Distribution of Arctic and Pacific Lampreys in the North Pacific: Comparative Study

Results of long-term research on spatial and vertical distributions of Pacific lamprey Lampetra tridentata (Richardson, 1836) and Arctic lamprey Lethenteron camtschaticum (Tilesius, 1811) in the North Pacific are presented. It is shown that the former species is most abundant in the Bering Sea. Maximum concentrations of this lamprey within the whole year occurred off Navarin Cape, along the Koryak shelf, off the eastern Aleutian Islands and western US coast. The latter species most frequently occurred in the northwestern Sea of Japan and western Bering Sea. Highest catches are characteristic for southern Primorye, southwestern Sakhalin, northwestern Sea of Okhotsk and northern Bering Sea. Pacific lamprey reaches highest abundance near the bottom at depths < 500 m. It is rare in water column most frequently occurring within upper 100 m layer. Arctic lamprey is most abundant in water column within upper 100 v layer. Near the bottom, it is rather rare and occurs mainly at depths < 400 m. Pattern of vertical distribution testify that Arctic lamprey serves as main predator for Pacific salmon while Pacific lamprey attacks predominantly walleye pollock, Pacific cod, halibuts and other demersal fishes. Seasonal and decadal changes of pattern of spatial distribution are presented for both lampreys.