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Species of the tubenose poacher genus Pallasina are assessed following examination of over 450 specimens from throughout the Pacific Rim, from the coast of California to the Chukchi Sea and Sea of Japan. The results presented here, including both morphological and mitochondrial DNA datasets, indicate that three species of Pallasina occur in the North Pacific and surrounding seas. Pallasina aix is found in the eastern North Pacific from California to southeast Alaska and in the Salish Sea. It has the shortest barbel of the three species and a unique haplotype in the mitochondrial COI region. Pallasina barbata is the most widespread species, ranging from the Gulf of Alaska to the Chukchi Sea and west to northern Japan. It is distinguished by having a moderate barbel length and can be separated from the other two species using a variety of meristic characters. Pallasina eryngia is found only in the central and northern Japanese Archipelago, and it is a relatively deep-water species. It is distinguished by having a long barbel, as well as relatively high counts of vertebrae and dermal plates. This study presents redescriptions of all three species and a key to their identification. [ABSTRACT FROM AUTHOR]

Poleward species range shifts have been predicted to result from climate change, and many observations have confirmed such movement. Poleward shifts may represent a homogeneous shift in distribution, seasonal northward movement of specific populations, or colonization processes at the poleward edge of the distribution. The ecosystem of the Bering Sea has been changing along with the climate, moving from an arctic to a subarctic system. Several fish species have been observed farther north than previously reported and in increasing abundances. We examined one of these fish species, Pacific cod, in the northern Bering Sea (NBS) to assess whether they migrated from another stock in the eastern Bering Sea (EBS), Gulf of Alaska, or Aleutian Islands, or whether they represent a separate population. Genetic analyses using 3,599 single nucleotide polymorphism markers indicated that nonspawning cod collected in August 2017 in the NBS were similar to spawning stocks of cod in the EBS. This result suggests escalating northward movement of the large EBS stock during summer months. Whether the cod observed in the NBS migrate south during winter to spawn or remain in the NBS as a sink population is unknown. [ABSTRACT FROM AUTHOR]