Physiological changes in fish from stress in aquaculture with emphasis on the response and effects of corticosteroids

The American Fisheries Society herein provides a list of depleted Pacific salmon, steelhead, and sea-run cutthroat stocks from California, Oregon, Idaho, and Washington, to accompany the list of rare inland fishes reported by Williams et al. (1989). The list includes 214 native naturally-spawning stocks: 101 at high risk of extinction, 58 at moderate risk of extinction, 54 of special concern, and one classified as threatened under the Endangered Species Act of 1973 and as endangered by the state of California. The decline in native salmon, steelhead, and sea-run cutthroat populations has resulted from habitat loss and damage, and inadequate passage and flows caused by hydropower, agriculture, logging, and other developments; overfishing, primarily of weaker stocks in mixed-stock fisheries; and negative interactions with other fishes, including nonnative hatchery salmon and steelhead. While some attempts at remedying these threats have been made, they have not been enough to prevent the broad decl...

http://frndumq.krisweb.com/krisrussian/krisdb/html/krisweb/biblio/gen_afs_nehlsenetal_1991.pdf

Pacific Salmon at the Crossroads: Stocks at Risk from California, Oregon, Idaho, and Washington

Fish welfare: Current issues in aquaculture

This paper addresses the genetic consequences of aquaculture on natural fish populations. The study is motivated by rapidly increasing numbers of intentionally and accidentally released fish and is based on empirical observations reported in the literature. A wide variety of outcomes, ranging from no detectable effect to complete introgression or displacement, has been observed following releases of cultured fish into natural settings. Where genetic effects on performance traits have been documented, they always appear to be negative in comparison with the unaffected native populations. These findings are consistent with theoretical considerations of the implications of elevated levels of gene flow between cultured and locally adapted natural populations; they raise concerns over the genetic future of many natural populations in the light of increasing numbers of released fish. Strategies for the genetic protection of native populations from the effects of aquaculture are outlined including more secure co...

Genetic Effects of Cultured Fish on Natural Fish Populations

Millions of dollars are spent annually on watershed restoration and stream habitat improvement in the U.S. Pacific Northwest in an effort to increase fish populations. It is generally accepted that watershed restoration should focus on restoring natural processes that create and maintain habitat rather than manipulating instream habitats. However, most process-based restoration is site-specific, that is, conducted on a short stream reach. To synthesize site-specific techniques into a process-based watershed restoration strategy, we reviewed the effectiveness of various restoration techniques at improving fish habitat and developed a hierarchical strategy for prioritizing them. The hierarchical strategy we present is based on three elements: (1) principles of watershed processes, (2) protecting existing high-quality habitats, and (3) current knowledge of the effectiveness of specific techniques. Initially, efforts should focus on protecting areas with intact processes and high-quality habitat. Fol...

A Review of Stream Restoration Techniques and a Hierarchical Strategy for Prioritizing Restoration in Pacific Northwest Watersheds

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 spr...

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

We used a BACI (before-after-control-impact) experimental design to examine the effects of increasing winter habitat on the abundance of downstream migrant salmonids. Two reference streams and two ...

http://online.sfsu.edu/efc/classes/pa/fish1.pdf

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

We evaluated the effectiveness of using hatchery coho salmon (Oncorhynchus kisutch) presmolts to rebuild wild populations in Oregon coastal streams. Juvenile and adult populations were monitored in 15 stocked and 15 unstocked streams from summer 1980 until summer 1985. During the summers following the planting of presmolts, the number of juveniles per square metre of pool surface area was higher in the stocked streams than in the unstocked streams. However, wild juveniles were significantly less abundant in the stocked streams during the 2 yr when density of wild juveniles was estimated separately from hatchery juveniles. Adult returns to the stocked streams were not significantly different from adult returns to the unstocked streams, but returns tended to be earlier in the stocked streams than in the unstocked streams. Despite similar numbers of adults per kilometre in the stocked streams and unstocked streams in the years the presmolts returned to spawn, the resulting densities of juveniles in the stock...

Use of Hatchery Coho Salmon (Oncorhynchus kisutch) Presmolts to Rebuild Wild Populations in Oregon Coastal Streams

To aid in the recovery of depressed wild salmon populations, the operation of hatcheries must be changed to reduce interactions of juvenile hatchery fish with wild fish. Evidence suggests that productivity of wild populations can be reduced by the presence of large numbers of hatchery smolts in lower rivers and estuaries that attract predators. An index of productivity based on the density-independent rate of reproduction of wild coho salmon (Oncorhynchus kisutch) in 12 Oregon coastal river basins and two lake basins was negatively correlated with the average number of hatchery coho salmon smolts released in each basin. The index of productivity was not significantly correlated with the average proportion of hatchery coho salmon in each naturally spawning population or with habitat quality. Alterations to hatchery programs that could encourage recovery of wild populations include (i) avoiding release of large numbers of smolts in areas with high concentrations of wild fish, (ii) decreasing the number of s...

The influence of hatchery coho salmon (Oncorhynchus kisutch) on the productivity of wild coho salmon populations in Oregon coastal basins

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 ...

Effectiveness of selected stream improvement techniques to create suitable summer and winter rearing habitat for juvenile coho salmon oncorhynchus kisutch in oregon coastal streams

Thomas E. Nickelson

Papers

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

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

Use of Hatchery Coho Salmon (Oncorhynchus kisutch) Presmolts to Rebuild Wild Populations in Oregon Coastal Streams

The influence of hatchery coho salmon (Oncorhynchus kisutch) on the productivity of wild coho salmon populations in Oregon coastal basins

Effectiveness of selected stream improvement techniques to create suitable summer and winter rearing habitat for juvenile coho salmon oncorhynchus kisutch in oregon coastal streams