bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of a Sport Fish Stocking Program in Lakes of the Southern Murray–Darling Basin, Australia
Authors: Hunt Taylor L. , Allen Micheal S. , Douglas John , Gason Anne 
Published: July 2010

Abstract
The golden perch Macquaria ambigua is a recreationally important freshwater sport and food fish species found throughout southeastern Australia. Stocking golden perch in impoundments has been used by fisheries managers to enhance existing wild populations for over 30 years. Despite widespread stocking, the contribution of stocked fish to golden perch populations has not been investigated. We evaluated the stocking contribution by using chemically marked golden perch fingerlings introduced into three lakes in which natural recruitment is low. We surveyed the lakes to determine the contribution of the stocked fish to the lake populations and found an overall contribution of 47 ± 9% (mean ± SE) at Reedy Lake, 55 ± 9% at Kangaroo Lake, and 90 ± 5% at Lake Charm. Our results indicate that, rather than replacing wild fish, stocked fish increased the abundance of adult fish at all three lakes. The contribution of stocked fish to each population declined with increased connectedness to the Loddon River, which served as the probable source for the wild fish population. Stocking programs can substantially augment fish populations when natural recruitment is very low.
Evaluating the Status and Trends of Physical Stream Habitat in Headwater Streams within the Interior Columbia River and Upper Missouri River Basins Using an Index Approach
Authors: Al‐Chokhachy Robert , Roper Brett B. , Archer Eric K. 
Published: July 2010

AbstractIdentifying the overall status of freshwater streams is an important step in evaluating effects of land management and prioritizing restoration activities. To address these needs, we developed an index of physical habitat condition for headwater streams based on physical stream habitat data (2003–2007) and evaluated the condition status of 217 reference streams and 934 managed streams in the interior Columbia River and upper Missouri River basins. We used data collected from reference reaches to generate this index, which consisted of eight commonly collected metrics used in stream habitat monitoring. We incorporated landscape and climatic covariates into multiple linear regression analyses to control for inherent differences in physical habitat attributes among reaches, and we scored the overall condition of reaches with index values ranging from 0 to 100. Our results indicated that the condition index score of physical habitat was significantly higher in reference reaches (mean ± SE = 47.1 ± 1.4) than in managed reaches (30.4 ± 0.7); relative to reference reaches, a greater frequency of managed reaches had low habitat condition and a lower frequency of managed reaches had high habitat condition. Analyses evaluating the relationship between management activities and the condition of physical habitat in streams indicated a significant negative relationship with lower index scores in stream reaches within catchments containing higher densities of roads. When roads and livestock grazing occurred within catchments, we found the presence of grazing had an additional, significant negative effect on the relationship between road density and the condition of physical habitat of streams. Our results suggested that once natural variability and geoclimatic differences among reaches are accounted for, a multimetric index approach can provide managers with an easily interpretable tool to monitor the status of the overall condition of physical habitat.
Avian Piscivores as Vectors forMyxobolus cerebralisin the Greater Yellowstone Ecosystem
Authors: Koel Todd M. , Kerans Billie L. , Barras Scott C. , Hanson Katie C. , Wood John S. 
Published: July 2010

AbstractMyxobolus cerebralis, the cause of whirling disease in salmonids, has dispersed to waters in 25 states within the USA, often by an unknown vector. Its incidence in Yellowstone cutthroat troutOncorhynchus clarkii bouvieriwithin the highly protected environment of Yellowstone Lake, Yellowstone National Park, is a prime example. Given the local abundances of piscivorous birds, we sought to clarify their potential role in the dissemination ofM. cerebralis. Six individuals from each of three bird species (American white pelicanPelecanus erythrorhynchos, double‐crested cormorantPhalacrocorax auritus, and great blue heronArdea herodias) were fed known‐infected or uninfected rainbow troutO. mykiss. Fecal material produced during 10‐d periods before and after feeding was collected to determine whetherM. cerebraliscould be detected and, if so, whether it remained viable after passage through the gastrointestinal tract of these birds. For all (100%) of the nine birds fed known‐infected fish, fecal samples collected during days 1–4 after feeding tested positive forM. cerebralisby polymerase chain reaction. In addition, tubificid wormsTubifex tubifexthat were fed fecal material from known‐infected great blue herons produced triactinomyxons in laboratory cultures, confirming the persistent viability of the parasite. No triactinomyxons were produced fromT. tubifexfed fecal material from known‐infected American white pelicans or double‐crested cormorants, indicating a potential loss of parasite viability in these species. Great blue herons have the ability to concentrate and release viable myxospores into shallow‐water habitats that are highly suitable forT. tubifex, thereby supporting a positive feedback loop in which the proliferation ofM. cerebralisis enhanced. The presence of avian piscivores as an important component of aquatic ecosystems should continue to be supported. However, given the distances traveled by great blue herons between rookeries and foraging areas in just days, any practices that unnaturally attract them may heighten the probability ofM. cerebralisdispersal and proliferation within the Greater Yellowstone Ecosystem.
Juvenile Salmonid Use of Reconnected Tidal Freshwater Wetlands in Grays River, Lower Columbia River Basin
Authors: Roegner G. Curtis , Dawley Earl W. , Russell Micah , Whiting Allan , Teel David J. 
Published: July 2010

AbstractDegraded wetland systems with impaired hydraulic connections have resulted in diminished habitat opportunity for salmonid fishes and other native flora and fauna in the Pacific Northwest. Many of these lost habitats were once intertidal freshwater marshes and swamps. Restoration of these systems is effected in part by reestablishing tidal processes that promote connectivity, with a central goal of restoring rearing habitat for juvenile Pacific salmon Oncorhynchus spp. In the Grays River tidal freshwater system of Washington, we measured hydrologic changes that resulted from the removal of tide gates from diked pastureland and we determined the subsequent time series of salmonid abundance and size frequency in the restoring marshes. Dike breaching caused an immediate return of full semidiurnal tidal fluctuations to the pasturelands. Juvenile Pacific salmonids quickly expanded into this newly available habitat and used prey items that were presumably produced within the marshes. Habitat use varied by species and life history stage. Fry of chum salmon O. keta migrated rapidly through the system, whereas populations of Chinook salmon O. tshawytscha and coho salmon O. kisutch resided from March to at least July and were composed of fry, fingerlings, and (for coho salmon) yearlings. Based on salmon size at date and the timing of hatchery releases, we concluded that most salmon sampled in restored and reference sites were the progeny of natural spawners. However, the presence of adipose‐fin‐clipped Chinook salmon indicated that hatchery‐raised fish originating outside the Grays River system also used the restoring wetland habitat. Because of extensive mixing of stocks through hatchery practices, genetic analyses did not provide additional insight into the origins of the Chinook salmon but did reveal that out‐migrating juveniles were an admixed population composed of lower Columbia River ancestry and nonindigenous Rogue River stock. Restoration of tidal wetlands in the Columbia River estuary will improve overall ecosystem connectivity and reduce habitat fragmentation and may therefore increase survival of a variety of Pacific salmon stocks during migration.
Influence of Body Size and Prey Type on the Willingness of Age‐0 Fish to Forage under Predation Risk
Authors: Parkos Joseph J. , Wahl David H. 
Published: July 2010

AbstractOntogenetic diet shifts have been shown to be the outcome of changes either in vulnerability to predators or foraging efficiency for different prey types. More information is needed on how changes in vulnerability and prey value with forager size interact to influence the responses to predation risk. Piscivorous fishes are a significant source of predation risk for many other fish species, but as young of the year (age 0) they themselves are vulnerable to predators. We experimentally compared the foraging behavior of three vulnerable size‐classes of largemouth bass Micropterus salmoides with respect to zooplankton, chironomid larvae, and bluegills Lepomis macrochirus when a larger predator was visible and when none were present. The size‐classes of age‐0 largemouth bass represented a documented ontogenetic diet progression from zooplankton to benthic invertebrates to fish. The size of the largemouth bass influenced their consumption rate and amount of foraging activity in the presence of a predator, but prey type did not. All sizes of largemouth bass reduced their foraging time and total consumption when a larger predator was visible except for age‐0 largemouth bass that are typically piscivorous in the wild. Predation risk may affect the ontogeny of piscivory by decreasing the feeding rate on all prey types, changes in vulnerability with size having more influence on risk‐taking than foraging efficiency for different prey types.
Effects of Predator–Prey Interactions and Benthic Habitat Complexity on Selectivity of a Foraging Generalist
Authors: Weber Michael J. , Dettmers John M. , Wahl David H. , Czesny Sergiusz J. 
Published: July 2010

AbstractPredators typically prefer specific prey types but include others in their diet as a result of opportunistic foraging, prey availability, or foraging costs. Habitat complexity may interact with preferences by altering prey availability and foraging strategies, affecting the preferences and consumption patterns of predators. Yellow perch Perca flavescens is perceived as a foraging generalist and the predominant predator in numerous systems. In the laboratory, we compared the prey selection of yellow perch (230–311 mm) foraging on common Great Lakes prey species—northern crayfish Orconectes virilis, round gobies Neogobius melanostomus, and alewives Alosa pseudoharengus—in simple and complex benthic habitats. Yellow perch selected alewives in both simple and complex habitats. Removal of the preferred prey species resulted in neutral selection for both of the remaining prey species in simple benthic habitat but selection for round gobies and against crayfish in complex habitat. Predator behaviors indicated that alewives were captured efficiently and easily handled whereas round gobies and crayfish were not. The diets of yellow perch in Lake Michigan reflected patterns established in mesocosm experiments. Although prey species were probably not equally abundant in the natural environment, alewives comprised the greatest biomass in yellow perch diets, followed by round gobies and crayfish. Our results indicate that predators typically considered as generalist foragers can have prey preferences and rely heavily on a single prey species as a result of differences in prey vulnerability, profitability, and habitat complexity.
The Effects of a Surgically Implanted Microacoustic Tag on Growth and Survival in Subyearling Fall Chinook Salmon
Authors: Frost Deborah A. , McComas R. Lynn , Sandford Benjamin P. 
Published: July 2010

AbstractThe objective of this study was to evaluate a newly miniaturized prototype of an implantable acoustic tag for use in subyearling hatchery Chinook salmon Oncorhynchus tshawytscha. In 2003, when the study was conducted, the relatively large size of most acoustic tags limited their use in juvenile fish. We evaluated this miniaturized prototype tag (21 × 7 × 6 mm, 0.9 g in air) for effects on growth, survival, and tag retention. All fish were passive integrated transponder (PIT) tagged in accordance with the proposed practical application in which PIT‐tagged fish from known sources were separated from the general migrating population. The PIT tags also permitted tracking of individual fish growth in relation to treatment. We compared growth and acoustic tag retention over 30 d among tagged, sham‐tagged, and control fish. Ratio of tag weight to body weight ranged from 2.6% to 5.9% at tagging. The acoustic tag significantly affected growth (P = 0.001 for both length and weight differences), but no fish died as a result of the tagging. Partial to complete tag expulsion was noted in 37% of the tagged fish after 30 d. Our study showed that impeded growth and tag expulsion may affect the successful use of this tag size in juvenile Chinook salmon. This evaluation led to physical tag modifications that improved biological acceptance by the fish, thus facilitating the tag's use in applied studies. Implanted devices should be evaluated before use to ensure compatibility and to avoid data misinterpretations due to their effects on the fish.
Differing Catchability among Lakes: Influences of Lake Basin Morphology and other Factors on Gill‐Net Catchability of Northern Pike
Authors: Pierce Rodney B. , Tomcko Cynthia M. , Pereira Donald L. , Staples David F. 
Published: July 2010

AbstractUnderstanding factors that affect catchability is important for interpreting fish catches from research index netting and comparing fish populations from different habitats. Population density estimates and gill‐net catch rates were compared for age‐2 and older northern pikeEsox luciusin 16 north‐central Minnesota lakes that varied in physical characteristics and northern pike populations. When northern pike density was calculated using total surface area of the lakes, numerous factors appeared to influence gill‐net catchability. Those factors included several lake basin shape metrics, northern pike size structure, and northern pike density, with density dependence in catchability being especially problematic for interpreting gill‐net catches. The critical finding in this study was that calculating density using littoral area rather than total surface area caused evidence of density‐dependent catchability and all other relationships with catchability to completely disappear. Catchability became independent of northern pike density and lake basin shape metrics when density was calculated using littoral area. Correlations with density (calculated from total surface area) and other factors were simply artifacts of underlying interrelationships between the morphology of lake basins, northern pike population characteristics, and density‐dependent processes. Catchability estimates for littoral habitat averaged 0.20 ha/net and ranged from 0.09 to 0.43 ha/net among the lakes. Although the relationship between gill‐net catch and population density indicated that gillnetting could be a useful tool for comparing northern pike populations from different lakes, a predictive model fitted to the observed gill‐net catch rates and population densities from 16 lakes had low precision. Results from this study illustrate the importance of a comprehensive understanding of fish ecology, including spatial habitat use, when interpreting survey results.
Common Carp Distribution, Movements, and Habitat Use in a River Impounded by Multiple Low‐Head Dams
Authors: Butler Steven E. , Wahl David H. 
Published: July 2010

AbstractThe common carp Cyprinus carpio is an introduced species that is abundant in many impounded rivers. We assessed habitat conditions and common carp abundance in three flowing sites and three impounded sites of the Fox River, Illinois, to examine factors that influence the success of common carp in these systems. Radiotelemetry was used to determine long‐term movement and habitat use patterns of common carp among flowing and impounded areas. Impounded areas were wider and deeper than flowing areas and had lower current velocities, smaller substrates, and lower abundances of cover. Common carp were found at all sites during summer, with catch rates being similar between flowing and impounded areas. The proportion of the fish assemblage consisting of common carp was similar between flowing and impounded areas during two of the study years but was higher in impounded areas than in flowing areas during the other two years. Radio‐tagged common carp displayed a variety of movement patterns but used impounded areas most frequently during all seasons. Many common carp were always located in impounded areas, but some individuals moved upstream into flowing areas in spring and summer and returned to impounded areas by fall. Common carp positively selected for intermediate depths and low current velocities. Few consistent relationships were apparent in the use of substrate categories, but common carp selected most strongly for wood cover. Management activities targeting common carp should account for movements of this species among different habitat types and should focus on specific aspects of common carp life history. Dam removal or modification may also lead to declines in common carp abundance in some rivers.
Private Waterfront Householders Catch Less per Trip than other Fishers: Results of a Marine Recreational Survey
Authors: Ashford Julian , Jones Cynthia , Fegley Lynn 
Published: July 2010

AbstractMarine recreational fishery surveys that estimate catch rate by sampling fishers who use public access often assume that fishers using private access and public access catch the same amount per trip taken. Despite the risk of bias, this assumption has not been tested by comparing private‐access users to the general population of fishers. During a survey of the recreational fishery for blue crabs Callinectes sapidus in Maryland, households from a list of waterfront properties were sampled by telephone at the same time as sampling of households from all coastal counties. Fishers from waterfront households overwhelmingly used private access. Waterfront households often caught a similar amount per month as coastal county households did, but catches for waterfront households were taken during more trips, resulting in catch rates that were 74% lower. Consequently, estimating catch rate by sampling only public‐access users results in a bias towards overestimation of the recreational catch. We strongly recommend that marine recreational surveys test this assumption for frames that only cover public‐access users, especially in regions with substantial private access.
Genetic Diversity and Variation of Mitochondrial DNA in Native and Introduced Bighead Carp
Authors: Li Si‐Fa , Yang Qin‐Ling , Xu Jia‐Wei , Wang Cheng‐Hui , Chapman Duane C. , Lu Guoqing 
Published: July 2010

AbstractThe bighead carp Hypophthalmichthys nobilis is native to China but has been introduced to over 70 countries and is established in many large river systems. Genetic diversity and variation in introduced bighead carp have not previously been evaluated, and a systematic comparison among fish from different river systems was unavailable. In this study, 190 bighead carp specimens were sampled from five river systems in three countries (Yangtze, Pearl, and Amur rivers, China; Danube River, Hungary; Mississippi River basin, USA) and their mitochondrial 16S ribosomal RNA gene and D‐loop region were sequenced (around 1,345 base pairs). Moderate genetic diversity was found in bighead carp, ranging from 0.0014 to 0.0043 for nucleotide diversity and from 0.6879 to 0.9333 for haplotype diversity. Haplotype analysis provided evidence that (1) multiple haplotype groups might be present among bighead carp, (2) bighead carp probably originated from the Yangtze River, and (3) bighead carp in the Mississippi River basin may have some genetic ancestry in the Danube River. The analysis of molecular variance showed significant genetic differentiation among these five populations but also revealed limited differentiation between the Yangtze and Amur River bighead carp. This large‐scale study of bighead carp genetic diversity and variation provides the first global perspective of bighead carp in the context of biodiversity conservation as well as invasive species control and management.
Homing and Spawning Site Selection by Supplemented Hatchery‐ and Natural‐Origin Yakima River Spring Chinook Salmon
Authors: Dittman Andrew H. , May Darran , Larsen Donald A. , Moser Mary L. , Johnston Mark , Fast David 
Published: July 2010

AbstractIt is well known that salmon home to their natal rivers for spawning, but the spatial scale of homing within a river basin is poorly understood and the interaction between natal site fidelity and habitat‐based spawning site selection has not been elucidated. Understanding the complex trade‐offs among homing to the natal site, spawning site selection, competition for sites, and mate choice is especially important in the context of hatchery supplementation efforts to reestablish self‐sustaining natural spawning populations. To address these questions, we examined the homing patterns of supplemented Yakima River spring Chinook salmon Oncorhynchus tshawytscha released from satellite acclimation facilities after common initial rearing at a central facility. Final spawning location depended strongly on where fish were released as smolts within the upper Yakima River basin, but many fish also spawned in the vicinity of the central rearing hatchery, suggesting that some fish imprinted to this site. While homing was clearly evident, the majority (55.1%) of the hatchery fish were recovered more than 25 km from their release sites, often in spawning areas used by wild conspecifics. Hatchery and wild fish displayed remarkably similar spawning distributions despite very different imprinting histories, and the highest spawning densities of both hatchery and wild fish occurred in the same river sections. These results suggest that genetics, environmental and social factors, or requirements for specific spawning habitat may ultimately override the instinct to home to the site of rearing or release.