Distribution and demography of snow crab (Chionoecetes opilio) males on the Newfoundland and Labrador Shelf

Distribution and demography of snow crab (Chionoecetes opilio) males on the Newfoundland and Labrador Shelf

E.G. Dawe and E.B. Colbourne

Distribution and demography of snow crab (Chionoecetes opilio) males on the Newfoundland and Labrador ShelfThis is part of Crabs in Cold Water Regions: Biology, Management, and Economics
PDF    
To download the free PDF [700.8 KB], please enter:
-or-

Description

The distribution of snow crab (Chionoecetes opilio [Fabricius, 1788]) males on the Newfoundland and southern Labrador continental shelf is described based on 1995-2000 fall multispecies bottom trawl surveys. Snow crabs were broadly distributed from the southern Labrador Shelf to the Northern Grand Bank and extended farther south along the eastern slope of the continental shelf to the tail of the Grand Bank. Mean size of males was related to depth, with maximum mean size at greatest depths and minimum mean size at about 200 m. The largest and smallest males were segregated by both bottom depth and temperature. This size segregation was more pronounced in the northern portion of the survey area than on the northern Grand Bank and it may be related to spatial variation in bathymetry and thermal habitat. Annual size composition was characterized by consistent low catch rates of intermediate sized males and failure of modal groups of small crabs to progress through the size spectrum over time, suggesting an effect of variation in trawl efficiency. Annual trends in abundance indices were similar for all sizes, further suggesting an annual effect that was likely related to variation in catchability or efficiency of the survey trawl. Possible sources of variation in efficiency oft he survey trawl in sampling snow crab are discussed and the implications of this variation in interpreting survey results are considered.

Item details