Fisheries Experimental Station, Wakayama Research Center of Agriculture, Forestry and Fisheries, Kushimoto-cho, Higashimuro-gun, Wakayama 649-3503, Japan
To evaluate the relative importance of possible carbon sources such as phytoplankton and benthic microalgae for Trichiurus japonicus, 32 specimens were collected from the Kii Channel, Japan, and their carbon and nitrogen stable isotope distributions were analyzed. Furthermore, 32 fishes representing an additional 13 benthic species were analyzed for comparison. The δ13C and δ15N values of T. japonicus were −16.2±0.5‰ and 17.6±1.2‰, respectively, and differed from those of other benthic species (−15.4±0.7‰ and 16.1±1.7‰, respectively). The relative contributions of phytoplankton and benthic microalgae as carbon sources of fishes were calculated. The contribution of phytoplankton for T. japonicus (51.6%) was higher than that for other benthic fishes (3.1%-43.0%). This likely reflected the diel vertical migration pattern of T. japonicus during which it feeds mainly on fishes and crustaceans present in the pelagic rather than the benthic environment.