Differences in spawning migration timing and mortality between males and females of the pelagic goby Gymnogobius isaza in Lake Biwa, central Japan

• Published in: Fisheries science Vol. 90; no. 1; pp. 29 - 39
• Main Authors: Takenaka, Tsuyoshi, Ishizaki, Daisuke, Hatano, Masataka, Fujioka, Yasuhiro, Kai, Yoshiaki, Kikko, Takeshi
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 01.01.2024; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Bottom trawling; Conservation; Endangered & extinct species; Females; Fish; Fish & Wildlife Biology & Management; Fisheries; Fisheries management; Fishery management; Food Science; Freshwater; Freshwater & Marine Ecology; Freshwater lakes; Gillnets; Gymnogobius; Gymnogobius isaza; Inland water environment; Japan; Lakes; Life Sciences; Males; Marine fishes; Mortality; Nature conservation; Offshore; Original Article; Pelagic fisheries; reproduction; Sex ratio; Spawning; Spawning migrations; species; Sufflogobius bibarbatus; summer; Threatened species; Winter; Sex ratio; Freshwater goby; Deep lakes; Spawning migration; Mortality
• ISSN: 0919-9268; 1444-2906
• DOI: 10.1007/s12562-023-01726-1

Isaza Gymnogobius isaza , a small freshwater goby endemic to Lake Biwa, Japan, is categorized as “Endangered” in the International Union for Conservation of Nature Red List of Threatened Species; nevertheless, it remains subject to fishing without any specific management strategies. The sex ratio, and gonadosomatic and hepatosomatic indices of Isaza caught by commercial bottom trawl and set net while migrating to and from an offshore pelagic area and nearshore spawning area were investigated in Lake Biwa from winter to early summer. Male spawning migrations preceded those of females. In addition, mortality during spawning was male-biased. Both findings suggested a possible impact of the commercial set net fishery on Isaza reproduction. Future conservation and fisheries management of the species need to be considered.