Damage, autotomy and arm regeneration in starfish caught by towed demersalfishing gears

Arm damage and loss were examined in the starfish Asterias rubens that had been caught in a variety of towed commercial fishing gears deployed on diff erent sea bed types. Between 7% and 38% of the starfish in each catch lost one or more arms, and arm loss was positively correlated with the volume of the catch for two of the fishing gears examined. Subsequent monitoring of damaged animals showed that arms were autotomised for at least 3 weeks foll owing capture. Mortality was highest in starfish with damaged or missing ar ms, compared with those that appeared intact after fishing. Arm regeneratio n was delayed in a small proportion of the animals caught by commercial gea rs. In a parallel study, 17% of starfish caught by a 4m beam trawl had a da maged ambulacral ossicle at the point of autotomy (cf. none from a control group that were induced to autotomise under controlled conditions). There w as no difference in regeneration rates between the animals caught by commer cial gears and a control set (caught by a small trawl and forced to autotom ise an arm in the laboratory) once the animals that delayed regeneration we re excluded from the dataset. After I year under laboratory conditions the starfish had, on average, regenerated the missing arm to 75% of the length of the other four arms. During this time period the lengths of the undamage d arms increased by ca. 50%. The implications of this study for using arm l oss in starfish as an indicator of fishing disturbance are discussed.