Escape ring selectivity, bycatch, and discard survivability in the New England fishery for deep-water red crab, Chaceon quinquedens

Abstract

The trap fishery for red crab, Chaceon quinquedens, occurs at depths of 600-800 m along the continental slope of New England. The target product is a male crab with a carapace width of ∼105 mm or greater. Selectivity was tested at two discrete depths (600 and 800 m), for four different escape ring scenarios: control trap with no escape rings, and escape rings with internal diameters of 9, 10, and 11 cm. Proportions of non-marketable C. quinquedens were large (71-100%) at both depths for all traps, but were smallest in traps with escape rings. Discard mortality was estimated at ∼5% through caging experiments across three haul frequency conditions (every 24 h, every 4 d, and after 8 d), which represented the likely reality of multiple recaptures during a commercial trip. The impact of discarding techniques (low and high impact) was also assessed. If discard proportion estimates of >71% are realistic, and if an estimated ∼5% of these discards die, the recommendation must be made for fishery participants to improve gear selectivity, and thereby to minimize discard mortality rates. On the management side, stock assessments will be more accurate if estimates of discard mortality are incorporated. © 2007 International Council for the Exploration of the Sea. Published by Oxford Journals. All rights reserved.