R. Scott McKinley

The Use of Clove Oil as an Anesthetic for Rainbow Trout and Its Effects on Swimming Performance

Abstract The only anesthetic registered in North America for use in fisheries science is 3-aminobenzoic acid ethyl ester methanesulfate (tricaine or MS-222). Although MS-222 is a very effective anesthesia for several fish species, its application in the field is limited because U.S. Food and Drug Administration guidelines demand a 21-d withdrawal period after exposure to MS-222 before fish can be released and enter the food chain. As a consequence, carbon dioxide (CO2) has been used as a substitute anesthetic; however, induction and recovery times with CO2 are long, and anesthesia is shallow in comparison with MS-222. We compared the efficacy of MS-222 to that of clove oil, a naturally occurring substance, for use as an anesthetic for juvenile and adult rainbow trout Onchorhynchus mykiss. Clove oil was as effective as MS-222 in inducing anesthesia in both age-groups. Furthermore, exposure to either clove oil or MS-222 at the concentrations tested was not detrimental to critical swimming speed of juvenile ...

Evidence to Challenge the “2% Rule” for Biotelemetry

Abstract Swimming performance was compared among groups of juvenile rainbow trout Oncorhynchus mykiss (5–10 g) with and without intraperitoneally implanted radio transmitters. The generally accepted rule of 2% body weight : transmitter weight was extended to a 6–12% ratio, and swimming performance was not altered by the presence of the transmitter or effects of the operation. Also, no relationship was found between the weight of the fish and its swimming performance among the groups examined. Although we found swimming performance was not affected by implantation of transmitters weighing up to 12% of the body weight, changes in behavior were not evaluated. We suggest further research be done so that the “2% rule” can be replaced by an index with a more scientific basis. Instead of using a scale based on percentage of transmitter to body weight in air, preferred indices could be weight in water, volume of the tag, or both.

Freshwater and marine migration and survival of endangered Cultus Lake sockeye salmon (Oncorhynchus nerka) smolts using POST, a large-scale acoustic telemetry array

Freshwater and early marine migration and survival of endangered Cultus Lake sockeye (Oncorhynchus nerka) salmon were studied using the Pacific Ocean Shelf Tracking (POST) array. Smolts were acoustically tagged in 2004-2007, and their migration was recorded within the lower Fraser River and coastal southern British Columbia waters. Most smolts showed rapid directional movement (swimming speeds of ~15-30 kmday -1 ). Average exit time from the Fraser River was 4.0-5.6 days after release, and average residence time within the Strait of Georgia was 25.6-34.1 days. Most individuals migrated northward, generally close to the mainland coast. Survival rates, assessed using standard mark-recapture meth- ods, were generally high during the downstream migration (50%-70%), except in 2005 when survival was <20%, possibly because of a late release. Marine survival rates were stable among years, between 10%-30% at a subarray sited 500 km away from the release site. Movement rates were similar to those of previously published work, but the POST array pro- vided direct measurements of movement and estimates of survival and demonstrated the feasibility of establishing conti- nental-scale acoustic arrays for management and conservation of marine species.

Fjord migration and survival of wild and hatchery-reared Atlantic salmon and wild brown trout post-smolts

The behaviour of wild (n = 43, mean LT = 152 mm) and hatchery-reared (n = 71, mean LT = 198 mm) Atlantic salmon and wild anadromous brown trout (n = 34, mean LT = 171 mm) post-smolts with acoustic transmitters was compared in a Norwegian fjord system. There was no difference in survival between wild and hatchery reared salmon from release in the river mouth to passing receiver sites 9.5 km and 37.0 km from the release site. Mortality approached 65% during the first 37 km of the marine migration for both groups. There was no difference between wild and hatchery-reared salmon either in time from release to first recording at 9.5 km (mean 135 and 80 h), or in the rate of movement through the fjord (mean 0.53 and 0.56 bl s−1). Hatchery-reared salmon reached the 37 km site sooner after release than the wild salmon (mean 168 and 450 h), but rate of movement in terms of body lengths per second did not differ (mean 0.56 and 0.77 bl s−1). The brown trout remained a longer period in the inner part of the fjord system, with much slower rates of movement during the first 9.5 km (mean 0.06 bl s−1).

Survival of migrating salmon smolts in large rivers with and without dams.

The mortality of salmon smolts during their migration out of freshwater and into the ocean has been difficult to measure. In the Columbia River, which has an extensive network of hydroelectric dams, the decline in abundance of adult salmon returning from the ocean since the late 1970s has been ascribed in large measure to the presence of the dams, although the completion of the hydropower system occurred at the same time as large-scale shifts in ocean climate, as measured by climate indices such as the Pacific Decadal Oscillation. We measured the survival of salmon smolts during their migration to sea using elements of the large-scale acoustic telemetry system, the Pacific Ocean Shelf Tracking (POST) array. Survival measurements using acoustic tags were comparable to those obtained independently using the Passive Integrated Transponder (PIT) tag system, which is operational at Columbia and Snake River dams. Because the technology underlying the POST array works in both freshwater and the ocean, it is therefore possible to extend the measurement of survival to large rivers lacking dams, such as the Fraser, and to also extend the measurement of survival to the lower Columbia River and estuary, where there are no dams. Of particular note, survival during the downstream migration of at least some endangered Columbia and Snake River Chinook and steelhead stocks appears to be as high or higher than that of the same species migrating out of the Fraser River in Canada, which lacks dams. Equally surprising, smolt survival during migration through the hydrosystem, when scaled by either the time or distance migrated, is higher than in the lower Columbia River and estuary where dams are absent. Our results raise important questions regarding the factors that are preventing the recovery of salmon stocks in the Columbia and the future health of stocks in the Fraser River.

Activity patterns of largemouth and smallmouth bass determined with electromyogram biotelemetry

Abstract Electromyogram (EMG) biotelemetry was used to assess activity patterns for adult free-swimming largemouth bass Micropterus salmoides and smallmouth bass Micropterus dolomieu. We first conducted laboratory respirometry trials and found a strong association between EMG signal and swimming activity which indicated that EMG biotelemetry could be used to assess activity of wild fish. A field study confirmed that both species exhibit diurnal activity patterns. When EMG activity was compared with estimates of swimming activity from location tracking, elevated EMG activity was often recorded for apparently stationary fish. These observations suggested that fish activity at spatial and temporal scales too small for detection by location tracking may account for a significant proportion of daily activity. We argue that EMG biotelemetry, combined with location tracking, may be a versatile tool for application to a wide variety of problems in fisheries biology, including the study of physiological energetics...

Movement and summer habitat of brown trout (Salmo trutta) below a pulsed discharge hydroelectric generating station

Radiotelemetry was used to investigate detailed movement and summer habitat of brown trout Salmo trutta (size range 157–488 mm TL, n=18) in the Kananaskis River, Alberta. Flows in the Kananaskis River respond to pulsed daily discharge from an upstream hydroelectric generating facility (range 0.15–25 m3 s−1). Wetted area available for brown trout doubled during periods of high flow. Fluctuating river levels did not appear to influence the degree to which brown trout moved within the study site. However, there was evidence that brown trout used cover and pools more as discharge increased. During high flow conditions, brown trout used similar depths (63 cm), and significantly lower surface water velocities than during low flow conditions. Brown trout also moved closer to shore into interstitial spaces among woody debris and root complexes during high flow. Pool habitats were used most often compared with all other habitat types combined. Pools with large woody debris accounted for 75% of all habitat observations. Woody debris was used more often than all other cover types. Results of the study indicate that the effects of river regulation on brown trout appear to have been moderated by woody debris in pools and along river banks, which provided refuge from high water velocities during periods of high flow. Copyright

The Effect of Scented Lures on the Hooking Injury and Mortality of Smallmouth Bass Caught by Novice and Experienced Anglers

Abstract Although regulations prohibiting the use of natural baits are relatively common, new regulations specifically targeting the use of chemical attractants have recently been implemented. While no citeable evidence for these new regulations exists, they may have been promulgated due to a perceived increase in the risk of fish mortality from scented lures compared with unscented lures. The present study investigated the hooking injury and short-term mortality of 238 adult smallmouth bass Micropterus dolomieu captured on Lake Erie by both experienced (fished > 100 d/year) and novice (fished < 10 d/year) anglers on actively fished jigs similarly threaded with minnows, nonscented plastic grubs, or grubs scented with chemical attractants. The depth of hook ingestion, the anatomical hooking location, the presence of bleeding at the hook wound, and the total amount of time taken to remove the hook were noted on all captured fish. The fish were then transferred to a retention cage, and their survival was mon...

Assessment of the Dunnville Fishway for Passage of Walleyes from Lake Erie to the Grand River, Ontario

A Denil fishway in Dunnville, Ontario was built to provide upstream passage for walleyes (Stizostedion vitreum) from Lake Erie to the Grand River. Few walleyes have been observed to use this fishway. Coded radiotelemetry was used to track 24 adult walleyes (12 male, 12 female) downstream from the fishway to explore reasons for limited use. Activity was monitored by a fixed array of three antennas within the fishway that continuously scanned for signals from all radio-tagged fish, and by mobile tracking. In April and May 1997, 17 attempts to use the fishway by 3 male and 2 female radiotagged walleyes were recorded. During this period, the attraction efficiency of the Dunnville Fishway was approximately 21%. All attempts took place between 1600 and 0600 hours, with most activity near midnight. Walleyes occupied the first resting pool of the fishway for up to 17 h. Subsurface water velocity during the study was approximately 2 m/s. No radio-tagged walleyes passed through the Dunnville Fishway. Behavior modifying hydraulic conditions including turbulence, entrained air, backcurrents and whirlpools in fishway resting areas may delay or prevent successful upstream passage of walleyes. There was also evidence of large-scale movements by walleyes that may have spawned in the Grand River downstream from Dunnville.

Genetic versus Rearing-Environment Effects on Phenotype: Hatchery and Natural Rearing Effects on Hatchery- and Wild-Born Coho Salmon

With the current trends in climate and fisheries, well-designed mitigative strategies for conserving fish stocks may become increasingly necessary. The poor post-release survival of hatchery-reared Pacific salmon indicates that salmon enhancement programs require assessment. The objective of this study was to determine the relative roles that genotype and rearing environment play in the phenotypic expression of young salmon, including their survival, growth, physiology, swimming endurance, predator avoidance and migratory behaviour. Wild- and hatchery-born coho salmon adults (Oncorhynchus kisutch) returning to the Chehalis River in British Columbia, Canada, were crossed to create pure hatchery, pure wild, and hybrid offspring. A proportion of the progeny from each cross was reared in a traditional hatchery environment, whereas the remaining fry were reared naturally in a contained side channel. The resulting phenotypic differences between replicates, between rearing environments, and between cross types were compared. While there were few phenotypic differences noted between genetic groups reared in the same habitat, rearing environment played a significant role in smolt size, survival, swimming endurance, predator avoidance and migratory behaviour. The lack of any observed genetic differences between wild- and hatchery-born salmon may be due to the long-term mixing of these genotypes from hatchery introgression into wild populations, or conversely, due to strong selection in nature—capable of maintaining highly fit genotypes whether or not fish have experienced part of their life history under cultured conditions.