Nutrients in Salmonid Ecosystems: Sustaining Production and Biodiversity

Aquatic Animal Colonization of Chum Salmon Carcasses in Hokkaido, Northern Japan

Miyuki Nakajima and Tomiko Ito


Abstract.—We observed that the aquatic animals, especially macroinvertebrates, colonized chum salmon Oncorhynchus keta carcasses in six rivers of five coastal districts in Hokkaido, northern Japan, 1997–2000. Fifty-six taxa of aquatic macroinvertebrates were found with the carcasses. Taxa and number of the macroinvertebrates were different among rivers and districts. Three taxa, Gammaridea (Amphipoda), Hydatophylax spp. (Trichoptera: Limnephilidae), and Chironomidae (Diptera), were widely and abundantly found. Hydatophylax larvae were more abundant on the carcasses, in comparison with the streambed, in some sites. The maximum number of macroinvertebrates colonizing a carcass was observed near an estuary site of the Shiretoko District, 747 on average of Eogammarus spp. (Gammaridea).