The interplay of ontogeny and scaling in the interactions of fish larvae and their predators

In this review and synthesis, new data from field and laboratory experiments on red drum, Sciaenops ocellatus , larvae as prey to larger fishes are presented to illustrate two approaches to the study of developmental effects on predation. Various sizes and species of predatory fishes imposed very different levels of mortality on experimental populations of red drum larvae. Differences in predator size explained little of the overall variation in mortality rates. In the laboratory, responsiveness of red drum to a single size and species of predatory fish was relatively low through much of the developmental period but increased steadily. Response effectiveness improved and the predator's capture success decreased once the prey exceeded 20 mm in length. General ontogenetic trends in the behavioural interaction of various larvae and their piscine predators are described by combining 22 data sets on a scale of roughly comparable ontogenetic state. This scale, together with absolute and relative measures of predator and prey size, are used to assess the roles of ontogeny and scaling in the predation interaction. Ontogeny is shown to be a significant contributor to changes in responsiveness, response effectiveness, and capture success. The influence of scaling always took the form of an interaction with ontogeny and not a main effect.