2019 Volume 13 Pages 85-96
We estimated the diet of carnivorous snakeheads Channa argus, native to China, Korea and Russia, using carbon and nitrogen stable isotopes in Lake Izunuma in 2006 and compared their diet with those of largemouth bass Micropterus salmoides. The relative contributions of potential prey to the diet of snakehead and largemouth bass were estimated using Bayesian mixing model (Stable Isotope Analysis in R). Largemouth bass smaller than 100 mm in total length (TL) foraged mainly on planktonic copepods and small fishes. In contrast, juvenile snakehead (56 to 69 mm TL) fed mostly on cladoceran zooplankton and rarely consumed fish. This result suggests that there was a scarcity of appropriately sized prey fish for juvenile snakehead in Lake Izunuma. Largemouth bass larger than 300 mm TL relied mostly on red swamp crayfish Procambarus clarkii. Adult snakehead (530 to 780 mm TL) also foraged mainly on red swamp crayfish as well as small fishes, though dietary contribution of crayfish to snakehead was smaller than that of largemouth bass. In the case where a population of red swamp crayfish increased after the extermination of largemouth bass, snakehead could add predation pressure on red swamp crayfish. Because snakehead could also consume native fishes, monitoring the population and diet of snakehead is required.
