Feeding habits of Diaphus chrysorhynchus from continental slope region in northern South China Sea in autumn

Based on the samples collected by amid-water trawl in the epipelagic zone of continental slope region in northern South China Sea in October, 2014, we examined the diet composition, feeding intensity, diversity index, ontogenetic feeding habit shifts and trophic level of Diaphus chrysorhynchus by traditional stomach content analysis. The results show that D. chrysorhynchus from the continental slope region in the South China Sea were classified as a zooplankton carnivorous predator, with planktonic crustaceans ( copepoda, euphausiacea, etc. ) as the main prey groups. Among the crustaceans, copepoda was the most dominant prey group, and the relative importance index percent ( %IRI) , individual percentage, quality percentage and occurrence percentage were 74.00, 85.64, 18.39 and 100.00, respectively. The feeding intensity of D. chrysorhynchus was high with a total feeding rate of 100%. The average percentage of stomach fullness index was 2.68% . There was no significant difference in preys among different standard-length groups. The standard length ( 60 mm) was the turning point of diet, and the bigger prey groups in diets increased for fish body lengths longer than60 mm. The trophic level of D. chrysorhynchus was 3.49, which indicates that this species belongs to third-grade and lower carnivore animals.