Research Document - 2005/028

An assessment of the 2004 snow crab populations resident on the Scotian Shelf (CFAs 20 to 24)

By Choi, J.S., B.M. Zisserson, and A.R. Reeves

Abstract

Fisheries exploitation has been at all-time highs for the past 4 years, at TACs of approximately 10,000 t/year. Landings (9,629 t) nearly met these TACs (9,657 t) in 2004 with 1,417, 7,914 and 298 t landed in the northern, southern and slope areas, respectively. The catch rates for all of the shelf was 93.1 kg/th derived from approximately 100,200 trap hauls. Catch rates in the northern crab fishing areas (CFAs) were at their lowest levels in the past five years (60.6 kg/th), with the exception of CFA 22 Outer (Glace Bay Hole) which exhibited catch rates of 165.0 kg/th. Catch rates in the southern crab fishing areas (CFAs 23 & 24), increased slightly since the year 2000 (103.0 kg/th). The southern fishing areas continued to expand (spatially) in 2004.

The abundance of snow crab on the Scotian Shelf declined in 2004, continuing the downward trend observed since the peak abundances of the late 1990s and early 2000s. Fishable biomass estimates as of the winter of 2005 stands at approximately 29,000 t, which comprised of 1,600 t in the northern CFAs and 27,700 t in the southern CFAs. Other indicators of the status of the stock were also indicative of a continued decline and disequilibrium: sex ratios were dominated by males with extremely few mature females resident on the system for more than 4 years running, aging of the population with limited signs of rejuvenation, and rapidly increasing exploitation rates (presently, 32 % by biomass). A strong note of caution is advised in the management of the Scotian Shelf snow crab fishery: there are very few signs of recruitment for another 3 to 5 years and therefore greater uncertainty in it’s long-to mid-term sustainability.

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