FISHING-GEAR-INDUCED SKIN ULCERATIONS IN BALTIC COD, GADUS-MORHUA L

In 1982 a high prevalence of skin ulcerations was observed in Baltic c od in the vicinity of the Danish island of Bornholm. In March the prev alence varied from G to 13%, and in May it had increased to between 26 and 48%. The ulcerations had a sequential development. The initial st age appeared as severe skin abrasions in the area from the pectoral fi n posterior to the level of the anus. The skin abrasions developed int o large spots of necrotic dermal tissue with a diameter of 2-5 cm. The central part of the necrotic area sloughed off exposing a large haemo rrhagic ulcer. Characteristically most of the ulcerations on the trunk occurred bilaterally. A common histopathological finding was coagulat ion necrosis of the muscular tissue. The ulcerated fish were mainly 24 -28 cm in length. P, correlation between high concentrations of cod ar ound Bornholm, high fishing activity in the area, length of fish escap ing from the nets, combined with bilateral occurrence of the ulcers, s trongly indicates that the skin ulcers were induced by the fishing gea r. Features of the pathology could be linked to the temporary retentio n of cod in trawl meshes.