Damage sustained by epibenthic invertebrates discarded in the Nephrops fishery of the Clyde Sea area, Scotland

The Clyde Sea Nephrops fishery produces ca. 25 000 t y(-1) discards with in vertebrates accounting for up to 90% of the number of animals discarded. Tr awling and handling of the (by-)catch often results in physical injury, the extent of which was previously unknown. Damage sustained by invertebrate d iscards was assessed following commercial trawling (of 62-270 min duration) and sorting on deck. Brittlestars Ophiura ophiura were most vulnerable wit h 100% incurring damage, followed by squat lobsters Munida rugosa (57%) and starfish Astropecten irregularis (56%). Harder-shelled species such as her mit crabs Pagurus bernhardus and queen scallops Acquipecten opercularis sus tained fewer injuries (14 and 2%, respectively). Shell chirping, loss and d amage of limbs were the most frequent types of injury incurred. The severit y and frequency of damage was mainly correlated with species-specific morph ological and bt bevioural characteristics. Vessel type, tow duration and an imal size had a major influence on damage to the epibenthic invertebrates c aught. While damage may potentially be repaired, survival is adversely affe cted and sublethal effects might significantly impair fitness of frequently trawled individuals and populations. (C) 2001 Elsevier Science B.V. All ri ghts reserved.