bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conservation of Population Diversity of Pacific Salmon in Southeast Alaska
Authors: Halupka Karl C. , Willson Mary F. , Bryant Mason D. , Everest Fred H. , Gharrett Anthony J. 
Published: June 2004

Abstract
We analyzed intraspecific variation in selected biological characteristics of five species of Pacific salmon Oncorhynchus spp. in southeast Alaska and adjacent areas of Canada with a particular interest in describing the variation among populations and suggesting conservation priorities to preserve existing variation. We identified traits that showed high levels of among-population variation, evaluated the interspecific consistency of variation patterns, and noted the relationship of these traits to potential adaptive variation. In addition, we graphically identified populations with distinctive phenotypic and demographic characteristics as outliers from the distribution of mean values of traits taken from populations throughout the region. We also reviewed allozyme surveys to identify populations that differed in terms of the geographic clustering patterns of allele frequencies. Approximately 9,000 salmon populations occur in the study area, and sufficient data were available from 2,062 (23%) of them to analyze at least one characteristic. We identified 47 populations represented by adequate data sets that have distinctive characteristics. An additional 35 populations, represented by limited samples or unusual nominal traits, may be regionally distinctive. Of the 47 adequately sampled, distinctive populations, 22 met our criteria for conservation consideration: (1) high potential for adaptive variation (including distinctive run timing), (2) a distinctive trait combined with high spawner abundance or allozyme frequencies that diverge from geographic clustering patterns, and (3) more than one distinctive characteristic or freshwater habitat shared with other distinctive populations. Freshwater habitats for 6 of those 22 populations are located in watersheds that do not have restrictive land use designations and warrant the highest conservation priority.
Evaluation of Stomach Tubes and Gastric Lavage for Sampling Diets from Blue Catfish and Flathead Catfish
Authors: Waters D. Scott , Kwak Thomas J. , Arnott Joshua B. , Pine William E. 
Published: June 2004

Abstract
We compared the ability to extract all stomach contents by using stomach tubes or gastric lavage to sample diets from blue catfish Ictalurus furcatus and flathead catfish Pylodictis olivaris. Pulsed gastric lavage (PGL) removed a significantly greater proportion of stomach content mass (95.6%) from blue catfish than did stomach tubes (14.6%). Percent mass of flathead catfish contents removed with PGL (96.0%) was not significantly different from that removed with stomach tubes (86.9%). Based on the greater effectiveness of PGL for blue catfish, combined with a shorter mean time required per sample (69 versus 118 s) and the better preservation of extracted diet material, we recommend using PGL as a nonlethal technique to collect diet samples from large catfishes.
Portable Floating Electrofishing Unit for Fish Collections in Freshwater Stream Systems
Authors: Price David J. , Beiting Michael G. , Birge Wesley J. 
Published: June 2004

Abstract
Fish collection can be difficult if the stream being sampled is too deep for backpack electroshockers and does not allow boat access. A design for a portable, flat-bottomed, floating electroshocking unit is described. The unit consists of a one-piece, structural-foam big-wheel cart from which the wheels and stand were removed. In tests, the unit was able to float loads weighing up to 90.8 kg. The total weight of the unit with the electronics and generator installed is approximately 68.1 kg, which allows two persons to transport the unit to a stream and lift it over shallow riffles and log jams. The unit allows sampling of stream pools that can be waded and provides greater mobility and less fatigue for the sampler carrying the anode and cathode poles. Due to its larger electrical field, this unit offers greater sampling distance than backpack electroshockers. The total cost, including the electronics, anode and cathode poles, and generator, was about US$3,800.
Relationship between Surface Water Temperature and Steelhead Distributions in Lake Michigan
Authors: Höök Tomas O. , Rutherford Edward S. , Brines Shannon J. , Schwab David J. , McCormick Michael J. 
Published: June 2004

Abstract
Salmonines support valuable recreational fisheries and are the predominant predators in the open waters of the Great Lakes, yet the spatial distributions of salmonines in these systems have not been fully documented. We analyzed the horizontal distributions of steelhead Oncorhynchus mykiss in Lake Michigan from 1992 to 1997 and related these distributions to mean surface temperature and temperature variation. We used angler catch rate data from Lake Michigan natural resources agencies to index the spatial and temporal distributions of steelhead and obtained surface water temperature data from advanced very-high-resolution radiometer satellite imagery through the National Oceanic and Atmospheric Administration's CoastWatch Program. During most months, steelhead catch rates were negatively related to surface temperature and were highest in areas of high temperature variation (i.e., vertical thermal fronts and upwelling zones) where thermal conditions and prey densities may have been optimal for growth. Our results demonstrate how remotely sensed and creel survey data can be integrated to allow for more effective exploitation and management of lakewide fish stocks while enabling researchers to generate and test hypotheses regarding the spatial distributions of fish populations.
Verifying Residuals from Catch Curves to Detect Recruitment Variation in Largemouth Bass and Crappies
Authors: Maceina Michael J. 
Published: June 2004

Abstract
Residuals associated with catch-curve regressions can represent variable recruitment in fish populations, but the use of this method to quantify recruitment variation has not been verified. I computed age-0 and age-1 catch rates of crappies Pomoxis spp. collected with trap nets set in the fall in three Alabama reservoirs and the age-1 catch rate of largemouth bass Micropterus salmoides captured with electrofishing during spring over a 13-year period in a single Georgia reservoir. These indices of juvenile abundance were correlated (r = 0.52–0.81, P &lt; 0.01) to residuals generated from catch-curve regressions for electrofishing data collected when these same year-classes recruited to the fishery at age 3 and older. At higher age-0 crappie and age-1 largemouth bass catch rates, these relations became curvilinear, and improved fit was computed with data transformation and nonlinear fits to the data. An asymptotic relation was observed between age-0 and age-1 catch rates for the same crappie year-classes, and an inverse relation was evident between mean length at age 1 and juvenile crappie catch rates. This result suggested that density-dependent growth suppression and mortality occurred, as age-0 fish did not proportionally recruit to the age-3+ fishery. However, the age-1 crappie (about 18 months old) catch rate was linearly related (r2 = 0.48–0.55; P &lt; 0.01) to residuals when data were compared separately for each reservoir, which suggested that full recruitment to the population occurred at this age. For largemouth bass, mean length at age 1 was positively related to age-1 catch rate, and recruitment of strong year-classes to the fishery appeared proportionally greater than for abundant age-0 crappies. Residuals generated from catch-curve regressions can serve as a useful quantitative index of juvenile crappie and largemouth bass abundance that can be used in subsequent analyses to explain recruitment variation. However, in some instances, initial strong year-class abundance may not be fully expressed in the fishery later in life.
Species Richness and Centrarchid Abundance in Littoral Habitats of Three Southern U.S. Reservoirs
Authors: Hugh Barwick D. 
Published: June 2004

Abstract
Species richness and centrarchid abundance associated with coarse woody debris (CWD), residentially developed habitats (DEV), and undisturbed (UND) habitats in Lake James (North Carolina), Lake Hickory (North Carolina), and Fishing Creek Lake (South Carolina) were evaluated by use of a boat-mounted electrofisher in spring, summer, and fall of 1999–2000. Species richness and centrarchid abundance were generally higher in CWD and DEV habitats than in UND habitat during most seasons in all reservoirs. Higher species richness and centrarchid abundance in CWD and DEV habitats were probably related to greater habitat complexity than in UND habitat, which made these two habitats more desirable to fish. My findings indicate the beneficial role of complex littoral structure on the distribution of fish in these reservoirs and the need for natural resource managers, riparian landowners, and reservoir owners to work cooperatively to protect and enhance habitat where possible.
Prevalence of Myxobolus cerebralis at Juvenile Salmonid Acclimation Sites in Northeastern Oregon
Authors: Sollid Sarah A. , Lorz Harriet V. , Stevens Donald G. , Reno Paul W. , Bartholomew Jerri L. 
Published: June 2004

Abstract
Fry of rainbow trout Oncorhynchus mykiss held as sentinel fish became infected with Myxobolus cerebralis when held at all juvenile acclimation sites for spring Chinook salmon O. tshawytscha and steelhead O. mykiss (anadromous rainbow trout) and thus expand the known range of M. cerebralis in northeastern Oregon. In spring 2001, replicate cages of rainbow trout fry were placed at the intake site of each facility and sampled at approximately 14, 28, and 50 d. Infection prevalence, as determined by the presence of M. cerebralis DNA following polymerase chain reaction (PCR) amplification, was relatively low (&lt;17.5%) at most acclimation sites. However, a significantly higher prevalence of infection in sentinel fry held at the Wallowa facility (65%) identified this site as presenting a higher risk for juvenile steelhead to M. cerebralis exposure than other sites. Further, PCR analysis of ossified cranial elements from steelhead juveniles held at the Wallowa facility for 6 weeks demonstrated a comparable prevalence of infection, 52%. Detection of similar infection prevalence in fry and juveniles at the same site demonstrates the usefulness of sentinel exposures as a surrogate for lethally sampling valuable salmonid juveniles. In addition, this study suggests that infection of anadromous salmonids may complicate management efforts to contain the parasite within northeastern Oregon.
Coded Wire Tag Retention in Ebonyshell Mussels Fusconaia ebena
Authors: Layzer James B. , Heinricher Jackie R. 
Published: June 2004

Abstract
Ebonyshell Fusconaia ebena (38–75 mm long) were collected from Kentucky Lake, Tennessee, and tagged in the hinge ligament with coded wire tags. Mussels were then suspended in pocket nets in an embayment of Kentucky Lake. After 2 years, the 50 tagged individuals were retrieved. Survival and tag retention were 100%. Eleven individuals were sacrificed and their tags were retrieved by making a longitudinal cut through the hinge ligament. Because coded wire tags are not visible externally, they are especially useful for detecting illegally harvested mussels.
Length at Release Affects Movement and Recapture of Lake-Stocked Brown Trout
Authors: Hyvärinen Pekka , Vehanen Teppo 
Published: June 2004

Abstract
The effect of length (total length = 15-50 cm) at release on the yield and recapture of stocked brown trout Salmo trutta was examined by tagging experiments in a large boreal lake, Lake Oulujärvi in Finland (928 km2). The time the fish spent in the lake before harvesting and the size of the area from which they were harvested diminished with increasing length at release. Small brown trout (&lt;40 cm) moved towards a part of the lake where the highest densities of pelagic prey fish are found, whereas large brown trout (≥40 cm) were captured near their release sites. The longer the distance between the release site of the small brown trout and the good foraging area, the lower their recapture rate. Both relative yield and recapture rate (per 1,000 fish released) increased with increasing fish length at release. However, the positive relation between recapture rate and fish length at release disappeared or turned negative (depending on the release site) when the production costs of fish were taken into account and the recapture rate was calculated per constant investment (€100,000 (euros)).
Oviduct Insertion of Radio Transmitters as a Means of Locating Northern Pike Spawning Habitat
Authors: Pierce Rodney B. 
Published: June 2004

Abstract
I inserted radio transmitters into the oviducts of northern pike Esox lucius in an attempt to find their spawning grounds. Oviduct insertion of miniature radio transmitters was quick and easy. I hoped that transmitters would be expelled with the eggs to aid in identifying critical habitat used for egg deposition. Ten transmitters were implanted in the egg masses of female northern pike that were staging for spawning. Four of the transmitters were expelled during the spawning period, two in emergent shoreline vegetation and two in submerged vegetation. Northern pike that retained transmitters were smaller than fish that expelled them, indicating that expulsion was influenced by the size of the transmitter in relation to the fish's size. Although transmitters were not expelled by all study fish, advances in miniaturization and refinements in transmitter shape hold promise for future application of this technique.
Evaluation of the Use of Visible Implant Tags in Age-0 Atlantic Cod
Authors: Olsen Esben M. , Gjøsæter Jakob , Stenseth Nils C. 
Published: June 2004

Abstract
The visible implant elastomer (VIE) tag and the soft visible implant alphanumeric (VIAlpha) tag were evaluated as methods for tagging age-0 Atlantic cod Gadus morhua. Tank experiments on laboratory-bred Atlantic cod (82–141 mm) lasted 150 d. The VIE tag proved to be a good alternative when put on the dorsal part of the fish, with no tag loss and good tag visibility. When put on the ventral part of the fish, however, many VIE tags were covered by growing silvery scales. Retention of soft VIAlpha tags injected behind the eye was quite low (67%), but larger fish had higher tag retention than smaller fish. Survival of experimental fish was high (96%). Mean specific growth rates ranged from 0.46% to 0.51% per day. Both VIE and soft VIAlpha tags were used to individually tag age-0 Atlantic cod (85–290 mm) in the wild. Skin pigmentation of wild Atlantic cod made reading soft VIAlpha tags difficult, while VIE tagging on the dorsal part of the fish still worked well. We suggest that VIE tags are a good alternative for short-term demographic studies on age-0 Atlantic cod, while low retention rates cast doubt on the use of soft VIAlpha tags on these small fish.
Influence of Habitat Type on Food Supply, Selectivity, and Diet Overlap of Bonneville Cutthroat Trout and Nonnative Brook Trout in Beaver Creek, Idaho
Authors: Hilderbrand Robert H. , Kershner Jeffrey L. 
Published: June 2004

Abstract
We collected invertebrate drift samples and stomach contents of native Bonneville cutthroat trout Oncorhynchus clarki utah and nonnative brook trout Salvelinus fontinalis in Beaver Creek, Idaho, during August 1995 to assess food availability and the potential for competition. Regardless of whether samples came from beaver pond or from high-gradient or low-gradient reaches, aquatic Diptera numerically dominated drifting invertebrates by at least fivefold over all other categories captured in 1-h drift samples. Abundances and drift densities of drifting invertebrates were high in the three reach habitat types sampled: beaver pond (3,152 individuals; 18.9 invertebrates/m3), high-gradient reach (5,216 individuals; 26.5 invertebrates/m3), and low-gradient reach (4,908 individuals; 17.2 invertebrates/m3). Cutthroat trout consumed significantly more invertebrates per individual than did brook trout. However, there was no relationship between fish length and consumption. Diets of both brook and cutthroat trout were dominated by Diptera in beaver ponds and terrestrial invertebrates in the high-gradient reach. In the low-gradient reach, Diptera dominated brook trout diets, whereas both Diptera and terrestrial invertebrates dominated diets of cutthroat trout. Both trout species consistently selected terrestrial invertebrates and Trichoptera in all reach types. Diet overlap between brook and cutthroat trout was 92% in beaver ponds, 75% in the high-gradient reach, and 65% in the low-gradient reach. The high degree of diet overlap suggests the possibility of competition between nonnative brook trout and cutthroat trout if food should become limiting, but we found little evidence that food was limiting during late summer in Beaver Creek.
Development and Use of a Simple DNA Test to Distinguish Larval Redhorse Species in the Oconee River, Georgia
Authors: Wirgin Isaac , Currie Diane D. , Stabile Joseph , Jennings Cecil A. 
Published: June 2004

Abstract
The robust redhorse Moxostoma robustum is a rare catostomid species that was recently “rediscovered” in three Atlantic slope drainages in the southeastern United States, including the Oconee River, Georgia. Adult population size in the Oconee River is declining, and the population may be senescent due to recruitment failure. Evaluation of the environmental factors affecting the success of young life stages requires the ability to distinguish robust redhorse larvae from those of other redhorse species in the Oconee River. The use of morphological approaches, including size at collection date, have proven to be problematic in distinguishing larval robust redhorse from notchlip redhorse M. collapsum from the Oconee River. We developed a mitochondrial DNA (mtDNA) assay to distinguish between reference adults of these two redhorse species from the Oconee, Savannah, and Pee Dee rivers. This mtDNA assay was then applied to unknown larval redhorse collections from the Oconee River. In one collection, discordance was revealed in 40% of the individual larvae identified by both size at collection date and mtDNA. Of these, 75% of the fish thought to be notchlip redhorses based on size at date of collection exhibited robust redhorse mtDNA haplotypes. These results illustrate the utility of DNA techniques in characterizing the young life stages of fish and suggest that earlier surveys underestimated the abundance of larval robust redhorses in the Oconee River.
Construction of a Junction Box for Use with an Inexpensive, Commercially Available Underwater Video Camera Suitable for Aquatic Research
Authors: Cooke Steven J. , Bunt Christopher M. 
Published: June 2004

Abstract
Underwater video camera apparatus is an important fisheries research tool. Such cameras, developed and marketed for recreational anglers, provide an opportunity for researchers to easily obtain cost-effective and waterproof video apparatus for fisheries research. We detail a series of modifications to an inexpensive, commercially available underwater video camera (about US$125) that provide flexibility for deploying the equipment in the laboratory or in the field. Specifically, we describe the design of a junction box between the camera cable and the power supply and video feed that can be constructed for about $25. We also describe different deployment configurations and detail several examples of the data we have been able to collect using this technology.
Electrofishing Injury and Short-Term Mortality in Hatchery-Reared Rainbow Trout Stocked into an Ozark Stream
Authors: Walsh Maureen G. , Winkelman Dana L. , Bahr Robert J. 
Published: June 2004

Abstract
We conducted an electrofishing injury study to evaluate potential effects of sampling procedures on survival and health of hatchery rainbow trout Oncorhynchus mykiss (187–307 mm total length) stocked into an Ozark stream. We assessed two groups of trout: one group had acclimated to stream conditions for 1 month; the other group was handled and transported just before the study. Each group was sampled by electrofishing (boat-mounted, 60-Hz AC) and seining (controls), resulting in four treatment groups (N = 21). We held fish for 48 h to evaluate mortalities in that period, then euthanized all fish and examined them for hemorrhages and spinal damage. No fish died during the 48-h holding period, indicating that our procedures did not cause significant sampling-related mortality among stocked trout in Brush Creek. Spinal damage was observed in 5% of fish collected with electrofishing but in none of the control fish. We found hemorrhages in 90% of electrofished trout but none in control fish, and recently handled and hauled trout had a greater occurrence and severity of hemorrhaging.
Movement, Home Range, and Site Fidelity of Bluegills in a Great Plains Lake
Authors: Paukert Craig P. , Willis David W. , Bouchard Michelle A. 
Published: June 2004

Abstract
Little is known about the distribution, movement, and home ranges of bluegills Lepomis macrochirus in lentic environments. Therefore, the objectives of this study were to evaluate the seasonal and diel differences in movement rates, site fidelity, and home range of bluegills in a shallow, natural Great Plains lake. A total of 78 bluegills (200–273 mm total length) were implanted with radio transmitters in March and May 2000. Of these fish, 10 males and 10 females were randomly selected and located every 2 h during one 24-h period each month from April to September 2000. Bluegill movement peaked during midsummer; however, there was little difference in diel movements, suggesting relatively consistent movement throughout the 24-h period. Home range estimates (which included the 24-h tracking plus an additional six locations from the same fish located once per day for six consecutive days each month) ranged up to 172 ha, probably because only about half of the bluegills exhibited site fidelity during any month sampled. Bluegill movement did not appear to be strongly linked with water temperature, barometric pressure, or wind speed. These results suggest that bluegills move considerable distances and that many roam throughout this 332-ha shallow lake. However, diel patterns were not evident. Sampling bluegills in Great Plains lakes using passive gears (e.g., trap nets) may be most effective during the summer months, when fish are most active. Active sampling (e.g., electrofishing) may be more effective than the use of passive gears in spring and fall, when bluegills are less active.