Evidence for Attacks by the Bathypelagic Fish Anotopterus pharao (Myctophiformes) on Pacific Salmon (Oncorhynchus spp.)

Abstract

Adult Pacific salmon (Oncorhynchus spp.) returning from offshore waters to spawn frequently bear a wide range of wounds and scars. One of the most common wounds is a single slash mark on the posterior third of one side of the body, running posteroventrally from near the dorsal fin at a roughly 45° angle. The evidence is reviewed for the occurrence of slash-marked salmon around the Pacific Rim over the past 30 yr. A jaw fragment removed from the wound of a slash-marked sockeye salmon (O. nerka) and identified as belonging to a daggertooth (Anotopterus pharao: order Myctophiformes), a highly modified bathypelagic fish, provides the first direct evidence for the cause of these wounds. Given the frequency of slash-marked adult salmon in coastal fisheries, A. pharao may be a significant cause of mortality in Pacific salmon that has previously gone unrecognized.