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At least 145 records · Page 8Linked to original sources
USGS1995

Genetic contribution of hatchery fish to walleye stocks in Saginaw Bay, Michigan

Stocks of walleye ( Stizostedion vitreum ) were severely depressed in Saginaw Bay in the 1970s. In 1979, the Michigan Department of Natural Resources began intensive stocking of walleye fingerlings to bolster fish populations. Subsequent to stocking, the walleye fishery has recovered. The study objective was to determine if recovery was due to the stocking program or natural reproduction. Inherent genetic differences between hatchery fish and endemic walleyes were used to determine the effect and contribution of hatchery fish to Saginaw Bay.

Michigan↗
USGS2003

The use of traditional Hawaiian knowledge in the contemporary management of marine resources

It is traditional for Hawaiians to "consult nature" so that fishing is practiced at times and places, and with gear that causes minimum disruption of natural biological and ecological processes. The Ho'olehua Hawaiian Homestead continues this tradition in and around Mo'omomi Bay on the northwest coast of the island of Moloka'i. This community relies heavily on inshore marine resources for subsistence and consequently, has an intimate knowledge of these resources. The shared knowledge, beliefs, and values of the community are culturally channeled to promote proper fishing behavior. This informal system brings more knowledge, experience, and moral commitment to fishery conservation than more centralized government management. Community-based management in the Mo'omomi area involves observational processes and problem-solving strategies for the purpose of conservation. The system is not articulated in the manner of Western science, but relies instead on mental models. These models foster a practical understanding of local inshore resource dynamics by the fishing community and, thus, lend credibility to unwritten standards for fishing conduct. The "code of conduct" is concerned with how people fish rather than how much they catch.

Hawai'i↗
USGS2018

Fight and air exposure times of caught and released salmonids from the South Fork Snake River

Catch-and-release regulations are among the most common types of fishing regulations. In recent years, concerns have arisen regarding the exposure of fish to air during catch-and-release angling. The purpose of our study was to quantify the length of time angled fish were exposed to air by anglers in a typical catch-and-release fishery and relate it to the lengths of time reported to produce negative effects. In total, 312 individual anglers were observed on the South Fork Snake River, Idaho, from May through August 2016. Fight time varied from 1.1 s to 230.0 s, and average fight time was 40.0 s (SD = 36.8). Total air exposure times varied from 0.0 s to 91.8 s and averaged 19.3 s (SD = 15.0). Though not statistically significant, a trend in reduced fight times was observed when anglers were guided and increased air exposure times when a net was used and a picture was taken. Results of the current study suggest that anglers expose fish to air for periods that are much less than those reported to cause mortality.

Idaho↗
USGS2008

Minnesota anglers' fisheries-related value orientations and their stewardship of fish resources

Research on natural resource-related values and value orientations has grown substantially over the past decade. However, existing studies have focused almost exclusively on value orientations related to wildlife and forests. This article reports data from two mail surveys of Minnesota anglers used to develop scales for measuring fisheries-related value orientations. We report results of regression analyses examining the relationship between anglers' value orientations and norms concerning fisheries stewardship and the use of technological aids to angling. Results indicate 10 items reliably measure three value orientations we termed utilitarianism, dominance, and protectionism. Regression analyses suggest anglers' stewardship norms are influenced by all three value orientation types, while support for the use of technological aids was related with protectionism and utilitarianism, but not dominance. Results suggest anglers' fisheries-related value orientations cannot be adequately captured using single domain scales. Implications for the study of natural resources-related value orientations are discussed. Copyright ?? Taylor & Francis Group, LLC.

Human Dimensions of Wildlife↗
USGS2021

The impact of COVID-19 on freshwater fisheries fieldwork and data collection

COVID-19 has affected almost every aspect of society including freshwater fisheries fieldwork. Our study quantified the effects of the pandemic on fisheries fieldwork in the United States. We administered a survey to fisheries chiefs in all 50 states to assess the pandemic’s impact on fisheries fieldwork. Of the 37 participants, 91% reported the pandemic affected their fieldwork and 92% adapted their sampling methods in response to the pandemic. Common adaptation strategies included using Personal Protective Equipment (PPE; 100%), practicing social distancing (97%), using smaller crews (82%), and developing contingency plans (51%). Based on the survey results, we identified potential challenges to adaptations and offered strategies to improve them. Strategies we identified include adopting novel data collection techniques, finding new positions for temporary employees, and publicly sharing contingency plans. Ultimately, this paper offers novel guidance on how fisheries professionals can best move forward with fieldwork during a time of crisis.

Fisheries Magazine↗
USGS2014

U.S. response to a report of infectious salmon anemia virus in Western North America

Federal, state, and tribal fishery managers, as well as the general public and their elected representatives in the United States, were concerned when infectious salmon anemia virus (ISAV) was suspected for the first time in free-ranging Pacific Salmon collected from the coastal areas of British Columbia, Canada. This article documents how national and regional fishery managers and fish health specialists of the U.S. worked together and planned and implemented actions in response to the reported finding of ISAV in British Columbia. To date, the reports by Simon Fraser University remain unconfirmed and preliminary results from collaborative U.S. surveillance indicate that there is no evidence of ISAV in U.S. populations of free-ranging or marine-farmed salmonids on the west coast of North America.

Fisheries↗
USGS2003

Comparative hydraulics of two fishery research circular tanks and recommendations for control of experimental bias

Hydraulic characteristics inside two research circular tanks (1.5-m and 1.2-m diameter) with the same volume of water were studied to understand how they might affect experimental bias by influencing the behavior and development of juvenile fish. Water velocities inside each tank were documented extensively and flow behavior studied. Surface inflow to the 1.5-m tank created a highly turbulent and aerated surface, and produced unevenly distributed velocities within the tank. A low-flow velocity, or "dead" zone, persisted just upstream of the surface inflow. A single submerged nozzle in the 1.2-m tank created uniform flow and did not cause undue turbulence or introduce air. Flow behavior in the 1.5-m tank is believed to have negatively affected the feeding behavior and physiological development of a group of juvenile fall chinook salmon, Oncorhynchus tshawytscha. A new inflow nozzle design provided comparable flow behavior regardless of tank size and water depth. Maintaining similar hydraulic conditions inside tanks used for various biological purposes, including fish research, would minimize experimental bias caused by differences in flow behavior. Other sources of experimental bias are discussed and recommendations given for reporting and control of experimental conditions in fishery research tank experiments.

Journal of Applied Aquaculture↗
USGS2017

Sub-indicator: Prey fish

Prey fish communities across the Great Lakes continue to change, although the direction and magnitude of those changes are not consistent across the lakes. The metrics used to categorize prey fish status in this and previous periods are based on elements that are common among each of the lake’s Fish Community Objectives and include diversity and the relative role of native species in the prey fish communities. The diversity index categorized three of lakes as ‘fair’, while Superior and Erie were ‘good’ (Table 1). The short term trend, from the previous period (2008-2010) to the current period (2011-2014) found diversity in Erie and Superior to be unchanging, but the other three lakes to be ‘deteriorating’, resulting in an overall trend categorization of ‘undetermined’ (Table 1). The long term diversity trend suggested Lakes Superior and Erie have the most diverse prey communities although the index for those prey fish have been quite variable over time (Figure 1). In Lake Huron, where non-native alewife have substantially declined, the diversity index has also declined. The continued dominance of alewife in Lake Ontario (96% of the prey fish biomass) resulted in the lowest diversity index value (Figure 1). The proportion of native species within the community was judged as ‘good’ in Lakes Superior and Huron, ‘fair’ in Michigan and Erie and ‘poor’ in Ontario (Table 2). The short term trend was improving in in all lakes except Michigan (‘deteriorating’) and Ontario (‘unchanging’), resulting in an overall short term trend of ‘undetermined’ (Table 2). Over the current period, Lake Superior consistently had the highest proportion native prey fish (87%) while Lake Ontario had the lowest (1%) (Figure 2). Lake Michigan’s percent native has declined as round goby increase and comprises a greater proportion of the community. Native prey fish make up 51% of Lake Erie, although basin-specific values differed (Figure 2). Most notably, native species in Lake Huron comprised less than 10% of the community in 1970, but since alewife have declined, now represent nearly 80% of the community (Figure 2). Prey fish data are most consistent for in-lake populations, which are reported here; data from connecting channels was not consistently available across the basin. Abundance was not used to judge prey fish status since successful, basin-wide management actions, including mineral nutrient input reductions and piscivore restoration, both inherently reduce prey fish abundance. However, recent abundance trends as they relate to predator prey balance are referenced, such as in Lakes Michigan and Huron where piscivore stocking is being reduced to lower predation demand on prey fish populations and maintain sport fisheries.

Great Lakes↗
USGS2016

Evaluation of Caspian tern ( Hydroprogne caspia ) and snowy plover ( Charadrius alexandrinus nivosus ) nesting on modified islands at the Don Edwards San Francisco Bay National Wildlife Refuge, California—2015 Annual Report

Executive Summary In order to address the 2008/10 NOAA Fisheries Biological Opinion for operation of the Federal Columbia River Power System, the U.S. Army Corps of Engineers (USACE) and the Bureau of Reclamation (Reclamation) have developed and begun implementation of Caspian tern ( Hydroprogne caspia ) management plans. This implementation includes relocating nesting Caspian terns out of the Columbia River estuary and the mid-Columbia River region to reduce predation on salmonids listed under the Endangered Species Act. USACE and Reclamation developed Caspian tern nesting habitat at the U.S. Fish and Wildlife Service Don Edwards San Francisco Bay National Wildlife Refuge (DENWR), California prior to the 2015 nesting season. Further, to reduce or eliminate potential conflicts between nesting Caspian terns and threatened western snowy plovers ( Charadrius alexandrinus nivosus), nesting habitat for snowy plovers also was developed. Seven recently constructed islands within two managed ponds (Ponds A16 and SF2) of DENWR were modified to provide habitat attractive to nesting Caspian terns (5 islands), and snowy plovers (2 islands). These seven islands were a subset of 46 islands recently constructed in Ponds A16 and SF2 to provide waterbird nesting habitat as part of the South Bay Salt Pond (SBSP) Restoration Project. We used social attraction methods (decoys and electronic call systems) to attract Caspian terns and snowy plovers to these seven modified islands, and conducted surveys between March and September 2015 to evaluate nest numbers, nest density, and productivity. Results from the 2015 nesting season indicate that island modifications and social attraction measures were successful in establishing Caspian tern breeding colonies at Ponds A16 and SF2 of DENWR. Caspian terns nested on three of the five islands modified for Caspian terns (1 island in Pond A16 and 2 islands in Pond SF2). Caspian terns initiated at least 224 nests, fledged at least 174 chicks, and exhibited a breeding success rate of 0.78 fledged chicks/breeding pair. These results are promising considering it was the first year of the study and there was no prior history of Caspian terns nesting at Ponds A16 and SF2. In contrast, snowy plovers did not attempt to nest on any island in Ponds A16 and SF2. These results demonstrate the potential of social attraction measures to help establish tern nesting colonies in San Francisco Bay. Social attraction measures similar to those used in this study, but targeting other species such as Forster’s terns and American avocets, may help to establish waterbird breeding colonies at wetlands enhanced as part of the SBSP Restoration Project.

California↗
USGS2010

Interactions between walleyes and smallmouth bass in a Missouri River reservoir with consideration of the influence of temperature and prey

Walleyes Sander vitreus are the most popular fish among South Dakota anglers, but smallmouth bass Micropterus dolomieu were introduced to provide new angling opportunities. Some walleye anglers have reported reductions in the quality of walleye fisheries since the introduction of smallmouth bass and attribute this to the consumption of young walleyes by smallmouth bass and competition for shared prey resources. We quantified the diets of walleyes and smallmouth bass in the lower reaches of Lake Sharpe (a Missouri River reservoir), calculated the diet overlap between the two predators, and determined whether they partitioned shared prey based on size. We also quantified walleye diets in the upper reach of the reservoir, which has a different prey base and allowed us to compare the growth rates of walleyes within Lake Sharpe. Age-0 gizzard shad Dorosoma cepedianum composed a substantial proportion of the diets of both predators, regardless of location, for most of the growing season; the patterns in shad vulnerability appeared to drive the observed patterns in diet overlap. Smallmouth bass appeared to consume a smaller size range of gizzard shad than did walleyes, which consumed a wide range. Smallmouth bass consumed Sander spp. in some months, but in very low quantities. Given that global climate change is expected to alter the population and community dynamics in Great Plains reservoirs, we also used a bioenergetics approach to predict the potential effects of limiting prey availability (specifically, the absence of gizzard shad and rainbow smelt Osmerus mordax ) and increased water temperatures (as projected from global climate change models) on walleye and smallmouth bass growth. The models indicated that the absence of rainbow smelt from the diets of walleyes in upper Lake Sharpe would reduce growth but that the absence of gizzard shad would have a more marked negative effect on both predators at both locations. The models also indicated that higher water temperatures would have an even greater negative influence on walleye growth; however, smallmouth bass growth was predicted to increase with higher temperatures. Fisheries managers should consider strategies to enhance the prey base or mitigate the effects of increased water temperatures that may occur in the future as a result of global climate change. Such proactive actions may alleviate potential future competition between walleyes and smallmouth bass resulting from changes in the fish community.

North American Journal of Fisheries Management↗
USGS2012

Monitoring of endangered Roanoke logperch ( Percina rex ) in Smith River upstream from the Philpott Reservoir on U.S. Army Corps of Engineers property near Martinsville, Virginia

The purpose of this study was to continue annual monitoring of Roanoke logperch ( Percina rex ), an endangered fish, in the Smith River immediately upstream from Philpott Reservoir. This river reach is owned by the U.S. Army Corps of Engineers (USACE), which must ensure that appropriate actions are undertaken to aid in recovery of logperch. Monitoring of fish abundance and habitat conditions provides a means for assessing the species’ status and its responses to USACE management actions. The Roanoke logperch is a large darter (Percidae: Etheostomatinae) endemic to the Roanoke, Dan, and Nottoway River basins of Virginia and North Carolina, where it occupies third- to sixth-order streams containing relatively silt-free substrate (Jenkins and Burkhead, 1994). Because of its rarity, small range, and vulnerability to siltation, the Roanoke logperch was listed in 1989 as endangered under the U.S. Endangered Species Act (ESA) (U.S. Federal Register 54:34468-34472). Within the Dan basin, Roanoke logperch have long been known to occupy the Smith River and one of its largest tributaries, Town Creek (Jenkins and Burkhead, 1994). Logperch also recently were discovered in other tributaries of the Dan River, including North Carolina segments of the Mayo River, Cascade Creek, Big Beaver Island Creek, Wolf Island Creek (William Hester, U.S. Fish and Wildlife Service, personal commun., 2012). Within the Smith River, Roanoke logperch are present both upstream and downstream from Philpott Reservoir, a hydroelectric and water storage project owned and operated by the USACE. Although logperch have not been observed in the reservoir itself, the species is relatively abundant in a free-flowing, ≈ 2.5-km-long segment of Smith River upstream from the reservoir on USACE property (Lahey and Angermeier, 2006). This segment is bounded on the downstream end by the lentic conditions of the reservoir and on the upstream end by White Falls, a natural waterfall that presumably allows fish passage during all but the lowest streamflow (Roberts and Angermeier, 2009). The ESA stipulates that USACE must ensure that its actions do not jeopardize Roanoke logperch and ensure that appropriate actions are taken to aid in the recovery of Roanoke logperch. USACE recognized that additional information was needed to assess compliance with these stipulations, including data on baseline population levels, habitat availability, and potential threats to the species on USACE property. USACE therefore contracted with Virginia Tech (VT) and the U.S. Geological Survey via the Virginia Cooperative Fisheries and Wildlife Research Unit (VCFWRU) to continue ecological monitoring that was initiated in a pilot study in 2005 (Lahey and Angermeier, 2006). The VCFWRU is jointly sponsored by the U.S. Geological Survey, Virginia Tech, Virginia Department of Game and Inland Fisheries, and Wildlife Management Institute. This final report summarizes results of biological monitoring performed by VT and the VCFWRU in 2011, and compares these data to data collected during 2006–2010 (Roberts and Angermeier, 2011). Where appropriate, a comparison was made to data on Roanoke logperch collected previously in the study reach (Lahey and Angermeier, 2006) and in the upper Roanoke River (Roberts and Angermeier, 2011). This work was performed under the auspices of VT’s Institutional Animal Care and Use Committee (IACUC) protocol 11-035-FIW. Specifically, the following objectives were addressed: * Estimate population density of Roanoke logperch on USACE property; * Measure and map by suitability class the distribution of habitat suitable for Roanoke logperch in the project area; * Assess water quality relative to Roanoke logperch habitat in the project area; * Use the data on logperch abundance, habitat suitability, and water quality to test the general validity of correlates of logperch abundance from other locations; * Identify opportunities and threats related to protecting and enhancing Roanoke logperch habitat; and * Provide suggestions on the necessity and scale of future studies and monitoring related to logperch in and near USACE waters.

Virginia↗
USGS2008

Sources and implications of lead ammunition and fishing tackle on natural resources

A technical review of lead sources that originate from hunting, shooting sports, and fishing activities was undertaken by the American Fisheries Society and The Wildlife Society. The report addresses (1) sources of lead that originate from hunting, shooting sports, and fishing activities, (2) the hazard and risk that lead from these activities pose to natural resources, and (3) the management implications for fish and wildlife professionals and policy makers.

Wildlife Society Technical Review↗
USGS2025

Fisheries dependent and independent data inform a capture technique for an emerging invasive fish species in the mainstem Mississippi River; Black Carp Mylopharyngodon piceus

Black Carp Mylopharyngodon piceus were imported into the United States in the 1970s and 1980s for use in aquaculture; escape occurred and reported wild captures increased. Lacking species-specific capture methods, we assessed fisheries dependent incidental Black Carp catches for a common method, hoop nets, by kernel density analysis to identify an area of increased reporting and compare frequency of reports for water temperature, river stage, and capture date to identify seasonality. We then used fisheries independent effort to identify co-occurrence of species via non-metric multi-dimensional scaling and fit Black Carp catch and environmental covariates by generalized linear models to assess site-specific environmental covariates facilitating capture. The best approximating distribution was refitted for predictions and inference. The greatest density of fisheries dependent hoop net captures (39 %) was near the confluence of the Missouri and Mississippi rivers, primarily from July-September. Captures were characterized by median water temperature 26.7°C, river stage 5.02 m, and 223 day-of-year (DOY; mid-August). Ordination of fisheries independent catch identified similarity in environmental covariates of Smallmouth Buffalo Ictiobus bubalus and Black Carp. The probability of capturing ≥ 1 Black Carp increased with DOY, decreased with increasing current velocity, and increased with depth. Most captures occurred in outside bends (87 %) or side channels (12 %). Probability of Black Carp capture was low but increased in summer and early fall when stage is lower, facilitating reduced current velocity and access to deeper areas. Results may be validated beyond this river segment to test if site-specific hydrology or habitat characteristics facilitated increased commercial and biologist capture and for replication.

Illinois, Missouri↗
USGS2020

Fisheries research and monitoring activities of the Lake Erie Biological Station, 2019

A comprehensive understanding of fish populations and their interactions is the cornerstone of modern fishery management and the basis for Fish Community Goals and Objectives for Lake Erie (Ryan et al. 2003). This report is responsive to U.S. Geological Survey (USGS) obligations via Memorandum of Understanding (MOU) with the Great Lakes Council of Lake Committees (CLC) to provide scientific information in support of fishery management. Goals for the USGS Great Lakes Deepwater Fish Assessment and Ecological Studies in 2019 were to monitor long-term changes in the fish community and population dynamics of key fishes of interest to management agencies. Specific to Lake Erie, expectations of this agreement were sustained investigations of native percids, forage (prey) fish populations, and Lake Trout. Our 2019 deepwater program operations began in April and concluded in December, and utilized trawl, gillnet, hydroacoustic, lower trophic sampling, and telemetry methods. This work resulted in 88 bottom trawls covering 65 ha of lake-bottom and catching 24,140 fish totaling 3,622 kg during three separate trawl surveys in the West and Central basins of Lake Erie. Overnight gillnet sets (n=44) for cold water species were performed at 42 unique locations in the West and East basins of Lake Erie. A total of 8.0 km of gillnet was deployed during these surveys, which caught 286 fish, 114 of which were native coldwater species: Lake Trout, Burbot, and Lake Whitefish. USGS hydroacoustic surveys in 2019 produced 240 km of transects, and lower trophic sampling provided data from zooplankton samples (n=21) and water quality profiles (n=21) to populate a database maintained by the Ontario Ministry of Natural Resources and Forestry (OMNRF), Ohio Division of Natural Resources (ODNR), Michigan Division of Natural Resources (MDNR), Pennsylvania Fish and Boat Commission (PFBC), and New York State Department of Environmental Conservation (NYSDEC). USGS also assisted CLC member agencies with deployment and maintenance of the Great Lakes Acoustic Telemetry Observation System (GLATOS) throughout all three Lake Erie sub-basins, supporting multiple coordinated telemetry investigations. In 2019, Lake Trout investigations included annual gill net surveys and acoustic telemetry of spawning migration and habitat use in coordination with OMNRF, NYSDEC, and PFBC. Results from Lake Trout investigations were reported in the Coldwater Task Group annual report to the Great Lakes Fishery Commission (GLFC) and the CLC (Coldwater Task Group 2020). Likewise, interagency forage fish assessments conducted with hydroacoustics were summarized and reported in the Forage Task Group annual report (Forage Task Group 2020). This report presents biomass-based summaries of fish communities in western Lake Erie derived from USGS bottom trawl surveys conducted from 2013 to 2019 during June and September. The survey design provided temporal and spatial coverage that did not exist in the historic interagency trawl database, and thus complemented the August ODNR-OMNRF effort to reinforce stock assessments with more robust data. Analyses herein evaluated trends in: total biomass, abundance of dominant predator and forage species, non-native species composition, biodiversity and community structure. Data from this effort can be explored interactively online (https://lebs.shinyapps.io/western-basin/), and are accessible for download (https://doi.org/10.5066/P9LL6YOR, Keretz et al. 2020). Annual survey data are added to these sources as the data become available.

Lake Erie↗
USGS2007

Evidence of lake whitefish spawning in the Detroit River: Implications for habitat and population recovery

Historic reports imply that the lower Detroit River was once a prolific spawning area for lake whitefish ( Coregonus clupeaformis ) prior to the construction of the Livingstone shipping channel in 1911. Large numbers of lake whitefish migrated into the river in fall where they spawned on expansive limestone bedrock and gravel bars. Lake whitefish were harvested in the river during this time by commercial fisheries and for fish culture operations. The last reported landing of lake whitefish from the Detroit River was in 1925. Loss of suitable spawning habitat during the construction of the shipping channels as well as the effects of over-fishing, sea lamprey ( Petromyzon marinus ) predation, loss of riparian wetlands, and other perturbations to riverine habitat are associated with the disappearance of lake whitefish spawning runs. Because lake whitefish are recovering in Lake Erie with substantial spawning occurring in the western basin, we suspected they may once again be using the Detroit River to spawn. We sampled in the Detroit River for lake whitefish adults and eggs in late fall of 2005 and for lake whitefish eggs and fish larvae in 2006 to assess the extent of reproduction in the river. A spawning-ready male lake whitefish was collected in gillnets and several dozen viable lake whitefish eggs were collected with a pump in the Detroit River in November and December 2005. No lake whitefish eggs were found at lower river sites in March of 2006, but viable lake whitefish eggs were found at Belle Isle in the upper river in early April. Several hundred lake whitefish larvae were collected in the river during March through early May 2006. Peak larval densities (30 fish/1,000 m3 of water) were observed during the week of 3 April. Because high numbers of lake whitefish larvae were collected from mid- and downstream sample sites in the river, we believe that production of lake whitefish in the Detroit River may be a substantial contribution to the lake whitefish population in Lake Erie.

Michigan↗
USGS2014

Blue Growth: the 2014 FAO State of the World Fisheries and Aquaculture

The latest United Nations Food and Agriculture Organization report (FAO 2014) addresses the prospect of feeding a human population set to rise to 9.6 billion by 2050. Aquaculture products now provide approximately one-half of all food fish consumed, and fish also provide important food security and economic growth. In the FAO analyses, food fish included finfish, crustaceans, mollusks, amphibians, freshwater turtles, and other aquatic animals (such as sea cucumbers, sea urchins, sea squirts, and edible jellyfish) produced for human consumption. At the present time, food fish provides the world population of nearly 7.3 billion people with an average of one-fifth of total animal protein intake.

Fisheries↗
USGS2018

Effects of transmitter type, tagging method, body size, and temperature on behavior, physiology, and swimming performance of juvenile Chinook salmon (Oncorhynchus tshawytscha)

The objective of this study was to assess the impact of different tagging methods and transmitter types on juvenile salmonid behavior, mortality, physiology, and swimming performance over a range of water temperatures and fish sizes. In Chapter 1, two laboratory experiments were conducted to assess maximum burst-swimming speeds, the probability of gulping air, swimming angles, and the probability of resting on a screen in a swim tunnel. For the burst swim speed experiment, we identified a slightly reduced, but statistically significant difference in burst-swimming speeds for gastric- and surgical-tagged fish implanted with dummy radio and acoustic transmitters. For the swim tunnel experiment, surgical-tagged fish were one-half as likely to gulp air at the surface of the swim tunnel as untagged and gastric-tagged fish. We observed higher probabilities of fish gulping air at the surface for fish with tag ratios greater than 5 percent, suggesting that smaller fish required greater adjustment to their buoyancy than larger fish. We also observed that gastric-tagged fish had, on average, steeper swimming angles than untagged and surgical-tagged fish in the swim tunnel. In Chapter 2, we conducted a field-based laboratory experiment at John Day Dam to assess the sustained swimming performance (i.e., critical swimming speed or U crit ) of in-river migrating subyearling Chinook salmon that were surgically implanted with dummy radio and acoustic transmitters. Statistical tests indicated a significant reduction (about 8.3 centimeters per second [cm/s] or 1 body length per second) in sustained swimming performance for fish implanted with either radio or acoustic transmitters. We also found a significant reduction in U crit of -1.38 cm/s for every 1 degree Celsius (°C) increase in temperature. In Chapter 3, we assessed the effects of water temperature on the physiology, mortality, and swimming performance of juvenile Chinook salmon in laboratory and field experiments. Juvenile Chinook salmon generally showed elevated stress response, elevated mortality, and reduced swimming performance as water temperature increased. We concluded that the water temperature threshold for handling and tagging fish with minimal impacts seems to be near 23 °C. At 25 °C, we documented very high mortality and dramatically reduced swimming performance of tagged fish relative to controls. Telemetry studies conducted at 25 °C would not meet the critical assumption that the transmitter has minimal impacts on the study fish. In the Chapter 4, we evaluated the effects of antenna length and antenna material on the subsequent tag output power, reception, and detection of tagged fish. In a laboratory, we compared the relative signal strengths in water of 150-megahertz transmitters over a range of antenna lengths (from 6 to 30 cm) and materials (one weighing about one-half of the other). The peak relative signal strengths were at 20 and 22 cm, which are about 1 wavelength underwater at the test frequency. The peak relative signal strengths at these antenna lengths were about 50 percent greater than those of 30-cm antennas, a length commonly used in fisheries research.

Open-File Report↗