Journal of Fishery Sciences of China (中国水产科学) 2013/20:6 PP.1284-1292
Wild populations of Nibea albiflora are supplemented by release of hatchery individuals in Xiangshan Bay. There is little information describing the basic biology of N. albiflora, which hinders efforts to improve the supplementation program. We evaluated the diet composition and prey selection of N. albiflora in Xiangshan Bay. We collected 365 N. albiflora individuals from Xiangshan Bay between October 2011 and September 2012, and analyzed the stomach contents and the prey species from them. We used dietary prey species percentage in weight, dietary prey species percentage in number, and occurrence frequency of species in stomach content to analyze the organism composition in diets. We used the importance index (IRI) and IRI% to determine the importance of the prey species in diets, used the empty stomach rate and stomach fullness index to evaluate the feeding intensity of fish, and used selection index Va to verify certain species of N. albiflora selection. We identified 34 prey species in the stomachs of N. albiflora, suggesting it was a generalist. Shrimps were the dominant prey groups. At the species level, the main prey items were Palaemon macrodactylus, Palaemon gravieri, Oratosquilla oratoria, Alpheus hoplocheles, and Alpheus japonicus. Feeding activity varied seasonally and with ontogeny. The feeding intensity was lowest in winter and in large-sized individuals (>190 mm). Feeding activity was also correlated with gonad maturation. The diet composition of N. albiflora was similar in autumn, winter, and spring, consisting primarily of Palaemon macrodactylu, Palaemon gravieri, Oratosquilla oratori, and Marsupenaeus japonicas, whereas the diet in summer consisted of Palaemon macrodactylus, Exopalaemon carinicauda, and Solenocera crassicornis. Shrimps were the dominant prey groups of small-sized individuals (80-220 mm), whereas the marine fishes and Oratosquilla oratori were the dominant prey groups of large-sized individuals (>220 mm). N. albiflora strongly preferred Palaemon macrodactylus (V=0.145, χ2=4.192, P<0.05) and Alpheus hoplocheles (V=0.141, χ2=3.957, P<0.05). Penaeus japonicas was abundant in the environment, but it was negatively selected in the diet (V=–0.174, χ2=6.030, P<0.05) of N. albiflora. The feeding selectivity of N. albiflora was related to the composition and individual size of food organisms in the environment. To a certain degree, the prey animals’ ability to escape predators and the length of the individual also affected the feeding ecology of N. albiflora individuals. The conclusions imply the N. albiflora in Xiangshan Bay has abundant feed resources and the prey species are various, and the composition of prey species and feeding intensity in different season or different body size class are variational, and this species has a unique feed selection and ecology. It suggests that the distribution of prey organism for N. albiflora in Xiangshan Bay should be considered during the selection of releasing scope, releasing season and releasing spot for the purpose of conservation and enhancement of this species.