Helminthes from juveniles of pacific salmons (Oncorhynchus) at the continental coast of the northern Okhotsk Sea

Abstract

Fauna of helminthes and feeding of pacific salmon (pink, chum, and coho) juveniles at the continental coast of the northern Okhotsk Sea are considered both for freshwater and early marine stages of their life. Possible conditions of the parasitic worms invasion are discussed. In total, 17 species of parasitic worms are found in salmon juveniles including cestodes (2 species), trematodes (8), nematodes (4), and acanthocephalans (3). The trematodes Brachyphallus crenatus and Pronoprymna petrowi have the highest values of infestation. The helminthes are mainly the representatives of freshwater ecological group (10 species are found in fresh waters and 8 species in estuaries), only 6 species represent the marine ecological group. One marine species ( Hysterothylacium gadi aduncum ) is found in estuarine coho juvenile and one freshwater species ( Diplostomum sp., met.) is found in marine coho juvenile.