IMPORTANCE OF TRIBUTARY STREAMS FOR RAINBOW TROUT REPRODUCTION: INSIGHTS FROM A SMALL STREAM IN GEORGIA AND A BI-GENOMIC APPROACH

Authors


  • The unit is jointly supported by the US Geological Survey, Oklahoma State University, the Oklahoma Department of Wildlife Conservation, the Wildlife Management Institute and the US Fish and Wildlife Service.

J. M. Long, US Geological Survey, Oklahoma Cooperative Fish and Wildlife Research Unit, Department of Natural Resource Ecology and Management, Oklahoma State University, 404 Life Sciences West, Stillwater, OK 74078, USA.

E-mail: longjm@okstate.edu

ABSTRACT

Tributaries of tailwater fisheries in the southeastern USA have been used for spawning by stocked rainbow trout (Oncorhynchus mykiss), but their importance may have been underestimated using traditional fish survey methods such as electrofishing and redd counts. We used a bi-genomic approach, mitochondrial DNA sequences and nuclear microsatellite loci, to estimate the number of spawning adults in one small tributary (Cabin Creek) of the Chattahoochee River, Georgia, where rainbow trout are known to spawn and have successful recruitment. We extracted and analysed DNA from seven mature male rainbow trout and four juveniles that were captured in February 2006 in Cabin Creek and from 24 young-of-year (YOY) trout that were captured in April 2006. From these samples, we estimated that 24 individuals were spawning to produce the amount of genetic variation observed in the juveniles and YOY, although none of the mature males we sampled were indicated as sires. Analysis of the mitochondrial D-loop region identified four distinct haplotypes, suggesting that individuals representing four maternal lineages contributed to the offspring. Our analyses indicated that many more adults were spawning in this system than previously estimated with direct count methods and provided insight into rainbow trout spawning behavior. Copyright © 2011 John Wiley & Sons, Ltd.

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