Growth conditions after recruitment determine residence-emigration tactics of female Japanese eels Anguilla japonica

• Published in: Fisheries science 2016-09, Vol.82 (5), p.729-736
• Main Authors: Wakiya, Ryoshiro, Kaifu, Kenzo, Mochioka, Noritaka
• Format: Article
• Language: English
• Subjects: Age; Analysis; Animal migration; Biology; Biomedical and Life Sciences; Brackish water; Coasts; Downstream; Emigration; Endangered & extinct species; Estuaries; Females; Fish; Fish & Wildlife Biology & Management; Fisheries; Food Science; Freshwater & Marine Ecology; Growth conditions; Habitat selection; Habitats; Life Sciences; Original Article; Rivers; Studies; Upstream
• ISSN: 0919-9268; 1444-2906
• DOI: 10.1007/s12562-016-1006-8

Back-calculated annual growth of 156 yellow-phase female Japanese eels Anguilla japonica sampled from freshwater sites in the Tsuchikawa River, Kagoshima, Japan, were compared among eels from the upper reaches (“upstream emigrants”), large eels (≥240 mm) from the lower reaches (“downstream residents”), and small eels (3 years of age. Back-calculated annual growth of large eels captured in the lower reaches was significantly greater than that of eels in the upper reaches for the first 3 years after recruitment (age 0–2 years), and small eels in the lower reaches had intermediate growth. These results suggest that female eels in this river decide whether to emigrate or reside in the lower reaches approximately 3 years after recruitment, and that slower-growing eels emigrate upstream, whereas faster-growing eels reside downstream.