bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of the Flathead Catfish Population in a Lightly Exploited Fishery in Lake Wilson, Alabama
Authors: Marshall Matthew D. , Holley Michael P. , Maceina Michael J. 
Published: October 2009

Abstract
Population metrics and the fishery for flathead catfish Pylodictis olivaris were examined in Lake Wilson, an impoundment of the Tennessee River in Alabama. We described the recreational and commercial exploitation, angler size selectivity, and population demographics and used modeling to assess the impact of exploitation and minimum length limits on the abundance of memorable (860-mm) and trophy (1,020-mm) fish. A total of 1,113 flathead catfish were collected, and 646 of these fish (≥300 mm) were tagged and released to estimate exploitation. The length distribution indicated that there was a high proportion of larger fish in the population, the relative stock densities of preferred-, memorable-, and trophy-length fish being 21, 8, and 2%, respectively. Ages were estimated from otoliths (N = 198), and it was found that fish were slow growing (von Bertalanffy growth coefficient, 0.066) and long-lived (maximum age, 34 years) and expressed a high annual survival rate (83%) and low instantaneous natural mortality (range, 0.099–0.159). From a liberal tag loss rate (2.617%/month) and range of angler nonreporting (20–70%), estimates of exploitation ranged from 5% to 13%. Commercial angling accounted for 26% of the harvest. However, comparison of the observed and simulated length distributions and the difference between catch-curve survival and natural mortality strongly suggested that exploitation was about 5%. Anglers preferred to harvest larger fish, the highest selection being for fish 600–800 mm long. A reduction in harvest rates would have a larger impact on the maintenance of memorable- and trophy-length fish in the population than 356-, 508-, or 610-mm minimum length limits. At exploitation rates greater than 12%, very few trophy-size flathead catfish would remain in the population even if a high minimum length limit (610 mm) were imposed. Currently, flathead catfish are lightly exploited in this section of the Tennessee River and regulations to maintain the quality size of the population are not necessary at this time. However, this population is slow growing and long-lived with low natural mortality and would be sensitive to overfishing. If exploitation should increase and exceed natural mortality, the abundance of memorable- and trophy-size fish would be greatly reduced.
The Effect of Cull Rings on Catch Rates of Blue Crabs Callinectes sapidus in the North Carolina Trap Fishery
Authors: Rudershausen Paul J. , Turano Marc J. 
Published: October 2009

Abstract
We sampled seven North Carolina estuaries (Currituck, Core, Albemarle, Bogue, and eastern Pamlico sounds and the Cape Fear and Pamlico rivers) to determine the separate and interacting effects of cull ring size and the number of cull rings per trap on the catch rate (catch per trap) of blue crabs Callinectes sapidus. Since a single minimum cull ring size is required in North Carolina and regional differences in blue crab shape may mediate its effectiveness, we also measured subsamples of male and mature female blue crabs to determine whether there were shape differences among estuaries. The cull ring sizes tested in Currituck and Core sounds were 58.7, 60.3, and 61.9 mm. The smallest two sizes were tested in the other five estuaries. We also varied the number of cull rings from two to four per trap. Thus, there were nine treatments in Currituck and Core sounds and six in the other estuaries. Three blue crab types dominated the catches: legal males (≥127 mm), sublegal males, and mature females. Increasing ring size and number did not significantly affect the catch per unit effort (CPUE) of legal males except in Currituck Sound, where they positively affected CPUE. Increasing ring size negatively affected the CPUE of sublegal males in all estuaries except eastern Pamlico Sound, where if had no effect. Increasing ring number negatively affected the CPUE of sublegal males in two estuaries: Currituck and Albemarle sounds. Increasing ring size negatively affected the CPUE of mature females in two pairwise cases in one estuary (Core Sound); ring size and number did not impact the CPUE of mature females in other estuaries. Despite the apparent differences in the shapes of blue crabs among estuaries, the influences of cull ring size and number were consistent. Our data indicate that a 1.6- or 3.2-mm increase in cull ring size would not negatively impact the catch rates of legal blue crabs but would increase the escapement of sublegal blue crabs.
Effect of Temperature on Growth, Condition, and Survival of Juvenile Shovelnose Sturgeon
Authors: Kappenman Kevin M. , Fraser William C. , Toner Matt , Dean Jan , Webb Molly A. H. 
Published: October 2009

AbstractWater temperature plays a key role in determining the persistence of shovelnose sturgeon Scaphirhynchus platorynchus in the wild and is a primary factor affecting growth both in the hatchery and in natural waters. We exposed juvenile shovelnose sturgeon to temperatures from 8°C to 30°C for 87 d to determine the effect of temperature on growth, condition, feed efficiency, and survival. Growth occurred at temperatures from 12°C to 30°C; the optimal temperature predicted by regression analysis was 22.4°C, and the minimum temperature needed for growth was greater than 10.0°C. The maximum feed efficiency predicted by regression analysis was 24.5% at 21.7°C, and condition factor was highest in the 18°C treatment. Mortality was significantly higher at 28°C and 30°C than at lower temperatures but less than 10% across the thermal regimes tested and 0% at 14‐18°C. Mortality was observed at and below 12°C, suggesting that extended periods of low temperature may deplete energy reserves and lead to higher mortality. Rearing juvenile shovelnose sturgeon at temperatures above 24°C reduced the growth rate and feed efficiency and increased mortality. Temperatures in the range 18‐20°C appeared to maximize the combination of condition, growth, and feed efficiency while not increasing thermal stress. This study corroborates field studies suggesting that altered temperature regimes in the upper Missouri River reduce the growth of shovelnose sturgeon. This information may help protect the thermal habitat critical to the species and guide restoration efforts by delineating temperature regime standards for regulated rivers and those affected by hydroelectric facilities and suggesting new criteria for conservation propagation.
Energy Density of Introduced Round Goby Compared with Four Native Fishes in a Lake Michigan Tributary
Authors: Ruetz Carl R. , Strouse Dana L. , Pothoven Steven A. 
Published: October 2009

AbstractThe round goby Neogobius melanostomus is an invasive species that has changed Great Lakes food webs and become an important prey for many predators. We tested whether the round goby from a Lake Michigan tributary was energetically equivalent to four native fishes: Mottled sculpin Cottus bairdii, johnny darter Etheostoma nigrum, bluntnose minnow Pimephales notatus, and rock bass Ambloplites rupestris. We found positive linear relationships between energy density and the percent dry weight of a fish for each species. We also found evidence of temporal and spatial variation in round goby energy density. Energy density was lower in spring and summer than in fall. The spatial variation in energy density may be linked to the inclusion of the low‐quality prey, dreissenid mussels, in the diets of larger round goby. For a given size, the johnny darter and bluntnose minnow had the highest energy density while mottled sculpin had the lowest. Our results show that the energy density of the round goby is intermediate to those of the four native fishes, suggesting that the round goby is an energetically average prey in a Lake Michigan tributary.
Lethality of Sea Lamprey Parasitism on Lake Sturgeon
Authors: Patrick Holly K. , Sutton Trent M. , Swink William D. 
Published: October 2009

AbstractParasitism by sea lampreys Petromyzon marinus may contribute to the delayed recovery of imperiled populations of lake sturgeon Acipenser fulvescens in the Great Lakes. Our study objectives were to examine the survival, growth, and condition of four size‐classes of lake sturgeon following a single sea lamprey attack. Lake sturgeon from one of four size‐groups (I: 470‐570 mm fork length; II: 570‐650 mm; III: 650‐760 mm; and IV: 950‐1,500 mm) were individually subjected to a sea lamprey attack in a series of 55 experimental trials. Direct mortality of lake sturgeon, resulting from acute anemia after an attack, was greatest for smaller lake sturgeon (I: 11%; II: 31%; III: 8%; IV: 0%). Similarly, indirect mortality resulting from secondary fungal infection was also size dependent (I: 11%; II: 19%; III: 8%; IV: 0%). No direct relationship was found between attachment duration and host survival; short intense attachments were as likely to result in host mortality as longer attachments. More than 50% of sea lamprey attacks occurred on the ventral surface of the rostrum or pectoral fin axils, and attachment at these locations resulted in the mortality of the host more often than did attachments at other locations. Declines in lake sturgeon growth and condition after an attack were more pronounced for smaller (size‐classes I‐III) than larger (size‐class IV) lake sturgeon hosts. Although much uncertainty remains about the effects of sea lamprey parasitism on lake sturgeon, the levels of mortality observed in this study suggest that the no‐observable‐effect lampricide treatment protocol, which is designed to protect larval lake sturgeon at the expense of increased production of sea lampreys, may not be the optimal strategy for the concurrent rehabilitation of self‐sustaining lake sturgeon populations and sea lamprey control in the Great Lakes.
Nonlethal Sampling of Fish Caudal Fins Yields Valuable Stable Isotope Data for Threatened and Endangered Fishes
Authors: Sanderson Beth L. , Tran Chau D. , Coe Holly J. , Pelekis Vija , Steel E. Ashley , Reichert William L. 
Published: October 2009

AbstractFin clipping is gaining momentum for stable isotope analysis in fish as a nonlethal alternative to lethally collecting dorsal white muscle tissue. The main advantage of fin clipping is the elimination of lethal collection, which thus increases the potential for stable isotope research involving threatened or endangered species. To make comparisons across studies using different methods, the degree to which fin clips and dorsal muscle are correlated for both δ15N and δ13C across time and space must be quantified. We evaluated the efficacy of using caudal fin clips by comparing tissues collected across time (2003‐2005), space (21 streams), and body size (fork length, 40‐140 mm) for juvenile Chinook salmon Oncorhynchus tshawytscha and O. mykiss (rainbow trout and steelhead [anadromous rainbow trout]). We also addressed several analytical and sampling issues to assess the potential benefits and limitations of using fin clips for δ15N and δ13C determination. We found that the relationship between fin and muscle tissue was consistent across years and streams. On average, δ15N was lower in fin tissue than in muscle tissue, whereas δ13C was greater in fin tissue. Although the magnitude of the difference between fin and muscle tissue is lower than the thresholds typically used to define trophic level increases, the biological significance of these differences is context dependent. Power analyses indicated that fin and muscle tissue were equal in their ability to detect differences in δ15N and δ13C in juvenile fish and that larger sample sizes are needed to statistically quantify these differences. Finally, the use of fin clips is not a viable option for smaller fish (<50 mm) because the majority of the caudal fin is necessary for analysis. Nonetheless, fin clipping does represent a promising nonlethal sampling technique for quantifying δ15N and δ13C in juvenile salmonids.
The Interplay of Morphology, Habitat, Resource Use, and Genetic Relationships in Young Yellow Perch
Authors: Parker Aaron D. , Stepien Carol A. , Sepulveda‐Villet Osvaldo J. , Ruehl Clifton B. , Uzarski Donald G. 
Published: October 2009

AbstractMorphological divergence resulting from differences in resource and habitat use is common in many fishes inhabiting postglacial ecosystems. We tested whether young yellow perchPerca flavescensdiffer in morphology, genetic composition, or diet in the nearshore (deep open‐water) versus wetland and littoral habitats (shallow zones) of Lake Michigan and Saginaw Bay, Lake Huron. Twenty‐one morphological measurements and six meristic counts were compared for 132 age‐1 yellow perch, and the genetic variation at 12 nuclear DNA microsatellite loci was assessed for a subset of age‐1 individuals across habitats and adults from nearshore zones. The results showed morphological and genetic divergence in yellow perch between Lake Michigan and Lake Huron and among those in nearshore versus wetland habitats in Lake Michigan (but not Lake Huron). Lake Huron yellow perch had deeper, longer bodies and larger dorsal fins than those from Lake Michigan. Those in nearshore habitats from both lakes had deeper, longer bodies and larger dorsal fins than did those occupying wetlands, which may reflect an adaptive response to predators and open‐water cruising. In Lake Michigan, these differences may have a genetic basis that is not apparent in Lake Huron, suggesting a role for phenotypic plasticity. Piscivorous and zooplanktivorous individuals had similar morphologies, with larger body depths than insectivores, which may be useful for fast‐starts during prey capture and provide protection from predation in open water. Comparisons of morphology, population structure, and diet thus reveal that the morphological diversity of yellow perch between habitats and lake basins reflects an interplay between phenotypic plasticity and genetic divergence.
Plasma Vitellogenin and Estradiol Concentrations in Adult Gulf Sturgeon from the Pascagoula River Drainage, Mississippi
Authors: Heise Ryan J. , Bringolf Robert B. , Patterson Rhonda , Cope W. Gregory , Ross Stephen T. 
Published: October 2009

AbstractGulf sturgeon Acipenser oxyrinchus desotoi are anadromous, the adults moving into rivers by early spring for spawning and migrating back to salt water in the fall. Because Gulf sturgeon lack readily discernable secondary sex characteristics, minimally invasive means, such as evaluation of plasma vitellogenin (an egg yolk protein precursor) and sex steroid hormones, have been used to determine gender. Our objectives were to explore the use of vitellogenin (Vtg) and estradiol (E2) to identify the gender of adult Gulf sturgeon captured in the Pascagoula River drainage and to determine whether these substances were useful in identifying which females would be spawning in a given spring. Our enzyme‐linked immunosorbent assay detected Vtg in all samples at concentrations ranging from 5.47 to 7,634.2 μg/mL. For samples collected from March through May, the plasma Vtg concentrations generally clustered into one of two groups, low (<100 μg/mL) and high (>1,000 μg/mL). During the same months, plasma E2 values followed a similar pattern of separation into low (<0.5‐ng/mL) and high (>8‐ng/mL) concentrations. Based on the clear delineation of Vtg and E2 concentrations in spring‐captured sturgeon and comparison with previous studies in which gender was definitively determined, fish with high Vtg (>1,000‐μg/mL) and high E2 (>8‐ng/mL) concentrations were putatively identified as spawning females. The plasma Vtg concentrations in 10 known males (based on the release of milt) were 13‐86 μg/mL. Our work provides the first information regarding Vtg and E2 concentrations for threatened Gulf sturgeon throughout the freshwater phase of their life cycle. It is currently unclear whether the Vtg concentrations measured in male Gulf sturgeon are within a normal range for this species in the wild or are a biomarker of endocrine disruption due to exposure to xenobiotic substances.
A License Registry Improves Sampling Efficiency for a Marine Recreational Survey
Authors: Ashford Julian R. , Jones Cynthia M. , Fegley Lynn 
Published: October 2009

AbstractMarine recreational surveys that use lists of coastal households for a sampling frame have been encouraged to improve their efficiency by using angler license registries instead. However, few studies have compared surveys of license holders and coastal households or assessed the gain in efficiency. During a survey of the recreational fishery for the blue crab Callinectes sapidus in Maryland, sport crab license holder and coastal county households were sampled by telephone. Overall, 40.5% of license holder households interviewed reported activity compared with 2.7% of coastal households interviewed. The license list showed no disadvantage in statistical properties compared with coastal households. However, the response rate was low for both lists; for the license survey, 30.5% of telephone numbers called resulted in interviews compared with 29.3% for coastal households. To improve response rates, we recommend that license registries incorporate incentives and alternative information for reaching license holders, such as cell‐phone numbers and e‐mail addresses.
Development and Evaluation of a Stream Channel Classification for Estimating Fish Responses to Changing Streamflow
Authors: Peterson James T. , Jackson C. Rhett , Shea Colin P. , Li Guoyuan 
Published: October 2009

AbstractCurrent approaches to assessing the potential effects of river regulation and water use on stream fish communities are based on physical habitat simulation and are not feasible for estimating these effects over large spatial scales. We developed a channel classification for streams in the lower Flint River basin, Georgia, based on gross channel morphology and geology and evaluated its usefulness at 23 study sites representing the four channel types in the basin. Our channel classification separated stream channel types based on dominant geology (upland residuum versus Ocala limestone) and channel form (confined versus unconfined). Fish were sampled and habitat measured at the study sites in spring, summer, and winter from 2001 to 2004, a period that included some of the lowest and highest seasonal flows ever recorded. The channel types differed with respect to diurnal variability in temperature and dissolved oxygen concentration as well as habitat characteristics (substrate, large wood). Statistical habitat modeling indicated that channel unit (e.g., pool, riffle) availability could be predicted accurately for each channel type using streamflow, with errors rates that averaged 0.7% across channel unit types. Comparisons between the accuracy of species presence and fish abundance models fit using habitat characteristics to those fit using geomorphic channel characteristics indicated similar model accuracy with slightly less bias (6% on average) for the geomorphic channel characteristics models. Our results indicate that the channel types were useful for predicting changes in habitats and stream fish presence and abundance in response to changing streamflow. Channel classification is potentially a useful and cost‐effective approach to quantifying changes in the physical environment in response to varying streamflow. Additionally, channel classification could be combined with dynamic fish population models to evaluate the effects of river regulation and water use across large spatial scales.
Temporal Stability of Genetic Variation within Natural Populations of Summer Steelhead Receiving Mitigation Hatchery Fish
Authors: Blankenship Scott M. , Small Maureen P. , Bumgarner Joseph D. 
Published: October 2009

AbstractStochastic fluctuation in allele frequencies may reflect microevolutionary processes responsible for genetic change, such as small effective population size (Ne), which is a legitimate concern for imperiled populations affected by environmental or anthropogenic factors. In salmonids, recent empirical studies have provided conflicting results regarding the consistency of within‐population genetic variation over time. In the present study, we surveyed the genetic variation at 14 microsatellite loci in two endemic populations of summer steelhead Oncorhynchus mykiss (Tucannon and Touchet) for seven consecutive years and the Lyons Ferry Hatchery stock (LFH) for 4 years. The LFH (mitigation) stock is used to enhance fishing opportunities in southeastern Washington State and not to aid in the recovery of natural populations. We observed statistically significant differences in allele frequencies between replicated collections from the same location. One of twenty‐one genic tests for the Tucannon River collections, 9 of 21 genic tests for the Touchet River collections, and all genic tests regarding LFH collections were statistically significant. Temporal variation was larger than spatial variation (0.86% and 0.44%, respectively). We also used genetic data to infer effective population sizes for natural steelhead populations and the LFH mitigation hatchery stock, with point estimates of 729.7, 599.4, and 266.7 for the Tucannon, Touchet, and LFH populations, respectively. Despite the temporal variation observed, relative genetic differentiation was stable over time, replicated collections tending to cluster together in factorial correspondence analyses of allele frequency data. However, the genetic data were consistent with the potential for gene flow between the Tucannon River and LFH populations. The potential benefits of stocking genetically differentiated hatchery fish to enhance fishing opportunities in the Tucannon River may be offset by the negative effects of hatchery introgression and the small Ne in hatchery fish.
Using Mg as a Proxy for Crystal Structure and Sr as an Indicator of Marine Growth in Vaterite and Aragonite Otoliths of Aquaculture Rainbow Trout
Authors: Veinott Geoffrey Ian , Porter T. Rex , Nasdala Lutz 
Published: October 2009

AbstractOtoliths of rainbow trout Oncorhynchus mykiss reared in marine cages were analyzed by laser ablation‐inductively coupled plasma mass spectrometry to determine their Sr and Mg concentrations and by micro‐Raman spectrometry to assess mineralogy. Analyses of transects from the core of the otolith to the growing edge (incorporating otolith material produced during freshwater hatchery and marine cage growth) revealed that these transects were composed of aragonite, vaterite, or both. The concentration of Sr varied significantly between mineral polymorphs and environments (hatchery or marine). In vaterite transects, Sr concentrations increased an average of 130 μg/g between freshwater hatchery growth and marine growth. This increase represents a near doubling of the Sr concentration in vaterite and made Sr a suitable indicator of a change in the environment as reflected in vaterite transects. In aragonite transects, Sr concentrations increased an average of 1,330 μg/g between hatchery and marine growth, which simplified the identification of the timing of marine transfer. The concentrations of Mg also varied significantly between mineral polymorphs, the difference in the average concentration between aragonite and vaterite being 1,179 μg/g. This allowed for the use of Mg as a proxy for mineralogy. While there was an increase in Mg concentration between hatchery and marine growth in some vaterite otoliths, the change was small compared with the change as a result of mineralogy. The average aragonite‐vaterite partition coefficients were 5.238 and 8.096 for Sr and 0.057 and 0.128 for Mg for hatchery and marine growth, respectively.