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.