bluuebunny/crossref_metadata_2025_split huggingface dataset:
Findings on American Shad and Striped Bass in the Hudson River Estuary: A Fish Community Study of the Long-Term Effects of Local Hydrology and Regional Climate Change
Authors: O'Connor Megan P. , Juanes Francis , McGarigal Kevin , Gaurin Steven 
Published: July 2012

Abstract
It has been hypothesized that climate change is an underlying factor in determining fish abundances in the Hudson River estuary (HRE). To study the effects of hydrology and climate on the HRE fish community, we applied multivariate statistical methods to data on 20 species–life history stages collected from 1974 to 2005. We confirm that the HRE fish community has changed over this period. These changes are correlated with local hydrology (freshwater flow and water temperature) and regional climate (the Atlantic Multidecadal Oscillation [AMO] and North Atlantic Oscillation). We found that the abundances of striped bass Morone saxatilis larval stages are positively correlated with high freshwater flows and those of juvenile American shad Alosa sapidissima negatively correlated with the AMO or warmer sea surface temperatures. Our findings suggest that climate-related variability affects HRE juvenile shad abundances and that management strategies for this declining species should include the implications of climate change.
Received March 19, 2011; accepted January 10, 2012
Evaluating Changes in Diadromous Species Distributions and Habitat Accessibility following the Penobscot River Restoration Project
Authors: Trinko Lake Tara R. , Ravana Kyle R. , Saunders Rory 
Published: July 2012

Abstract
The Penobscot River basin, covering approximately 22,265 km2, is the largest river wholly within Maine and the second largest river system in New England. The Penobscot River Restoration Project (PRRP) is a multimillion-dollar endeavor that aims to restore native sea-run fish through the removal of two main-stem dams and improved fish passage at a third dam on the Penobscot River. We used geographical information systems, accounts of historic ranges, and barrier survey data to estimate species-specific distributions and habitat accessibility for 11 diadromous species before and after the proposed restoration. We predict a range of outcomes in terms of expected distribution and accessibility that are largely based on habitat use and life history differences. For 4 out of 11 species (Atlantic sturgeon Acipenser oxyrinchus, shortnose sturgeon A. brevirostrum, Atlantic tomcod Microgadus tomcod, and striped bass Morone saxatillis), the PRRP is anticipated to provide access to 100% of their historic freshwater habitat. However, for alewives Alosa pseudoharengus, approximately 69% of the historic spawning and rearing habitat will remain inaccessible due to the presence of other passage barriers. Our results demonstrate that the PRRP is an important step toward ecosystem recovery in the Penobscot River basin but that other restoration activities will be needed to realize the full potential of the PRRP, particularly for alosines. Further, our results provide the first spatial analysis of diadromous fish distribution and access following the PRRP and serve as the baseline for developing a guiding image for expected diadromous fish population responses following the dam removals.
Received March 21, 2011; accepted August 21, 2011
Striped Bass Consumption of Blueback Herring during Vernal Riverine Migrations: Does Relaxing Harvest Restrictions on a Predator Help Conserve a Prey Species of Concern?
Authors: Davis Justin P. , Schultz Eric T. , Vokoun Jason C. 
Published: July 2012

Abstract
Anadromous blueback herring Alosa aestivalis are declining throughout much of their range, and fishery closures in some systems have failed to produce population recovery. A potential contributing factor is increased predation pressure from sympatric striped bass Morone saxatilis. We integrated data on the predator–prey interaction between striped bass and blueback herring during vernal migrations into the Connecticut River with data on the in-river striped bass fishery to assess the potential for mitigation of blueback herring mortality via increased striped bass harvest. Striped bass abundance, size structure, diets, and angler catches were assessed within a river segment during spring 2005–2008. We estimate that striped bass consumed 400,000 blueback herring (90% confidence interval = 200,000–800,000) annually in our study area during the spring migration season. The predator–prey interaction between striped bass and blueback herring was predator size dependent. Blueback herring were most commonly found in the stomachs of striped bass between 650 and 999 mm total length. Intermediate size-classes (650–799 mm) made the greatest contribution to population-level consumption. Highly abundant small striped bass (400–549 mm) consumed herring infrequently, yet still made substantial contributions to population-level consumption. Anglers caught 17,000 striped bass in our study area during March–June 2008; only 11% of these fish could be harvested under the current 28-in (710-mm) minimum length limit. Allowing anglers to harvest up to 15,000 sublegal striped bass from a “bonus harvest” slot limit would reduce annual predatory losses of blueback herring by up to 10%. Alternatively, a smaller bonus harvest of legal-sized striped bass could achieve reductions in consumption of up to 7%. The recreational fishery in our study area, however, may not be intense enough to realize such harvest levels.
Received March 21, 2011; accepted October 18, 2011
Use of a Natural Isotopic Signature in Otoliths to Evaluate Scale-Based Age Determination for American Shad
Authors: Upton Sally A. , Walther Benjamin D. , Thorrold Simon R. , Olney John E. 
Published: July 2012

Abstract
We used δ18O signatures in otoliths as a natural tag for hatch year to evaluate the scale-based age determination method used for adult American shad Alosa sapidissima in the York River, Virginia. Juveniles of the 2002 year-class exhibited high δ18O values in otolith cores that identified adult members of the cohort as they returned to spawn. Recruitment of the 2002 cohort was monitored for three consecutive years, identifying age-4, age-5, and age-6 individuals of the York River stock. The scale-based age determination method was not suitable for aging age-4, age-5, or age-6 American shad in the York River. On average, 50% of the individuals from the 2002 year-class were aged incorrectly using the scale-based method. These results suggest that the standard age determination method used for American shad is not applicable to the York River stock. Scientists and managers should use caution when applying scale-based age estimates to stock assessments for American shad in the York River and throughout their range, as the applicability of the scale-based method likely varies for each stock. This study highlights a promising new direction for otolith geochemistry to provide cohort-specific markers, and it identifies several factors that should be considered when applying the technique in the future.
Received March 21, 2011; accepted August 18, 2011
Comparison of Juvenile Alewife Growth and Movement in a Large and a Small Watershed
Authors: Turner Sara M. , Limburg Karin E. 
Published: July 2012

Abstract
The freshwater behaviors of juvenile alewives Alosa pseudoharengus and the variables affecting their survival to recruitment are relatively unknown, even though recruitment to marine populations is critical to sustaining and restoring populations. Fish were collected in fall 2009 from a large watershed (the Hudson River, New York; N = 10) and a small watershed (the Peconic River, New York; N = 14), otolith chemistry was used to associate the fish to groups, and growth rates were compared both within and between rivers. Otolith Sr:Ca and Ba:Ca were measured along growth transects, and significant changes in these values were determined. In many instances, changes in these values are associated with changes in daily otolith growth increments. More variation was observed in the Ba:Ca ratios and daily growth rates of Hudson River alewives, possibly because they had more available nursery habitats. While there was variation in otolith chemistry and daily growth within Peconic River fish, fewer otolith chemistry patterns were observed in this group. Comparison of cumulative daily growth rates between the two groups showed that Hudson River alewives were smaller at younger ages but that their growth rate increased and their size at age eventually surpassed that of the Peconic River alewives. The results presented here provide the foundation for future work investigating the abiotic and biotic variables influencing juvenile alewife growth, behavior, and survival in different-size watersheds.
Received March 21, 2011; accepted September 26, 2011
Spatial and Temporal Variability in Instantaneous Growth, Mortality, and Recruitment of Larval River Herring in Tar–Pamlico River, North Carolina
Authors: Overton Anthony S. , Jones Nicholas A. , Rulifson Roger 
Published: July 2012

Abstract
We estimated the variation in the instantaneous rates of growth and mortality between cohorts of larval alewife Alosa pseudoharengus and blueback herring A. aestivalis in the Tar–Pamlico River, Pamlico Sound, North Carolina. The age of larvae captured by push net was estimated by counting the daily rings on sagittal otoliths. Weight-at-age and abundance-at-age data were used to generate instantaneous daily growth (G) and mortality rates (M) for 7-d cohorts. The instantaneous daily growth rate was relatively constant between cohorts, ranging from 0.103 to 0.277 for alewives and from 0.105 to 0.200 for blueback herring. The instantaneous daily mortality rate was more variable between cohorts, ranging from 0.064 to 0.270 for alewives and from 0.100 to 0.251 for blueback herring. All but one blueback herring cohort had an M/G value exceeding 1.0, indicating that these cohorts were losing biomass during the early larval stage. For alewives, M/G values were more variable, with 50% of the cohorts having values less than 1.0. The effect of habitat was consistent between species, with M/G values being higher and closer to 1.0 at sites in tributary creeks and backwater areas of Tar River. The overall M/G values were 0.57 for alewives and 1.60 for blueback herring from both backwater and main-channel sites, indicating that the environmental conditions in the Tar–Pamlico River are more favorable for alewives.
Received March 25, 2011; accepted November 10, 2011
Foraging Potential of Larval Alosines in the Lower Roanoke River and Albemarle Sound, North Carolina
Authors: Binion Samantha M. , Overton Anthony S. , Riley Kenneth L. 
Published: July 2012

Abstract
Zooplankton composition and abundances were quantified in the lower Roanoke River and Albemarle Sound, North Carolina. The spatial and temporal overlap between larval alosines, including American shad Alosa sapidissima, river herring (alewife A. pseudoharengus and blueback herring A. aestivalis), hickory shad A. mediocris, and zooplankton were examined to determine whether larval alosines in this system are food limited. Samples were collected weekly at 19 stations from March through June 2008–2009 in three habitats: River, Delta, and Sound. Spatial differences in zooplankton were observed, with the abundance in the Sound (16,546 ± 14,678 [number/m3 ± SD]) being significantly higher than those in the River (4,934 ± 3,806) and Delta areas (4,647 ± 2,846). Zooplankton composition was dominated by Daphniidae, Bosminidae, calanoid and cyclopoid copepods, copepod nauplii, and rotifers. The spatial patterns in alosine abundance were the opposite of those for zooplankton, being highest in the River (21.0 ± 127.6) and lower in the Delta (7.5 ± 35.5) and Sound (4.6 ± 24.8). Mouth gape models for each alosine species showed that copepod nauplii and rotifers are the most suitable-sized prey for the first feeding after yolk sac absorption. There was a high degree of spatial and temporal overlap between larval alosines and size-appropriate prey items, suggesting that the larval alosines are not food limited in Albemarle Sound.
Received March 25, 2011; accepted January 24, 2012
Estimating the Food Requirements and Prey Size Spectra of Larval American Shad
Authors: Riley Kenneth L. , Binion Samantha M. , Overton Anthony S. 
Published: July 2012

Abstract
Widespread declines in American shad Alosa sapidissima along the Atlantic coast have been attributed to overfishing, a decrease in water quality, and loss of habitat. Recent surveys along the Roanoke River and Albemarle Sound, North Carolina, suggest that stocks are continuing to decline despite extensive management and stock enhancement efforts. Laboratory experiments were conducted to evaluate the effect of prey density on the growth and survival of American shad and to determine whether larvae can survive and grow in a riverine environment with a limited forage base. Larvae were reared from 11 to 20 d posthatch in one of five treatments: (1) no food; (2) low food (1 prey/L), which simulated the prey densities in the Roanoke River; (3) medium food (50 prey/L), which simulated the prey densities typical of coastal watersheds; (4) high food (500 prey/L); and (5) Artemia spp. (500/L). Larval survival was 35 ± 7% (mean ± SE) and was not significantly different among treatments. Treatments with starved fish had the lowest survival (22 ± 12%), while the highest survival was observed in treatments with high densities of wild zooplankton (46 ± 18%) and Artemia (40 ± 16%). Length-specific growth rates were 0.017 mm/d for the starved treatments and 0.024, 0.029, 0.034, and 0.039 mm/d for the low-prey, medium-prey, high-prey, and Artemia treatments, respectively. Larval growth as a function of length was not significantly different between the Artemia and high-prey treatments; however, growth in these treatments was significantly higher than in those with lower prey densities. Weight-specific growth rates (Gw) were significantly higher for the Artemia treatment (Gw = 0.129) than for all the other treatments (Gw = 0.081). Analysis of stomach contents indicated that American shad were selectively feeding on the smallest zooplankton (80–250 μm) and that larvae exhibited a strong preference for copepod nauplii and rotifers. These results suggest that spatial and temporal overlap between larvae and zooplankton is important for larval growth and survival.
Received March 31, 2011; accepted September 12, 2011
Assessing Freshwater Habitat of Adult Anadromous Alewives Using Multiple Approaches
Authors: Mather Martha E. , Frank Holly J. , Smith Joseph M. , Cormier Roxann D. , Muth Robert M. , Finn John T. 
Published: July 2012

Abstract
After centuries of disturbance, environmental professionals now recognize the need to restore coastal watersheds for native fish and protect the larger ecosystems on which fish and other aquatic biota depend. Anadromous fish species are an important component of coastal ecosystems that are often adversely affected by human activities. Restoring native anadromous fish species is a common focus of both fish and coastal watershed restoration. Yet restoration efforts have met with uneven success, often due to lack of knowledge about habitat availability and use. Using habitat surveys and radio tracking of adult anadromous alewives Alosa pseudoharengus during their spring spawning migration, we illustrate a method for quantifying habitat using multiple approaches and for relating mobile fish distribution to habitat. In the Ipswich River, Massachusetts, measuring habitat units and physical conditions at transects (width, depth, and velocity) provided an ecological basis for the interpretation of landscape patterns of fish distribution. Mapping habitat units allowed us to efficiently census habitat relevant to alewives for the entire 20.6 river kilometers of interest. Our transect data reinforced the results of the habitat unit survey and provided useful, high-resolution ecological data for restoration efforts. Tagged alewives spent little time in riffle–run habitats and substantial time in pools, although the locations of pool occupancy varied. The insights we provide here can be used to (1) identify preferred habitats into which anadromous fish can be reintroduced in order to maximize fish survival and reproduction and (2) pinpoint habitat types in urgent need of protection or restoration.
Received April 3, 2011; accepted January 9, 2012
Relative Sensitivity of New England American Shad to Fishing, Discard Mortality, and Dam Passage Failure or Mortality
Authors: Kahnle Andrew , Hattala Kathryn 
Published: July 2012

Abstract
American shad Alosa sapidissima in Atlantic coastal rivers of the New England states are affected by anthropogenic sources of mortality, such as discards of immature fish (bycatch) in various fisheries, directed fishing on prespawning adults, and the passage failure or mortality of mature fish at migratory barriers. We evaluated the relative importance of these factors, independently and in combination, by modeling the predicted lifetime spawning stock biomass of an age-1 female recruit (SSBR) with an assumed constant rate of natural mortality. Discard losses had the greatest impact on the SSBR, followed by directed fishing and upstream passage mortality, upstream passage failure (the fish survived but did not pass the barrier or spawn), and downstream losses of postspawning adults. Fishery managers strive to keep mortality rates below those that reduce SSBR to less than 30% of that of a stock with no anthropogenic mortality. In our modeling, SSBR dropped below that benchmark when bycatch rates exceeded 0.21, directed fishing or upstream passage mortality exceeded 0.45, and upriver passage failure without mortality exceeded 0.70. Since the downriver passage mortality of adults occurred after spawning, SSBR did not decline below the benchmark even at 100% downriver loss. The impacts of upstream passage mortality always exceeded those from comparable downstream passage mortality. Fishing and discard losses seriously reduced any gain in SSBR from reduced fish passage mortality or failure. The results in this paper suggest that among the anthropogenic factors evaluated, American shad in New England are most sensitive to discard losses of immature shad in ocean fisheries and that fish passage improvements at dams are most effective when they are developed in combination with reductions in fishery-related losses.
Received April 25, 2011; accepted November 29, 2011
Maximizing Age-0 Spot Export from a South Carolina Estuary: An Evaluation of Coastal Impoundment Management Alternatives via Structured Decision Making
Authors: Robinson Kelly F. , Jennings Cecil A. 
Published: July 2012

Abstract
Estuaries are among the most productive of all ecosystems and provide critical nursery habitat for many young-of-the-year (age-0) marine fish. Along the South Carolina coast, former rice field impoundments in some estuarine areas are now managed to provide habitat for waterfowl. Marine fish that enter these structures during water level manipulation become trapped and suffer high mortality rates. Because these fish cannot emigrate back to coastal waters to complete their life cycles, these impoundments appear to act as sinks for marine-transient species. Our goal was to identify which of a set of management options would maximize export of age-0 spot Leiostomus xanthurus from the Combahee River, South Carolina, to the coastal population. We used a structured decision-making approach to evaluate four decision alternatives: to maintain status quo, to close all impoundments while age-0 spot are most abundant in the river, to change the water level manipulation strategy to improve fish passage from impoundments, or to breach all impoundments. We also wanted to evaluate how impoundments and natural mortality influence the export of age-0 spot. The optimal management decision was to change the water level manipulation strategy to increase fish passage from the impoundments. Spot export was most sensitive to juvenile settlement in the estuary and natural mortality. The results of this model can be used adaptively for impoundment management along the Combahee River and can be modified for other estuarine areas or other fish species.
Received August 11, 2011; accepted February 11, 2012
Anomalous Ocean Conditions May Explain the Recent Extreme Variability in Fraser River Sockeye Salmon Production
Authors: Thomson Richard E. , Beamish Richard J. , Beacham Terry D. , Trudel Marc , Whitfield Paul H. , Hourston Roy A. S. 
Published: July 2012

Abstract
Record low returns of sockeye salmon Oncorhynchus nerka to the Fraser River in 2009 were followed by record high returns to the river in 2010, providing an unprecedented opportunity to examine links between oceanic factors and the survival of Pacific salmon stocks. The low returns in 2009 indicated poor early marine survival of juvenile sockeye salmon in 2007. The poor survival was likely due to low food levels arising from unfavorable wind and runoff conditions in the Strait of Georgia and the Queen Charlotte Sound–Hecate Strait region in the spring of 2007. Conversely, the high returns in 2010 were associated with a large smolt output from the Fraser River and good early marine survival in 2008. This enhanced survival was likely associated with adequate food levels arising from favorable oceanic conditions in the Strait of Georgia and the Queen Charlotte Sound–Hecate Strait region in the spring of 2008. We speculate that ocean factors during the subsequent marine years also affected brood year strength. Specifically, the back-to-back La Niña winters of 2007–2008 and 2008–2009 would have negatively influenced the survivability of the 2007 entry stocks, while the El Niño winter of 2009–2010 would have positively affected the survivability of the 2008 entry stocks. We conclude that poor early marine survival leads to low production. However, if large numbers of healthy fish survive the early marine entry, and if conditions during at least one of the two ocean winters in the Gulf of Alaska are favorable to stock survivability, then returns to the river can be high.
Received September 27, 2011; accepted February 29, 2012
Performance of a Full-Duplex Passive Integrated Transponder (PIT) Antenna System in Estuarine Channels
Authors: Bass Arthur L. , Giannico Guillermo R. , Brooks Gabriel T. 
Published: July 2012

Abstract
Passive integrated transponder (PIT) technology is rarely utilized in estuaries due to (1) saline water's attenuation of an antenna's electromagnetic field, (2) rapidly changing water properties and levels, and (3) the challenges of installing and maintaining antennas in silty, brackish conditions. We present methods for the construction and installation of antennas that can detect 12-mm full-duplex PIT tags in salinities up to 33‰. We evaluated their reading performance under variable water salinities, temperatures, and depths in the upper estuaries of three streams. We found that water depth, salinity, and temperature were all negatively correlated with antenna current, but that the relative importance of these variables varied depending upon aspects of the antenna deployment. Since our antennas held amperage levels adequate for maintenance of a complete electromagnetic field throughout all test conditions, we suggest that successful detection was more dependent upon the antenna system's coverage of the water column and the swimming path of fish through the antenna system than individual antenna performance. In addition to fish, this technology could be applied to studies of mammals, crustaceans, and particles transported through estuarine channels.
Received July 28, 2011; accepted February 19, 2012