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Gary Wedemeyer

Publications and source records attributed to Gary Wedemeyer.

At least 19 recordsLinked to original sources
USGS2008

Physiological response of some economically important freshwater salmonids to catch-and-release fishing

Catch-and-release fishing regulations are widely used by fishery resource managers to maintain both the quantity and quality of sport fish populations. We evaluated blood chemistry disturbances in wild brook trout Salvelinus fontinalis, brown trout Salmo trutta, cutthroat trout Oncorhynchus clarkii, and Arctic grayling Thymallus arcticus that had been hooked and played for 1-5 min in waters of the intermountain western United States. A hatchery stock of brown trout was included for comparison. To assess time needed for recovery, additional test groups were played for 5 min and then released into net-pens, where they were held for up to 72 h. The osmoregulatory and metabolic disturbances associated with catch-and-release fishing under the conditions we tested were minimal and judged to be well within normal physiological tolerance limits. In fish that were held for recovery, the blood chemistry alterations that did occur appeared to be related to stress from confinement in the net-pens. Our results confirm the results of previous studies, showing that prerelease air exposure and handling cause more physiological stress than does either hooking per se or playing time. Fishery managers must be aware of the differences in the perceptions, attitudes, and values of different societal groups, some of which feel that catch-and-release fishing should be banned because it is cruel to the animals. On the basis of brain anatomy, it seems highly unlikely that fish experience pain in the same manner as humans experience it, because fish lack a neocortex, the brain structure that enables the sensation of pain in higher vertebrates. However, independent of the neurobiological argument, our results indicate that under conditions similar to those tested, fish subjected to catch and release are neither suffering nor particularly stressed. Improved education programs about the relatively benign physiological effects of catch-and-release fishing as a fishery management practice would be beneficial to anglers and the nonfishing public alike.

North American Journal of Fisheries Management↗
USGS2006

Co-oxidation of the sulfur-containing amino acids in an autoxidizing lipid system

Oxidation of the sulfur amino acids by autoxidizing lipids was studied in a model system consisting of an amino acid dispersed in cold-pressed, molecularly distilled menhaden oil (20–80% w/w). Under all conditions investigated, cysteine was oxidized completely to cystine. Preliminary results suggest that at 110°C the oxidation follows first-order kinetics for at least the first 8 hr. A specific reaction rate constant of 0.25 per hour was calculated. When fatty acids were added to the system, cystine was oxidized to its thiosulfinate ester. When the fatty acid-cystine ratio was 1:2, oxidation of cystine was a maximum. No oxidation of cystine occurred unless either a fatty acid, volatile organic acid, or ethanol was added. Under the conditions investigated, methionine was not oxidized to either its sulfoxide or its sulfone.

Journal of Food Science↗
USGS2006

The role of free and bound water in irradiation preservation: Free radical damage as a function of the physical state of water

English sole fillets previously equilibrated with aqueous 0.1% cysteine were dehydrated by three methods to moisture levels ranging from 2 to 72%. Model systems using cellulose to replace the fish tissue were also used. The samples were irradiated at 1 Mrad in an air, nitrogen, or oxygen atmosphere. The destruction of −SH groups was measured and related to the amount and physical state of the tissue water. As free water was removed, destruction steadily increased, reaching a maximum at about 20% moisture. Destruction decreased markedly at moisture levels below 10%, and calorimetric measurements confirmed that 10% moisture was about the level of bound water in this species. These data suggest that dehydration favors the reaction of solute molecules with free radicals formed in the free water of muscle cells. At moisture levels greater than about 20%, simple free radical recombination is more likely than reaction with solute molecules, while below 20% moisture the reverse is true. The calculated α values support this conclusion, as do the results from model systems using cellulose.

Journal of Food Science↗
USGS2006

Some potentials and limits of the leucocrit test as a fish health assessment method

The sensitivity of the leucocrit as a stress tolerance and fish health assessment method was evaluated by subjecting juvenile coho salmon, Oncorhynchus kisutch , or steelhead trout, Salmo gairdneri , to standardized crowding, handling, temperature and disease challenges. The leucocrit was a sensitive indicator of the physiological stress resulting from crowding at population densities of 0·2–0·4 kg l −1 , and to the stress of handling and to temperature changes. It was relatively insensitive to physiological sampling procedures which supports its continued development as a stress assessment method. In the case of fish diseases, subclinical or active Renibacterium salmoninarum and Yersinia ruckeri infections had essentially no effect on leucocrit values. In contrast, active Aeromonas salmonicida infections significantly depressed the leucocrit. However, no change was seen during the subclinical (incubation) phase prior to the development of an epizootic. Thus, the potential of the leucocrit as a fish health assessment method appears limited.

Journal of Fish Biology↗
USGS2004

The controversy about salmon hatcheries

The use of hatcheries has been a subject of lengthy debate in the management of salmon and trout resources in the Pacific Northwest. The problem has resulted in part from the wide distribution of hatchery fish in circumstances where natural populations were disadvantaged by management policy involving hatchery fish and the confusion of the effects of management with the effects of artificial propagation. Recently, the controversy has been epitomized by the recommendations to fisheries management agencies that excess hatchery fish should not be allowed to spawn in the wild, and hatchery fish should be excluded from salmon populations listed under the Endangered Species Act. The authors of the present article disagree with those recommendations and conclude that hatchery fish have an important role in recovery and supplementation of wild stocks. The present article is an attempt to help give balance to the discussion by providing a different perspective on hatchery fish and the literature pertaining to artificial propagation.

Fisheries Magazine↗
USGS1984

Effects of freshwater exposure to arsenic trioxide on the parr-smolt transformation of coho salmon ( Oncorhynchus kisutch )

The effects of chronic (6 months) exposure to arsenic trioxide in fresh water on the Parr-smolt transformation of coho salmon ( Oncorhynchus kisutch ) were evaluated. Exposure to 300 μg As/L (as As 2 O 3 ) appeared to delay the onset of the normal increase in plasma thyroxine concentration and cause a transient reduction of gill Na + ,K + -ATPase activity. Fish exposed to 300 μg As/L also migrated to the sea less successfully than did nonexposed smolts, but there were no effects on the survival and growth of smolts held in 28‰ salt water for 6 months.

Environmental Toxicology and Chemistry↗
USGS1984

Assessing the tolerance of fish and fish populations to environmental stress: The problems and methods of monitoring

Environmental stress is an inescapable aspect of life in the aquatic environment. The chemical and physical demands of life underwater impose somewhat rigorous constraints on aquatic species (Smith, 1982a). Superimposed on such demands may be the additional. physiological constraints of particular ecological niches. It is true that aquatic species are adapted to these conditions, but this does not imply the absence of energy drains (Lugo, 1978). For example, thermophilic fishes must still cope physiologically with the demands of high temperatures even though they are adapted to high temperatures per se.

Book chapter↗
USGS1984

Disease caused by environmental stressors

The use of the terms 'stress' and 'stressor' is sometimes inconsistent (e.g., Pickering, 1981). The term 'stressor' should be used to describe environmental or other factor intensities severe enough to require a compensatory response at any level of biological organization. A stressor is normally extrinsic. The term 'stress' indicates the organismic response initiated by the stressor, also at any level of biological organization. Thus, the original concept of Selye (1950) that stress is 'the sum of all the physiological responses by which an animal tries to maintain or re-establish a normal metabolism in the face of a physical or chemical force' has evolved into the concept that stress is the biological effect of any force that challenges homeostatic or stabilizing processes and extends them beyond their normal limits, at any level of biological organization - individual, population, or ecosystem (Esch and Hazen, 1978; Bayne, 1980).

Book chapter↗
USGS1983

Reproduction by the endangered cui-ui in the lower Truckee River

Adult spawning behavior and emigration of larvae of the endangered cui-ui Chasmistes cujus were studied in a natural side channel of the lower Truckee River. External radio-tags placed on eight apparently did not affect spawning behavior. Cui-uis spawned in clusters of two to seven fish; usually a single female was flanked by two males. Each spawning act lasted 3–6 seconds, and individual fish spawned numerous times. The most active tagged male and female spawned at least 294 times and 114 times, respectively. Individual females broadcast eggs over an area of up to 50 m 2 . Males spawned over a 4–5-day period, and females over 2.5–4 days. Most spawning occurred at night in water depths ranging from 9 to 43 cm, water velocities ranging from 23 to 87 cm/second, and temperatures of 12–17 C. The preferred spawning substrate was gravel. Peak emergence and out-migration of cui-ui larvae occurred 14 days after peak spawning.

California, Nevada↗
USGS1983

Physiological effects of handling and hauling stress on smallmouth bass

Mortalities associated with the handling and transporting (hauling) of fishes have long been a problem. Tolerance to these stressors varies greatly among species (Davis and Parker 1979; Tomasso et al. 1980; Wydoski and Wedenmeyer 1976). In most fishes, however, handling and hauling losses are caused by two major factors - activation of latent infections as a result of increased endocrine activity (cf. Wedemeyer 1970), and osmoregulatory dysfunctions due to blood electrolyte disturbances (Lewis 1971; Wydoski and Wedemeyer 1976). Basic physiological information on the stress caused by current hatchery practices is helpful in developing new and improved techniques to increase survival. In view of the present fishery management requirements for stocking smallmouth bas ( Micropterus dolomieu ), baseline information on the physiological effects of handling and hauling hatchery-reared fish is needed to serve as the foundation for improving transport methods. Shell (1959) summarized several physiological characteristics of smallmouth bass, but little information on their physiological tolerance to stress exists. The present study was designed to determine the physiological effects of handling and short-term hauling in small mouth bass. Plasma chloride, sodium, potassium, and glucose dynamics were monitored in indicate the severity of the resulting stress and the recovery time needed.

Progressive Fish-Culturist↗