Ulcers associated with larval Anisakis simplex B (Nematoda: Ascaridoidea) in the forestomach of harbour porpoises Phocoena phocoena (L.)

Abstract

Anisakis simplex B larvae and adults occurred in the forestomach of 7 of 10 Phocoena phocoena found drowned in cod nets in the winters (November–January) of 1977–1978, 1980–1981, 1981–1982, and 1983–1984, along the Scottish east coast. A cluster of third- and fourth-stage larvae was found in one large, crater-like ulcer in the wall of the ventral "hemisphere" of the forestomach in five porpoises. A sixth infected animal had one large ulcer bearing a larval nematode cluster, plus, at a separate site in the ventral hemisphere, an aggregation of six very small ulcers, three of which contained larvae. The remaining infected porpoise harboured a large multiple ulcer at a single site in the ventral hemisphere, each of its five craters bearing a cluster of larvae. Adult male and female nematodes were apparently "free" in the forestomach lumen. One third-stage larva of Contracaecum sp. was the only other parasite found in the gastrointestinal tract of the 10 porpoises. Whiting (Merlangius merlangus) was the dominant prey item, and may have been the source of A. simplex B infection.