Dietary habits of spinyhead sculpin, Dasycottus setiger inhabiting eastern coast of Korea

Abstract

Spinyhead sculpin (Dasycottus setiger) is cold water demersal teleosts belonging to Perciformes and Psychrolutidae, and distributed in the coastal areas of North Pacific regions at depth of 15-800m. In Korea, spinyhead sculpin was mainly caught in the middle-eastern coast of Korea (especially, off Gangwon-do and Gyeongsangbuk-do provinces) at depth deeper than 100m. In this study, the dietary habits of spinyhead sculpin were studied based on 156 specimens collected seasonally between May 2018 and February 2019 from the part of East Sea off the Korean coast. Fish samples were collected at both northern (Ayajin, Goseong) and middle (Hupo, Uljin) coasts of eastern Korea using bottom gill net at depth of 80-250m to investigate any spatial, size-related and seasonal trends in the diets of spinyhead sculpin. The total length of spinyhead sculpin was 11.1-36.0cm. In terms of weight contribution (%W), the main food items of spinyhead sculpin was teleosts (33.5%), followed by carid shrimps (13.8%), amphipods (13.3%), cephalopods (12.0%) and polychaetes (7.1%). Dietary analyses based on the weight contribution of different prey taxa to the diets revealed significant variations in dietary composition in terms of sampling region, fish size and season implying intra-specific dietary segregations. In the northern region, amphipods dominated the diets of smaller individuals, whereas the contributions of carid shrimps and teleosts increased as body sized increases. While, spinyhead sculpin showed size-related dietary shift from carid shrimps and bivalves to teleosts and cephalopods in the middle coast. Seasonally, teleosts and carid shrimps were dominated to the spring and summer diets, whereas relative contribution of amphipods to the diets were increased during autumn and winter in the northern coast. Teleosts, on the other hand, was common food item of the diets during all season except summer when various food items were together contributed to spinyheas sculpin diets in the middle coast of eastern Korea.