1Tochigi Prefectural Fisheries Experiment Station, Nasu, Tochigi 324-0404, 2Freshwater Fisheries Research Division, National Research Institute of Fisheries Science, Nikko, Tochigi 321-1661, 3Department of Aquatic Biosciences, 4Department of Marine Environmental Sciences, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, Japan
Mortality and growth of Japanese charr Salvelinus leucomaenis and masu salmon Oncorhynchus masou masou after catch and release were examined in experimental ponds, using hatchery-reared fish divided into smaller (<15 cm in total length) and larger (>15 cm) size groups. When the hooks stuck in the mouth and were removed for both species, the mortality within 21 days after catch and release was low (0-15.0%) for each size and fishing gear (bait and fly-fishing, using barbed hooks). When hooks in bait fishing were removed from the esophagus, mortalities were relatively high (66.7% in the smaller sized charr and 45.0% in the larger sized salmon). All the fish of both species and both size groups were alive when the hooks in fly-fishing were removed from the mouth, however the mortality was relatively high (40.0%) when the hooks were not removed from the mouth of the larger sized charr. Of all the fish that died, 63.0 and 98.1% died within 3 and 14 days after catch and release, respectively. There was no negative effect of the catch and release on the growth and condition factor of both species and both size groups. These results suggest that catch and release is effective for conserving Japanese charr and masu salmon populations in rivers and lakes when anglers pay attention to the removal of hooks.