After an experimental box had been fished 10 times with a 4-m commercial beam trawl, the density of sessile animals such as Alcyonium digitatum and hydroids decreased by ca. 50 %. The density of more mobile animals, such as fishes, crabs andPalaemon spp. remained constant or increased. Assessment of the survival of animals caught in the codend indicated large variation between species. Echinoderms with flexible tests, eg Asterias rubens , showed low mortality, whereas those with brittle tests, eg Psammechinus miliaris, were readily damaged leading to high mortality. The extent of fish mortality, as a result of being caught and landed, was related to the presence or absence of phenotypic features such as scales, spines, boney plates and slime. After 120 h in tanks of running seawater, between 68 to 97 % of Callionymus spp. and 34 and 38 % of Pleuronectes platessa and Raja naevus died. Those animals which have predatory or scavenging feeding behaviour, and are able to survive the trauma of being caught in the codend and handled on deck (eg. A. rubens ), may increase in abundance as a result of fishing activities. |