PARENT SESSION
Thursday, August 10, 1:30-5:00 pm
COS 96 - Population and community genetics
L-3, Lobby Level, Cook Convention Center
Presiders: J Lau

Dammed fish! Rapid differentiation of steelhead /rainbow trout, Oncorhynchus mykiss, in Pacific Northwest rivers.

Graham, Suzanne^*,1, Moran, Paul², ¹ University of Washington, Seattle, WA² Northwest Fisheries Science Center, Seattle, WA

ABSTRACT- For nearly a century, man-made dams have isolated salmonids in many Pacific Northwest Rivers, preventing these anadromous fish from completing their natural life cycle. Dam construction impedes adult migration to natal streams and creates two separate fish populations: one group of land-locked upstream residents and a second that retains its anadromy. Over time, dam-divided populations may have become adapted to different (upstream vs. downstream) environments, and life history variance between populations could prove to be maladaptive upon dam removal. This project seeks to find a dams unique genetic impact on above and below barrier steelhead/rainbow trout, Oncorhynchus mykiss, populations. Microsatellite markers embedded within 20 sequences of expressed genes were analyzed between above and below barrier groups of O. mykiss. F_ST values show dam effects, with above- and below- dam populations statistically separate. These results show that recently isolated populations can differentiate in a short time period, highlighting the population level impact of dams. By understanding the influence of genetic changes and environmental influences between land-locked and anadromous fish, resource managers can better plan dam construction, restoration and recolonization efforts.

Key words: Ecological Genetics, Reproductive Isolation & Differentiation, Rivers