Response of Young-of-the-Year Cutthroat Trout to Manipulation of Habitat Structure in a Small Stream

Abstract

In Mack Creek, a third-order stream flowing through a 450-year-old coniferous forest in Oregon's Cascade Mountains, population size of young-of-the-year cutthroat trout Salmo clarki was positively correlated with length of stream edge and area of lateral habitat. Lateral habitats included backwaters and eddies at the margin of the channel that made up 10-15% of total stream area. Lateral habitat area was reduced at higher or lower streamflow, but the length of channel perimeter formed by lateral habitats was never less than twice the length of the reach. In an experimental manipulation of lateral habitat before the emergence of young fish from the redd, an increase in lateral habitat area of 2.4 times the area observed in control reaches resulted in a 2.2times greater density of age-0 cutthroat trout. Young-of-the-year fish were virtually eliminated from stream sections with reduced area of lateral habitat. Growth was not affected by the greater density of fish in reaches with enhanced lateral habitat.

Bull Trout Life History, Genetics, Habitat Needs, and Limiting Fact in Central and Northeast Oregon. Annual Report 1999.

“…The degree of piscivory depends on the abundance and accessibility of small forage fish. In montane streams young-of-the-year fish reside frequently near stream margins and are not found often in the same microhabitat with large fish (Mundie 1969;Moore and Gregory 1988;Hubert and Rhodes 1992). The difference in microhabitat use between size classes decreases the likelihood of predation on small trout by larger trout.…”

Effect of water depth and water velocity upon the surfacing frequency of the bimodally respiring freshwater turtle,Rheodytes leukops

“…Assuming a similar relationship for freshwater turtles, results from this study suggest that R. leukops preferentially selected low-velocity microhabitats to minimise the metabolic cost required to hold a position with increasing water flow. Support for this assertion comes from investigations on stream-dwelling salmonids, where the distribution and abundance of fish in fast-flowing reaches is determined by the presence of low-velocity cover (Fausch, 1984;Cunjak and Power, 1987;Moore and Gregory, 1988;Facey and Grossman, 1992;Meyer and Griffith, 1997;Vehanen et al, 2000). Moreover, McLaughlin and Noakes (1998) calculated that utilisation of current-velocity refuges by brook trout (Salvelinus fontinalis) decreased the fishes metabolic expenditure by 10%.…”

Changes in habitat use and preference by newly emerged masu salmon fry, <i>Oncorhynchus masou</i>, in Hokkaido streams

“…Lateral habitats with slow and shallow water support benthic invertebrate communities that were important in the diet of cutthroat fry. 12) A distinct shift in microhabitat use by masu salmon juveniles occurred from May to June. Although some juvenile masu used habitats with slow velocity, shallow water and dense cover in June as well as in April and May, others occupied new habitats with fast water velocity and deeper water and less cover.…”