Research Document - 2000/121

Status of the Newfoundland and Labrador Snow Crab Resource in 1999

By E. Dawe, H.J. Drew, P.C. Beck, and P.J. Veitch

Abstract

Data on catch rate, size (carapace width, CW) and molt status (chela allometry) from various sources were used to infer resource status of Newfoundland and Labrador snow crab (Chionecetes opilio). Data from 1995-99 fall bottom trawl surveys throughout Div. 2GHJ3KLMNO were particularly useful. These surveys are conducted near the end of the fishing season and so are considered to provide an index of residual biomass. Legal-sized males were broadly distributed throughout much of the survey area but were absent from Div. 2GH and 3M, some inshore areas, and across much of the shallow southern Grand Bank. The exploitatable biomass available to the Div. 2J3KLNO fishery in 2000 was projected to be about half that of the previous year due to substantial decreases in both recruitment and the residual biomass. A regular decline in abundance of smallest males since 1996 implies that recruitment will continue to decline for several years. Biomass of mature females has declined since 1995 in Div. 2J3KLNO. September inshore Div. 3K surveys showed that intermediate-sized males (about 40-75 mm) predominated in both small-meshed trap and Campelen trawl catches and were particularly abundant in the shallowest strata. Trap survey catch rates of such intermediate-sized crabs in White Bay increased regularly during 1995-98 but declined in 1999, possibly reflecting density-dependent and size-related changes in distribution patterns in recent years. Incidence of bitter crab disease (BCD) in the September trap survey has increased in legal-sized males since 1996 but also increased in smallest males in 1999. Spatial BCD trends from fall Div. 2J3KLNO bottom trawl surveys suggest a northward shift of highest prevalence during 1997-99. BCD may be under-represented in research samples and could represent an important source of mortality to small crabs of both sexes. Biomass estimates from 1996-99 spring Div. 3Ps bottom trawl surveys were unrealistically low, highly variable, and unreliable.

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