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

Large catchment basins may be viewed as ecosystems in which natural and cultural attributes interact. Contemporary river ecology emphasizes the four-dimensional nature of the river continuum and the propensity for riverine biodiversity and bioproduction to be largely controlled by habitat maintenance processes, such as cut and fill alluviation mediated by catchment water yield. Stream regulation reduces annual flow amplitude, increases baseflow variation and changes temperature, mass transport and other important biophysical patterns and attributes. As a result, ecological connectivity between upstream and downstream reaches and between channels, ground waters and floodplains may be severed. Native biodiversity and bioproduction usually are reduced or changed and non-native biota proliferate. Regulated rivers regain normative attributes as distance from the dam increases and in relation to the mode of dam operation. Therefore, dam operations can be used to restructure altered temperature and flow regimes which, coupled with pollution abatement and management of non-native biota, enables natural processes to restore damaged habitats along the river’s course. The expectation is recovery of depressed populations of native species. The protocol requires: restoring peak flows needed to reconnect and periodically reconfigure channel and floodplain habitats; stabilizing baseflows to revitalize food-webs in shallow water habitats; reconstituting seasonal temperature patterns (e.g. by construction of depth selective withdrawal systems on storage dams); maximizing dam passage to allow recovery of fish metapopulation structure; instituting a management belief system that relies upon natural habitat restoration and maintenance, as opposed to artificial propagation, installation of artificial instream structures (river engineering) and predator control; and, practising adaptive ecosystem management. Our restoration protocol should be viewed as an hypothesis derived from the principles of river ecology. Although restoration to aboriginal state is not expected, nor necessarily desired, recovering some large portion of the lost capacity to sustain native biodiversity and bioproduction is possible by management for processes that maintain normative habitat conditions. The cost may be less than expected because the river can do most of the work.

/pdf/a-general-protocol-for-restoration-of-regulated-rivers-fvjbpe1895.pdf

A general protocol for restoration of regulated rivers

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

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

Mark-recapture, removal, and snorkel population estimates were compared with a known number of juvenile coho salmon Oncorhynchus kisutch stocked in 18 pools in the same stream during the summer. The effects of fish density, pool size, and habitat complexity on the percentage of the actual population estimated by the three methods were examined. Mark–recapture estimates were also compared with known numbers of juvenile coho salmon stocked in six pools in the same stream during the winter, and snorkel counts were compared with mark–recapture estimates obtained in other Oregon coastal streams during the summer and winter. After all pool sizes and fish densities were combined, during the summer 85% of the actual number of fish present were accounted for by mark–recapture, 67% by removal, and 40% by snorkel counts. Summer pool surface area explained 44% of the variation in the accuracy of mark–recapture estimates. Pool surface area and the percentage of the pool volume taken up by rootwads explained 7...

Comparison of Three Techniques to Estimate Juvenile Coho Salmon Populations in Small Streams

Electroshocking elicited an immediate increase in plasma corticoid and lactate concentrations and thrombocyte:leucocyte ratio in rainbow troul (Salmo gairdneri). Plasma glucose concentrations increased significantly after 3 h. Plasma protein, calcium, magnesium, and androgen levels were not measurably affected. Plasma lactate returned to preshock levels within 3 h, but corticoid and glucose concentrations remained elevated for at leasi 6 h. The fish coughed violently or did not resume normal breathing rates for 60 s post shocking. Although breathing frequency did not increase, buccal pressure increased substantially and riquired at least I h to return to preshock levels. Cardiac activity was irregular immediately after shocking, but no predictable alterations in rate were evident thereafter. The height of the T wave ln ECGs increased markedly l-3 min after shocking. The electrophoretic patterns of l3 isoenzymes from liver, white muscle, and plasma did not differ between fish captured by dipnet and those captured by electrofishing. Responses exhibited by fish to shocking are most likely attributable to combined effects of trauma, factors associated with paying offofan oxygen debt, and attributes associated with the general adaptation syndrome of stress. A substantial period oftime of more than 6 h is required for fish to return to "normal" preshock conditions.

Mario F. Solazzi

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

Comparison of Three Techniques to Estimate Juvenile Coho Salmon Populations in Small Streams

Physiological Responses of Rainbow Trout (Salmo gairdneri) to Electroshock