bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Ciscoes as Prey in the Trophy Growth Potential of Walleyes
Authors: Kaufman Scott D. , Morgan George E. , Gunn John M. 
Published: April 2009

Abstract
Analysis of the growth characteristics of 215 populations of walleye Sander vitreus across Ontario revealed that female walleyes reached larger asymptotic lengths in lakes in which ciscoes Coregonus artedi provided a relatively large prey species for them. The stomach contents of walleyes from a set of intensively studied lakes revealed that walleyes of all sizes depended on ciscoes but that ciscoes were most important to larger walleyes. In lakes without ciscoes, the walleye diet closely tracked the availability of young-of-year yellow perch Perca flavescens; when such prey were in short supply, walleyes consumed invertebrates. The prey size in walleye stomachs was significantly larger in lakes with ciscoes, but the probability of finding empty stomachs was also greater. This suggests that although walleyes in lakes with ciscoes foraged less often, more energy was available for growth. Exceptions to this general pattern occurred when ciscoes were too large to be consumed by walleyes or ciscoes were absent but small prey (i.e., yellow perch) were very abundant. We propose that lakes without ciscoes will provide higher catch rates for anglers, whereas those with ciscoes (particularly small ciscoes) are more likely to provide opportunities for trophy size fish.
Sex-Specific Natural Mortality of Arrowtooth Flounder in Alaska: Implications of a Skewed Sex Ratio on Exploitation and Management
Authors: Wilderbuer Thomas K. , Turnock Benjamin J. 
Published: April 2009

Abstract
Conservative fisheries management in Alaskan waters typically limits harvest to maintain a target biomass of female spawners (40% of the female biomass observed in the absence of fishing). This harvest calculation does not consider the male population level for a species. If natural mortality rates (M) differ between sexes and if females outlive males, then a reduction in males relative to females could diminish the reproductive potential of the stock. This problem was examined in the present study by estimating separate sex-specific M-values for the arrowtooth flounder Atheresthes stomias in Alaska, where females are almost always found at higher proportions than males during trawl surveys. Age data indicated that females outlive males, and estimates of M ranged from 0.10 to 0.33 for females and from 0.16 to 0.51 for males. Based on four estimation methods, male M was consistently higher than female M. Simulated harvest scenarios in which male M and selectivity were varied indicated that increasing male M and lowering the age of males at first capture skewed the sex ratio even more toward females; in the most extreme harvest scenario, the percentage of females in the population was as high as 89% (Gulf of Alaska) and 96% (Bering Sea). Because reproductive success under a skewed sex ratio is probably linked to reproductive behavior, we developed a simple conceptual model to consider three reproductive strategies that differed in the number of females (1–3) that could be paired with a single male. Although a population's reproductive potential was much more resilient to changes in sex ratio for 1:2 or 1:3 (male : female) pairings (reduced by only 15% when the population was 70% female), the fishing mortality rate (F) that corresponded to a reduction in egg fertilization was much higher than the target F (i.e., that maintained biomass at 40% of the unfished biomass) and exceeded overfishing levels when the population was over 80% female.
Using Species Composition Data from a Trawl Survey to Determine Potential Bycatch of the Commercial Trawl Fishery for Horseshoe Crab Limulus polyphemus in the Middle Atlantic Bight
Authors: Graham Larissa J. , Murphy Brian R. , Hata David 
Published: April 2009

Abstract
The National Marine Fisheries Service has encouraged regional management councils to develop fisheries ecosystem plans that, among other things, identify the bycatch species within each fishery and describe each species' spatial and temporal distribution. Horseshoe crabs Limulus polyphemus have been harvested along the eastern coast of the USA since the 1800s; however, a fishery management plan was only recently created for this species, and bycatch in the horseshoe crab trawl fishery has not been quantified. We identified species likely to be caught as bycatch in the commercial fishery by using species composition data from a fishery-independent horseshoe crab trawl survey conducted in 2005 and 2006. Seventy-six taxa were caught, including 47 finfish species from 33 families. Skates (family Rajidae) comprised more than one-half of the total biomass caught, and horseshoe crabs comprised one-third of the total biomass. Catch per unit effort (kg/km towed) was greatest for little skate Leucoraja erinacea, winter skate Leucoraja ocellata, horseshoe crab, and clearnose skate Raja eglanteria. We also caught species that are currently on the World Conservation Union's Red List (e.g., Atlantic sturgeon Acipenser oxyrinchus) and unmanaged within U.S. waters (e.g., cownose ray Rhinoptera bonasus and smooth dogfish Mustelus canis). Nonmetric multidimensional scaling was used to cluster sites based on species abundance. The sites strongly clustered into two distinct groups, suggesting that species composition differs between northern and southern sites. Bottom water temperature was a significant factor in determining species composition, explaining almost 70% of the variation in species composition among sites. The results of this study provide managers with a better understanding of which nontarget populations may be affected by the horseshoe crab trawl fishery, a first step in understanding the broader ecosystem-level effects of this fishery.
Effects of Variable Mortality and Recruitment on Performance of Catch-Curve Residuals as Indicators of Fish Year-Class Strength
Authors: Catalano Matthew J. , Dutterer Andrew C. , Pine William E. , Allen Micheal S. 
Published: April 2009

Abstract
We built a simulation model to assess the performance of catch-curve residuals as an index of year-class strength for a short-lived and a long-lived fish life history type across a range of assumed values for the variation in recruitment (CVR) and fishing mortality (CVF). The magnitude of CVR strongly influenced the utility of catch-curve residuals in assessing year-class strength. The probability of finding a significant correlation between catch-curve residuals and true recruitment values exceeded 0.9 when CVR was greater than 0.5 for the long-lived and greater than 1.0 for the short-lived life history types. This suggests that larger recruitment values have a greater probability of being successfully “tracked” through the age structure. Conversely, the magnitude of interannual variation in fishing mortality weakly influenced the performance of catch-curve residuals. The inspection of individual catch-curve residuals relative to the known recruitment values that produced them showed considerable scatter, indicating that the utility of this metric in assessing individual year-class strength is small. Sensitivity analyses showed that the performance of catch-curve residuals improved modestly with equal sampling vulnerability across ages and decreased slightly with increased fishing mortality. Our results suggest that catch-curve residuals can serve as a rudimentary measure of recruitment under ranges of recruitment and mortality variation similar to those frequently observed in field studies.
Size at Implantation Affects Growth of Juvenile Steelhead Implanted with 12-mm Passive Integrated Transponders
Authors: Tatara Christopher P. 
Published: April 2009

Abstract
Passive integrated transponder (PIT) tags have led to greater understanding of fish growth, survival, predation, migration, behavior, and the effects of human-caused environmental manipulation. Technological advances have reduced the size of PIT tags, permitting their implantation into smaller fish. To reap the benefits of PIT tag technology, implantation must not adversely impact growth, survival, or behavior. Steelhead Oncorhynchus mykiss parr reared in a natural-like environment were implanted with 12-mm PIT tags, and implantation effects on growth rate were measured. Steelhead had fork lengths ranging from 45 to 96 mm after 4 weeks of rearing in an outdoor stream channel. Thirty (17.4%) of the 172 steelhead parr that were under 74 mm at the time of PIT tag implantation had instantaneous growth rates of 0 [loge (g)]/d or less, while all parr (n = 72) over 75 mm exhibited positive growth rates. Logistic regression indicated that fork length at implantation was significantly related to the probability of positive growth rates (P &lt; 0.001). For steelhead parr that exceeded 74 mm at implantation, the probability of experiencing positive growth was greater than 95%. The data suggest that fork length of steelhead parr should be above 74 mm at implantation to minimize negative growth effects associated with 12-mm PIT tags.
Movements of Prespawn Adult Atlantic Salmon Near Hydroelectric Dams in the Lower Penobscot River, Maine
Authors: Holbrook Christopher M. , Zydlewski Joseph , Gorsky Dimitry , Shepard Steven L. , Kinnison Michael T. 
Published: April 2009

Abstract
Acoustic telemetry was used to assess riverine behavior and passage success for prespawn male adult Atlantic salmon Salmo salar in the lower Penobscot River, Maine, in 2005 (n = 10) and 2006 (n = 25). Only 3 of 10 (30%) and 2 of 25 (8%) tagged Atlantic salmon successfully passed all three dams between the head of tide and presumed spawning habitat in 2005 and 2006, respectively. Migrants that failed to pass the second upstream dam frequently fell back into the estuary (3 of 4 in 2005; 17 of 23 in 2006), and few successfully reascended Veazie Dam at the head of tide. Fallback behavior was associated with temperatures exceeding 22°C and may reflect a strategy for coping with thermal stress and migratory delays. Atlantic salmon were also observed to actively seek out thermal refuge near one of the dams. Passage data were compared with results from previous telemetry studies that used Carlin tags and radio telemetry from 1987–1990 and 1992, and passive integrated transponder tags from 2002–2004. For all 10 years of study combined, median passage success was 64, 72, and 93% for the three dams. While 2006 may represent an uncommonly poor year for upstream passage at these dams, median cumulative passage past two of these dams was only 71% and ranged from 8% to 87% among years. Study results indicate that poor upstream passage severely limits migratory success in this system, particularly during periods of high discharge. Planned removal of two of these lower river dams is expected to improve migratory success for adult Atlantic salmon in the Penobscot River system.
Migration Patterns and Spawning Distribution of Adult Hatchery Sockeye Salmon Released as Parr from Net-Pens in Lake Wenatchee, Washington
Authors: Murdoch Andrew R. , Tonseth Michael A. , Miller Todd L. 
Published: April 2009

Abstract
Artificial propagation of sockeye salmon Oncorhynchus nerka interrupts the early phases of their life history cycle, typically between the egg and smolt stages. Sockeye salmon reared initially in a hatchery and subsequently released as parr from freshwater net-pens suspended in a lake cannot imprint on a specific tributary water source. As a result, the spawning distribution of returning adults may differ from that of naturally produced fish. We used radio tags and carcass surveys to determine whether the spawning distribution and location of adult hatchery sockeye salmon reared and released from net-pens in Lake Wenatchee, Washington, were similar to the spawning distribution and location of their naturally produced counterparts. Over 2 years, 100 hatchery sockeye salmon were radio-tagged and tracked to their spawning location. No radio-tagged sockeye salmon were found spawning in Lake Wenatchee, the lake outlet, or other nearby rivers. All radio-tagged sockeye salmon that were tracked into tributaries of Lake Wenatchee spawned in locations (i.e., river reaches) similar to those of naturally produced fish. Based on carcass surveys, the spawning distribution of hatchery sockeye salmon among spawning tributaries was different from that of naturally produced fish; this difference was attributed to the inability of hatchery fish to imprint on a natal stream during their early life history. Although the spawning distribution among tributaries differed between hatchery and naturally produced fish, the mean difference was small (10.8%) and ranged between 0% and 29%.
The Number of Redds Constructed per Female Spring Chinook Salmon in the Wenatchee River Basin
Authors: Murdoch Andrew R. , Pearsons Todd N. , Maitland Travis W. 
Published: April 2009

Abstract
The number of redds in a watershed is routinely used to monitor the population status of Pacific salmon Oncorhynchus spp. One limitation of this approach is that spawning escapement estimates derived from redd counts often assume one redd per female. We tested this assumption on spring-run Chinook salmon O. tshawytscha in the Wenatchee River watershed, Washington. Female spring Chinook salmon (N = 3,590) were injected with passive integrated transponder (PIT) tags at Tumwater Dam and were monitored annually on the spawning grounds over a 3-year period. Female Chinook salmon were observed on 75% of the 1,784 redds that were counted, and PIT-tagged females were detected on 42% of the redds. Of the female Chinook salmon detected on the spawning grounds, only 10 were detected on more than one redd. The number of redds constructed per PIT-tagged female (1.01 redds/female) was identical during each year of the study despite differences in the abundance of spawners. These results support the common assumption of one redd per female spring Chinook salmon.
The Effect of Deposited Fine Sediment on Summer Survival and Growth of Rainbow Trout in Riffles of a Small Stream
Authors: Harvey Bret C. , White Jason L. , Nakamoto Rodney J. 
Published: April 2009

Abstract
Elevated fine-sediment inputs to streams can alter a variety of conditions and processes, including the amount of fine sediment stored in riffles. We sought to measure the influence of deposited fine sediment on the survival and growth of juvenile rainbow trout Oncorhynchus mykiss (106–130 mm fork length) using a field experiment that included 18 enclosures in riffles of a small northwestern California stream. The experiment included six replicates of three levels of deposited fine sediment (low, background, and high) that embedded riffle cobbles at 0, 50, and 100%, respectively. Only 1 of 12 fish survived in high-sediment enclosures, while survival of fish in low- and background-sediment treatments equaled or exceeded 50%. Low- and background-sediment treatments could be distinguished from each other by a difference in fish growth: fish in the low-sediment treatment gained mass, on average, while all surviving fish in the background-sediment treatment lost mass. In addition to providing relatively high survival and growth benefits for juvenile rainbow trout, low-sediment experimental units were colonized at significantly higher rates by other vertebrates, particularly coastal giant salamanders Dicamptodon tenebrosus. The amount of stored fine sediment in small streams may substantially influence the total amount of habitat available to vertebrates at the watershed scale.
Morphometric and Meristic Differences among Bluehead Suckers, Flannelmouth Suckers, White Suckers, and Their Hybrids: Tools for the Management of Native Species in the Upper Colorado River Basin
Authors: Quist Michael C. , Bower Michael R. , Hubert Wayne A. , Parchman Thomas L. , McDonald David B. 
Published: April 2009

Abstract
Hybridization with nonnative fishes is a major factor influencing the status of native catostomids in the Colorado River basin. In Wyoming, hybridization with nonnative white suckers Catostomus commersonii is a particular concern in the conservation of native bluehead suckers C. discobolus and flannelmouth suckers C. latipinnis. The purpose of this study was to describe the meristic and morphometric characteristics of bluehead suckers, flannelmouth suckers, white suckers, and their hybrids from Muddy Creek, Wyoming, for which genotypic data were available to verify the classification of individual fish as pure species or hybrids. We also sought to develop discriminant function models that can be used in the field. Bluehead suckers and flannelmouth suckers had more lateral line scales, shorter and narrower heads, and narrower caudal peduncles than white suckers. Bluehead suckers and bluehead sucker × white sucker hybrids had a cartilaginous biting ridge in their mouth. Important characteristics for discriminating among these taxa included the number of postdorsal lateral line scales and the exterior width of the mouth. The discriminant function correctly classified 100% of the bluehead suckers and bluehead sucker × white sucker hybrids. Flannelmouth suckers, white suckers, and flannelmouth sucker × white sucker hybrids lacked a cartilaginous biting ridge. The number of postdorsal scales, caudal peduncle depth, and ratio of mouth length to the interior width of the mouth discriminated among taxa without a ridge. The discriminant function correctly classified 100% of the flannelmouth suckers, 92% of the white suckers, and 91% of the flannelmouth sucker × white sucker hybrids. None of the white suckers or flannelmouth sucker × white sucker hybrids were misclassified as flannelmouth suckers. Our results suggest that native bluehead suckers and flannelmouth suckers, nonnative white suckers, and hybrids of these species can be accurately identified by a few, easily measured meristic and morphometric characteristics.
Comparison of Failure Time Analysis and Abbott's Formula for Estimating Survival of Organisms Entrained at Power Stations
Authors: Young John R. 
Published: April 2009

Abstract
During the 1970s and 1980s, numerous studies were conducted to estimate the survival of ichthyoplankton following passage through power plant cooling systems. These studies generally used Abbott's formula to adjust the observed survival of organisms collected at the discharge for sampling mortality, as measured at the intake. The U.S. Environmental Protection Agency (USEPA) criticized these past studies for methodological faults (including the data analysis methods) on the basis that Abbott's formula may introduce a bias if sample sizes are small or unequal at the intake and discharge locations, sampling mortality is high, the samples contain organisms that were already dead, or the organisms are heterogeneous with respect to their probability of surviving entrainment. The effects of these issues on the bias and precision of entrainment survival estimates calculated using Abbott's formula and using failure time analysis were determined from simulated samples. Failure time analysis produced estimates that were minimally biased in terms of the issues raised by the USEPA and often more accurate and precise than Abbott's formula estimates. The failure time models were applied to experimental data used to estimate sampling stress at the Indian Point Generating Station in 1980 and supported the equality of sampling stress at the intake and discharge samplers, a critical requirement for obtaining unbiased survival estimates.
Precision of Hard Structures Used to Estimate Age of Bowfin in the Upper Mississippi River
Authors: Koch Jeff D. , Quist Michael C. , Hansen Kirk A. 
Published: April 2009

Abstract
The bowfin Amia calva has traditionally been considered a nuisance species that competes for resources with more desirable fish species. However, an emerging market for bowfin roe has increased the species' economic importance and raised awareness associated with the lack of information on its ecology and population dynamics. Furthermore, few studies have investigated the utility and precision of hard structures used to estimate bowfin age. The objective of this study was to examine the precision of age estimates obtained from sectioned pectoral fin rays, otoliths, scales, gular plates, and branchiostegal rays of bowfin collected from the upper Mississippi River. Structures from 255 bowfin were examined. Otoliths, scales, and branchiostegal rays were excluded from analyses because of poor readability. Sectioned pectoral fin rays provided the highest between-reader agreement and lowest variation between age estimates.
Capture Efficiency and Size Selectivity of Channel Catfish and Blue Catfish Sampling Gears
Authors: Buckmeier David L. , Schlechte J. Warren 
Published: April 2009

Abstract
We used proportional recapture data from mark–recapture experiments to directly estimate capture efficiency (percentage of fish captured per standard level of effort) and size selectivity (for 50-mm size-groups) of catfish sampling gears. Hoop-net series were evaluated for collecting channel catfish Ictalurus punctatus, and low-frequency, pulsed DC electrofishing was evaluated for collecting blue catfish I. furcatus. To examine spatial and temporal variability, capture efficiency and size selectivity were estimated in river and reservoir habitats during June, July, and September 2005. Selectivity of experimental gill nets was also assessed. Capture efficiency of hoop nets for channel catfish was consistent across months and between river and reservoir habitats (2.7–14.3% per 12 hoop-net series). Capture efficiency of low-frequency electrofishing was low (frequently, ≤1% per 120 min) and variable; recapture rates were greatest in river habitat during July and September. Hoop-net series collected representative samples of channel catfish between 250 and 556 mm total length. Likewise, blue catfish between 250 and 855 mm were fully vulnerable to low-frequency electrofishing. Although fish smaller than 250 mm were captured, they were frequently underrepresented in the catch of both gears. Size selectivity was not affected by habitat or month sampled for either gear type or either species. Capture efficiency of experimental gill nets was very low for both channel catfish and blue catfish (about 0.2% in 46 gill-net nights), and gill nets were more size selective than other gears. Based on our findings, hoop-net series and low-frequency electrofishing provide accurate size structure data for adult channel catfish and blue catfish, respectively, from both river and reservoir habitat types. Hoop-net series also provide consistent estimates of channel catfish relative abundance; however, relative abundance data for blue catfish collected with low-frequency electrofishing should be used with caution due to observed variability in capture efficiency.