Spawning site characteristics of Kirikuchi charr Salvelinus leucomaenis japonicus: Southernmost population, and effects of angling pressure
2004
Sato, T. (Mie Univ., Tsu (Japan). Faculty of Bioresources) | Watanabe, K.
Abstract Population size and spawning site environment of the endangered southernmost population of Kirikuchi charr Salvelinus leucomaenis japonicus were investigated in a tributary on the upper reaches of the Totsu River system, Nara Prefecture, central Japan, in 2001. The total number of fish GE 100 mm in fork length (FL) in May was estimated to be 308 =+- 50 (SE). Water depth and gravel size at spawning sites were 15 =+- 13 cm (mean =+- SD) and 31 =+-8 cm, respectively. Spawning sites were found mainly at upstream sites, freely accessible to the fish. The number of fish GE 130 mm in FL had dropped in the lower section of the tributary in July, most probably as a result of leisure fishing. Spawning redds were clearly fewer in the lower sections than further upstream. These results indicated that fishing pressure on the population had been heavy, resulting in a decreased level of reproduction population.
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