Research Document - 2015/085

Indices of abundance to 2014 for six groundfish species based on the September research vessel and August sentinel vessel bottom-trawl surveys in the southern Gulf of St. Lawrence

By L. Savoie

Abstract

Each autumn since 1971 and each August since 2003, a standardized research vessel bottom-trawl survey (RV survey) and a sentinel bottom-trawl survey (SM survey) have been conducted in the southern Gulf of St. Lawrence (NAFO Division 4T). The primary objective of those surveys is to obtain abundance indices for the major demersal fish resources in the area. The biomass indices for southern Gulf cod, in 2011 and 2012 were at the lowest levels observed in the 44-year survey record, indicating 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. The biomass index for 2014 increased to near the value observed in 2009. The SM survey showed a decreasing trend from 2003 to 2014. Indices from both surveys 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 abundance and biomass indices of American plaice reached their highest levels in the late 1970s. The stock has since declined and has reached its lowest level in recent years. In 2014, the overall biomass index for American plaice remained near the lowest levels observed in both surveys. The abundance and biomass from both surveys indices for witch flounder have been relatively stable since 2007. In 2014, the abundance and biomass indices were near the long-term average. The survey index for winter flounder abundance has been below the long term average in recent years and the biomass index has been generally declining since the late 1980s. The abundance index of yellowtail flounder in 2014 from the RV survey remained comparable to the long-term average. In contrast, the biomass index has declined since the mid-1990s. The biomass index for yellowtail from the SM survey decreased over the 2003-2014 time series, with the value in 2014 the lowest on record. The abundance and biomass indices of small yellowtail flounder (< 25 cm) for the areas surrounding the Magdalen Islands (strata 428 and 434 to 436) remained high in 2014 whereas large (≥25 cm) yellowtail flounder abundance indices remained low.

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