Spatial and Temporal Patterns in the Diet of Striped Bass in Chesapeake Bay

Abstract

We collected striped bass Morone saxatilis from 1998 to 2001 (n = 2,703) and compared the seasonal feeding patterns of four size-groups (small [150-300 mm total length], medium [301-500 mm], large [501-700 mm], and extra large [>700 mm]) among three general regions (upper, middle, and lower) in Chesapeake Bay. Invertebrates dominated the diet of small striped bass during spring in all regions, and by fall bay anchovy Anchoa mitchilli became the dominant prey in the middle and lower regions. Pelagic schooling fishes were the primary prey for the larger size-groups. For medium striped bass, bay anchovy accounted for most of the prey eaten during spring and represented more than 50% of the diet by weight in summer in the upper and lower regions. Collectively, Atlantic menhaden Brevoortia tyrannus and bay anchovy accounted for more than 60% of the diet by weight in the lower region. Gizzard shad Dorosoma cepedianum and Atlantic menhaden were the dominant prey for medium and large fish from summer through winter in the upper region. Blue crab Callinectes sapidus accounted for 45% of the diet by weight for large striped bass during the summer in the middle and lower regions of the bay. For extra-large striped bass, menhaden, along with bay anchovy and spot Leiostomus xanthurus, were the primary prey eaten throughout the year in all regions. Bay anchovy have become more important for extra-large fish, representing between 16.0% and 29.0% of the diet by weight during the spring and summer. This increase represents a greater reliance by larger striped bass on small pelagic prey. It also suggests a greater ecological connection between bay anchovy and striped bass production.