| Summary: | I investigated colonization patterns of coho salmon (Oncorhynchus kisutch), cutthroat trout (Oncorhynchus clarki), largemouth bass (Micropterus salmoides), and the endangered Salish sucker (Catostomus Sp) and Nooksack dace (Rhinichthys Sp.) into a newly constructed channel in a headwater stream in British Columbia's Fraser Valley over a one-and-a-half year period. Fish fence and mark-recapture data indicated that the study area was colonized by all species beyond the level found in the original channel in terms of numerical abundance indicating no net loss. The densities found in high quality natural habitat were not reached by the end of the study period. A total of 4897 fish entered and 710 exited the study area during the first year. Coho achieved highest numbers and densities in the shortest period followed by cutthroat trout and Salish sucker with few Nooksack dace entering or remaining. Colonization was greatest during the spring months for all species and from upstream and downstream sources. Coho salmon and cutthroat trout were mainly juveniles dispersing shortly after hatching in spring. Salish sucker colonizers were primarily spawning adults. The relatively small number of Salish sucker and Nooksack dace colonizers reflects their rareness, more restricted movements and, in the case of the dace, selectivity of the fences. Other than smolt migration, little coho movement occurred at temperatures below 9°C and most movement took place at temperatures from 10 to 15°C, roughly corresponding to preferred temperatures. Movement of cutthroat trout occurred at temperatures from 2°C to over 20°C. The majority of adult Salish suckers entered from Pepin Brook between temperatures of 4 to 10°C. Males outnumbered females by almost 3:1. The condition factor and growth rates of Salish sucker in the study area were significantly greater than those in mainstem habitat. Largemouth bass moved most often at temperatures above 17°C, consistent with life history characteristics. ANOVA did not reveal consistent statistical results of fish movement in relation to season, temperature and discharge. However, season, discharge and temperature were inter-correlated. The relatively short time frame of movement for the vast number of fishes reflects the need for appropriate physiological, developmental and/or reproductive states of the fish to coincide with appropriate stream conditions for movement to occur together with an attempt to colonize new, unexploited habitat. === Science, Faculty of === Resources, Environment and Sustainability (IRES), Institute for === Graduate
|
|---|
