Journal articles: 'Salmón Coho'

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Montalico Pongo, Ederson Juan, Héctor Rodríguez Papuico, Julio Larenas Herrera, and Fernando Ricardo Ardito Saenz. "Detección y asociación de Piscirickettsia salmonis en órganos y heces de salmón coho (Oncorhynchus kisutch) cultivado en el mar." Revista de Investigaciones Veterinarias del Perú 32, no. 2 (April 22, 2021): e18041. http://dx.doi.org/10.15381/rivep.v32i2.18041.

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El objetivo de la investigación fue diagnosticar la presencia de Piscirickettsia salmonis en muestras de salmones coho (Oncorhynchus kisutch) provenientes de centros de cultivo de la Región de los Lagos, Chile, que presentaban brotes de piscirickettsiosis. Se emplearon 19 peces con signos clínicos de piscirickettsiosis. Se hicieron frotis de tejido renal, hepático, esplénico y de contenido intestinal que se procesaron mediante la prueba de inmunofluorescencia indirecta (IFI) para la detección de P. salmonis a través de un kit comercial. Los datos obtenidos se sometieron a la prueba de Q de Cochran y de McNemar en la distribución de Chi cuadrado. Se encontró mayor positividad en el hígado (68.4%) y riñón (52.6%). Además, se encontró la bacteria en las heces (47.4%), indicando que la eliminación vía fecal del agente es posible en condiciones de cultivo. Asociando los resultados de riñón e hígado solo de logra detectar el 78.9% de los peces positivos a la bacteria, en tanto que asociando los resultados de hígado, bazo y heces se logra detectar el 100% de los peces positivos a P. salmonis.

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Wehrhahn, C. F., and R. Powell. "Electrophoretic Variation, Regional Differences, and Gene Flow in the Coho Salmon (Oncorhynchus kisutch) of Southern British Colombia." Canadian Journal of Fisheries and Aquatic Sciences 44, no. 4 (April 1, 1987): 822–31. http://dx.doi.org/10.1139/f87-100.

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Populations of coho salmon (Oncorhynchus kisutch) in southern British Columbia were assayed for genetic variation at 26 enzyme loci. The mean heterozygosity was only 0.25 ± 0.06%. Previously studied wild Oregon cohos had a mean heterozygosity of 1.36 ± 0.37% compared with 0.30 ± 0.09% in Lower Coastal Mainland and 0.13 ± 0.08% in Upper Fraser River fish for the same enzyme loci. A plausible explanation for the very low mean heterozygosity is that British Columbia coho salmon went through an extreme population bottleneck during or after the last ice age. Lower Coastal Mainland salmon are significantly different from the fish of Vancouver Island and can be easily distinguished from Oregon and Capilano Hatchery (Coastal Mainland, B.C.) fish, it should be feasible to determine the relative proportions of different stocks in large oceanic coho salmon samples. The maximum likelihood estimate of the migration rate between spawning populations is 5.8 ± 1.2 breeding adults per generation. This is enough to prevent adaptation to local habitats by small populations of fewer than 100 breeding adults, but it is not high enough to impede selection in large populations of 1000 or more breeding adults.

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Pess, George R., David R. Montgomery, E. Ashley Steel, Robert E. Bilby, Blake E. Feist, and Harvey M. Greenberg. "Landscape characteristics, land use, and coho salmon (Oncorhynchus kisutch) abundance, Snohomish River, Wash., U.S.A." Canadian Journal of Fisheries and Aquatic Sciences 59, no. 4 (April 1, 2002): 613–23. http://dx.doi.org/10.1139/f02-035.

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We used temporally consistent patterns in the spatial distribution of returning adult coho salmon (Oncorhynchus kisutch) to explore relationships between salmon abundance, landscape characteristics, and land use patterns in the Snohomish River watershed, Wash. The proportion of total adult coho salmon abundance supported by a specific stream reach was consistent among years, even though interannual adult coho salmon abundance varied substantially. Wetland occurrence, local geology, stream gradient, and land use were significantly correlated with adult coho salmon abundance. Median adult coho salmon densities in forest-dominated areas were 1.53.5 times the densities in rural, urban, and agricultural areas. Relationships between these habitat characteristics and adult coho salmon abundance were consistent over time. Spatially explicit statistical models that included these habitat variables explained almost half of the variation in the annual distribution of adult coho salmon. Our analysis indicates that such models can be used to identify and prioritize freshwater areas for protection and restoration.

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Nickelson, Thomas E., Jeffrey D. Rodgers, Steven L. Johnson, and Mario F. Solazzi. "Seasonal Changes in Habitat Use by Juvenile Coho Salmon (Oncorhynchus kisutch) in Oregon Coastal Streams." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 4 (April 1, 1992): 783–89. http://dx.doi.org/10.1139/f92-088.

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Habitat use by juvenile coho salmon (Oncorhynchus kisutch) during spring, summer, and winter was examined in Oregon coastal streams. Coho salmon fry were most abundant in backwater pools during spring. During summer, juvenile coho salmon were more abundant in pools of all types than they were in glides or riffles. During winter, juvenile coho salmon were most abundant in alcoves and beaver ponds. Because of the apparent strong preference for alcove and beaver pond habitat during winter and the rarity of that habitat in coastal streams, we concluded that if spawning escapement is adequate, the production of wild coho salmon smolts in most coho salmon spawning streams on the Oregon Coast is probably limited by the availability of adequate winter habitat.

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Holtby, L. Blair, Thomas E. McMahon, and J. Charles Scrivener. "Stream Temperatures and Inter-Annual Variability in the Emigration Timing of Coho Salmon (Oncorhynchus kisutch) Smolts and fry and Chum Salmon (O. Keta) Fry from Carnation Creek, British Columbia." Canadian Journal of Fisheries and Aquatic Sciences 46, no. 8 (August 1, 1989): 1396–405. http://dx.doi.org/10.1139/f89-179.

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Variability in average stream temperatures between peak spawning and fry emergence accounted for 82 and 77% of the variance in the median emigration date of fry of chum (Oncorhynchus keta) and coho salmon (O. kisutch) respectively over a 9 to 10-yr period. The modeled relationships were indistinguishable from laboratory models that predicted time to maximum alevin wet weight. Variability in stream temperatures during the spring accounted for 60% of the variability in the median date of coho smolt emigration. As stream temperatures increased, the predicted thermal summations required for emigration were nearly constant for coho salmon fry, increased moderately for chum salmon fry and increased strongly for coho salmon smolts The duration of the emigration period also differed between the groups: 50% of the chum salmon fry emigrated over a 1-wk period compared with a 2- to 3-wk period for coho salmon fry and smolts. We speculate that the emigration timing —temperature relationships and timing of adult spawning represent adaptations for synchronizing emigration with "windows of opportunity" in the ocean or stream. The windows are of different widths and levels of predictability for coho and chum salmon fry and coho salmon smolts.

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Swales, S., F. Caron, J. R. Irvine, and C. D. Levings. "Overwintering habitats of coho salmon (Oncorhynchus kisutch) and other juvenile salmonids in the Keogh River system, British Columbia." Canadian Journal of Zoology 66, no. 1 (January 1, 1988): 254–61. http://dx.doi.org/10.1139/z88-036.

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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.

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Murray, C. B., and J. D. McPhail. "Effect of incubation temperature on the development of five species of Pacific salmon (Oncorhynchus) embryos and alevins." Canadian Journal of Zoology 66, no. 1 (January 1, 1988): 266–73. http://dx.doi.org/10.1139/z88-038.

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Embryo and alevin survival, time to hatching and emergence, and alevin and fry size of five species of Pacific salmon (Oncorhynchus) were observed at five incubation temperatures (2, 5, 8, 11, and 14 °C). No pink (Oncorhynchus gorbuscha) or chum (O. keta) salmon embryos survived to hatching at 2 °C. Coho (O. kisutch) and sockeye (O. nerka) salmon had higher embryo survival at 2 °C than chinook (O. tschawytscha) salmon. At 14 °C, chum, pink, and chinook salmon had higher embryo survival than coho or sockeye salmon. In all species, peaks of embryo mortality occurred at specific developmental stages (completion of epiboly, eye pigmentation, and hatching). Alevin survival to emergence was high for all species, except for coho and pink salmon at 14 °C. Hatching and emergence time varied inversely with incubation temperature, but coho salmon hatched and emerged sooner at all temperatures than the other species. Coho and sockeye salmon alevins were larger at 2 °C, pink, chum, and chinook salmon alevins were larger at 5 and 8 °C. Coho salmon fry were larger at 2 °C, chinook and chum salmon fry were larger at 5 °C, and sockeye and pink salmon fry were larger at 8 °C. High incubation temperatures reduced fry size in all species. Each species of Pacific salmon appears to be adapted to different spawning times and temperatures, and thus indirectly to specific incubation temperatures, to ensure maximum survival and size and to maintain emergence at the most favorable time each year.

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Chalde, Tomás, Cristina F. Nardi, and Daniel A. Fernández. "Early warning: detection of exotic coho salmon (Oncorhynchus kisutch) by environmental DNA and evidence of establishment at the extreme south of Patagonia." Canadian Journal of Fisheries and Aquatic Sciences 76, no. 12 (December 2019): 2343–49. http://dx.doi.org/10.1139/cjfas-2018-0271.

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The global expansion of aquaculture is a constant propagule pressure that enables the establishment of exotic species in freshwater and marine environments. Here, we provide the first report on the presence of exotic coho salmon (Oncorhynchus kisutch) at the extreme south of Patagonia, in the island of Tierra del Fuego (TDF). During the last 6 years, 43 juvenile coho salmon were captured along the Beagle Channel, while one adult was captured in fresh water. Scale analysis showed that migration from fresh water as smolt would occur during their first winter of life. Mitochondrial DNA analyses revealed two haplotypes previously reported in North America and a new haplotype not reported before. We developed an environmental DNA assay for detecting coho salmon DNA from fresh water, obtaining positive results in three rivers. Additionally, one of these rivers was monitored monthly for a year, and we detected coho salmon DNA over 7 months, revealing the probable occurrence of coho salmon juveniles in fresh water. These results suggest the potential establishment of self-sustaining populations of coho salmon in TDF.

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Rand-Weaver, M., P. Swanson, H. Kawauchi, and W. W. Dickhoff. "Somatolactin, a novel pituitary protein: purification and plasma levels during reproductive maturation of coho salmon." Journal of Endocrinology 133, no. 3 (June 1992): 393–403. http://dx.doi.org/10.1677/joe.0.1330393.

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ABSTRACT Somatolactin (SL), a newly discovered fish pituitary protein belonging to the GH/prolactin family, was isolated from coho salmon (Oncorhynchus kisutch). Antibodies were raised to purified coho SL, and a homologous radioimmunoassay was developed and validated. The assay was specific for SL as indicated by the absence of cross-reactivity with coho salmon GH, gonadotrophins I and II and less than 0·2% cross-reaction to prolactin. Serial dilutions of plasma and pituitary extracts from Oncorhynchus species including coho salmon, chinook salmon and rainbow trout were parallel to the coho salmon SL standard curve. Displacement curves for dilutions of Atlantic salmon (Salmo salar) plasma, but not pituitary extract were parallel to the standards. Plasma levels of SL were measured in coho salmon throughout the final year of reproductive maturation. During the period of gonadal growth, plasma SL levels increased and were highly correlated to oestradiol levels in females and 11-ketotestosterone levels in males. Peak levels of SL were observed at the time of final maturation and spawning in both sexes. It is hypothesized that SL may regulate some physiological aspect of reproduction. Journal of Endocrinology (1992) 133, 393–403

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Hargreaves, N. Brent, and Robin J. Lebrasseur. "Species Selective Predation on Juvenile Pink (Oncorhynchus gorbuscha) and Chum Salmon (O. keta) by Coho Salmon (O. kisutch)." Canadian Journal of Fisheries and Aquatic Sciences 42, no. 4 (April 1, 1985): 659–68. http://dx.doi.org/10.1139/f85-085.

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Predation on juvenile pink salmon (Oncorhynchus gorbuscha) and chum salmon (O. keta) by yearling coho (O. kisutch) was studied in marine enclosures in Masset Inlet, B.C. These experiments demonstrate that coho prey selectively upon pink salmon even when chums are both significantly smaller and more abundant than pink salmon. Reexamination of the results of similar experiments conducted in Burke Channel, B.C., also confirms that mortality was biased towards pink salmon. Prey species may be more important than prey size for coho that prey upon mixed populations of pink and chum salmon during early sea-life.

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Salonius, Kira, and George K. Iwama. "Effects of Early Rearing Environment on Stress Response, Immune Function, and Disease Resistance in Juvenile Coho (Oncorhynchus kisutch) and Chinook Salmon (O.tshawytscha)." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 4 (April 1, 1993): 759–66. http://dx.doi.org/10.1139/f93-087.

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Coho (Oncorhynchus kisutch) and chinook salmon (0. tshawytscha) from aquaculture and wild environments were subjected to handling (30–60 s of netting and aerial emersion) and disease challenges. Plasma cortisol concentrations ([cortisol]pl) in both coho and chinook salmon from wild environments were significantly elevated 4 h after handling. Colonized coho salmon (hatchery-reared fish, transported into a natural water body as fry) responded in a similar fashion to wild fish, while those reared entirely in the hatchery showed no significant rise in [cortisol]pl. The responses to handling stress were retained in wild and colonized coho salmon after 7 mo of hatchery rearing. A transient increase in the leukocyte to red blood cell ratio in both wild and hatchery-reared chinook salmon occurred 4 h after handling. Handling signficantly decreased the antibody-producing cell (APC) number in wild fish and elevated their [cortisol]plrelative to hatchery fish. Wild fish had the highest APC number among the three groups before the handling. No difference in resistance to Vibrio anguillarum was apparent in coho and chinook salmon among the different rearing environments, although chinook salmon were generally more susceptible; disease resistance was reduced in wild coho salmon after 7 mo of rearing in a hatchery.

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Anlauf-Dunn, Kara J., Eric J. Ward, Matt Strickland, and Kim Jones. "Habitat connectivity, complexity, and quality: predicting adult coho salmon occupancy and abundance." Canadian Journal of Fisheries and Aquatic Sciences 71, no. 12 (December 2014): 1864–76. http://dx.doi.org/10.1139/cjfas-2014-0162.

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The distribution, quality, and connectivity of instream habitat can influence adult salmon occupancy and abundance patterns and alter population dynamics. In this study, we evaluated the relationships between adult coho salmon (Oncorhynchus kisutch) occupancy and abundance with instream habitat conditions, including measures of spawning gravel, habitat complexity, and juvenile rearing habitat. We used corresponding adult salmon spawning and instream habitat data collected within coastal Oregon watersheds as part of a long-term monitoring program. We modeled two processes as a function of habitat characteristics: the number of coho salmon when they were present and the occupancy probabilities of coho salmon. The results from both submodels were then combined into an estimate of total abundance at each site. Adult coho salmon occupancy was best predicted by the capacity of the habitat to support parr during the winter, complex pools, percent bedrock, and site distance to the ocean. Although lacking the predictive capacity of the occupancy model, increases in adult coho counts at sites were also influenced by the site distance to the ocean, and there is evidence that both percent gravel and complex pools may also be valuable predictors. By taking advantage of long-term datasets with broad spatial range, using an integrative approach across coho salmon life stages, and utilizing innovative Bayesian modeling techniques, this study is a unique approach to understanding a complicated ecological narrative. Combined, our results indicate the spatial distribution and proximity of spawning and rearing habitats may maximize productivity for coho salmon in coastal Oregon watersheds.

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Beamish, Richard J., and Chrys-Ellen M. Neville. "Pacific salmon and Pacific herring mortalities in the Fraser River plume caused by river lamprey (Lampetra ayresi)." Canadian Journal of Fisheries and Aquatic Sciences 52, no. 3 (March 1, 1995): 644–50. http://dx.doi.org/10.1139/f95-064.

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River lamprey (Lampetra ayresi) enter the Strait of Georgia from the Fraser River and feed almost exclusively on Pacific herring (Clupea harengus) and salmon (Oncorhynchus spp.). Although the major prey of river lamprey is Pacific herring, the greater effect of lamprey predation was on the populations of chinook (O. tshawytscha) and coho (O. kisutch) salmon. In 1990 and 1991, river lamprey killed a minimum of 20 million and 18 million chinook salmon, respectively, and a minimum of 2 million and 10 million coho salmon in the same years. In 1991, river lamprey in the Fraser River plume killed an equivalent of approximately 65 and 25% of the total Canadian hatchery and wild production of coho and chinook salmon, respectively. These estimates are probably low because river lamprey also feed in other areas and the abundance estimates are conservative. These high mortality rates indicate that river lamprey predation must be considered as a major source of natural mortality of chinook and coho salmon in the Strait of Georgia.

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Shirvell, C. S. "Role of Instream Rootwads as Juvenile Coho Salmon (Oncorhynchus kisutch) and Steelhead Trout (O. mykiss) Cover Habitat Under Varying Streamflows." Canadian Journal of Fisheries and Aquatic Sciences 47, no. 5 (May 1, 1990): 852–61. http://dx.doi.org/10.1139/f90-098.

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Coho salmon fry (Oncorhynchus kisutch) and steelhead parr (O. mykiss) occupied previously infrequently-used mid-channel areas of Kloiya Creek, British Columbia, Canada, once artificial rootwads were placed there. Ninetynine percent of all coho salmon fry and 83% of steelhead parr occupied positions downstream of natural or artificial rootwads during artificially created drought, normal, and flood streamflows. Fish associated with rootwads regardless of distance from shore, but steelhead parr preferred rootwads away from shore while coho salmon fry preferred rootwads next to shore. Coho salmon fry increased their use of natural rootwads where currents were slow during floods, while steelhead parr increased their use of artificial and natural rootwads where light remained low during droughts. Young fish apparently selected areas having slower water 80% of the time because they provided shelter from adverse current, and areas having reduced light intensities 20% of the time because they provided protection from predators, juvenile coho salmon and steelhead in Kloiya Creek selected locations with slower water velocities and reduced light intensities irrespective of the physical structure that caused them.

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Reichert, William L., Correigh M. Greene, and Robert E. Bilby. "Seasonal variations in stable isotope ratios of juvenile coho salmon (Oncorhynchus kisutch) from western Washington rivers." Canadian Journal of Fisheries and Aquatic Sciences 65, no. 4 (April 1, 2008): 681–90. http://dx.doi.org/10.1139/f07-189.

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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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Anderson, Joseph H., Paul L. Faulds, Karl D. Burton, Michele E. Koehler, William I. Atlas, and Thomas P. Quinn. "Dispersal and productivity of Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon colonizing newly accessible habitat." Canadian Journal of Fisheries and Aquatic Sciences 72, no. 3 (March 2015): 454–65. http://dx.doi.org/10.1139/cjfas-2014-0180.

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Following construction of a fish ladder at Landsburg Diversion Dam on the Cedar River, Washington, USA, in fall 2003, we used DNA-based parentage to identify second generation Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon as recruits that were produced above the dam or “strays” dispersing into the new habitat that were produced elsewhere. For both species, strays colonized immediately but decreased as a proportion of the total run over time. Chinook salmon strays were more numerous in years when the species was more abundant below the dam and included a much larger proportion of hatchery origin salmon than did coho salmon. Productivity, calculated as the ratio of female recruits sampled at the dam to female spawners, exceeded replacement in all four coho salmon cohorts but only two of five Chinook salmon cohorts, leading to more rapid population expansion of coho salmon. However, estimates of fishing mortality and recruitment into the Cedar River below the dam substantially increased Chinook salmon productivity estimates. Our results demonstrate that Pacific salmon are capable of rapidly recolonizing habitat made accessible by restoration and emphasize the importance of demographic exchange with preexisting populations during the transition from recolonization to self-sustainability.

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LI, LINGBO, TONY J. PITCHER, and ROBERT H. DEVLIN. "Potential risks of trophic impacts by escaped transgenic salmon in marine environments." Environmental Conservation 42, no. 2 (September 15, 2014): 152–61. http://dx.doi.org/10.1017/s0376892914000319.

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SUMMARYThere is significant concern about potential ecological effects of introduced organisms, including non-indigenous species and those created by genetic modification. This paper presents an Ecopath with Ecosim modelling approach, designed to examine long-term trophic effects of growth hormone (GH) transgenic coho salmon should they ever escape to a coastal salmonid ecosystem, namely the Strait of Georgia in British Columbia (Canada). The model showed that the effects of introduced GH transgenic coho salmon varied with their biomass, diet, structure of the invaded ecosystem, and environmental conditions. Occasional escapes of non-reproductive salmon did not have a significant impact on the example ecosystem. However, effects of GH coho salmon varied with their diet when large numbers of these fish were present in the simulated ecosystem (for example, when they constituted 20% of total current aquaculture production in the area). Further, climate-driven changes in the biomass of low trophic levels (bottom-up effects) could have a greater impact on the ecosystem than the introduction of large numbers of GH coho salmon. A new version of Ecopath with Ecosim's Monte Carlo approach showed that the model predictions were robust to GH coho salmon's Ecopath parameters, but more sensitive to vulnerabilities of prey to GH coho salmon. Modelling ecosystem effects of genetically modified organisms provides a complementary approach for risk assessments when data from nature are not readily obtainable.

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Swales, S., R. B. Lauzier, and C. D. Levings. "Winter habitat preferences of juvenile salmonids in two interior rivers in British Columbia." Canadian Journal of Zoology 64, no. 7 (July 1, 1986): 1506–14. http://dx.doi.org/10.1139/z86-225.

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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.

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Nickelson, Thomas E., Mario F. Solazzi, Steven L. Johnson, and Jeffrey D. Rodgers. "Effectiveness of Selected Stream Improvement Techniques to Create Suitable Summer and Winter Rearing Habitat for Juvenile Coho Salmon (Oncorhynchus kisutch) in Oregon Coastal Streams." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 4 (April 1, 1992): 790–94. http://dx.doi.org/10.1139/f92-089.

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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.

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Khovanskaya, L. L., and E. A. Ryabukha. "Bio-physiological characteristics for juvenile coho salmon Oncorhynchus kisutch of artifcial and natural origin." Izvestiya TINRO 195 (December 27, 2018): 61–73. http://dx.doi.org/10.26428/1606-9919-2018-195-61-73.

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Results of biological and physiological surveys of juvenile coho salmon from hatcheries of Magadan Region (artifcial origin) and from the main rivers of the northern Okhotsk Sea coast (natural origin) are presented. Biological and morpho-physiological indices of coho fry are compared between different salmon hatcheries and different rivers. Hematological indices for the fsh of natural origin are considered in dynamics. Positive effect of the higher water temperature and longer growing in artifcial conditions on length, body weight, fatness, feeding intensity and morpho-physiological indices of internal organs (liver, intestines) is detected for the coho fry; effect of the water temperature on length and weight of coho salmon in natural conditions is also positive. There is concluded that the coho salmon growing from the larvae under relatively high and stable temperature (4–5 oC) can provide the weight of fry over 0.6 g no later than middle July. If coho salmon is cultivated in conditions of low temperature (0.8–1.0 оС), the short-term growing before release (2.0–2.5 months) under a higher temperature (> 5o) is recommended to improve its fry quality, possibly in the nursery ponds equipped in natural reservoirs — in this case, the juveniles with the weight over 1.0 g could be produced in late August. Hematological indices are measured for different age groups of coho salmon from several rivers. Their dependence on the water temperature was not determined because of high variety of physiological state. However, a signifcant deviation to decrease from the normal values was detected for the red cell count and hemoglobin content in blood of the coho juveniles caught from the Taui River in 2018, obviously reasoned by their younger age and lower size and weight. The juveniles caught from the Yana River in 2016 had no signifcant deviations from the normal values, except of the hematocrit value that indicated stable conditions of their habitat and normal age structure. The hematological indices (hemoglobin content and red cell count) of coho juveniles caught from the Taui River in 2013 and 2014 corresponded to the end of downstream migration. Increasing of hematological indices with age of juveniles is found for coho salmon of natural origin living in favorable environments (favorable water temperature, good food supply).

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Lawson, P. W., E. A. Logerwell, N. J. Mantua, R. C. Francis, and V. N. Agostini. "Environmental factors influencing freshwater survival and smolt production in Pacific Northwest coho salmon (Oncorhynchus kisutch)." Canadian Journal of Fisheries and Aquatic Sciences 61, no. 3 (March 1, 2004): 360–73. http://dx.doi.org/10.1139/f04-003.

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Climate variability is well known to affect the marine survival of coho salmon (Oncorhynchus kisutch) in Oregon and Washington. Marine factors have been used to explain up to 83% of the variability in Oregon coastal natural coho salmon recruitment, yet about half the variability in coho salmon recruitment comes from the freshwater life phase of the life cycle. This seeming paradox could be resolved if freshwater variability were linked to climate and climate factors influencing marine survival were correlated with those affecting freshwater survival. Effects of climate on broad-scale fluctuations in freshwater survival or production are not well known. We examined the influence of seasonal stream flows and air temperature on freshwater survival and production of two stock units: Oregon coastal natural coho salmon and Queets River coho salmon from the Washington Coast. Annual air temperatures and second winter flows correlated strongly with smolt production from both stock units. Additional correlates for the Oregon Coast stocks were the date of first fall freshets and flow during smolt outmigration. Air temperature is correlated with sea surface temperature and timing of the spring transition so that good freshwater conditions are typically associated with good marine conditions.

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Fisher, J. P., and W. G. Pearcy. "Growth of Juvenile Coho Salmon (Oncorhynchus kisutch) off Oregon and Washington, USA, in Years of Differing Coastal Upwelling." Canadian Journal of Fisheries and Aquatic Sciences 45, no. 6 (June 1, 1988): 1036–44. http://dx.doi.org/10.1139/f88-127.

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Estimated growth rates, condition, and stomach fullness of juvenile coho salmon (Oncorhynchus kisutch) caught in the ocean in early summer, when mortality was most variable, were as high in 1983 and 1984, years of very low survival and low early upwelling, as in 1981, 1982, and 1985, years of higher survival and higher early upwelling. Chronic food shortage leading to starvation, poor condition, or slow growth apparently was not the cause of the increased mortality of juvenile coho salmon in 1983 and 1984. Survival of juvenile coho salmon was positively correlated with purse seine catches of fish in June and with early summer upwelling, 1981–85. Hence, year-class success probably was determined early in the summer, soon after most juvenile coho salmon entered the ocean. Spacing of the first five ocean circuli, which was positively correlated with growth rate, was not significantly different for fish caught early in the summer and those caught late in the summer, suggesting that growth rate selective mortality in the ocean was not strong. The increase in mortality in 1983 and 1984 may have been caused by increased predation on juvenile coho salmon due to decreased numbers of alternative prey for predators.

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Rinella, Daniel J., Mark S. Wipfli, Craig A. Stricker, Ron A. Heintz, and Matthew J. Rinella. "Pacific salmon (Oncorhynchus spp.) runs and consumer fitness: growth and energy storage in stream-dwelling salmonids increase with salmon spawner density." Canadian Journal of Fisheries and Aquatic Sciences 69, no. 1 (January 2012): 73–84. http://dx.doi.org/10.1139/f2011-133.

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We examined how marine-derived nutrients (MDN), in the form of spawning Pacific salmon, influenced the nutritional status and δ15N of stream-dwelling fishes. We sampled juvenile coho salmon ( Oncorhynchus kisutch ) and Dolly Varden ( Salvelinus malma ) during spring and fall from 11 south-central Alaskan streams that ranged widely in spawning salmon biomass (0.1–4.7 kg·m–2). Growth rate (as indexed by RNA–DNA ratios), energy density, and δ15N enrichment in spring-sampled fishes increased with spawner biomass, indicating the persistence of spawner effects more than 6 months after salmon spawning. Point estimates suggest that spawner effects on nutrition were substantially greater for coho salmon than Dolly Varden (268% and 175% greater for growth and energy, respectively), indicating that both species benefitted physiologically, but that juvenile coho salmon accrued more benefits than Dolly Varden. Although the data were less conclusive for fall- than spring-sampled fish, they do suggest spawner effects were also generally positive during fall, soon after salmon spawned. In a follow-up analysis where growth rate and energy density were modeled as a function of δ15N enrichment, results suggested that both increased with MDN assimilation, especially in juvenile coho salmon. Our results support the importance of salmon runs to the nutritional ecology of stream-dwelling fishes.

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Kaiser, J. "CONSERVATION BIOLOGY: When Is a Coho Salmon Not a Coho Salmon?" Science 294, no. 5548 (November 30, 2001): 1806–7. http://dx.doi.org/10.1126/science.294.5548.1806.

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25

Quinn, Thomas P., and Graeme M. Tolson. "Evidence of chemically mediated population recognition in coho salmon (Oncorhynchus kisutch)." Canadian Journal of Zoology 64, no. 1 (January 1, 1986): 84–87. http://dx.doi.org/10.1139/z86-013.

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To test the hypothesis that population-specific pheromones guide adult salmonids to their natal streams, juvenile and adult coho salmon (Oncorhynchus kisutch) were tested for chemosensory responses in two-choice tanks. Coho salmon from Quinsam and Big Qualicum rivers, British Columbia, Canada, distinguished their own population from the other. Tagging evidence indicates that straying between these two rivers and a third, geographically intermediate river seldom occurs. Thus, population-specific chemicals constitute a potential source of information for homing coho salmon, though their role vis-à-vis imprinted odors from other sources could not be evaluated.

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Quinn, Thomas P., and Toshiaki J. Hara. "Sibling recognition and olfactory sensitivity in juvenile coho salmon (Oncorhynchus kisutch)." Canadian Journal of Zoology 64, no. 4 (April 1, 1986): 921–25. http://dx.doi.org/10.1139/z86-139.

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Previous experiments indicated that juvenile coho salmon (Oncorhynchus kisutch) can distinguish the chemical traces of siblings from nonsiblings of their own population. The present study confirmed the finding that coho salmon use chemoreceptor systems to distinguish tankmate siblings from nonsiblings that they have not been reared with. However, salmon did not distinguish siblings from nonsiblings or maternal half-siblings if they had been reared together. Electrophysiological experiments demonstrated that the olfactory sense of young coho salmon can detect certain amino acids and a bile acid at concentrations of about 10−8 to 10−9 M. Additional tests suggest that bile acids are probably of primary importance in chemically characterizing conspecifics and amino acids play a secondary role.

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27

Shirvell, C. S. "Effect of Changes in Streamflow on the Microhabitat Use and Movements of Sympatric Juvenile Coho Salmon (Oncorhynchus kisutch) and Chinook Salmon (O. tshawytscha) in a Natural Stream." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 7 (July 1, 1994): 1644–52. http://dx.doi.org/10.1139/f94-165.

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The microhabitats at positions selected by juvenile coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) following a change in streamflow differed from microhabitats occupied at normal streamflows. At drought streamflow (37% mean seasonal streamflow (MSF)), juvenile coho salmon selected slower, darker, and higher sites above the streambed (P < 0.05) than sites selected at normal (75% MSF) or flood (159% MSF) flows. Juvenile chinook salmon microhabitat use changed similarly with changes in streamflow, but the differences were not significant. Up to one fifth of the fish chose positions with faster water velocities than those available either 30 cm above or 30 cm lateral to them. These fish chose positions inconsistent with the hypothesis of optimal position selection based on maximizing net energy gain. On average, fish moved 6.8 m following a change in streamflow. Juvenile coho salmon generally moved upstream in response to decreasing streamflows and downstream in response to increasing streamflows. Juvenile chinook salmon tended to move offshore and downstream in response to all streamflow changes. These results show that juvenile coho and chinook salmon will move to find suitable microhabitat following a change in streamflow and that the microhabitats are not the same at all streamflows.

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Losee, James P., Jessica A. Miller, William T. Peterson, David J. Teel, and Kym C. Jacobson. "Influence of ocean ecosystem variation on trophic interactions and survival of juvenile coho and Chinook salmon." Canadian Journal of Fisheries and Aquatic Sciences 71, no. 11 (November 2014): 1747–57. http://dx.doi.org/10.1139/cjfas-2014-0043.

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The community of trophically transmitted marine parasites of juvenile coho (Oncorhynchus kisutch) and Chinook (Oncorhynchus tshawytscha) salmon across 8 years (2002–2009) was related to indices of physical and biological ocean conditions and adult returns. When the biomass of lipid-poor, southern origin copepods in the coastal ocean was high during juvenile salmon outmigration from fresh water (April–June), yearling coho and Chinook salmon harbored a different trophically transmitted parasite fauna and exhibited lower survival compared with years when the southern copepod biomass was low. As copepods are key intermediate hosts in many marine parasite life cycles, these results support a trophic linkage between the copepod community and salmon prey. Interannual variation in the parasite community was correlated with survival of coho salmon (r = −0.67) measured 1 year later and adult returns of Upper Columbia River summer and fall Chinook salmon (r = −0.94) 3 years from the time of ocean entry.

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Muzzall, Patrick M., and C. Robert Peebles. "Helminths of pink salmon, Oncorhynchus gorbuscha, from five tributaries of Lake Superior and Lake Huron." Canadian Journal of Zoology 64, no. 2 (February 1, 1986): 508–11. http://dx.doi.org/10.1139/z86-075.

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Adult salmon (93 pink salmon, Oncorhynchus gorbuscha; 8 coho salmon, O. kisutch; and 5 chinook salmon, O. tshawytscha) were collected from four tributaries of Lake Superior and one of Lake Huron in September–October 1983 and 1984, and examined for helminths. Fourteen species (1 Digenea, 4 Cestoda, 6 Nematoda, 3 Acanthocephala) were found in the digestive tract and other viscera. Nine, 6, and 7 new host records are reported for pink, coho, and chinook salmon, respectively. Cystidicola farionis and Echinorhynchus salmonis were the most common and numerous helminths in each salmon species. Fifty pink salmon fry and 35 chinook salmon fry collected in May 1984 were negative for parasites.

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30

Carney, B. L., A. K. Gray, and A. J. Gharrett. "Mitochondrial DNA restriction site variation within and among five populations of Alaskan coho salmon (Oncorhynchus kisutch)." Canadian Journal of Fisheries and Aquatic Sciences 54, no. 4 (April 1, 1997): 940–49. http://dx.doi.org/10.1139/f96-325.

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Mitochondrial DNA (mtDNA) from three Gulf of Alaska and two Bering Sea populations of coho salmon (Oncorhynchus kisutch) was assayed with 21 restriction endonucleases. A restriction site map was constructed for 15 enzymes that recognized hexanucleotide sequences and aligned to the rainbow trout (Oncorhynchus mykiss) gene map using the restriction map and known coho salmon sequences. The restriction site map and gene order of the coho salmon mtDNA genome are consistent with those of rainbow trout. Variation was observed for six enzymes at 10 sites that resulted in eight haplotypes. Variability and divergence observed exceeded those previously observed for allozyme loci in coho salmon. When variability that occurred only in single individuals was eliminated, two haplotypes that differed by four restriction sites remained. Variation at these sites was confirmed from polymerase chain reaction (PCR) amplified fragments. Bering Sea populations exhibited more variation than Gulf of Alaska populations. Explanations for the differences include more recent colonization by or smaller sizes of Gulf of Alaska populations.

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31

Volobuev, V. V., M. N. Gorokhov, A. M. Korshukova, and D. V. Makarov. "Biological characteristics, stock condition and commercial use of coho salmon Oncorhynchus kisutch (Walbaum) in Magadan Region at the beginning of the XXI century." Researches of the aquatic biological resources of Kamchatka and the North-West Part of the Pacific Ocean 1, no. 56 (December 8, 2020): 74–83. http://dx.doi.org/10.15853/2072-8212.2020.56.74-83.

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The information about of the features of the biological structure of coho salmon is provided, the issues of the dynamics of spawning runs, commercial use and adult escapement for spawning grounds are considered. The importance of coho salmon as commercial or recreational fishery object is demonstrated.

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Bugaev, V. F., G. V. Bazarkin, and D. P. Pogorelova. "FORMATION OF «FALSE ANNUAL RINGS» ON SCALES OF JUVENILE COHO SALMON ONCORHYNCHUS KISUTCH IN LAKE KURAZHECHNOYE (KAMAKOVSKAYA LOWLAND — KAMCHATKA RIVER BASIN)." Izvestiya TINRO 198 (October 2, 2019): 77–92. http://dx.doi.org/10.26428/1606-9919-2019-198-77-92.

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During spring-summer flood (in mid May — July), transit underyearlings of coho salmon, having or having no scales, migrate to Lake Kurazhechnoye at the lower Kamchatka River, where resident coho salmon never spawn. In this case, additional zones of closely–spaced sclerites (ZCS) can be formed on their scales because of feeding change (additional ZCS of the 1st type). Seasonal growth restarts and annual zone of close sclerites (annual ring) forms in May (or in early June for a part of juveniles) on scales of yearlings and elder coho salmon wintered in Lake Kurazhechnoye. In late July — August or sometimes later, other additional ZCS could form on the scale of juvenile coho salmon (ages 1+ and 2+) in the lake (additional ZCS of the 2nd type) because of their switching to feeding by fish (ninespine stickleback Pungitius pungitius, threespine stickleback Gasterosteus aculeateus, and smelt Hipomesus olidus). Rate of the sclerites forming was examined for the coho juveniles of age 1+ in Lake Kurazhechnoye in 2001 and evaluated as 8.52 days/sclerite, on average (one sclerite was formed in 9.18 days between June 13 — July 5 but in 7.86 days between July 5–23).

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Parkinson, Eric A., Chris J. Perrin, Daniel Ramos-Espinoza, and Eric B. Taylor. "Evidence for Freshwater Residualism in Coho Salmon, Oncorhynchus kisutch, From a Watershed on the North Coast of British Columbia." Canadian Field-Naturalist 130, no. 4 (March 29, 2017): 336. http://dx.doi.org/10.22621/cfn.v130i4.1928.

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The Coho Salmon, Oncorhynchus kisutch, is one of seven species of Pacific salmon and trout native to northeastern Pacific Ocean watersheds. The species is typically anadromous; adults reproduce in fresh water where juveniles reside for 1–2 years before seaward migration after which the majority of growth occurs in the ocean before maturation at 2–4 years old when adults return to fresh water to spawn. Here, we report maturation of Coho Salmon in two freshwater lakes on the north coast of British Columbia apparently without their being to sea. A total of 15 mature fish (11 males and four females) were collected in two lakes across two years. The mature fish were all at least 29 cm in total length and ranged in age from three to five years old. The occurrence of Coho Salmon that have matured in fresh water without first going to sea is exceedingly rare in their natural range, especially for females. Such mature Coho Salmon may represent residual and distinct breeding populations from those in adjacent streams. Alternatively, they may result from the ephemeral restriction in the opportunity to migrate seaward owing to low water levels in the spring when Coho Salmon typically migrate to sea after 1–2 years in fresh water. Regardless of their origin, the ability to mature in fresh water without seaward migration may represent important adaptive life history plasticity in response to variable environments.

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Habicht, Christopher, James E. Seeb, Richard B. Gates, Irvin R. Brock, and Carmen A. Olito. "Triploid Coho Salmon Outperform Diploid and Triploid Hybrids Between Coho Salmon and Chinook Salmon During Their First Year." Canadian Journal of Fisheries and Aquatic Sciences 51, S1 (December 19, 1994): 31–37. http://dx.doi.org/10.1139/f94-292.

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Sterile hybrid and triploid fish may provide hatchery programs with a tool to reduce the risk of genetic contamination of wild stocks, provided these fish have acceptable performance characteristics. We examined growth, survival, and deformities in diploid and triploid families of coho salmon (Oncorhynchus kisutch) and hybrids between coho salmon females × chinook salmon (O. tshawytscha) males. Data were collected from the half-sibling families through day 387. A reparameterized Gompertz growth model showed that conspecific coho salmon grew faster than hybrids, regardless of ploidy. No difference in growth rates was found between diploids and triploids. Abnormalities were significantly associated with the male parent but not with ploidy component, in contrast to previous observations of reduced deformity occurrence in triploid hybrids. Food conversion was better for conspecifics than hybrids during initial feeding, but not different during the second half of the experiment. No ploidy or cross × ploidy interaction effects on food conversion efficiency were observed. Finally, conspecifics had better posthatching survival than hybrids, regardless of ploidy. Of the treatments studied, conspecific triploid coho salmon may be the most viable alternative for sterile fish production: they performed as well as the conspecific diploids and better than either diploid or triploid hybrids.

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Murphy, Michael L., K. V. Koski, J. Mitchel Lorenz, and John F. Thedinga. "Downstream migrations of juvenile Pacific salmon (Oncorhynchus spp.) in a glacial transboundary river." Canadian Journal of Fisheries and Aquatic Sciences 54, no. 12 (December 1, 1997): 2837–46. http://dx.doi.org/10.1139/f97-178.

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Migrations of juvenile Pacific salmon (Oncorhynchus spp.) in the glacial Taku River (seventh order) were studied to assess movement from upriver spawning areas (in British Columbia) into lower-river rearing areas (in Alaska). Differences between fyke-net catches in the river and seine catches in the river's estuary indicated that many downstream migrants remained in the lower river instead of migrating to sea. In particular, age-0 coho salmon (O. kisutch) and chinook salmon (O. tshawytscha) moved downriver from May to November but were not caught in the estuary. Age-0 sockeye salmon (O. nerka), coho presmolts, and other groups delayed entry into the estuary after moving downriver. We tagged groups of juvenile coho (ages 0-2) from the fyke net with coded-wire to determine when they left the river. One-third of all tags recovered from sport and commercial fisheries occurred 2-3 years later, showing that many coho remained in fresh water for 1-2 years after moving to the lower river. Lower-river areas of large glacial rivers like the Taku River can provide essential rearing habitat for juvenile salmon spawned upriver and are important to consider in integrated whole-river management of transboundary rivers.

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Bucklin, Katherine A., Michael A. Banks, and Dennis Hedgecock. "Assessing genetic diversity of protected coho salmon (Oncorhynchus kisutch) populations in California." Canadian Journal of Fisheries and Aquatic Sciences 64, no. 1 (January 1, 2007): 30–42. http://dx.doi.org/10.1139/f06-171.

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California coho salmon (Oncorhynchus kisutch) are under legal protection owing to significant declines in abundance over the last decades. Previously, California coho salmon were characterized as having low genetic diversity and weak population subdivision, attributable potentially to homogenization by out-of-basin hatchery releases. Here, diversity at seven highly polymorphic microsatellite DNA markers is assessed within and among 32 collections of coho salmon from 16 California watersheds. In 71% of local populations, genotypic composition deviates significantly from that expected under the assumption of random mating. We develop and apply methods to adjust for two potential causes of deviation from random mating expectations: (i) Wahlund effects, owing to heterogeneous collections of individuals, and (ii) the "Allendorf–Phelp's effect", owing to closely related juveniles in samples. Such population-level "adjustments" reduce within-region and increase among-region variance; after adjustment, we find strong concordance of genetic and geographic distances. We conclude that stock transfers have had minimal impact on population structure and that California coho salmon populations likely comprise small numbers of endemic breeders, potentially experiencing high levels of genetic drift and inbreeding.

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Lang, Dirk W., Gordon H. Reeves, James D. Hall, and Mark S. Wipfli. "The influence of fall-spawning coho salmon (Oncorhynchus kisutch) on growth and production of juvenile coho salmon rearing in beaver ponds on the Copper River Delta, Alaska." Canadian Journal of Fisheries and Aquatic Sciences 63, no. 4 (April 1, 2006): 917–30. http://dx.doi.org/10.1139/f05-268.

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This study examined the influence of fall-spawning coho salmon (Oncorhynchus kisutch) on the density, growth rate, body condition, and survival to outmigration of juvenile coho salmon on the Copper River Delta, Alaska, USA. During the fall of 1999 and 2000, fish rearing in beaver ponds that received spawning salmon were compared with fish from ponds that did not receive spawners and also with fish from ponds that were artificially enriched with salmon carcasses and eggs. The response to spawning salmon was variable. In some ponds, fall-spawning salmon increased growth rates and improved the condition of juvenile coho salmon. The enrichment with salmon carcasses and eggs significantly increased growth rates of fish in nonspawning ponds. However, there was little evidence that the short-term growth benefits observed in the fall led to greater overwinter growth or survival to outmigration when compared with fish from the nonspawning ponds. One potential reason for this result may be that nutrients from spawning salmon are widely distributed across the delta because of hydrologic connectivity and hyporheic flows. The relationship among spawning salmon, overwinter growth, and smolt production on the Copper River Delta does not appear to be limited entirely to a simple positive feedback loop.

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Leatherland, J. F., L. Lin, N. E. Down, and E. M. Donaldson. "Thyroid Hormone Content of Eggs and Early Developmental Stages of Five Oncorhynchus Species." Canadian Journal of Fisheries and Aquatic Sciences 46, no. 12 (December 1, 1989): 2140–45. http://dx.doi.org/10.1139/f89-264.

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Measurements were made of thyroxine (T4) and triiodothyronine (T3) levels in the embryos and larvae of five species of the genus Oncorhynchus. Pink salmon (O. gorbuscha) embryos and larvae contained relatively low levels of both T4 and T3 throughout the early developmental stages. Sockeye salmon (O. nerka) had the highest levels of T4, with coho (O. kisutch), chum (O. keta), and chinook salmon (O. tshawytscha) having similar total T4 content. The chinook salmon embryos contained the highest T3 content of the five species studied, pink, sockeye, and chum salmon embryos had relatively low levels, and coho salmon embryos had intermediate levels of T3. In the pink salmon, there was little evidence of significant change in either T4 or T3 during development. In the other four species, the T4 content changed little between fertilization and hatch, but fell thereafter to stabilize at levels close to the lower detectable range of the assay used, except in the sockeye salmon larvae in which the values were considerably higher. The T3 content of chinook and coho salmon changed with development in a manner comparable with that observed for T4, but there was little evidence of a comparable posthatch decline in T3 levels in chum, sockeye, or pink salmon.

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Hargreaves, N. Brent, and Robin J. LeBrasseur. "Size Selectivity of Coho (Oncorhynchus kisutch) Preying on Juvenile Chum Salmon (O. keta)." Canadian Journal of Fisheries and Aquatic Sciences 43, no. 3 (March 1, 1986): 581–86. http://dx.doi.org/10.1139/f86-069.

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Predation may be a major source of size-dependent mortality of Pacific salmon (Oncorhynchus spp.) during early sea life. Our experiments conducted in large saltwater enclosures demonstrated that coho (Oncorhynchus kisutch) are size selective when preying on juvenile chum (O. keta) salmon. Yearling coho (112–130 mm fork length) consumed significantly more smaller chum over a range in prey size of 43–63 mm fork length. We hypothesize that the intensity of size selectivity by coho and other predators is variable, depending on the relative sizes of the predators and prey.

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Campbell, Pamela M., Marc P. Fernandez, Stephanie Royston, Jack L. Smith, Paul van Poppelen, Michael G. Ikonomou, and Robert H. Devlin. "Male Coho Salmon (Oncorhynchus kisutch) Exposed to a Time-Course of Urban Sewage Effluent Exhibit a Sporadic Low Incidence of Sex Reversal and Intersex." Water Quality Research Journal 41, no. 3 (August 1, 2006): 235–43. http://dx.doi.org/10.2166/wqrj.2006.027.

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Abstract Developing coho salmon alevin (Oncorhynchus kisutch) were exposed to concentrations of 1 to 10% municipal wastewater effluent (MWWE) during the labile period of sexual differentiation. MWWE was collected at regular time intervals from a municipal wastewater treatment plant during a 4-week period that coincided with the latter part of the spawning season of coho salmon. The salmon were exposed, from just prior to hatch until 28 d post hatch, to MWWE collected at 3 a.m., 8 a.m., 3 p.m. or 8 p.m. Subsequent gonadal development was assessed by histology and compared to genetic sex as determined by Y-chromosomal DNA markers. The MWWE (analyzed using GC-HRMS) had relatively high concentrations of steroidal estrogens and other endocrine active substances at some time points during the exposure period. A low incidence of intersex and sex reversal was noted in the coho salmon exposed to MWWE collected at only two time points; 3 a.m. (1% MWWE) and 8 p.m. (10% MWWE), and ≤19% of the male fish in these exposure groups were affected. The coho salmon utilized were of wild genetic backgrounds and thus the sporadic nature of the response observed may be due to a significant genetic influence on the ability to respond to exogenous hormones at this early stage of development.

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Steel, E. A., D. W. Jensen, K. M. Burnett, K. Christiansen, J. C. Firman, B. E. Feist, K. J. Anlauf, and D. P. Larsen. "Landscape characteristics and coho salmon (Oncorhynchus kisutch) distributions: explaining abundance versus occupancy." Canadian Journal of Fisheries and Aquatic Sciences 69, no. 3 (March 2012): 457–68. http://dx.doi.org/10.1139/f2011-161.

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Distribution of fishes, both occupancy and abundance, is often correlated with landscape-scale characteristics (e.g., geology, climate, and human disturbance). Understanding these relationships is essential for effective conservation of depressed populations. We used landscape characteristics to explain the distribution of coho salmon ( Oncorhynchus kisutch ) in the Oregon Plan data set, one of the first long-term, probabilistic salmon monitoring data sets covering the full range of potential habitats. First we compared data structure and model performance between the Oregon Plan data set and two published data sets on coho salmon distribution. Most of the variation in spawner abundance occurred between reaches but much also occurred between years, limiting potential model performance. Similar suites of landscape predictors are correlated with coho salmon distribution across regions and data sets. We then modeled coho salmon spawner distribution using the Oregon Plan data set and determined that landscape characteristics could not explain presence vs. absence of spawners but that the percentage of agriculture, winter temperature range, and the intrinsic potential of the stream could explain some variation in abundance (weighted average R2 = 0.30) where spawners were present. We conclude that the previous use of nonrandom monitoring data sets may have obscured understanding of species distribution, and we suggest minor modifications to large-scale monitoring programs.

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Taylor, Eric B., and J. D. McPhail. "Variation in Body Morphology Among British Columbia Populations of Coho Salmon, Oncorhynchus kisutch." Canadian Journal of Fisheries and Aquatic Sciences 42, no. 12 (December 1, 1985): 2020–28. http://dx.doi.org/10.1139/f85-249.

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Ten populations of juvenile coho salmon, Oncorhynchus kisutch, from streams tributary to the upper Fraser River, the lower Fraser River, and the Strait of Georgia region were morphologically compared. Juveniles from coastal streams (Fraser River below Hell's Gate and the Strait of Georgia) were more robust (deeper bodies and caudal peduncles, shorter heads, and larger median fins) than interior Juveniles. Discriminant function analysis indicated that juvenile coho could be identified as to river of origin with 71% accuracy. Juvenile coho from coastal streams were less successfully classified as to stream of origin; however, juveniles could be successfully identified as either coastal or interior with 93% accuracy. Juvenile coho from north coastal British Columbia, Alaska, and the upper Columbia system also fitted this coastal and interior grouping. This suggests that a coastwide coastal–interior dichotomy in juvenile body form exists. Three populations (one interior and two coastal) were studied in more detail. In these populations the coastal versus interior morphology was consistent over successive years, and was also displayed in individuals reared from eggs in the laboratory. Adult coho salmon also showed some of the coastal–interior morphological differences exhibited by juveniles. We concluded that the morphological differences between coastal and interior coho salmon are at least partially inherited.

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Tanasichuk, Ronald W., Jodi Grayson, Jennifer Yakimishyn, Seaton Taylor, and Gary D. Dagley. "The Early Marine Biology of the Hatchery/Wild Juvenile Salmonid (Oncorhynchus sp.) Community in Barkley Sound, Canada." Open Fish Science Journal 7, no. 1 (March 7, 2014): 8–22. http://dx.doi.org/10.2174/1874401x01407010008.

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We conducted 11 purse seine/beachseine surveys over the summers of 2000 and 2001 to learn about the migration timing, distribution, and diet of hatchery chinook (Oncorhynchus tshawytscha) and coho (O. kisutch), and wild chinook, coho, sockeye (O. nerka) and chum (O. keta) juvenile salmon, in Barkley Sound, West Coast Vancouver Island. Juvenile salmon partitioned Barkley Sound by time and space, and by diet except for hatchery and wild coho. The analysis of migration timing included historic data for 1987-89, and results showed that timing differed between species and was consistent over years. Sockeye and chum dominated the juvenile salmon community until mid-June and hatchery and wild chinook dominated subsequently. Fish tended to be dispersed contagiously. Results of correlation analyses of catch suggested that fish of different origins and species did not co-occur. The euphausiid Thysanoessa spinifera was an important prey item but different fish species selected different sizes of T. spinifera at different times. The diet overlap between hatchery and wild coho did not affect return. Migration timing for sockeye and wild coho seems to reflect a strategy to enter the ocean when the biomass of the size fraction of T. spinifera that each species selects is likely to be maximal. Descriptions of migration timing, fish interactions, and diet provide information which appears to be useful for learning about the biological basis of salmon return variability.

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Beacham, Terry D., Colin Wallace, Cathy MacConnachie, Kim Jonsen, Brenda McIntosh, John R. Candy, Robert H. Devlin, and Ruth E. Withler. "Population and individual identification of coho salmon in British Columbia through parentage-based tagging and genetic stock identification: an alternative to coded-wire tags." Canadian Journal of Fisheries and Aquatic Sciences 74, no. 9 (September 2017): 1391–410. http://dx.doi.org/10.1139/cjfas-2016-0452.

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Parentage-based tagging (PBT) and genetic stock identification (GSI) were used to identify individual coho salmon (Oncorhynchus kisutch) to specific populations and brood years. In total, 20 242 individuals from 117 populations were genotyped at 304 single nucleotide polymorphisms (SNPs) via direct sequencing of amplicons. Coho salmon from 15 populations were assigned via parentage analysis that required the genotypes of both parents. The overall accuracy of assignment for 1939 coho salmon to the correct population was 100%, and to correct brood year within population was also 100%. Inclusion of individuals requiring only a single parental genotype for identification resulted in assignments of 2101 individuals, with an accuracy of 99.95% (2000–2001) to population and 100.0% to age. With 23 regions defined by the coded-wire tag (CWT) program, and individuals displaying an assignment probability <0.85 excluded from the analysis, mean regional assignment accuracy of individuals via GSI was 98.4% over all 23 regions. A PBT–GSI or PBT system of identification will provide an alternate method of identification in the assessment and management of Canadian-origin coho salmon relative to the existing CWT program.

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Anderson, James L., and James E. Wilen. "Estimating the Population Dynamics of Coho Salmon (Oncorhynchus kisutch) Using Pooled Time-Series and Cross-Sectional Data." Canadian Journal of Fisheries and Aquatic Sciences 42, no. 3 (March 1, 1985): 459–67. http://dx.doi.org/10.1139/f85-062.

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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).

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Thomas, W. Kelley, Ruth E. Withler, and Andrew T. Beckenbach. "Mitochondrial DNA analysis of Pacific salmonid evolution." Canadian Journal of Zoology 64, no. 5 (May 1, 1986): 1058–64. http://dx.doi.org/10.1139/z86-158.

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The salmonids of Pacific North America are a group of closely related species with complex life histories and interesting distribution. Previous studies of their evolution and population structure have involved classical morphological and genetic techniques. We have analysed both intra- and inter-specific variation in mitochondrial DNA sequences of the five North American species of the genus Oncorhynchus and the rainbow trout species, Salmo gairdneri. Cleavage sites for 13 different restriction enzymes were sampled, comparing an average of 48 sites per individual, or approximately 1.7% of the genome. No obvious size variation in the 16 500 ± 500 base pair length was observed. Levels of intraspecific variation detected in the chum salmon and rainbow trout were 0.24 ± 0.23 and 0.45 ± 0.26%, respectively. This variation was population specific; no variation was detected within any of the populations sampled, suggesting the existence of population substructuring. Estimates of divergence between species range from 2.46 ± 0.72% in the coho–chinook salmon comparison to 6.88 ± 1.27% between coho and chum salmon. The phylogenetic relationship among these species, based on the levels of sequence divergence, organizes the species into three distinct groups. One group includes the pink and chum salmon while a second group contains the coho and chinook salmon, as well as the rainbow trout. The sockeye salmon are distinct from both groups. Although most of these results are in accordance with classical analyses, the relationship of the rainbow trout to the coho and chinook salmon suggests different interpretations of the evolution of life histories and morphological traits in these closely related species.

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Devlin, Robert H., Timothy Y. Yesaki, Edward M. Donaldson, Shao Jun Du, and Choy-Leong Hew. "Production of germline transgenic Pacific salmonids with dramatically increased growth performance." Canadian Journal of Fisheries and Aquatic Sciences 52, no. 7 (July 1, 1995): 1376–84. http://dx.doi.org/10.1139/f95-133.

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Transgenic Pacific salmon have been produced by microinjection of a DNA construct consisting of chinook salmon (Oncorhynchus tshawytscha) growth hormone sequences driven by an ocean pout (Macrozoarces americanus) antifreeze protein promoter. This construct was retained in approximately 4% of fish derived from injected eggs, and resulted in dramatic enhancement of growth relative to controls. For coho salmon (O. kisutch) at 15 months of age, the average size of transgenic fish was more than 10-fold that of controls, with the largest fish more than 30-fold larger than nontransgenic siblings. Dramatic growth enhancement was also observed in transgenic rainbow trout (O. mykiss), cutthroat trout (O. clarki), and chinook salmon using this same gene construct. Transgenic coho salmon underwent precocious parr–smolt transformation during their first fall, approximately 6 months in advance of their nontransgenic siblings. At 2 years of age, five male transgenic coho salmon became sexually mature, and four of these transmitted the gene construct to sperm, the negative fish being transgenic in blood but not fin tissue. These results show that while some fish are mosaic for the gene construct in different tissues, most are transgenic in both germline and somatic tissue.

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Thomas, Austen C., Benjamin W. Nelson, Monique M. Lance, Bruce E. Deagle, and Andrew W. Trites. "Harbour seals target juvenile salmon of conservation concern." Canadian Journal of Fisheries and Aquatic Sciences 74, no. 6 (June 2017): 907–21. http://dx.doi.org/10.1139/cjfas-2015-0558.

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Knowing the species and life stages of prey that predators consume is important for understanding the impacts that predation may have on prey populations, but traditional methods for determining diets often cannot provide sufficient detail. We combined data from two methods of scat analysis (DNA metabarcoding and morphological prey ID) to quantify the species and life stages of salmon (Oncorhynchus spp.) consumed by harbour seals (Phoca vitulina) in the Strait of Georgia, Canada, where juvenile Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon survival is poor. Harbour seals primarily consumed adult salmon of lesser conservation concern in the fall (August–November): chum (Oncorhynchus keta: 18.4%), pink (Oncorhynchus gorbuscha: 12.6%), sockeye (Oncorhynchus nerka: 7.4%), Chinook (7.1%), and coho (1.8%). However, the opposite species trend occurred during the spring when seals preferred juvenile salmon of greater conservation concern (April–July): coho (2.9%), Chinook (2.9%), sockeye (2.5%), pink (1.4%), and chum (0.8%) — percentages that can equate to many individuals consumed. Our data suggest that harbour seals select juveniles of salmon species that out-migrate at ages >1 year and provide evidence of a potential causal relationship between harbour seal predation and juvenile salmon survival trends.

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Clark, Steven M., Jason B. Dunham, Jeffrey R. McEnroe, and Scott W. Lightcap. "Breeding site selection by coho salmon (Oncorhynchus kisutch) in relation to large wood additions and factors that influence reproductive success." Canadian Journal of Fisheries and Aquatic Sciences 71, no. 10 (October 2014): 1498–507. http://dx.doi.org/10.1139/cjfas-2014-0020.

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The fitness of female Pacific salmon (Oncorhynchus spp.) with respect to breeding behavior can be partitioned into at least four fitness components: survival to reproduction, competition for breeding sites, success of egg incubation, and suitability of the local environment near breeding sites for early rearing of juveniles. We evaluated the relative influences of habitat features linked to these fitness components with respect to selection of breeding sites by coho salmon (Oncorhynchus kisutch). We also evaluated associations between breeding site selection and additions of large wood, as the latter were introduced into the study system as a means of restoring habitat conditions to benefit coho salmon. We used a model selection approach to organize specific habitat features into groupings reflecting fitness components and influences of large wood. Results of this work suggest that female coho salmon likely select breeding sites based on a wide range of habitat features linked to all four hypothesized fitness components. More specifically, model parameter estimates indicated that breeding site selection was most strongly influenced by proximity to pool-tail crests and deeper water (mean and maximum depths). Linkages between large wood and breeding site selection were less clear. Overall, our findings suggest that breeding site selection by coho salmon is influenced by a suite of fitness components in addition to the egg incubation environment, which has been the emphasis of much work in the past.

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Reinhardt, Ulrich G., and Michael C. Healey. "Size-dependent foraging behaviour and use of cover in juvenile coho salmon under predation risk." Canadian Journal of Zoology 75, no. 10 (October 1, 1997): 1642–51. http://dx.doi.org/10.1139/z97-791.

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Foraging and use of cover by juvenile coho salmon (Oncorhynchus kisutch) were affected by predation threat in both seminatural channels and laboratory streams. In the field, coho salmon preferred stream sections with brushy cover only when under threat from hunting common mergansers. The mergansers had their highest capture success in pools without cover. Predation threat also caused coho salmon to use cover more as foraging habitat and to aggregate more in favourable positions at the head of the pool. In the laboratory, under simulated predation threat, fish using a refuge were significantly larger than those in the risky habitat. This pattern persisted for 2 days after the predation threat was discontinued. The average growth of coho salmon under predation threat was depressed and the difference in growth between large and small individuals was less than in control groups. We argue that larger fish were more averse to predation risk than smaller fish and that the smaller fish took advantage of feeding opportunities indirectly provided as a result of the predation risk. We speculate that in natural environments, predation may depress growth rates because of risk-avoidance behaviour but may also serve to reduce growth-rate differences among size classes within a cohort.

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Journal articles on the topic 'Salmón Coho'

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