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Skewed reproductive success among male white‐spotted charr land‐locked by an erosion control dam: Implications for effective population size
Author(s) -
Maekawa Koji,
Koseki Yusuke,
Iguchi Kei'ichiro,
Kitano Satoshi
Publication year - 2001
Publication title -
ecological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.628
H-Index - 68
eISSN - 1440-1703
pISSN - 0912-3814
DOI - 10.1046/j.1440-1703.2001.00429.x
Subject(s) - tributary , population , reproductive success , biology , ecology , fluvial , mating , fishery , geography , demography , cartography , sociology , paleontology , structural basin
In 1996 and 1997, the spawning behavior of fluvial white‐spotted charr Salvelinus leucomaenis , was observed in the upstream area of an erosion control dam. A small number of males with relatively large body size mated successfully with females as a pair, while almost all satellite males did not sneak successfully, resulting in a non‐random mating system. The low sneaking success of subordinate males, in addition to the monopolization of spawning opportunities by a few dominant males, is one of the most important causes of skewed reproductive success among males. The total number of adult fishes in the study area ( N : approximately half of the whole tributary above a dam) was estimated as 148 and 102 in 1996 and 1997, respectively. Based on these findings and some further assumptions, the estimated effective population size ( N e ) was low in both years. The N e / N ratio ranged from 0.33 to 0.36 in both years. In addition to reduced population size by construction of an impassable dam, the above‐dam population suffered low N e due to skewed reproductive success among males. The low N e may be one cause of extinction in above‐dam populations of fluvial charr, especially just after the construction of impassable barriers.