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At least 703 records · Page 39Linked to original sources
USGS2005

Optimization of an acoustic telemetry array for detecting transmitter-implanted fish

The development of miniature acoustic transmitters and economical, robust automated receivers has enabled researchers to study the movement patterns and survival of teleosts in estuarine and ocean environments, including many species and age-classes that were previously considered too small for implantation. During 2001-2003, we optimized a receiver mooring system to minimize gear and data loss in areas where current action or wave action and acoustic noise are high. In addition, we conducted extensive tests to determine (1) the performance of a transmitter and receiver (Vemco, Ltd.) that are widely used, particularly in North America and Europe and (2) the optimal placement of receivers for recording the passage of fish past a point in a linear-flow environment. Our results suggest that in most locations the mooring system performs well with little loss of data; however, boat traffic remains a concern due to entanglement with the mooring system. We also found that the reception efficiency of the receivers depends largely on the method and location of deployment. In many cases, we observed a range of 0-100% reception efficiency (the percentage of known transmissions that are detected while the receiver is within range of the transmitter) when using a conventional method of mooring. The efficiency was improved by removal of the mounting bar and obstructions from the mooring line.

Idaho, Oregon, Washington↗
USGS2005

A new sampler design for measuring sedimentation in streams

Sedimentation alters aquatic habitats and negatively affects fish and invertebrate communities but is difficult to quantify. To monitor bed load sedimentation, we designed a sampler with a 10.16-cm polyvinyl chloride coupling and removable sediment trap. We conducted a trial study of our samplers in riffle and pool habitats upstream and downstream of highway construction on a first-order Appalachian stream. Sediment samples were collected over three 6-week intervals, dried, and separated into five size-classes by means of nested sieves (U.S. standard sieve numbers 4, 8, 14, and 20). Downstream sediment accumulated in size-classes 1 and 2, and the total amount accumulated was significantly greater during all three sampling periods. Size-classes 3 and 4 had significantly greater amounts of sediment for the first two sampling periods at the downstream site. Differences between upstream and downstream sites narrowed during the 5-month sampling period. This probably reflects changes in site conditions, including the addition of more effective sediment control measures after the first 6-week period of the study. The sediment sampler design allowed for long-term placement of traps without continual disturbance of the streambed and was successful at providing repeat measures of sediment at paired sites. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Fisheries Management↗
USGS2004

Anchor and visible implant elastomer tag retention by hatchery rainbow trout stocked into an Ozark stream

As part of a study to evaluate the stocking of rainbow trout Oncorhynchus mykiss in an Oklahoma Ozark stream, we tagged 2,542 hatchery-reared rainbow trout (123-366 mm total length) with individually numbered Floy FD-68B anchor tags and visible implant fluorescent elastomer (VIE) tags. We experimentally stocked double-marked rainbow trout into a small northeastern Oklahoma stream from November 2001 to March 2002 and resampled them monthly from December 2001 to October 2002 by electrofishing. Anchor tag retention was 91% through 6 months, and VIE tag retention was 96% through 6 months despite extensive handling of fish within 24 h of tagging. Based on the ease of application, high visibility, and high retention observed in this study, we recommend the use of VIE tags as a batch mark in similarly sized, similarly pigmented fish. The retention of VIE tags was slightly higher than that of anchor tags, and cost per fish was less for VIE than for anchor tags. However, VIE tags would have limited utility if numerous individual tags are necessary; therefore, we recommend anchor tags as individual marks in similarly sized salmonids. Retention for both tag types was relatively high and could be corrected for when estimating population parameters from tagging data.

North American Journal of Fisheries Management↗
USGS2005

Recent water temperature trends in the lower Klamath River, California

Elevated water temperatures have been implicated as a factor limiting the recovery of anadromous salmonids in the Klamath River basin. This article reviews evidence of a multi-decade trend of increasing temperatures in the lower main-stem Klamath River above the ocean and, based on model simulations, finds a high probability that water temperature has been increasing by approximately 0.5??C/decade (95% confidence interval [Cl] = 0.42-0.60??C/decade) since the early 1960s. The season of high temperatures that are potentially stressful to salmonids has lengthened by about 1 month over the period studied, and the average length of main-stem river with cool summer temperatures has declined by about 8.2 km/decade. Water temperature trends seem unrelated to any change in main-stem water availability but are consistent with measured basinwide air temperature increases. Main-stem warming may be related to the cyclic Pacific Decadal Oscillation, but if this trend continues it might jeopardize the recovery of anadromous salmonids in the Klamath River basin. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Fisheries Management↗
USGS2005

Effect of block net use and time of sampling on backpack electrofishing catches in three Kansas reservoirs

Using backpack electrofishing in three Kansas reservoirs, we investigated the need for block nets when estimating density (fish/ha) and species diversity and determined whether time of sampling affected catch rates (fish/h) of age-0 largemouth bass Micropterus salmoides and age-0 Lepomis spp. and species diversity. Block nets were used to enclose or buoys were used to mark the boundaries of 149 m2 of reservoir surface area. Species richness, diversity, and density of age-0 largemouth bass and Lepomis spp. did not differ significantly between areas enclosed with block nets and areas marked with buoys, but species richness, diversity, and catch rates differed significantly between day and night sampling. Age-0 largemouth bass and Lepomis spp. catch rates, species richness, and species diversity were all significantly higher during night sampling. Our results indicate that use of block nets may not be necessary to estimate age-0 largemouth bass and Lepomis spp. densities, species richness, or diversity in reservoir littoral areas. We recommend night sampling because of significantly higher catch rates and better representation of the littoral fish assemblage. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Fisheries Management↗
USGS2005

Juvenile rainbow trout production in New York tributaries of Lake Ontario: implications for Atlantic salmon restoration

Three Pacific salmonid species Onchorynchus spp. have replaced the extirpated Atlantic salmon Salmo salar as the main migratory salmonid in the Lake Ontario drainage. One of those species, the nonnative rainbow trout O. mykiss, has become widely distributed within the historical Atlantic salmon habitat, occupying an ecological niche similar to that of juvenile Atlantic salmon. Consequently, both a tributary's carrying capacity for Atlantic salmon and competition from established nonnative species are important when considering the feasibility of Atlantic salmon restoration. Estimation of juvenile rainbow trout production will help evaluate the capacity of tributaries to produce salmonids that occupy similar niches. Geostatistical methods were applied to standardized and efficiency-corrected electrofishing data from three of New York's best salmonid-producing streams to precisely estimate juvenile rainbow trout populations. Results indicated that each study stream could produce 20,000–40,000 age-0 and 4,000–10,000 age-1 and older rainbow trout per year. Statistical interpolation indicated areas of significantly different production potential and points of significant changes in productivity. Closer examination of the niche similarity and competitive potential of these two species is needed to properly interpret these estimates with regard to Atlantic salmon restoration.

New York↗
USGS2005

Evaluation of a prototype surface flow bypass for juvenile salmon and steelhead at the powerhouse of Lower Granite Dam, Snake River, Washington, 1996-2000

A surface flow bypass takes advantage of the natural surface orientation of most juvenile salmon Oncorhynchus spp. and steelhead O. mykiss by providing a route in the upper water column that downstream migrant fishes can use to pass a hydroelectric dam safely. A prototype structure, called the surface bypass and collector (SBC), was retrofitted on the powerhouse of Lower Granite Dam and was evaluated annually with biotelemetry and hydroacoustic techniques during the 5-year life span of the structure (1996-2000) to determine the entrance configuration that maximized passage efficiency and minimized forebay residence time. The best tested entrance configuration had maximum inflow (99 m 3/s) concentrated in a single surface entrance (5 m wide, 8.5 m deep). We identified five important considerations for future surface flow bypass development in the lower Snake River and elsewhere: (1) an extensive flow net should be formed in the forebay by use of relatively high surface flow bypass discharge (>7% of total project discharge); (2) a gradual increase in water velocity with increasing proximity to the surface flow bypass (ideally, acceleration 3 m/s) to entrain the subject juvenile fishes; (4) the shape and orientation of the surface entrance(s) should be adapted to fit site-specific features; and (5) construction of a forebay wall to increase fish availability to the surface flow bypass should be considered. The efficiency of the SBC was not high enough (maximum of 62% relative to passage at turbine units 4-5) for the SBC to operate as a stand-alone bypass. Anywhere that surface-oriented anadromous fish must negotiate hydroelectric dams, surface flow bypass systems can provide cost-effective use of typically limited water supplies to increase the nonturbine passage, and presumably survival, of downstream migrants. ??Copyright by the American Fisheries Society 2005.

Washington↗
USGS2005

Multilevel assessment of fish species traits to evaluate habitat degradation in streams of the upper midwest

We used species traits to examine the variation in fish assemblages for 21 streams in the Northern Lakes and Forests Ecoregion along a gradient of habitat disturbance. Fish species were classified based on five species trait-classes (trophic ecology, substrate preference, geomorphic preference, locomotion morphology, and reproductive strategy) and 29 categories within those classes. We used a habitat quality index to define a reference stream and then calculated Euclidean distances between the reference and each of the other sites for the five traits. Three levels of species trait analyses were conducted: (1) a composite measure (the sum of Euclidean distances across all five species traits), (2) Euclidean distances for the five individual species trait-classes, and (3) frequencies of occurrence of individual trait categories. The composite Euclidean distance was significantly correlated to the habitat index (r = -0.81; P = 0.001), as were the Euclidean distances for four of the five individual species traits (substrate preference: r = -0.70, P = 0.001; geomorphic preference: r = -0.69, P = 0.001; trophic ecology: r = -0.73, P = 0.001; and reproductive strategy: r = -0.64, P = 0.002). Although Euclidean distances for locomotion morphology were not significantly correlated to habitat index scores (r = -0.21; P = 0.368), analysis of variance and principal components analysis indicated that Euclidean distances for locomotion morphology contributed to significant variation in the fish assemblages among sites. Examination of trait categories indicated that low habitat index scores (degraded streams) were associated with changes in frequency of occurrence within the categories of all five of the species traits. Though the objectives and spatial scale of a study will dictate the level of species trait information required, our results suggest that species traits can provide critical information at multiple levels of data analysis. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Fisheries Management↗
USGS2005

Quantifying production of salmon fry in an unscreened irrigation system: A case study on the Rangitata River, New Zealand

Diversion of out-migrant juvenile salmon into unscreened irrigation and hydroelectric canals is thought to have contributed significantly to declining populations of anadromous salmonids in the Pacific Northwest but is seldom studied in detail. Here we describe a program to study the fate of Chinook salmon Oncorhynchus tshawytscha fry diverted into the unscreened Rangitata Diversion Race (RDR) on the Rangitata River, New Zealand, by trapping fish in a random sample of on-farm canals in irrigation schemes (systems) served by the RDR. The catch rate at a site 9 km below the intake was strongly related to Rangitata River flow, but catches further downstream were unrelated to flow. Most fish entering the RDR were fry or early postfry (<70 mm fork length (FL)), but up to 92% of the fish trapped in on-farm canals were fingerlings (>70 mm FL), suggesting that many such fish became resident in the RDR for up to 3 months. Consequently, our estimate of the total number of fish leaving the RDR via on-farm canals (204,200 fish; 95% confidence limits = 127,100 and 326,700) is a conservative measure of the number lost from the Rangitata River because it does not allow for mortality within the RDR. We did not quantify the proportion of Rangitata River out-migrants that entered the RDR, but our results suggest that this figure was at least 5% and that it may have been as high as 25%, depending on mortality rates within the Rangitata River main stem and the RDR itself.

Rangitata River↗
USGS2005

Electroshocking and PIT tagging of juvenile Atlantic salmon: Are there interactive effects on growth and survival?

Electroshocking and tagging of fish with passive integrated transponder (PIT) tags are two commonly used methods for conducting mark-recapture studies in freshwater environments and are frequently used in combination. We conducted an experiment to test for the effects of electroshocking, tagging, and a combination of electroshocking plus tagging on the growth and survival of Atlantic salmon Salmo salar parr. We used five treatments that included the presence or absence of PIT tags and electroshocking at 300 or 500 V plus a control group. Fish were measured, weighed, and electroshocked on four occasions separated by approximately 2-month intervals. The average (??1 SD) fork length was 62.1 ?? 1.9 mm and the average weight was 2.5 ?? 0.3 g at the start of the experiment; at the end of the experiment, length averaged 120.5 ?? 11.6 mm and weight averaged 20.9 ?? 6.1 g. We did not detect any significant effects of electroshocking on growth or survival over the course of the experiment. However, there was evidence that tagging negatively influenced survival over the first interval after initial tagging and that survival was positively correlated with fish size. In addition, tagged fish seemed to suffer a minor depression in growth over the first interval, although differences in size among tagged and untagged fish were nonsignificant throughout the course of the experiment. We suggest that the size at tagging may have a greater effect on survival and growth of small (<80-mm) Atlantic salmon parr than the amount of exposure to electroshocking. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Fisheries Management↗
USGS2005

Movements of fluvial Bonneville cutthroat trout in the Thomas Fork of the Bear River, Idaho-Wyoming

The majority of interior subspecies of cutthroat trout Oncorhynchus clarkii have been extirpated from large rivers by anthropogenic activities that have fragmented habitats and introduced nonnative competitors. Selective pressures against migratory behaviors and main-stem river occupation, coupled with conservation strategies that isolate genetically pure populations above barriers, have restricted gene flow and prevented expression of the fluvial life history in many populations. Existing knowledge about the movements and home range requirements of fluvial cutthroat trout is, therefore, limited. Our objectives in this study were to (1) determine the extent of seasonal home ranges and mobility of Bonneville cutthroat trout O. c. utah (BCT) in the Thomas Fork and main-stem Bear River and (2) evaluate the role of a water diversion structure functioning as a seasonal migration barrier to fish movement. We implanted 55 BCT in the Thomas Fork of the Bear River, Idaho, with radio transmitters and located them bimonthly in 1999–2000 and weekly in 2000–2001. We found fish to be more mobile than previously reported. Individuals above the diversion barrier occupied substantially larger home ranges than those below the barrier (analysis of variance: P = 0.0003; median = 2,225 m above barrier; median = 500 m below barrier) throughout our study, and they moved more frequently (mean, 0.89 movements/contact; range, 0.57–1.00) from October 2000 through March 2001 than fish below the barrier (mean, 0.45 movements/contact; range, 0.00–1.00). During the spring of both years, we located radio-tagged fish in both upstream and neighboring tributaries as far as 86 km away from our study site. Our results document the existence of a fluvial component of BCT in the Bear River and its tributaries and suggest that successful efforts at conservation of these fish must focus on main-stem habitats and the maintenance of seasonal migration corridors.

North American Journal of Fisheries Management↗
USGS2005

Validation of abundance estimates from mark–recapture and removal techniques for rainbow trout captured by electrofishing in small streams

Estimation of fish abundance in streams using the removal model or the Lincoln - Peterson mark - recapture model is a common practice in fisheries. These models produce misleading results if their assumptions are violated. We evaluated the assumptions of these two models via electrofishing of rainbow trout Oncorhynchus mykiss in central Idaho streams. For one-, two-, three-, and four-pass sampling effort in closed sites, we evaluated the influences of fish size and habitat characteristics on sampling efficiency and the accuracy of removal abundance estimates. We also examined the use of models to generate unbiased estimates of fish abundance through adjustment of total catch or biased removal estimates. Our results suggested that the assumptions of the mark - recapture model were satisfied and that abundance estimates based on this approach were unbiased. In contrast, the removal model assumptions were not met. Decreasing sampling efficiencies over removal passes resulted in underestimated population sizes and overestimates of sampling efficiency. This bias decreased, but was not eliminated, with increased sampling effort. Biased removal estimates based on different levels of effort were highly correlated with each other but were less correlated with unbiased mark - recapture estimates. Stream size decreased sampling efficiency, and stream size and instream wood increased the negative bias of removal estimates. We found that reliable estimates of population abundance could be obtained from models of sampling efficiency for different levels of effort. Validation of abundance estimates requires extra attention to routine sampling considerations but can help fisheries biologists avoid pitfalls associated with biased data and facilitate standardized comparisons among studies that employ different sampling methods.

Idaho↗
USGS2005

Refining boat electrofishing equipment to improve consistency and reduce harm to fish

A major concern with electrofishing is the standardization of sampling equipment and methods, particularly when collections are used to monitor spatial and temporal changes in fish communities. Standardization can not only ensure that stock assessment is consistent - that is, the data collected over time and space have equal meaning and are not influenced by differences in gear or gear application - but also reduce injury by constraining power to ranges that are likely to immobilize fish but unlikely to harm them. Standardization of electrofishing equipment requires adjusting power output to keep constant the amount of power transferred to fish in diverse water conditions. In this study, the power level thresholds required to immobilize and injure fish under controlled laboratory conditions were identified for various size-species combinations and applied to establish power minima and maxima suitable for successful and safe boat electrofishing. The target settings identified allowed survival of 99.4% of the fish collected and held for 2-3 h during field trials; all the mortalities were small fish (???53 mm long). The standardization procedure described herein may be adapted to single boats or fleets and can promote consistency in electrofishing, although it does not completely avoid harm to fish. Because electrofishing is an active capture method applied to changing microenvironments, complete standardization and total avoidance of harm to individual fish are not feasible with present technology, but standardization of controllable variables is advisable.

North American Journal of Fisheries Management↗
USGS2005

Winter ice processes and pool habitat associated with two types of constructed instream structures

There is little information on the winter features of salmonid habitats associated with constructed instream structures to provide guidance when planning habitat improvement projects. We assessed winter habitat features for trout of the genera Oncorhynchus and Salvelinus in pools associated with two types of instream structures constructed on a low-gradient reach of a mountain stream in western Wyoming with a mean wetted width of 6.4 m. Pool habitat was affected by temporal variability in ice formations from fall into winter. As surface ice and snow accumulated with the progression of winter, variation in ice formations was less frequent and winter habitat conditions became more stable. However, groundwater inflow that maintained water temperatures at 0.2-0.6??C in a portion of the study reach appeared to contribute to incomplete surface ice cover and variation in ice formations in pools through most of the winter. Hanging dams and anchor ice dams were the primary ice features that affected winter habitat in pools associated with constructed instream structures. Trout were observed in these pools in the fall but tended to abandon pools with variation in ice formations as winter progressed. The potential impacts of groundwater inflow and winter ice processes on trout habitat in pools associated with instream structures should be considered when planning habitat improvement projects. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Fisheries Management↗
USGS2005

Temporal and spatial variation in relative abundance and length structure of salmonids in reservoirs: Implications for monitoring

Spatial and temporal variations in salmonid catch per unit effort (C/f) may affect monitoring efforts in lakes and reservoirs. This study evaluated the spatial and temporal variation in gill-net C/f and length structure of captured salmonids in nearshore (???7.6-m bottom depth) and offshore (>7.6-m bottom depth) areas of two Wyoming reservoirs. Floating experimental gill nets were set as nearshore and offshore pairs at 24 locations in both reservoirs during each of four sampling periods (spring, early summer, late summer, and fall). Salmonid C/f was significantly higher in nearshore areas than in offshore areas during all periods in one reservoir and during all periods except spring in the other reservoir. Mean C/f of rainbow trout Oncorhynchus mykiss was not significantly different between nearshore and offshore areas when water temperatures were 10-13??C in both reservoirs. Length structure of salmonids differed significantly between nearshore and offshore locations and among periods in both reservoirs. These patterns should be considered in both the design and analysis phases of monitoring efforts that use floating experimental gill nets and other sampling gears. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Fisheries Management↗
USGS2005

Effect of measurement error on tests of density dependence of catchability for walleyes in northern Wisconsin angling and spearing fisheries

We sought to determine how much measurement errors affected tests of density dependence of spearing and angling catchability for walleye Sander vitreus by quantifying relationships between spearing and angling catch rates (catch/h) and walleye population density (number/acre) in northern Wisconsin lakes. The mean measurement error of spearing catch rates was 43.5 times greater than the mean measurement error of adult walleye population densities, whereas the mean measurement error of angling catch rates was only 5.6 times greater than the mean measurement error of adult walleye population densities. The bias-corrected estimate of the relationship between spearing catch rate and adult walleye population density was similar to the ordinary-least-squares regression estimate but differed significantly from the geometric mean (GM) functional regression estimate. In contrast, the bias-corrected estimate of the relationship between angling catch rate and total walleye population density was intermediate between ordinary-least-squares and GM functional regression estimates. Catch rates of walleyes in both spearing and angling fisheries were not linearly related to walleye population density, which indicated that catch rates in both fisheries were hyperstable in relation to walleye population density. For both fisheries, GM functional regression overestimated the degree of hyperdepletion in catch rates and ordinary-least-squares regression overestimated the degree of hyperstability in catch rates. However, ordinary-least-squares regression induced significantly less bias in tests of density dependence than GM functional regression, so it may be suitable for testing the degree of density dependence in fisheries for which fish population density is estimated with mark-recapture methods similar to those used in our study. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Fisheries Management↗
USGS2005

Understanding the output of a Smith-Root GPP electrofisher

There is confusion among biologists about the use of the percent of range control in the GPP series of Smith-Root electrofishers. We evaluated the output of a GPP 7.5 electrofisher to examine how adjustments to the percent of range control affect voltage, pulse width, duty cycle, and waveform. We found that contrary to how most users interpret the labels on the GPP unit, adjustments to the percent of range control are linked only indirectly to changes in peak voltage. Suggestions for dealing with the restrictions of the GPP units are offered. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Fisheries Management↗
USGS2005

Hooking mortality and physiological responses of striped bass angled in freshwater and held in live-release tubes

Mortality and physiological responses of adult striped bass Morone saxatilis angled from Lake Murray, South Carolina, and held in live-release tubes were evaluated during the spring and summer of 2003. To estimate mortality, we attached external ultrasonic transmitters to 59 striped bass (mean total length [TL] = 585 mm). Striped bass were caught with angling gear, tagged, and immediately released or held in live-release tubes for 2, 4, or 6 h prior to release. No mortality of striped bass was observed during spring. Overall mortality during summer was 83%. Mortality of summer-caught striped bass was not related to tube residence time, fish TL, depth of capture, or surface water temperature. To characterize physiological stress, we measured the plasma cortisol, glucose, lactate, and osmolality levels of 62 additional striped bass (mean TL = 563 mm) that were angled and immediately released or angled and held in live-release tubes. Plasma cortisol, glucose, lactate, and osmolality were positively related to tube residence time. When the hematological characteristics were considered only in relation to tube residence time, responses indicative of physiological stress continued for about 150 min, after which blood chemistry began to return to normal. Live-release tubes appear to be useful for keeping striped bass alive when they are angled from cool water, but they are not effective for striped bass angled from warm water. The high summer mortality of striped bass suggests a need for restrictive fishing regulations during the summer for the Lake Murray striped bass fishery. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Fisheries Management↗