ABSTRACT
Gut contents of two species of demersal fishes, Pleurogrammus azonus and Dasycottus steiger were examined to understand the importance of a euphausiid, Euphausia pacifica as prey of demersal fishes at coastal waters off Uljin, the eastem Korea where aggregations of large amounts of the euphausiids were found. Euphausiids were significantly important food source to the species of fishes examined. All of the stomachs of P. azonus examined contained euphausiids (% of a food item frequency occurred, F = 100%) in March and June 2003. Individual numbers of euphusiids in the guts ranged from 10 to 540 individuals per gut. Percents of individual number of food item were 99.60 and 99.96 for euphausiids in March and June 2003, respectively The guts of D. steiger also frequently contained euphausiids (F = 86.67 and 79.20% in October 2002 and June 2003, respectively), while amphipods (F = 36.67% and 16.17%,) and other fishes (F = 33.33% and 45.80%) were also often observed. Pleurogrammus azonus preferred larger euphausiids with size range 16.9-28.4 mm, while the range of euphausiids distributed in the ambient water column was much broader (from eggs to adults).