnes) were reported to get reasonable estimates. The average (over weeks) biomass estimated in the inshore of 3K was 8 500 tonnes in 1999, and 12 000 tonnes in 2000. The exploitation rates (landings divided by average biomass) in this region for 1999 and 2000 were 43% and 12%, respectively. In the northern part of 3L the average biomass and exploitation rates (in parentheses) were estimated to be 33 000 tonnes (10%) in 1999 and 39 000 tonnes (7%) in 2000, while in the southern part of 3L the estimates were 11 000 tonnes (16%) in 1999 and 9 000 tonnes (11%) in 2000. In 3Ps, the estimates for Placentia Bay were 36 000 tonnes (32%) in 1999 and 40 000 tonnes (24%) in 2000. For the area west of the Burin Peninsula and including Burgeo Bank, Hermitage Channel, and Northwestern St. Pierre Bank, the estimates were 67 000 tonnes (10%) in 1999 and 30 000 tonnes (19%) in 2000. In the remaining offshore areas of 3Ps, including the southern portion of St. Pierre Bank and the Halibut Channel, the estimates were 331 000 tonnes (1%) in 1999 and 464 000 tonnes (2%) in 2000. However, the high estimates are based on small numbers of tag-returns and a spatially restricted offshore fishery, and the estimates are not substantiated by other information.

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