Habitat Segregation in Sanguinicolid Blood Flukes (Digenea) of Scorpaenid Rockfishes (Perciformes) on the Pacific Coast of North America

Abstract

Aporocotyle macfarlani Holmes, 1971, was found in five species of Sebastes taken from the inland waters around the San Juan Islands, Washington, or the inshore waters around Vancouver Island, B.C. Psettarium sebastodorum Holmes, 1971, was found in 14 species of Sebastes from the same locations or from deeper offshore waters west of Vancouver Island. The two flukes have different dominant hosts. Their numbers show different relations with depth. Aporocotyle macfarlani appears to be associated with fish that frequent reefs.Aporocotyle macfarlani occupies the lumen of the afferent branchial arteries, the ventral aorta, and rarely parts of the heart; P. sebastodorum is threaded into the intertrabecular spaces of the ventricle and atrium. The overlap in the distributions of the two species is reduced in concurrent infections.