The ecology of substrate-associated juveniles of the genusSebastes

Synopsis This paper reviews current knowledge of substrate-associated juvenileSebastes. In general, juvenile rockfish recruit to shallower depths than those occupied by conspecific adults. Habitat use by newly recruited rockfish differs markedly among species. While a few species recruit to shallow-dwelling macrophytes, such asZostera, many others recruit to larger brown algae, such asNereocystis andMacrocystis. A few deeper dwelling species recruit to low relief or soft substrata. However, little is known on recruitment of these deeper dwellers. Crustaceans are the major component of the diets of newly recruitedSebastes. Species which continue to forage in the water column shift to larger crustaceans (e.g. euphausids) and fish as they grow. Species which shift to substrate-associated prey soon begin to feed on larger algal-associated gammarid amphipods, shrimps and isopods. Field studies indicate variation in intraspecific growth rates over large geographic distances, among nearby sites and among algal habitats on the same reef, with food availability and water temperature being major factors in the differences. In particular, laboratory studies have shown that temperature is one of the most important factors in growth rates. Many species of juvenile rockfish make ontogenetic movements, often moving into deeper water as they age. Most seasonal movements appear to be related to changes in water temperature and turbulence.