The feeding biology of the bat ray, Myliobatis californica in Tomales Bay, California
Karl S and Obrebski S. The feeding biology of the bat ray, Myliobatis californica in Tomales Bay, California. In Proceedings of 1st Pacific Northwest Technical Workshop on Fish Food Habits Studies. 13-15 October, 1976. Astoria, OR
The bat ray, M.california, occurs from Oregon to the Gulf of California and is common in California bays during the spring and summer. MacGinitie (1935) observed that during its feeding activities the bat ray can dig channels up to 1 m wide, 50 cm deep and 4 . 5 m long in benthic substrates. In preliminary studies of the effects of predation on benthic communities in Tomales Bay, information was obtained about changes in diets of bat rays in relation to size. As the bat ray increases in size, larger, deep-burrowing organisms become increasingly important in the diet. It is likely that bat ray feeding in Tomales Bay might also make more food available for other species of fish. During shallow water dives it was observed that Urechis caupo burrows were frequently used as hiding places for small crabs. This suggests that bat rays might also indirectly regulate abundances of small crabs by affecting the abundances of Urechis. These observations suggest that experimental studies of effects of bat ray predation on benthic community structure should include studies of indirect effects on other predator populations.