Science Advisory Report 2008/045

Assessment of Georges Bank Scallops (Placopecten magellanicus)

Summary

• The 2007 total allowable catch (TAC) was 4000 t for Zone ‘a’ and 400 t for Zone ‘b’. Total reported landings were 4000 t for Zone ‘a’ and 401 t for Zone ‘b’.
• The offshore scallop fleet fished primarily fresh scallop products until 2002, when freezer trawlers were incorporated into the fleet. In the first year of fishing the freezer trawlers landed nearly 12 % of the TAC. In 2007, the freezer trawlers landed 68% (2739 t) of the catches from Zone ‘a’, 57% (1571 t) of these landings came from within the voluntary closure area. The freezer trawlers also landed 55% (220 t) of the catches from Zone ‘b’.
• Commercial catch rates of the wetfish fleet reached historically high levels during 2000 to 2002, declined to near average levels between 2003 and 2006, and in 2007 are the third highest in the series. Freezer trawler catch rates increased dramatically between 2006 and 2007 and are at the highest level since these vessels began fishing in 2002.
• Discards of yellowtail flounder decreased sharply from 565 t in 2006 to 105 t in 2007, while discards of cod increased from 87 t in 2005 to 124 t in 2007. Discards of haddock declined from 67 t in 2006 to 61 t in 2007. Total fishing effort during this period peaked at 36,992 hours in 2006 and declined by more than half to 16,614 hours in 2007.
• Survey catch rates in Zone ‘a’ for pre-recruits, recruits, and commercial size scallops peaked between 1998 and 2001. All three indices were at or above their respective long-term median values in 2007.
• The 2008 interim TAC is 5000 t and a final TAC between 5500 and 6500 t could be supported based on evidence from the survey and commercial catch data showing a recent steady increase in the stock and above average incoming recruitment.
• A potential lack of proportionality between the commercial catch rate index and stock biomass, arising from changes in fishing practices, along with a lack of recent ageing data are important sources of uncertainty in this assessment. The cohort analysis used in previous assessments of this stock was deemed inadequate due to a poor fit to the data in recent years and to projections that were not consistent with our understanding of the resource.

Complete document (PDF, 418 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.