Spatial and temporal variability in the condition of postlarval and juvenile Penaeus plebejus sampled from a population subjected to pilot releases

The potential for hatchery-release programs to augment the harvest rates of fisheries can be limited by environmental factors associated with survival, growth and body condition among released individuals. We assessed spatial and temporal variability in the condition of postlarval and small juvenile (1-10 mm carapace length) eastern king prawns Penaeus plebejus Hess sampled from an estuarine population subjected to pilot releases of 3 million postlarvae per year in southeastern Australia. Variability in the length-weight relationship was used as a measure of condition and compared between (1) autumn/winter and spring/summer periods and (2) bare and macrophytic habitats for P. plebejus sampled from a population in a closed estuarine system. At a reference carapace length of 3.97 mm, condition was similar to 14% higher for individuals sampled from bare habitat and similar to 16% higher for those sampled during autumn/winter compared, respectively, with individuals sampled within macrophytic habitat and during spring/summer. Further experimental work on the factors investigated here is encouraged to increase our understanding of the environmental characteristics and mechanisms that lead to improved condition and thus persistence of stocked populations of P. plebejus.