Food availability is not a limiting factor in the growth of three Australian temperate reef fishes

An assumption often made but rarely tested is that post-recruitment stocks of temperate reef fishes are rarely resource limited, particularly for resources influencing growth. This has been particularly attributed to significant interranual variation in recruitment strength such that in most years stocks are not structured by intra-specific competition for resources. This assumption was tested for three temperate Australian species, the labrids Notolabrus fucicola and N. tetricus, and the monacanthid Penicipelta vittiger, by comparing growth rates from 4 to 5 randomly selected, isolated locations sharing similar habitats in south eastern Tasmania. If food resources were limiting, growth should have differed between locations depending on the ratio of population density to available food resources at each location. In comparisons of the length at age relationships between locations by ANOVA, no significant differences were detected, either in growth curve elevation or shape. These results indicate that growth is similar between locations, both spatially and temporally, and suggest growth is unlikely to be limited by density-dependent factors. Growth rates were also compared between two regions subject to differing environmental conditions. One region was influenced by river discharge waters, the other by oceanic waters. Growth differences were detected between the regions for N. fucicola and N. tetricus but not P. vittiger. The growth differences were related to either early juvenile growth rates or differing timing of recruitment between regions. For most species of temperate fishes, environmental conditions may influence growth to a greater extent than variations in food availability, presumably because local population sizes are usually below the level at which competition for food becomes important.