Trophic ecology of striped bass, Morone saxatilis, in a freshwater reservoir (Lake Texoma, U.S.A.)

Abstract

Many vertebrate predators consume a wide variety of prey types, depending upon availability and vulnerability. In contrast, striped bass, Morone saxatilis, that have been introduced to Lake Texoma (Oklahoma‐Texas, U.S.A.) use a very limited array of fish (mostly clupeids of the genus Dorosoma) as prey. As a large, mobile predator, M. saxatilis should be capable of capturing and consuming numerous other species of fish that are available in the reservoir. However, examination of 1845 stomachs year‐around over 5 years showed that the only marked ‘switching’ among prey was from Dorosoma to a diet including a high percentage of insects during spring–early summer, ignoring most other fish taxa that could have served as food. Even under essentially starvation conditions in late summer of years with scarce Dorosoma, M. saxatilis in Lake Texoma did not switch to other available fish as prey. Patterns of predation by M. saxatilis are trenchantly different from place to place: very narrow prey selectivity even under starvation conditions has been reported once previously for the species in a freshwater reservoir, but in its native marine and estuarine environment and in some other reservoirs the species is more catholic in its use of prey. Why this large predator shows fidelity in some environments to particular prey, even to the extent of starvation, remains an enigma.