Habitat factors affecting the abundance and distribution of juvenile cutthroat trout (Oncorhynchus clarki) and coho salmon (Oncorhynchus kisutch)

2000 ◽  
Vol 57 (4) ◽  
pp. 766-774 ◽  
Author(s):  
Jordan Rosenfeld ◽  
Marc Porter ◽  
Eric Parkinson
Keyword(s):  
Coho Salmon ◽  
Woody Debris ◽  
Oncorhynchus Kisutch ◽  
Cutthroat Trout ◽  
Habitat Associations ◽  
Channel Width ◽  
Oncorhynchus Clarki ◽  
Small Stream ◽  
Factors Affecting ◽  
Small Streams

The distribution, abundance, and habitat associations of juvenile anadromous coastal cutthroat trout (Oncorhynchus clarki) and coho salmon (Oncorhynchus kisutch) were evaluated using survey data from 119 sites in coastal British Columbia. Both cutthroat and coho occurred at their highest densities in very small streams (<5 m channel width), and bankfull channel width was the single best predictor of cutthroat presence (p = 0.0001) and density (R2 = 0.55). Within a channel, densities of coho and larger (yearling and older) cutthroat parr were highest in pools, while densities of young-of-the-year cutthroat were significantly lower in pools and highest in shallower habitats. Abundance of larger cutthroat parr and pool habitat were positively correlated with large woody debris (LWD) within a subset of intermediate-gradient gravel-cobble streams, where pools appear to be limiting to larger cutthroat parr abundance. More than 50% of pools were formed by scour associated with LWD in streams ranging from 1.2 to 11 m channel width, and pools formed by LWD scour were on average 10% deeper than pools formed by other mechanisms. Disproportionate use of small streams by cutthroat indicates that protection of small stream habitat is important for long-term conservation of sea-run populations.

Effects of increasing winter rearing habitat on abundance of salmonids in two coastal Oregon streams

2000 ◽  
Vol 57 (5) ◽  
pp. 906-914 ◽  
Author(s):  
M F Solazzi ◽  
T E Nickelson ◽  
S L Johnson ◽  
J D Rodgers
Keyword(s):  
Coho Salmon ◽  
Woody Debris ◽  
Cutthroat Trout ◽  
Stream Habitat ◽  
Oncorhynchus Clarki ◽  
Winter Habitat ◽  
Coastal Cutthroat Trout ◽  
Posttreatment Period ◽  
Complex Habitat ◽  
Downstream Migrant

We used a BACI (before-after-control-impact) experimental design to examine the effects of increasing winter habitat on the abundance of downstream migrant salmonids. Two reference streams and two treatment streams were selected in the Alsea and Nestucca basins of Oregon. Population parameters for juvenile coho salmon (Oncorhynchus kisutch), age-0 trout (Oncorhynchus spp.), steelhead (Oncorhynchus mykiss), and coastal cutthroat trout (Oncorhynchus clarki) were estimated each year for 8 years in each stream. Stream habitat was modified to increase the quality and quantity of winter habitat during the summers of 1990 (Nestucca Basin) and 1991 (Alsea Basin). Complex habitat was constructed by adding large woody debris to newly created alcoves and dammed pools. Numbers of coho salmon summer juveniles and smolts increased in the treatment streams relative to the control streams during the posttreatment period. Overwinter survival of juvenile coho salmon also increased significantly in both treatment streams posttreatment. Summer trout populations in the treatment streams did not change, but downstream migrant numbers the following spring did increase. These increases suggest that winter habitat was limiting abundance of all three species.

Density and size of juvenile salmonids in response to placement of large woody debris in western Oregon and Washington streams

2001 ◽  
Vol 58 (2) ◽  
pp. 282-292 ◽  
Author(s):  
Philip Roni ◽  
Thomas P Quinn
Keyword(s):  
Coho Salmon ◽  
Woody Debris ◽  
Cutthroat Trout ◽  
Large Woody Debris ◽  
Response To Treatment ◽  
Oncorhynchus Clarki ◽  
Steelhead Trout ◽  
Density Response ◽  
Total Pool ◽  
Pool Area

Thirty streams in western Oregon and Washington were sampled to determine the responses of juvenile salmonid populations to artificial large woody debris (LWD) placement. Total pool area, pool number, LWD loading, and LWD forming pools were higher in treatment (LWD placement) than paired reference reaches during summer or winter. Juvenile coho salmon (Oncorhynchus kisutch) densities were 1.8 and 3.2 times higher in treated reaches compared with reference reaches during summer and winter, respectively. The response (treatment minus reference) of coho density to LWD placement was correlated with the number of pieces of LWD forming pools during summer and total pool area during winter. Densities of age-1+ cutthroat trout (Oncorhynchus clarki) and steelhead trout (Oncorhynchus mykiss) did not differ between treatment and reference reaches during summer but were 1.7 times higher in treatment reaches during winter. Age-1+ steelhead density response to treatment during summer was negatively correlated with increases in pool area. Trout fry densities did not differ between reaches, but the response of trout fry to treatment was negatively correlated with pool area during winter. Our research indicates that LWD placement can lead to higher densities of juvenile coho during summer and winter and cutthroat and steelhead during winter.

scholarly journals Evaluating Coexistence of Fish Species with Coastal Cutthroat Trout in Low Order Streams of Western Oregon and Washington, USA

Fishes ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Kyle D. Martens ◽  
Jason Dunham
Keyword(s):  
Pacific Northwest ◽  
Species Interactions ◽  
Coho Salmon ◽  
Cutthroat Trout ◽  
Single Species ◽  
The Pacific ◽  
Small Streams ◽  
Coastal Cutthroat Trout ◽  
Multiple Species ◽  
Low Order

When multiple species of fish coexist there are a host of potential ways through which they may interact, yet there is often a strong focus on studies of single species without considering these interactions. For example, many studies of forestry–stream interactions in the Pacific Northwest have focused solely on the most prevalent species: Coastal cutthroat trout. To examine the potential for interactions of other fishes with coastal cutthroat trout, we conducted an analysis of 281 sites in low order streams located on Washington’s Olympic Peninsula and along the central Oregon coast. Coastal cutthroat trout and juvenile coho salmon were the most commonly found salmonid species within these streams and exhibited positive associations with each other for both presence and density. Steelhead were negatively associated with the presence of coastal cutthroat trout as well as with coho salmon and sculpins (Cottidae). Coastal cutthroat trout most frequently shared streams with juvenile coho salmon. For densities of these co-occurring species, associations between these two species were relatively weak compared to the strong influences of physical stream conditions (size and gradient), suggesting that physical conditions may have more of an influence on density than species interactions. Collectively, our analysis, along with a review of findings from prior field and laboratory studies, suggests that the net effect of interactions between coastal cutthroat trout and coho salmon do not appear to inhibit their presence or densities in small streams along the Pacific Northwest.

Osmoregulatory Ability of Wild Coho Salmon (Oncorhynchus kisutch) and Dolly Varden Char (Salvelinus malma) Smolts

1988 ◽  
Vol 45 (8) ◽  
pp. 1487-1490 ◽  
Author(s):  
Scott W. Johnson ◽  
Jonathan Heifetz
Keyword(s):  
Water Temperature ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Dolly Varden ◽  
Salvelinus Malma ◽  
Small Stream ◽  
Fish Size ◽  
Dolly Varden Char ◽  
Seawater Challenge ◽  
Osmoregulatory Ability

Osmoregulatory ability of wild coho salmon (Oncorhynchus kisutch) and Dolly Varden char (Salvelinus malma) smolts migrating from a small stream in southeastern Alaska was assessed by plasma Na+ levels after a 24-h seawater challenge. Osmoregulatory ability of coho salmon was unaffected by time of out-migration, water temperature, and fish size. Osmoregulatory ability of Dolly Varden char was apparently affected by time of out-migration or water temperature but not by fish size. Char migrating in the first half of the migration period, when water temperature was usually < 8.0 °C, had lower plasma Na+ levels than did char migrating in the second half when temperatures were [Formula: see text]. A plasma Na+ threshold of 170 mmol∙L−1, used by others to separate smolts from silvery parr, indicated that 70% of the coho salmon and 80% of the Dolly Varden char we sampled were physiologically prepared to enter seawater. The remaining fish may have suffered some level of osmoregulatory stress.

Empirical relationships between watershed characteristics and coho salmon (Oncorhynchus kisutch) smolt abundance in 14 western Washington streams

2001 ◽  
Vol 58 (7) ◽  
pp. 1453-1463 ◽  
Author(s):  
Rishi Sharma ◽  
Ray Hilborn
Keyword(s):  
Coho Salmon ◽  
Woody Debris ◽  
Oncorhynchus Kisutch ◽  
Empirical Relationships ◽  
Watershed Characteristics ◽  
Valley Slope ◽  
Two Measures ◽  
Western Washington ◽  
Lower Stream ◽  
Habitat Variables

We assembled data on coho salmon (Oncorhynchus kisutch) from 14 streams in western Washington, including annual smolt counts and annual escapement, either as absolute counts or as an index. We also compiled data on large woody debris (number·km%#150;1 of stream), road densities in the watersheds (km road·km%#150;2), gradient of the streams (%), valley slope adjacent to the stream (%), drainage area in the watershed (km2), and pool, pond, and lake areas (m2·km%#150;1). We explored the relationships between habitat variables and two measures of coho production, the maximum production of smolts in the stream (capacity) and the maximum smolts/spawner (productivity). Using the 11 streams with pool and pond counts, we found that pool and pond densities served as good predictors of smolt density (r2 = 0.85 for pools and 0.68 for ponds, independently). Pools produced 0.39 smolts·m%#150;2 and ponds produced 0.07 smolts·m%#150;2 in the multiple regression fit, accounting for 92% of the residual error. We also found that lower valley slopes, lower road densities, and lower stream gradients were correlated with higher smolt density.

Spatial and temporal factors affecting survival in coho salmon (Oncorhynchus kisutch) in the Pacific Northwest

1998 ◽  
Vol 55 (9) ◽  
pp. 2067-2077 ◽  
Author(s):  
Claribel Coronado ◽  
Ray Hilborn
Keyword(s):  
British Columbia ◽  
Pacific Northwest ◽  
Coho Salmon ◽  
Survival Rates ◽  
Oncorhynchus Kisutch ◽  
Dominant Factor ◽  
Spatial And Temporal Patterns ◽  
Factors Affecting ◽  
The Pacific ◽  
Ocean Conditions

Survival rates for coho salmon (Oncorhynchus kisutch) were estimated for all coded wire tag release groups in the Pacific Northwest between 1971 and 1990. The spatial and temporal patterns show considerable geographic variation, with most regions south of northern British Columbia showing declining survival since 1983, while northern areas have shown increasing survival during that period. The number of years of operation explained very little of the variation in survival, and many hatcheries showed major increases in survival after several years of operation. Survival of marked wild fish generally showed the same trend as hatchery fish. We conclude that the dominant factor affecting coho salmon survival since the 1970s is ocean conditions and that there are major geographic differences in the pattern of ocean conditions. The decline in survival seen in British Columbia and south over the last decade suggests that a major reduction in exploitation rates is necessary to maintain the populations.

Estimating the Population Dynamics of Coho Salmon (Oncorhynchus kisutch) Using Pooled Time-Series and Cross-Sectional Data

1985 ◽  
Vol 42 (3) ◽  
pp. 459-467 ◽  
Author(s):  
James L. Anderson ◽  
James E. Wilen
Keyword(s):  
Time Series ◽  
Population Dynamics ◽  
River Flow ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Cross Sectional ◽  
Factors Affecting ◽  
River Region ◽  
Parent Stock ◽  
Pooled Time Series

The population dynamics of natural and hatchery coho salmon (Oncorhynchus kisutch) were estimated for three regions, (1) Washington coastal, (2) Columbia River region, and (3) Oregon/California coastal, using pooled time-series and cross-sectional data. Two functional forms were compared: the Beverton–Holt and Ricker models. Both models yielded very similar results. In both cases, we found that the natural coho stock recruitment is significantly affected by parent stock level (positive), parent stock density (negative), river flow (positive), and hatchery smolt release (negative). The significant factors affecting hatchery coho salmon were smolt release level (positive), smolt release density (negative), and upwelling (positive).

Overwintering habitats of coho salmon (Oncorhynchus kisutch) and other juvenile salmonids in the Keogh River system, British Columbia

1988 ◽  
Vol 66 (1) ◽  
pp. 254-261 ◽  
Author(s):  
S. Swales ◽  
F. Caron ◽  
J. R. Irvine ◽  
C. D. Levings
Keyword(s):  
Gasterosteus Aculeatus ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Cutthroat Trout ◽  
River System ◽  
Salmo Gairdneri ◽  
Dolly Varden Char ◽  
Main River ◽  
The Mean ◽  
Density And Biomass

Catches of overwintering juvenile coho salmon (Oncorhynchus kisutch) in the Keogh River system, Vancouver Island, were higher in two small (8 and 25 ha), shallow (mean depth 2 – 3 m) lakes and their outlet and inlet streams than in the main river, where steelhead trout (Salmo gairdneri) were predominant. Dolly Varden char (Salvelinus malma), cutthroat trout (Salmo clarki), and threespine stickleback (Gasterosteus aculeatus) were also present in the lakes. The distribution of coho salmon in the lakes was restricted largely to areas close to the bank, with few fish being captured in offshore areas or in mid-water. Apparent differences in the abundance of coho salmon between the two lakes may have been related to differences in fish community composition, with sticklebacks being particularly numerous in Misty Lake, where catches of coho salmon were lower than in Long Lake. The population density and biomass of coho salmon overwintering in Long Lake were estimated to be 176 fish/ha and 1.14 kg ha−1, respectively. The mean length of coho salmon in the lakes was greater than that of coho salmon in the tributary streams and main river, and the mean length of the salmon in the lakes generally increased with distance away from shore.

Seasonal variations in stable isotope ratios of juvenile coho salmon (Oncorhynchus kisutch) from western Washington rivers

2008 ◽  
Vol 65 (4) ◽  
pp. 681-690 ◽  
Author(s):  
William L Reichert ◽  
Correigh M Greene ◽  
Robert E Bilby
Keyword(s):  
Stable Isotope ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Cutthroat Trout ◽  
Oncorhynchus Clarkii ◽  
Western Washington ◽  
Temporal And Spatial ◽  
Salmon Parr ◽  
Skagit River ◽  
Salmon Carcasses

Salmon carcasses provide a marine derived nutrient (MDN) subsidy to river systems, but the extent to which it affects juvenile salmon growth is unclear. To evaluate temporal and spatial nutrient contributions from watershed sources and MDNs using stable isotopes, Skagit River (Washington, USA) juvenile coho salmon (Oncorhynchus kisutch) were collected. Muscle samples were taken from fry through smolts to measure temporal changes in δ15N and δ13C. δ15N and δ13C levels declined from emergence until fall, when they approached values for resident cutthroat trout (Oncorhynchus clarkii) collected above anadromous barriers. Muscle δ13C was highly variable and did not increase subsequently. However, coho salmon δ15N increased during the winter. March coho salmon parr δ15N levels suggested high variability in carcass availability for consumption. During the next spring, δ15N levels again declined. In Griffin Creek, a Snoqualmie River tributary, a significant relationship between carcass density and δ15N and δ13C levels was found in March coho salmon parr. At high spawner densities, some parr δ15N exceeded carcass values; however, parr δ13C increased moderately. These findings show that stable isotope data provide insights on seasonal sources of nutrients. In addition, results indicate that March coho salmon parr δ15N levels would be a useful index of carcass availability for overwintering juvenile consumption.

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