Spatial Differences in the Distributions of Arctic and Pacific Lampreys in the Eastern Bering Sea

Abstract

The Arctic Lamprey Lethenteron camtschaticum and Pacific Lamprey Entosphenus tridentatus are ecologically and culturally valuable native species that co‐occur in the eastern Bering Sea. Lamprey wounds are often observed on fishes in this region, yet there is a paucity of information on the distribution of anadromous lampreys, lamprey–host interactions, and foraging behavior in the ocean. Our hypothesis was that each lamprey species would be positively associated (distribution and abundance) with their presumed hosts: Arctic Lampreys with smaller fishes that could easily be killed, and Pacific Lampreys with larger hosts that could sustain blood feeding. To examine lamprey distribution, abundance, and associations, we utilized data from two fishery‐independent surveys—one epipelagic trawl survey and one benthic trawl survey—conducted between 2002 and 2012 in the eastern Bering Sea. Distinct distributions of lamprey species were evident in models of their presence and absence by latitude and longitude. Arctic Lampreys inhabited the northern regions on the inner/middle continental shelf in depths less than 100 m, while Pacific Lampreys inhabited waters deeper than 150 m along the continental slope. Pacific Herring Clupea pallasii and juvenile salmonids were found in regions with relatively high Arctic Lamprey catches in the epipelagic trawl survey, and catches of lampreys and these potential hosts were positively correlated. Demersal groundfishes were found in regions with relatively high Pacific Lamprey abundance in the benthic trawl survey, but catches of Pacific Lampreys and these hosts were not consistent. We conclude that Arctic Lampreys and Pacific Lampreys are segregated in the eastern Bering Sea, and although differences in their distributions may be explained by species‐specific host preferences, alternate explanations include differences in seasonal movements, source river locations, and marine residence times. This study provides an initial baseline of the oceanic ecology of lampreys, which increases our understanding of species‐specific differences beyond traditional freshwater studies.

Factors that Affect Arctic Lampreys’ Ascent Behavior on Fishway Weirs

“…L. japonicum migrate across shallow-depth areas (less than 100 m deep) from the Sea of Japan to the northwestern Bering Sea (Potter and Hilliard, 1987;Orlov et al, 2014;Siwicke and Seitz, 2017). They migrate in the sea for about three years.…”