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Dispersal and tributary immigration by juvenile coho salmon contribute to spatial expansion during colonisation
Author(s) -
Anderson Joseph H.,
Pess George R.,
Kiffney Peter M.,
Bennett Todd R.,
Faulds Paul L.,
Atlas William I.,
Quinn Thomas P.
Publication year - 2013
Publication title -
ecology of freshwater fish
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 55
eISSN - 1600-0633
pISSN - 0906-6691
DOI - 10.1111/j.1600-0633.2012.00589.x
Subject(s) - biological dispersal , colonisation , fish migration , juvenile , tributary , population , ecology , habitat , range (aeronautics) , biology , fishery , geography , colonization , demography , materials science , cartography , sociology , composite material
Anadromous fishes are frequently restricted by artificial barriers to movement such as dams and culverts, so measuring dispersal helps identify sites where improved connectivity could promote range expansion and population viability. We used a combination of DNA ‐based parentage analysis and mark–recapture techniques to evaluate dispersal by juvenile coho salmon ( O ncorhynchus kisutch ) in a population in the initial stages of colonisation following installation of fish passage structures at a previously impassable dam on the C edar R iver, WA , USA . The spatial distribution of individuals within maternal families revealed that dispersal was common. Among the offspring of radio‐tagged mothers, 28% were collected outside the spawning reach and dispersed up to 6.3 km (median = 1.5 km). Most juveniles captured in a tributary ( R ock C reek, where few adults spawned) had immigrated from the C edar R iver and represented many different families. Juvenile dispersal therefore provided a secondary phase of spatial expansion following initial colonisation by adults. Consistent with the condition‐dependent dispersal hypothesis, juveniles that dispersed farther upstream in the tributary were larger than fish collected near the tributary mouth. Overall, the results demonstrated widespread dispersal in a system with low coho salmon densities, and this might increase the rate of population growth if it reduces the effects of local density dependence. By implication, juveniles can take advantage of rearing habitats reconnected through barrier removal, even when such areas are located several kilometres from adult breeding grounds.