Scharf, F.S., F. Juanes, and R.A. Rountree. (in review). Predator size-prey size relationships of marine fish predators: interspecific variation and the effects of ontogeny and body size on trophic niche breadth. Marine Ecology Progress Series 

Abstract

We utilized a long term data base collected over a broad geographic range to examine predator size - prey size relationships of marine fish predators from continental shelf waters off the northeast U.S. coast. Regression analysis was used to illustrate interspecific variation in ontogenetic patterns of prey size use, gape allometries, and ratio-based trophic niche breadths. Size-based feeding strategies were assessed through comparison of frequency distributions of relative prey sizes eaten and were related to general predator feeding tactics and gape morphology as well as behavioral and morphological characteristics of prey. Changes in the suite of predators with the ontogeny of specific prey were also identified. Results demonstrated that the range of prey sizes eaten expanded with increasing predator body size for each of the marine predators examined, leading to asymmetric predator size - prey size distributions. Absolute maximum prey size and slopes of maximum prey size versus predator size varied widely among predator taxa. Distinct size-based feeding strategies were evident as diets of some predators were dominated by prey that were 10-20 of predator size, whereas other predators frequently consumed prey greater than 50 of predator size. Gape sizes and allometric relationships with body size were also diverse among predators and often were closely associated with maximum prey sizes. Specific prey species experienced shifts in the suite of predators with increasing body size, while other prey remained vulnerable to a large group of predators despite changing body size. Ratio-based trophic niche breadths generally did not expand with predator ontogeny and tended to narrow for the largest predators, which may be common for animal taxa.