Research Document - 2006/007

Preliminary Results from the September 2005 Bottom-trawl Survey of the Southern Gulf of St. Lawrence

By Hurlbut, T., G.A. Poirier, G.A. Chouinard, D.P. Swain, R. Morin, C. LeBlanc, H.P. Benoît, and L. Currie

Abstract

Each September since 1971, a standardized research vessel bottom-trawl survey has been conducted in the southern Gulf of St. Lawrence (NAFO Division 4T). The primary objective of this survey is to obtain abundance indices for the major groundfish resources in the area. In preparation for the transition from the CCGS Alfred Needler (used for the survey from 1992 to 2002) to the CCGS Teleost in 2006, a comparative fishing experiment was conducted in 2004 and 2005 to calculate the relative fishing efficiency of these two vessels. In so doing, conversion factors were derived to allow catches by the Teleost to be compared with the historical time series of abundance indices. This report presents the preliminary results of the 2005 survey conducted from September 6 to 28. In 2005, the abundance index for southern Gulf of St. Lawrence cod was at the lowest level observed in the time-series suggesting that the abundance remains very low compared to the late seventies and eighties. The abundance of American plaice also continues to be near the lowest level observed in the history of this survey. The index of abundance for white hake in 2005 was below the long-term average and equivalent to the level observed in 1995 when the moratorium was imposed on this resource. The abundance index for witch flounder remained above the long-term average in 2005 and the abundance of yellowtail and winter flounder has remained largely unchanged relative to previous years. Bottom temperatures warmed in 2005 relative to 2004. The area covered by waters below 1°C also decreased relative to 2004, and remained below the high values seen during the 1989-1998 cold period.

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