Spawning activities and physical characteristics of the spawning ground of Lethenteron reissneri at the headstream of the Himekawa River, central Japan

Autor: Mitsuhiro Takayama
Rok vydání: 2002
Předmět:
Zdroj: Ichthyological Research. 49:165-170
ISSN: 1616-3915
1341-8998
DOI: 10.1007/s102280200022
Popis: The spawning period of the Far Eastern brook lamprey, Lethenteron reissneri, in the headstream of the Himekawa River is estimated to be between mid-March and late May with the peak of spawning activity between early April and early May. The sex ratio (female:male) in 1999 ranged from 1 : 2.5 to 1 : 3.0 (mean 1 : 2.8) and in 2000 from 1 : 0.8 to 1 : 4.0 (mean 1 : 2.4). In >90% of the observations of spawning nests, males outnumbered females. The construction area of spawning nests tended to shift upstream during the spawning period. The nests were constructed at water depths between 5 and 70 cm, water velocity between 10 and 30 cm/s, and on substrate with pebbles of 5–20 mm in diameter. Lethenteron reissneri constructed nests on substrate similar with Petromyzon marinus, but at shallower points and in areas with a slower water velocity.
Databáze: OpenAIRE
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