This study investigated the stomach and intestinal contents of 129 rock soles (Lepidopsetta bilineata) from the Eastern Bering Sea. The results showed that L. bilineata consumes about 1.61% of its body weight in food every day. These fish feed mostly in the late-afternoon to early-evening. The diet of this population of L. bilineata changes with body size. Smaller individuals of 20cm and under fed actively on amphipods, whereas larger fish of 30cm and larger fed opportunistically on both polychaete and echiuroid worms and amphipods. A variety of other organisms were present in the G.I. tract of the sampled fish, but they made up only about 2% of content by weight.

It is worth noting that diet of L. bilineata appears to vary by region; a prior study off the Oregon coast found that L. bilineata fed primarily on brittle stars. Others studies in the Northern Pacific indicated a higher prevalence of mollusks and sandlance above 50m. The 129 sampled fish in this study were taken farther out in the Bering Sea in deeper waters. Depth and region are factors affecting diet make-up.

This is wonderful to learn. Polychaete worms are terrifying, and I'm not saddened to know that they make a nice snack for adult rock soles.