LIFE HISTORY, FEEDING HABITS, AND FUNCTIONAL MORPHOLOGY OF JUVENILE SCIAENID FISHES IN THE YORK RIVER ESTUARY, VIRGINIA1,2

Abstract

Four abundant sciaenid fishes, Cynoscionregalis, Bairdiellachrysoura, Micropogoniasundulatus, and Leiostomusxanthurus, use the York River, Va., as a nursery ground and as an adult seasonal feeding ground. In addition, six species ofsciaenids, Menticirrhussuxatilis, M. americanus,Sciaenops ocellata, Cynoscion nebulosus, Pogoniascromis, and Larimusfasciatus, are present in the estuary occasionally. Yearling C. regalis were first caught in April and young-of-the-year in July or August. Yearling B. chrysoura were first caught in March or April and young-of-the-year in July or August. Juvenile Micropogoniasundulatus and Leiostomusxanthurus may be present in the York River all year-round. Young-of-the-year L. xanthurus were first caught in April and M. undulatus were first caught in August. Small M. undulatus «20 mm TL) were caught from August to June, which may indicate a prolonged spawningseason (or a late spawningstock). Emigration to the ocean was found in all the four species during late fall or early winter. Water temperature and dissolved oxygen seemedto be the most important factors in the spatial and temporal distributions of these four species in the York River. Mouth position, dentition, gill rakers, digestive tract, pores and barbels, nares, and body shape ofsix sciaenid species, Larimusfasciatus, C. regalis, B. chrysoura, M. undulatus, Menticirrhus suxatilis, and Leiostomusxanthurus, were found to be important in locating and ingesting prey in the water column. Stomach contents indicated that the food partitioning of these six species was closely correlated with the species and their prey habitat. Larimusfasciatus, C. regalis, andB.chrysoura fed mainly above the bottom, whereas Micropogonias undulatus, Menticirrhus suxatilis, and L. xanthurus fed on epifauna, infauna, or both. Juvenile sciaenids are able to coexist in the same area because ofdifferences in spatial and temporal distribution, relative abundance, and food habits.