Does hatchery-reared Siniperca chuatsi (Actinopterygii, Perciformes) compete significantly with two wild Siniperca populations for diets in a shallow lake?

This study aimed to evaluate whether hatchery-reared Siniperca chuatsi (HSC) competes significantly with wild Siniperca populations in a shallow lake. Two wild Siniperca fishes, S. chuatsi and Siniperca kneri, along with HSC, were collected in the shallow Biandantang Lake, and their diets were determined using both stomach contents and stable isotope analyses. The stomach contents showed that shrimps and fish were the major food items of HSC and wild Siniperca fishes, but their dietary composition and percentage contribution revealed significant differences. Isotopic mixing model analysis suggested similar conclusions that contribution proportions of end members were significantly different. The niche overlap index on the basis of prey importance from stomach content analysis indicated that there was not significant diet overlap between hatchery-reared and wild Siniperca populations in winter and summer. Similar results were found in winter based on the prey contributions from isotopic mixing model outputs, but meaningful diet overlap was observed in summer. Our findings demonstrated that HSC did not have apparent feeding competition with wild Siniperca fishes during the critical periods of the early stocking stages, suggesting that moderate stocking of HSC may not have a negative effect on the variability of wild Siniperca populations.