bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of a Volunteer Angler Survey for Assessing Length Distribution and Seasonal Catch Trends of Trophy Largemouth Bass
Authors: De Jesus Marcos J. , Magnelia Stephan J. , Bonds C. Craig 
Published: October 2009

Abstract
A volunteer angler survey was conducted from October 2004 to May 2006 at Fayette County Reservoir, Texas, to help determine the seasonal catch trends and length distribution of trophy (≥21 in long) largemouth bass Micropterus salmoides. Although previous Texas Parks and Wildlife creel and electrofishing surveys had collected data on the reservoir's largemouth bass fishery, little information was obtained on trophy bass. Quarterly catch and length distribution data from a volunteer angler survey were compared with data collected concurrently during an agency-staffed creel survey as a means to validate the volunteered data. The costs associated with each survey method were also compared. Anglers voluntarily reported catches of 177 trophy largemouth bass during the 20-month survey period. The length distributions by inch-group 21 in or longer were not significantly different between survey methods, validating the fish lengths reported by volunteers. The quarterly catch trends over a 1-year period were also similar between methods. The monetary costs of the 20-month volunteer survey were 16% those of the 12-month staffed creel survey. Managers should consider similar volunteer surveys on small impoundments when relatively low-cost length distribution and catch trend data are needed for trophy fish. Volunteer data may help justify the cost associated with additional creel surveys when more extensive data are needed. This information can also be used to complement data gathered in previous creel surveys.
A Spatial Model to Assess the Effects of Hydropower Operations on Columbia River Fall Chinook Salmon Spawning Habitat
Authors: Hatten James R. , Tiffan Kenneth F. , Anglin Donald R. , Haeseker Steven L. , Skalicky Joseph J. , Schaller Howard 
Published: October 2009

Abstract
Priest Rapids Dam on the Columbia River produces large daily and hourly streamflow fluctuations throughout the Hanford Reach during the period when fall Chinook salmon Oncorhynchus tshawytscha are selecting spawning habitat, constructing redds, and actively engaged in spawning. Concern over the detrimental effects of these fluctuations prompted us to quantify the effects of variable flows on the amount and persistence of fall Chinook salmon spawning habitat in the Hanford Reach. Specifically, our goal was to develop a management tool capable of quantifying the effects of current and alternative hydrographs on predicted spawning habitat in a spatially explicit manner. Toward this goal, we modeled the water velocities and depths that fall Chinook salmon experienced during the 2004 spawning season, plus what they would probably have experienced under several alternative (i.e., synthetic) hydrographs, using both one- and two-dimensional hydrodynamic models. To estimate spawning habitat under existing or alternative hydrographs, we used cell-based modeling and logistic regression to construct and compare numerous spatial habitat models. We found that fall Chinook salmon were more likely to spawn at locations where velocities were persistently greater than 1 m/s and in areas where fluctuating water velocities were reduced. Simulations of alternative dam operations indicate that the quantity of spawning habitat is expected to increase as streamflow fluctuations are reduced during the spawning season. The spatial habitat models that we developed provide management agencies with a quantitative tool for predicting, in a spatially explicit manner, the effects of different flow regimes on fall Chinook salmon spawning habitat in the Hanford Reach. In addition to characterizing temporally varying habitat conditions, our research describes an analytical approach that could be applied in other highly variable aquatic systems.
Factors Affecting Fish Entrainment into Massive Water Diversions in a Tidal Freshwater Estuary: Can Fish Losses be Managed?
Authors: Grimaldo Lenny F. , Sommer Ted , Van Ark Nick , Jones Gardner , Holland Erika , Moyle Peter B. , Herbold Bruce , Smith Pete 
Published: October 2009

Abstract
We examined factors affecting fish entrainment at California's State Water Project and Central Valley Project, two of the largest water diversions in the world. Combined, these diversions from the upper San Francisco Estuary support a large component of the municipal and agricultural infrastructure for California. However, precipitous declines in the abundance of several estuarine fish species, notably the threatened delta smelt Hypomesus transpacificus, have generated major concern about entrainment as a possible cause of the declines. We examined a 13-year data set of export pumping operations and environmental characteristics to determine factors affecting entrainment (as indexed by salvage at fish screens) and the potential for manipulation of these factors to improve conditions for fish. Entrainment of three migratory pelagic species—delta smelt, longfin smelt Spirinchus thaleichthys, and striped bass Morone saxatilis—was primarily determined by the seasonal occurrence of particular life stages close to the export facilities. We also found that the direction and magnitude of flows through the estuary and to the export facilities were reasonable predictors of pelagic fish entrainment. Entrainment of resident demersal species (prickly sculpin Cottus asper and white catfish Ameiurus catus) and littoral species (Mississippi silverside Menidia audens and largemouth bass Micropterus salmoides) was not explained by diversion flows, although large numbers of individuals from these species were collected. Our study suggests that entrainment of pelagic species can be effectively reduced by manipulating system hydrodynamics.
Evaluating the Reintroduction Potential of Lahontan Cutthroat Trout in Fallen Leaf Lake, California
Authors: Al-Chokhachy Robert , Peacock Mary , Heki Lisa G. , Thiede Gary 
Published: October 2009

Abstract
We evaluated the potential for reintroducing Lahontan cutthroat trout Oncorhynchus clarkii henshawi, a species listed under the Endangered Species Act, into a lacustrine system where the biotic community has changed dramatically since the species' extirpation there. Since 2002, 76,547 Lahontan cutthroat trout have been reintroduced into Fallen Leaf Lake, California; we used creel surveys, diet data, mark–recapture methods, bioenergetics modeling, and netting data across seasons to evaluate the habitat use, growth, and relative abundance of Lahontan cutthroat trout and the abundance, diet, habitat use, and predation by nonnative species. Sampling totals (n = 2) and survey observations (n = 3) indicate low survival and abundance of reintroduced fish and together with creel data indicate the importance of epilimnetic habitats across size-classes. Despite substantial growth, Lahontan cutthroat trout exhibited low condition factor values (average = 0.69). We found substantial predation pressure from a large population of lake trout Salvelinus namaycush (Ṋ = 8,799 fish; 95% confidence interval [CI] = 4,990–16,530 fish); analysis of lake trout diets showed an increase in piscivory and in the percentage of stomachs containing Lahontan cutthroat trout anchor tags with increasing predator size. Overall, we estimated that lake trout consumed over 38% of reintroduced Lahontan cutthroat trout (mean number consumed = 7,736 fish; 95% CI = 4,388–14,534 fish). With bioenergetics modeling, however, we estimated that lake trout consumed considerable amounts of salmonid biomass during this period (mean biomass = 3,137 kg; 95% CI = 1,779–5,893 kg), which greatly exceeded the biomass of Lahontan cutthroat trout reintroduced in 2006. During the stratification period, there was little overlap in habitat use between lake trout and Lahontan cutthroat trout, but overlap was high during the spring and autumn. We found moderate-sized populations of nonnative brown trout Salmo trutta, kokanee O. nerka (lacustrine sockeye salmon), and rainbow trout O. mykiss. Together, our results suggest that Lahontan cutthroat trout have few refugia from direct and indirect negative interactions with nonnative species and that alternative approaches are needed.
Use of Carcass Recovery Data in Evaluating the Spawning Distribution and Timing of Spring Chinook Salmon in the Chiwawa River, Washington
Authors: Murdoch Andrew R. , Pearsons Todd N. , Maitland Travis W. 
Published: October 2009

Abstract
Spawning ground surveys are routinely conducted to assess status and trends for many populations of Pacific salmon Oncorhynchus spp. Biological data from carcasses recovered during spawning ground surveys are used for various stock assessment purposes but may also be useful in comparing the spawning distribution and timing of hatchery- and naturally produced fish. The objective of this study was to measure the distance between redd and carcass locations of spring Chinook salmon O. tshawytscha in the Chiwawa River and assess whether carcass location adequately represents spawning location. We also estimated the redd residence time (d) of hatchery- and naturally produced spring Chinook and compared the spawn timing using both redd and carcass data for hatchery- and natural-origin fish. We determined the redd location, spawn timing, and carcass location of individual hatchery- and naturally produced spring Chinook salmon during spawning ground surveys using passive integrated transponder tags implanted during the adults' migration to the spawning grounds. Differences in mean carcass drift (the distance between redd location and carcass location) were detected between male (4,465 m) and female (150 m) spring Chinook salmon (P &lt; 0.003) but not between hatchery- and naturally produced females (P = 0.32). The mean spawn date and the estimated spawn date derived from carcasses were not significantly different for either hatchery- or natural-origin spring Chinook salmon (P &gt; 0.05). We concluded that the use of carcass data from female spring Chinook salmon to estimate the spawning location and timing is appropriate when surveys are conducted on a consistent weekly schedule throughout the entire spawning period.
Morphological Patterns of Hybridization between Yellowstone Cutthroat Trout and Introduced Rainbow Trout in the South Fork of the Snake River Watershed, Idaho and Wyoming
Authors: Seiler Steven M. , Gunnell Kelly , Ptacek Margaret B. , Keeley Ernest R. 
Published: October 2009

Abstract
Hybridization between native and introduced species is considered a serious threat for many native fish populations. In western North America, native cutthroat trout Oncorhynchus clarkii subspecies are declining dramatically across their ranges; competition and hybridization with nonnative rainbow trout O. mykiss are recognized as key factors in their decline. Presently, identification of cutthroat trout × rainbow trout hybrids is commonly made using molecular genetic markers because morphological differences are thought to be inaccurate. We sampled trout from the South Fork of the Snake River and 10 tributary streams to test for morphological differences that could predict genetic identity of individual Yellowstone cutthroat trout O. clarkii bouvieri, rainbow trout, and their hybrids. We found distinctive body shape differences among the three groups: Yellowstone cutthroat trout and hybrids had larger heads than rainbow trout. Yellowstone cutthroat trout had shallower bodies and caudal peduncles than rainbow trout, whereas hybrids exhibited intermediate body depth and caudal peduncle depth. Using logistic regression with a suite of morphological measurements, we found an overall rate of 92% for correctly classifying trout as Yellowstone cutthroat trout, hybrids, or rainbow trout. Over 99% of Yellowstone cutthroat trout and 80% of rainbow trout were correctly categorized; however, the correct classification rate for hybridized individuals was considerably lower. This study demonstrates that consistent morphological differences exist between Yellowstone cutthroat trout and rainbow trout in the wild, and the degree of introgression accounts for a significant portion of morphological variation in Yellowstone cutthroat trout × rainbow trout hybrids, thus causing difficulty in the use of morphology alone to classify trout.
Seasonal Comparison of Catch Rates and Size Structure Using Three Gear Types to Sample Sturgeon in the Middle Mississippi River
Authors: Phelps Quinton E. , Herzog David P. , Brooks Ronald C. , Barko Valerie A. , Ostendorf David E. , Ridings Joseph W. , Tripp Sara J. , Colombo Robert E. , Garvey James E. , Hrabik Robert A. 
Published: October 2009

Abstract
We evaluated the efficacy of three gears commonly used to sample shovelnose sturgeon Scaphirhynchus platorynchus, pallid sturgeon S. albus, and lake sturgeon Acipenser fulvescens in large rivers. We stratified habitats and randomly sampled sites with trawls, gill nets, and trotlines in the middle Mississippi River from June 2003 through May 2005 (N = 3,476 samples). A total of 3,523 shovelnose sturgeon, 31 pallid sturgeon, and 13 lake sturgeon were captured. When sample sizes were adequate (based on power analysis), we used a mixed analysis of variance (ANOVA) procedure to determine the relative impact of season and gear type on sturgeon catch per unit effort (CPUE). Kolmogorov–Smirnov tests were used to determine whether the length frequency distributions for each species differed among gears. Overall, the power analyses indicated that there were adequate sample sizes for comparing standardized CPUE for shovelnose sturgeon among seasons; however, too few pallid or lake sturgeon were collected to make statistical comparisons. Shovelnose sturgeon catch rates varied among gears and seasons; season and gear type interacted in the ANOVA model. Among gear types, 5.08-cm gill nets produced the highest standardized CPUE, and catch rates were highest during spring. The length frequency distributions of shovelnose sturgeon depended on gear type. Shovelnose sturgeon can be sampled in large rivers using stratified random sampling with this combination of gear. However, pallid sturgeon and lake sturgeon may be too rare to sample with this approach.
Impacts of Commercial Gill-Net Bycatch and Recreational Fishing on a Florida Black Crappie Population
Authors: Dotson Jason R. , Allen Micheal S. , Johnson William E. , Benton John 
Published: October 2009

Abstract
Commercial bycatch can potentially induce high fishing mortality and represents serious concerns for the sustainability of some fisheries. We evaluated the potential population-level impacts of commercial gill-net bycatch and recreational fishing mortality on black crappie Pomoxis nigromaculatus in Lake Dora, Florida. We assessed total black crappie bycatch and the mortality rates of black crappie entangled in gill nets, quantified recreational fishing effort and harvest, and estimated exploitation for the recreational and commercial (bycatch) fisheries. We used an equilibrium age-structured population model to assess potential population-level impacts of bycatch and recreational fishing mortality. Onboard observer data of commercial fishers showed that about 17,000 and 30,000 black crappie were captured in gill nets in 2005 and 2006, respectively. Cage experiments revealed that about 30% and 47% of black crappie captured in gill nets experienced mortality after 72 h in 2005 and 2006, respectively. The recreational fishery exploitation rate was estimated to be 42% based on angler tag returns in 2006, and commercial exploitation via bycatch from commercial gill nets was 15%. The population model suggested that the level of recreational fishing mortality observed in 2006 was probably sustainable but that additional commercial or recreational exploitation would create a risk of recruitment overfishing. The greatest risk for recruitment overfishing via bycatch occurs when other sources of exploitation are also high (e.g., via a recreational fishery).
Effects of Temporary Tributary Use on Escapement Estimates of Adult Fall Chinook Salmon in the Deschutes River, Oregon
Authors: Naughton George P. , Jepson Michael A. , Peery Christopher A. , Brun Christopher V. , Graham Jennifer C. 
Published: October 2009

Abstract
International managers use escapement estimates of the Deschutes River, Oregon, population of fall Chinook salmon Oncorhynchus tshawytscha to forecast abundance and assess population health. Fish are externally marked in the Deschutes River, and a subsample of the marked fish is recovered on the spawning grounds to provide data for estimating escapement. Escapement would be overestimated if some of the marked fish exited the Deschutes River prior to spawning (i.e., used this tributary temporarily). We used mark–recapture and radiotelemetry techniques to calculate (1) the proportion of adult fall Chinook salmon that entered the Deschutes River and subsequently exited the river prior to spawning and (2) the effect of such temporary entrances on spawning ground escapement estimates. We used separate criteria to calculate maximum and minimum temporary tributary use rates, which were then used to adjust the escapement estimates made with external-tag data alone. Over the 3 years of study, the adjusted estimates were approximately 4–29% lower than the unadjusted estimates. We conclude that failure to adjust escapement estimates for temporary tributary use might lead to inflated harvest targets. To partially account for temporary tributary use, the lower 95% confidence limit for an escapement estimate could be used to regulate harvest.
A Preliminary Fishery Quality Index for Portuguese Streams
Authors: Oliveira João M. , Ferreira Maria T. , Morgado Paula , Hughes Robert M. , Teixeira Amílcar , Cortes Rui M. , Bochechas Jorge H. 
Published: October 2009

Abstract
There is a need to quantify the multivariate quality of a recreational fishery at the site scale to better communicate the relative quality among sites to the public and anglers. Borrowing on the general approach of multimetric indices of biotic integrity (IBIs), we developed fishery quality indices (FQIs) from species quality indices (SQIs) based on measures of fish abundance and size structure for northern and central Portuguese streams. Our FQIs showed regional patterns indicating a range in fishery quality. Higher coldwater FQI scores were mostly found in the northwestern (Minho and Lima), northeastern Douro, and northern Tagus basins. Higher warmwater FQI scores occurred in the eastern Tagus basin. The species that contributed the most to warmwater FQI scores were largemouth bass Micropterus salmoides, pumpkinseed Lepomis gibbosus, the cyprinid Luciobarbus bocagei, chubs Squalius carolitertii and S. pyrenaicus, and nases Pseudochondrostoma duriense and P. polylepis. The chubs, nases, and brown trout Salmo trutta contributed the most to coldwater FQI scores. As expected, our indices were correlated with river size and with disturbance at the catchment, segment, and site scales. Regression models for separate coldwater and warmwater FQIs were stronger than those for the individual SQIs and for an all-site FQI. The correlation was positive between the coldwater FQI and a coldwater IBI but negative between the warmwater FQI and warmwater IBIs. The proposed FQIs offer a quantitative approach for assessing relative fishery quality among sites and for making regional assessments given an appropriate study design. The component SQIs and SQI metrics of the FQIs can be disassociated to determine the population and species characteristics most affected by various environmental variables.
Fish Assemblage Relationships with Physical Habitat in Wadeable Iowa Streams
Authors: Rowe David C. , Pierce Clay L. , Wilton Thomas F. 
Published: October 2009

Abstract
Fish assemblages play a key role in stream ecosystems and are influenced by physical habitat. We analyzed fish assemblages and physical habitat at 93 randomly selected sites on second- through fifth-order wadeable Iowa streams to explore fish assemblage relationships with reach-scale physical habitat in this agriculturally dominated landscape. Sites were sampled using DC electrofishing and the wadeable streams physical habitat protocol of the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program. In all, 82 species were collected, with species richness at sites averaging 14. Over 80% of the sites had fish assemblages rated as fair (53%) or poor (32%) based on a fish index of biotic integrity (FIBI). Ordination separated sites from the two major river drainages along an axis of impairment, with sites in the Missouri River drainage exhibiting lower FIBI scores than sites in the Mississippi River drainage. Physical habitat at most sites exhibited fine substrates, eroding banks, and low-gradient, nonmeandering channel and was dominated by glides. Thirty physical habitat variables describing channel morphology, channel cross section and bank morphology, fish cover, human disturbance, large woody debris, relative bed stability, residual pool, riparian vegetation, and substrate differed significantly between sites with FIBI scores rated as poor and those with FIBI scores rated as good or excellent. Eighteen physical habitat variables were significant predictors of fish assemblage metrics and FIBI in multiple linear regression models, with adjusted R2 values ranging from 0.12 to 0.58. Seventy percent of the model coefficients reflected substrate (40%), residual pool (21%), and fish cover (9%) variables. Fish assemblages in wadeable Iowa streams are strongly associated with the quality of physical habitat. Thus, understanding and addressing the determinants of physical habitat are crucial for managing streams in Iowa and other agricultural regions.
Physical Habitat and Fish Assemblage Relationships with Landscape Variables at Multiple Spatial Scales in Wadeable Iowa Streams
Authors: Rowe David C. , Pierce Clay L. , Wilton Thomas F. 
Published: October 2009

Abstract
Landscapes in Iowa and other midwestern states have been profoundly altered by conversion of native prairies to agriculture. We analyzed landscape data collected at multiple spatial scales to explore relationships with reach-scale physical habitat and fish assemblage data from 93 randomly selected sites on second- through fifth-order wadeable Iowa streams. Ordination of sites by physical habitat showed significant gradients of channel shape, habitat complexity, substrate composition, and stream size. Several landscape variables were significantly associated with the physical habitat ordination. Row crop land use was associated with fine substrates and steep bank angles, whereas wetland land cover and greater sinuosity and catchment land area were associated with complex channel and bank morphology and greater residual pool volume, woody debris, and canopy cover. Thirteen landscape variables were significant predictors of physical habitat variables in multiple linear regressions, with adjusted R2 values ranging from 0.07 to 0.74. Inclusion of landscape variables with physical habitat variables in multiple regression models predicting fish assemblage metrics and a fish index of biotic integrity resulted in negligible improvements over models based on only physical habitat variables. Physical habitat in wadeable Iowa streams is strongly associated with landscape characteristics. Results of this study and previous studies suggest that (1) landscape factors directly influence physical habitat, (2) physical habitat directly influences fish assemblages, and (3) the influence of landscape factors on fish assemblages is primarily indirect. Understanding how landscape factors, such as human land use, influence physical habitat and fish assemblages will help managers make more informed decisions for improving Iowa's wadeable streams.