Traumatization of Kamchatka River Pacific salmon by lampreys

Abstract

Salmon that enter the Kamchatka River are intensively traumatized by lamprey (from 12.0 to 74.0% in different years). An analysis of the frequency distribution of oral disk marks on salmon revealed two types of marks: (1) small (diameter < 2.2 cm, mainly of oval form, located in the middle of the fish in the upper part of the body) and (2) large (diameter > 2.2 cm, of roundish form, located in the front in the lower third of body). The small marks (type I) are mainly left by the Kamchatka lamprey Lethenteron camtschaticum . The second type of trauma is inflicted by large individuals of the Pacific lamprey Enthosphenus tridentatus in the 2nd and 3rd year of marine life. The most typical traumatic injuries caused by lamprey to salmon are described. Injury data are provided for six species of salmon, namely, sockeye, pink, chum, coho, chinook, and char.