Selective feeding in a generalist invertivore, age-0 striped bass

Abstract

IntroductionFish feed opportunistically yet are often selective intheir diets (Ehlinger & Wilson 1988, Gerking 1994,Fry et al.1999). Selective feeding behaviour resultsfrom internal factors that may be anatomical, physi-ological or behavioural, and from external factors suchas prey encounter and catchability (Juanes 1994,Juanes et al. 2002). The interaction and dynamics ofthese factors can result in variable and non-randomfeeding behaviour even in species often consideredgeneralists. Feeding behaviour at the level of preyselection can have implications at the individual(Fraser et al. 2007), population (Herwig & Zimmer2007), and community levels (Schleuter & Eckmann2007).Striped bass, Morone saxatilis (Walbaum, 1792), isimportant commercially and recreationally along theeastern coast of the United States (ASMFC 2005) andis often considered to be a feeding opportunist (Markle& Grant 1970, Boynton et al. 1981, Cooper et al.1998, Hurst & Conover 2001). Age-0 striped bass areabundant in the Hudson River estuary (Boreman K and epibenthic (hyperben-thic) prey including gammarid amphipods, decapodshrimp and crabs, and mysid shrimp (Hurst & Conover2001, Jordan et al. 2003). Their diets vary spatiallyand temporally (Jordan et al. 2003), but it is unknownhow much of this variation reflects prey availability oris a function of prey selectivity.In this study, we sampled age-0 striped bassstomach contents and potential benthic and epibenthicprey on four dates between July and October, 2000 atthree locations in the mid-estuarine portion of theHudson River. We then related prey consumption toprey availability to investigate the role of selectivity infeeding behaviour. We also examined stomach fullnessto investigate the potential implications of preyavailability and selectivity on feeding success. Stripedbass are visual predators and the visual environment inestuarine habitats is dynamic, we therefore also testedthe hypothesis that turbidity affects striped bassfeeding behaviour.