Fish Fauna Associated with Drifting Seaweed in the Coastal Area of Tongyeong, Korea

Abstract

Fishes associated with drifting seaweed were investigated monthly between April 1998 and March 1999 in the coastal area of Tongyeong, Korea. Depending on the size of seaweed patches, we collected fish by dip net, purse seine, or surface trawl. The behavior of fish in and around drifting seaweed was observed by scuba diving and in an aquarium. The most abundant types of seaweed were in the genus Sargassum, including S. horneri, S. miyabei, and S. thunbergii. The size of seaweed patches varied by season; patches larger than 4 m in diameter were found in May, whereas patches smaller than 50 cm in diameter were abundant in August and September. Patch weights varied from 0.1 to 11.0 kg in spring and summer but averaged less than 1 kg in autumn. We collected a total of 56 fish species from 27 families, the number of species varying from season to season. We found the most species in May (N = 29) and June (N = 26), and the fewest in February (N = 1). Some species, including Syngnathus schlegeli, Hexagrammos agrammus, Histrio histrio, Petroscirtes breviceps, Rudarius ercodes, and Stephanolepis cirrhifer, were present for 6 to 9 months, whereas Mugil cephalus, Siganus fuscescens, and Furcina osimae were collected only once during the study period. There was no significant relationship between the number of species collected and the weights of the seaweed patches (P < 0.05).