First records of abnormal fishes in the Arctic and possible reasons of the anomalies

Abstract

External anomalies in fish are diverse and include abnormal development of external organs (eyes, jaws, fins, etc.), deformity and curvature of the trunk, discoloration of the skin, reversal of the sides (in flounders) and others that reduce the survival of individuals with such disorders. Although they are not uncommon in nature, reports of fish anomalies in Arctic seas are extremely rare. There have been no published records of anomalous Bering flounder Hippoglossoides robustus or polar cod Boreogadus saida. We document here for the first time on albinism, ambicoloration, reversal of the sides, or curved spine in individuals of Bering flounder, as well as a specimen of polar cod with a vertebral deformity captured in the western Chukchi Sea. Photographs of both normal and abnormal individuals are provided. We hypothesize that of all the possible causes of the anomalies we have found, the most likely is the recent dramatic warming in the Arctic.