Off-channel Habitats Research Articles

Effectiveness of Selected Stream Improvement Techniques to Create Suitable Summer and Winter Rearing Habitat for Juvenile Coho Salmon (Oncorhynchus kisutch) in Oregon Coastal Streams

We examined the use of constructed pools by juvenile coho salmon (Oncorhynchus kisutch) during summer and winter. Log, gabion, and rock structures placed across the full stream width provided good summer habitat but poor winter habitat for juvenile coho salmon. Rearing densities in constructed habitats during summer and winter were generally similar to those in natural habitats of the same type, except that constructed dammed pools supported lower densities during winter than natural dammed pools. The addition of brush bundles to pools created by full-stream-width structures increased the density of juvenile coho salmon in dammed pools during winter, but not in plunge pools. We concluded that the development of off-channel habitat has the greatest potential to increase production of wild coho salmon smolts in Oregon coastal streams.

Distribution and Notes on the Biology of Phoxinus eos (Cyprinidae) in Colorado

Distribution of the northern redbelly dace, Phoxinus eos, in the South Platte River Basin, Colorado, was historically restricted to a narrow band of stream habitat in the transition zone along the Front Range of the Rocky Mountains. Phoxinus eos has been taken only in the West Plum Creek drainage since 1951, where it mainly occupies off-channel entic habitats that are cool, clear, vegetated, and without large predaceous fishes. Age and growth, reproduction, and diet characteristics are similar to those known for populations of P. eos in the center of the species' range. The naturally limited range and habitat of P. eos in Colorado has been much reduced by stream channelization, reductions in discharge, and changes in water quality. Continued urban development threatens remaining populations. The northern redbelly dace, Phoxinus eos, inhabits cool, boggy lakes, ponds, and streams in the northern United States and Canada (Scott and Crossman, 1973; Stasiak, 1980). The southern-most population known for the species occurs in the South Platte River Basin, Colorado (Fig. 1). Collections of P. eos in Colorado are uncommon, both historically and at present, and the species is considered rare (Propst and Carlson, 1986). The range of P. eos in Colorado apparently has declined in the period of historic collecting (since 1891), and little is known of the habitat requirements and biology of the species there. The purpose of this paper is to describe the past and present distribution patterns of the species and suggest probable reasons for the decline of P. eos in Colorado. Notes on aspects of the life history and ecology of this species are also presented. MATERIALS AND METHODS-Lotic systems in the South Platte River Basin ranged from cold, highgradient montane streams with large substrate particles to low gradient, seasonally warm, sandybottomed streams on the plains. Streams flowing through a short transition zone between the montane and plains-types had intermediate gradient, substrate, and temperature characteristics. Discharge was maintained primarily by melting snowpack and groundwater discharge. Plum Creek, a south-to-north flowing transition zone stream, emptied into Chatfield Lake, a mainstream reservoir on the South Platte River. The drainage basin encompassed 782 km2 above the U.S. Geological Survey gage near Louviers, Colorado (gage no. 06709500). Mean discharge was 0.96 m3/s; high and low values of 4,360 m3/s and 0.00 m3/s, respectively, have been recorded (United States Geological Survey, 1985). Streams were shallow and braided extensively over a predominantly shifting sand substrate. Runs were the dominant habitat type; pools and riffles were uncommon. Woody riparian vegetation was composed primarily of willow (Salix sp.), and various grasses and sedges grew extensively along stream banks. Instream vegetation was nearly non-existent due to shifting sand and scouring streamflows. Abundant submergent and emergent vegetation grew in or near standing water habitats that were adjacent to mainstream channels. Distributional data were derived from field collections made in conjunction with monitoring studies on transition zone stream reaches in Colorado (T. Chart and S. Gillihan, in litt.; K. D. Fausch, pers. comm.; Department of Fishery and Wildlife Biology, Colorado State University, personal collections), museum records, and the literature. Fishes collected by the author in a survey of Plum Creek were fixed in 10% formalin. Adult fishes were preserved in 45% isopropanol, and age-0 specimens in 3% buffered formalin. Notes of physical habitat parameters, microhabitats, and species associates were HWESTERN URALIST 34(2):225-231 JUNE 1989 The Southwestern Naturalist

Utilization of off-channel habitats by juvenile coho salmon (Oncorhynchus kisutch) in interior and coastal streams in British Columbia

Utilization of off-channel habitats by juvenile coho salmon (<i>Oncorhynchus kisutch</i>) in interior and coastal streams in British Columbia

The Effect of Stream Cleaning on Salmonid Habitat and Populations in a Coastal Oregon Drainage

Abstract Habitat conditions and use by anadromous salmonids were evaluated in five reaches of Upper Lobster Creek, a major stream system in the central Oregon Coast Range, to determine the effect of different levels of stream cleaning. Stream clearance associated with post-World War II logging practices and a 100-year flood event that occured in 1964 severely altered channel configurations and loading patterns of large woody debris. This caused the subsequent removal of log jams. An uncleaned reach had large amounts of woody debris and the highest density of pools, greatest percentage of off-channel habitat, and highest salmonid use. In contrast, a totally cleaned reach had the lowest density of pools and lowest salmonid use. Rehabilitated sections of a reach that had been partially cleaned showed increases in density of pools and salmonid use compared to the remainder of the partially cleaned reach. Retention of standing timber in the riparian zone and maintenance in instream accumulations of large woody debris is recommended to allow streams to reach their productive potential for anadromous salmonids. West. J. Appl. For. 2(3):84-87, July 1987.

Winter habitat preferences of juvenile salmonids in two interior rivers in British Columbia

The winter distribution and abundance of juvenile salmonids was investigated in various main channel and off-channel habitats in the Coldwater and Nicola rivers in the southern interior region of British Columbia. Catches were generally low in all main channel habitats, with coho salmon and steelhead trout being most abundant and chinook salmon and Dolly Varden char being present in smaller numbers. Coho salmon and steelhead trout catches were generally highest in pools with abundant instream and riparian cover. Steelhead trout was the main species in riprap bank protected areas, although catches were generally low. Highest overall catches were recorded in side channels and off-channel ponds, where water temperatures were usually several degrees higher than in the main river. Coho salmon was the main species in the two Coldwater off-channel ponds with overwintering populations of approximately 4000 and 1000 in 1- and 0.1-ha ponds, respectively (0.4–1.5 fish/m2): overwinter survival of coho salmon in the ponds was estimated to be 87 and 54%, respectively. High densities of coho salmon were also recorded in side channels on the Nicola River (1.5–1.8 fish/m2), together with smaller numbers of chinook salmon and steelhead trout (0.2–0.3 fish/m2). Growth in ponds and side channels appeared to be faster than in main channel habitats. We conclude that juvenile salmonids in the rivers investigated showed considerable habitat segregation during the winter. As in coastal rivers, juvenile coho salmon made extensive use of off-channel ponds, while rainbow trout and chinook salmon were generally most abundant in riprap and deep pools containing log debris, respectively.