溜池におけるバラタナゴRhodeus ocellatusの繁殖期と移動
1985 年 32 巻 1 号 p. 79-89
詳細
1985 年 32 巻 1 号 p. 79-89
The spawning period and migration of the rose bitterling, Rhodeus ocellatus (Kner) in a small pond, Shimizu-ike, Osaka Prefecture, were investigated from November 1973 to December 1975.
It was suggested that the population was composed mainly of 0-to 3-year-old fish, and the sex ratio was comfirmed to be one.The spawning period was assumed to be from March to September.Means of both ovipositor length and the proportion of individuals possessing ripe eggs of 2-and 3-year-old females took the highest value from April to the end of May, and that of 1-year-old fish was the highest in late July.The minimum size for reproduction was 23-24mm in body length.
In spawning season, males migrated toward the shore where bivalves were distributed in a high density, and matured females migrated several times between the offshore and the near shore, i.e., after they laid eggs into bivalves at the shore they returned to the offshore.
