2024 Volume 72 Issue 1 Pages 59-68
The browsing behavior of the parrotfish, Calotomus japonicus, was examined under tank-rearing conditions to help improve the efficiency of longline fishing. The amount of a seaweed Sargassum fusiforme browsed by the fish during the four periods (morning: 5:00 - 10:00, daytime: 10:00 - 15:00, evening: 15:00 - 20:00 and nighttime: 20:00 - 5:00) was 8.6 ± 4.7 g/kg-fish/h, 8.8 ± 3.4 g/kg-fish/h, 5.5 ± 2.5 g/kg-fish/h and 0.1 ± 0.1 g/kg-fish/h, respectively. Browsed rates for morning and daytime were higher than evening. Furthermore, the amount of Ecklonia cava subsp. kurome browsed by the fish ranged 76.9 -224.9 g/kg-fish/day from June to August during the season of rising water temperature. The amounts in other months ranged 8.4 - 37.6 g/kg-fish/day. In addition, the six seaweeds species, S. fusiforme, Padina arborescens, Dictyopteris undulata, Palisada papillosa, Gelidium elegans and Codium fragile, were fed to the fish. The browsed rate of S. fusiforme was 87.2 ± 19.7%, and the rates were higher than the other seaweeds (2.4 - 72.8%). Based on these results, the time period for longline fishing to remove C. japonicus is preferable during morning to daytime in spring to early summer, and the suitable bait is S. fusiforme.
