琵琶湖産イサザの産卵習性(豫報)
1950 年 15 巻 12 号 p. 808-812
詳細
1950 年 15 巻 12 号 p. 808-812
Chaenogobius isaza TANAKA, an endemic goby, is one of the important fish of Lake Biwa, and its annual catch ranks third among all fishes in that lake.
The life history of this goby has been studied by the present authors in field as well as in aqualia.
This paper is a preliminary report of that study especially of spawning habit.
In spring it spawns in shallow and gravel-bottomed water along the northern coast of the lake. Female parent lays her eggs in a colony on the flat and smooth lower surface of gravels, and the male guards them.
The egg is oblong in shape and (1.5-1.6)×(0.5-0.7mm) in diameter.
The egg colony which is 20-30cm in diameter is circular or elliptical, and composed of 33-997 eggs.
The egg hatches in 152 hours at the water temperature of 16-19°C, and in 115 hours at 16-23°C. The newly hatched larva is 3.06mm in total length; miotomes 30 in number.
The young fish grows to a length of 16mm in late June, 20mm in July, 27mm in August, 30mm in September and 34mm in October.
