Diet and feeding ecology of invasive icefish Neosalanx taihuensis in Erhai Lake, a Chinese plateau mesoeutrophicated lake

Abstract

A comprehensive study of the invasive icefish Neosalanx taihuensis feeding ecology in Erhai Lake was conducted from November 2009 to October 2010. Prey items in the guts of the icefish sampled varied significantly according to season. This finding suggests a relationship between fluctuations in available prey in the environment and selective feeding by icefish. N. taihuensis preferred large-sized zooplankton, such as Daphnia and calanoids. Additionally, the gut fullness values differed significantly (P<0.001) among sampling times. To compare the values at different times, samples were taken over a 24 h period every 2 months for the entire year. The feeding activities of the fish were concentrated either in the morning (8:00) and/or at dusk (20:00), except in September 2010. This finding can be explained primarily by the variation in optimum light intensity. Daily N. taihuensis zooplankton consumption varied significantly, both diurnally and among seasons. The daily consumption values ranged from 0.089 to 0.237 g (wet weight) per 100 g wet fish weight in temperatures between 11.50°C and 24.68°C. This is the first report of diel feeding periodicity and daily food consumption of icefish in their invaded ecosystems.