Research Document - 2003/088

Assessment of Greenland Halibut (Reinhardtius hippoglossoides) in the Gulf of St. Lawrence (4RST) in 2002

By Morin, B. and Bernier, B.

Abstract

The 2002 landings increased by 25% compared to 2001 levels, primarily because Newfoundland fishermen exceeded their allocation by around 100 T and because significant catches (275 T) were made during an experimental fishery in Quebec. Yet again, the total allowable catch (TAC) was not reached, despite a 1,000 tons reduction. The catch rates of gillnet fishermen rose in 2002, mainly in the Esquiman Channel. Landings consisted of females for the most part. As mean catch size has decreased since 1998, the number of Greenland halibut per landed ton grew of 30% between 1998 and 2002. A comparative fishing experiment conducted in Quebec in 2002 using 5.5-inch and 6-inch mesh showed a high proportion of females in landings (greater than 80%) with either mesh size. Mean catch sizes for the 5.5-inch and 6.0-inch mesh were 43 cm and 45 cm, respectively, while the proportions of immature females in landings made with 5.5-inch and 6-inch mesh were 62% and 42%, respectively. However, catch per unit effort (CPUE) was at least three times higher when using 5.5-inch mesh. Biomass indices from surveys increased between 1995 and 2000, but were down in 2001 and 2002. However, the 2002 DFO survey index was still higher than the 1990s index average. It should be noted that the DFO survey index was boosted by the large year-classes of 1997 and 1999. Survey indices show that abundance of fish of 44 cm and more (fish available to the fishery) has been declining since 1999. The individual growth rate of the large 1997 year- lass was lower than that of the previous year-classes in the western Gulf, which means that it will take longer for the 1997 year-class to reach the commercial size. The lower growth rate was less marked in the Esquiman Channel, which explains why fishing was better there in 2002. However, in 2002, the feeding, condition and growth rate of juvenile Greenland halibut improved, and size at sexual maturity increased for males. Although the abundance of pre-recruits (1997 and 1999 yearclasses) is high, it is difficult to predict how successful the fishery will be in 2003 considering the weaker growth rate of the 1997 year-class.

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