Research Document - 2012/067

Preliminary Results from the September 2010 and 2011 Bottom-trawl Survey of the Southern Gulf of St. Lawrence

By L. Savoie, R. Morin, T. Surette, H.P. Benoît, and C. LeBlanc

Abstract

Each autumn 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 demersal fish resources in the area. This report presents the preliminary results of the surveys conducted from 7–29 September 2010 and from September 12 to October 2 2011. In 2010 and 2011, the abundance and biomass indices for southern Gulf of St. Lawrence cod were at record-low levels, and indicate that the abundance and biomass of this stock continue to be very low compared to the levels observed in the late 1970s and during the 1980s. Indices from the survey of 2010 and 2011 suggest that the abundance and biomass of white hake remain extremely low compared to the indices observed in the late 1980s and early 1990s. The southern Gulf American plaice stock has declined to its lowest level in the 2000s with the abundance index at record low in 2002. The biomass index reached its lowest point in the 2009 survey. Recent fluctuations in survey indices have occurred for this species. The 2010 and 2011 survey registered an increase in abundance and biomass since 2002. In 2010, the abundance index for witch flounder was near the long-term average whereas the biomass index was about one-half of the long-term average. For 2011, the abundance index was over the long-term average and the biomass index was closer to the long-term average. The survey index for winter flounder abundance has fluctuated in recent years at the level of the long term average; however, since 2006 the biomass index has been well below the long-term average. The abundance of yellowtail flounders in 2010 remains comparable to the global average since 1985 but is lower for 2011. The abundance surrounding the Magdalen Islands (strata 428 and 434 to 436) has increased in the past four years but the biomass in 4T and in the area around the Magdalen Islands has decreased in recent years. Bottom temperatures were coldest over the central Magdalen Shallows and increased shoreward as depth decreased and along the Laurentian Channel as depth increased. No sub-zero bottom temperatures were recorded throughout the survey area in 2010 and 2011 and the area covered by waters colder than 1°C decreased to the lowest level observed since 1988.

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