The Northwest Atlantic deep-sea red crab (Chaceon quinquedens) population before and after the onset of harvesting

Abstract

Abstract Wahle, R. A., Bergeron, C. E., Chute, A. S., Jacobson, L. D., and Chen, Y. 2008. The Northwest Atlantic deep-sea red crab (Chaceon quinquedens) population before and after the onset of harvesting. – ICES Journal of Marine Science, 65: 862–872. The population structure of deep-sea red crab (Chaceon quinquedens) in a nearly unexploited state is compared with its condition three decades later after more than a decade of sustained harvesting. Our study is based on a camera and net trawl survey conducted in 1974, which we repeated between 2003 and 2005 on the southern New England shelf break. Although the overall biomass of red crabs was estimated to be higher than in 1974, the abundance of large males, which are targeted by the fishery, was considerably lower. In particular, the biomass of large males (≥114 mm carapace width), considered in 1974 to be marketable, declined by 42%. Declines were most evident at depths and regions most accessible to the fishing fleet based in southern New England. With the change in fishery selectivity towards smaller male crabs, the abundance of currently harvestable crabs is about equal to 1974 levels. No declines were observed in the biomass of female and smaller male crabs not targeted by the fishery. Indeed, the abundance of juveniles appears considerably higher than in 1974. Perhaps, adverse effects on reproduction attributable to a reduction in the numbers of large males may be a consequence of fishing, but fishery impacts and productivity are difficult to assess because key biological information is lacking.