Potential benefits of a conservation hatchery program for supplementing Oregon coast coho salmon (Oncorhynchus kisutch) populations: a stochastic model investigation

This study developed a stochastic life cycle model to simulate idealized supplementation strategies to investigate the following question: under what circumstances could hatchery fish stocking contribute to the recovery of Oregon coast coho salmon (Oncorhynchus kisutch)? Simulations were used to find a solution space, defined by the attributes of wild and hatchery-bred salmon, their offspring, and their environments, where hatchery fish could supplement natural production without further depressing it until natural or human factors restricting production were relieved. These simulations suggest that short-duration, tightly controlled, low-intensity conservation hatchery programs designed to minimize genetic and ecological risks may yield minor short-term increases in adult coho salmon abundance while posing significant ecological and genetic risks. No solution space was found that indicated clear long-term benefits from such a supplementation program. Of all the management actions modeled, habitat restoration offered by far the largest and only permanent gains in coho salmon abundance while posing no genetic or ecological risk to the fish. The modeled benefits of habitat restoration were significant regardless of assumptions made about the fitness of hatchery fish and their offspring.

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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 ◽

10.1139/f93-087 ◽

1993 ◽

Vol 50 (4) ◽

pp. 759-766 ◽

Cited By ~ 47

Author(s):

Kira Salonius ◽

George K. Iwama

Keyword(s):

Disease Resistance ◽

Chinook Salmon ◽

Coho Salmon ◽

Vibrio Anguillarum ◽

Oncorhynchus Kisutch ◽

Significant Rise ◽

Wild Fish ◽

Handling Stress ◽

Hatchery Fish ◽

Natural Water Body

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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Effects of Streamflow and Upwelling on Yield of Wild Coho Salmon (Oncorhynchus kisutch) in Oregon

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f81-066 ◽

1981 ◽

Vol 38 (4) ◽

pp. 471-475 ◽

Cited By ~ 29

Author(s):

Dennis L. Scarnecchia

Keyword(s):

Coho Salmon ◽

Oncorhynchus Kisutch ◽

Positive Relation ◽

Significant Relation ◽

Oregon Coast ◽

Growth And Survival ◽

Coastal Rivers ◽

High Flows ◽

Oceanic Upwelling

To investigate the dependence of coho salmon (Oncorhynchus kisutch) yield on streamflow and oceanic upwelling, I regressed catch by the Oregon commercial troll fishery from 1942 to 1962 against indices of offshore upwelling the previous spring and measurements of streamflow from five Oregon coastal rivers during the freshwater rearing phase. A highly significant positive relation was found between total streamflows during the freshwater residency of the fish for the five rivers combined and the weight of the annual catch of coho salmon from 1942 to 1962. There was also a significant positive relation between total combined annual (January–December) flows for these rivers and the catch 2 yr later. Conversely, I found no significant relation between the 60 consecutive days of lowest flow during summer and catch 2 yr later. High flows during freshwater rearing probably provide more habitat and better conditions for growth and survival. I also found a significant positive relation between April through June upwelling at two stations and catch of coho salmon the following year from 1947 to 1962. Fifty-six percent of the variation in catch from 1947 to 1962 was explained by the total flows during freshwater residency, 60 consecutive days of lowest flow, plus combined April through June upwelling at both stations. It is suggested that some stocks of coho salmon smolts may move southward or remain in local offshore waters after they enter the ocean to take advantage of the production of invertebrates resulting from upwelling.Key words: streamflow, upwelling, coho salmon, Oregon coast

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Effect of forecast skill on management of the Oregon coast coho salmon (Oncorhynchus kisutch) fishery

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f2012-040 ◽

2012 ◽

Vol 69 (6) ◽

pp. 1016-1032 ◽

Cited By ~ 5

Author(s):

David E. Rupp ◽

Thomas C. Wainwright ◽

Peter W. Lawson

Keyword(s):

Coho Salmon ◽

Oncorhynchus Kisutch ◽

Status Quo ◽

Forecast Skill ◽

Oregon Coast ◽

Performance Metric ◽

Specific Performance ◽

The Status ◽

Target Performance ◽

Fish Survival

Better fisheries management is often given as one justification for research on improving forecasts of fish survival. However, the value gained from expected improvements in forecast skill in terms of achieving management goals is rarely quantified as part of research objectives. Using Monte Carlo simulations of population dynamics, we assessed the effect of forecast skill under two strategies for managing Oregon coast natural (OCN) coho salmon ( Oncorhynchus kisutch ). The first, or status quo, strategy is currently being used to rebuild threatened OCN coho populations. This strategy determines harvest based on both a forecasted marine survival rate and parental spawner abundance. The second strategy relies on a forecast of preharvest adult abundance to achieve a constant spawner escapement target. Performance of the status quo strategy was largely insensitive to forecast skill, while the second strategy showed sensitivity that varied with escapement target and specific performance metric. The results imply that effort towards improving forecasts is not justifiable solely on the basis of improved management under the status quo strategy, though it may be were the management strategy altered.

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Differences in Measurements of Smolt Development Between Wild and Hatchery-Reared Juvenile Coho Salmon (Oncorhynchus kisutch) Before and After Saltwater Exposure

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f94-218 ◽

1994 ◽

Vol 51 (10) ◽

pp. 2170-2178 ◽

Cited By ~ 50

Author(s):

J. Mark Shrimpton ◽

Nicholas J. Bernier ◽

George K. Iwama ◽

David J. Randall

Keyword(s):

Citrate Synthase ◽

Coho Salmon ◽

Sea Water ◽

Salt Water ◽

Oncorhynchus Kisutch ◽

Sodium Concentration ◽

Chloride Cells ◽

Plasma Sodium ◽

Hatchery Fish ◽

Saltwater Tolerance

We compared the saltwater tolerance of coho salmon (Oncorhynchus kisutch) juveniles that were reared in different environments. The groups examined consisted of fish reared exclusively in the hatchery, a hatchery group transplanted into the upper watershed of the river (colonized), and wild fish from natural spawning broodstock in the river. Although hatchery fish were much larger than their wild or colonized counterparts, they consistently showed a reduced saltwater tolerance as assessed by a much greater perturbation in plasma sodium concentration following transfer to salt water. Within each group there was no relationship between size of the fish and saltwater tolerance. Following transfer to sea water, hatchery fish showed a significant decline in haematocrit and a significant increase in circulating plasma cortisol concentration. Neither of these changes was seen in wild smolts. Hatchery fish possessed fewer chloride cells, and lower specific activities of the enzymes Na+K+ATPase and citrate synthase. The weaker osmoregulatory ability of hatchery fish led to a greater mortality following abrupt transfer to 35‰ seawater. We believe that the differences in saltwater tolerance seen among the different groups of fish are due to rearing environment.

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Density-Dependence at Sea for Coho Salmon (Oncorhynchus kisutch)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f90-200 ◽

1990 ◽

Vol 47 (9) ◽

pp. 1765-1772 ◽

Cited By ~ 24

Author(s):

J. M. Emlen ◽

R. R. Reisenbichler ◽

A. M. McGie ◽

T. E. Nickelson

Keyword(s):

Density Dependence ◽

Coho Salmon ◽

Oncorhynchus Kisutch ◽

Density Dependent ◽

Density Dependent Mortality ◽

Hatchery Fish ◽

Statistical Assumptions ◽

Diminishing Returns ◽

Salmon Hatchery ◽

Dependent Mortality

The success of expanded salmon hatchery programs will depend strongly on the degree of density-induced diminishing returns per smolt released. Several authors have addressed the question of density-dependent mortality at sea in coho salmon (Oncorhynchus kisutch), but have come to conflicting conclusions. We believe there are compelling reasons to reinvestigate the data, and have done so for public hatchery fish, using a variety of approaches. The results provide evidence that survival of these public hatchery fish is negatively affected, directly by the number of public hatchery smolts and indirectly by the number of private hatchery smolts. These results are weak, statistically, and should be considered primarily as a caution to those who, on the basis of other published work, believe that density-dependence does not exist. The results reported here also re-emphasize the often overlooked point that inferences drawn from data are strongly biased by investigators' views of how the systems of interest work and by the statistical assumptions they make preparatory to the analysis of those data.

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Social interactions of coho salmon (Oncorhynchus kisutch) smolts in seawater

Canadian Journal of Zoology ◽

10.1139/z85-355 ◽

1985 ◽

Vol 63 (10) ◽

pp. 2401-2407 ◽

Cited By ~ 11

Author(s):

Cynthia A. Paszkowski ◽

Bori L. Olla

Keyword(s):

Social Behavior ◽

Social Interactions ◽

Social System ◽

Agonistic Behavior ◽

Coho Salmon ◽

Oncorhynchus Kisutch ◽

Distribution Patterns ◽

Oregon Coast ◽

Fish Hatchery ◽

Free Ranging

The behavior of coho salmon (Oncorhynchus kisutch) smolts was examined under laboratory conditions to determine if the hierarchical–territorial social system characteristic of this species in freshwater persisted in seawater. When held in groups of two to eight fish, hatchery-reared, accelerated underyearling smolts formed hierarchies controlled by a single dominant who was responsible for most of the observed movement, chases, and feeding. Agonistic behavior also occurred within pairs of recently smolted fingerlings from two hatchery stocks with different rearing histories and in groups containing free-ranging fish captured off the Oregon coast. Possible relationships between the observed social behavior and marine distribution patterns of juvenile coho salmon are discussed.

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Survival and life history characteristics among wild and hatchery coho salmon (Oncorhynchus kisutch) returns: how do unfed fry differ from smolt releases?

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f09-200 ◽

2010 ◽

Vol 67 (3) ◽

pp. 486-497 ◽

Cited By ~ 18

Author(s):

Véronique Thériault ◽

Gregory R. Moyer ◽

Michael A. Banks

Keyword(s):

Life History ◽

Reproductive Success ◽

Molecular Analysis ◽

Coho Salmon ◽

Oncorhynchus Kisutch ◽

Adult Survival ◽

Life History Characteristics ◽

Hatchery Program ◽

Release Strategy ◽

Integrated Hatchery Program

Survival and life history characteristics were evaluated for a coho salmon ( Oncorhynchus kisutch ) integrated hatchery program using two stocking strategies. Fish were released as unfed fry or smolts and returned as adults, and then molecular analysis was employed to pedigree the entire population. We showed that mean adult survival of individuals released as unfed fry was less than that of individuals released as smolts (0.03% vs. 2.39%). The relative reproductive success (RRS) of the fry release strategy to wild spawning was significantly greater for one of two cohorts, whereas the smolt release strategy to wild RRS was significantly greater for both cohorts. Fish released as smolts were significantly smaller upon returning as adults than either those released as unfed fry or wild returns. Mean run timing was also significantly biased towards an earlier run time for hatchery-released fish when compared with the wild component. The incidence of jacking (males maturing at age 2) was greater among fish stocked as smolts than for fish stocked as fry. Differences in survival, RRS, and life history appeared to be the result of hatchery practices and indicated that a fry stocking strategy produced fish more similar to the wild component of the population than to that of fish released as smolts.

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Straying Patterns of Coho Salmon (Oncorhynchus kisutch) Stock from Southeast Vancouver Island, British Columbia

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f92-204 ◽

1992 ◽

Vol 49 (9) ◽

pp. 1843-1855 ◽

Cited By ~ 58

Author(s):

M. Labelle

Keyword(s):

British Columbia ◽

Selective Breeding ◽

Coho Salmon ◽

Oncorhynchus Kisutch ◽

Vancouver Island ◽

Water Sources ◽

Adult Age ◽

Hatchery Fish ◽

Genetic Makeup ◽

Average Adult

Fourteen coho salmon (Oncorhynchus kisutch) stocks of wild and hatchery origin were tagged from 1985 to 1988 in nine streams within a 150-km coastal section of Vancouver Island. Tag escapements to natal streams were estimated from fence counts, stream surveys, and mark–recapture operations. On average, adult (age 3+) strays accounted for ~4.7% of escapements, but for > 40% of the adult escapements in some cases. Adult straying rate, averaged across all years and stocks, was < 2%. Straying rates tended to be lower for hatchery fish and highest for stocks subjected to certain enhancement practices. Adult strays escaped to streams 2–159 km from their home stream (average 15.7 km); over 50% escaped to streams < 7 km from their stream of release. Straying rates of jacks (age 2+) in a given year and that of their adult siblings during the following year were not related. Genetic makeup, age-at-return, run timing, and exposure to nonnatal water sources during the rearing stage did influence homing. Changes in natural straying patterns should be suspected where enhancement measures include flow controls, selective breeding, and exposure of fry to various water sources. Straying levels and stray contributions should be considered when estimating survival and exploitation rates

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Seasonal Changes in Habitat Use by Juvenile Coho Salmon (Oncorhynchus kisutch) in Oregon Coastal Streams

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f92-088 ◽

1992 ◽

Vol 49 (4) ◽

pp. 783-789 ◽

Cited By ~ 136

Author(s):

Thomas E. Nickelson ◽

Jeffrey D. Rodgers ◽

Steven L. Johnson ◽

Mario F. Solazzi

Keyword(s):

Habitat Use ◽

Seasonal Changes ◽

Coho Salmon ◽

Oncorhynchus Kisutch ◽

Beaver Pond ◽

Winter Habitat ◽

Oregon Coast ◽

Beaver Ponds ◽

Salmon Fry ◽

Coastal Streams

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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