*Bittner, Steven1,2, Allison H. Roy1,2,3, Matthew T. Devine1,2, Habibollah Mohammadi2,4, Adrian Jordaan2. Dietary preferences among juvenile and adult River Herring in freshwater lakes.
1Massachusetts Cooperative Fish and Wildlife Research Unit, 2Department of Environmental Conservation, University of Massachusetts Amherst, Amherst, MA, 3US Geological Survey, 4Department of Fisheries, University of Kurdistan, Sanandaj, Iran
Each Spring, anadromous River Herring (Alosa pseudoharengus & Alosa aestivalis) migrate from the ocean to freshwater lakes to spawn and then return to the ocean after 2-6 weeks. While in lakes, these fish deposit marine-derives nutrients, provide forage for many species (e.g., predatory fish, waterbirds, and mammals), and prey heavily on zooplankton. Studies have shown that River Herring dietary preference is system-specific, but have not compared juvenile and adult diets among lakes to assess dietary overlap. We sampled River Herring from two lakes (Whitman’s Pond and Upper Mystic Lake) in Massachusetts using a beach seine at dusk and a pelagic purse seine at night. For each lake, 20 individuals from each life stage (adult and juvenile) were immediately frozen on dry ice. In the lab, fish were thawed and sagittal otoliths were extracted, mounted and aged; stomachs were removed and dissected with food items identified, enumerated, and measured. We describe differences in dietary preferences among juvenile and adult River Herring and use an electivity index to assess preference for certain prey items. If juveniles and adults are consuming the same resources, there is potential for intraspecific competition while adults reside in the lakes that may impact juvenile growth rates. This work will help fill knowledge gaps about trophic dynamics of River Herring in these lakes. Fully understanding River Herring dietary preferences allows us to assess potential for alteration of trophic dynamics during and after their spawning migration and evaluate density-dependent interactions.
Boucher, Jason M.1, Richard McBride2. A reconsideration of testing within-gonad homogeneity of oocyte density as a precursor to estimating fecundity: what is the goal?
1Integrated Statistics, Woods Hole, MA, 2Northeast Fisheries Science Center, Woods Hole, MA
Due to the high fecundity of many fish species, measurement is regarded as complicated and time consuming. Less attention has been paid to testing a basic assumption: are subsamples of oocyte density within the gonad homogeneous? There are two ramifications of heterogeneity: 1) does it bias or affect precision of the estimate? 2) what is the pattern among taxa? In our review of fecundity studies, most have been focused on the first question, because this affects the reliability of the reported estimates. Nonetheless, we note that the rigor of methods varies considerably between studies, and some studies do not test for homogeneity. Standardized methodology was established in the 1980s to address whether bias exists, and if so, how many samples are needed to obtain accurate, precise estimates. Herein, we also introduce an alternative procedure that measures heterogeneity within the gonad of individuals. Regarding the second question, we find no pattern among a review of 24 fish species from 15 families. Most studies found no location effect, but the majority also did not follow the standard procedure. Five studies identified a location effect, four of which followed the standard procedure. Testing for homogeneity of oocyte density is a necessary step of quality assurance that is unlikely to be publishable on its own. We recommend that a standard effort is still needed to demonstrate that estimates are reliable, and point out that more of such studies should eventually lead to understanding the pattern among taxa, and separate its statistical and biological significance.
Bronger, Kristen1. International year of Salmon, 2019: research for the future.
1Integrated Statistics in support of NOAA Fisheries, Gloucester, MA
The North Atlantic Salmon Conservation Organization (NASCO) and the North Pacific Anadromous Fish Commission (NPAFC) are collaborating to celebrate salmon restoration and recovery with an International Year of the Salmon in 2019. The overall theme is Salmon and people in a changing world. During the International Year of the Salmon, our outreach efforts will raise awareness of what humans can do to better to ensure salmon and their varied habitats are conserved and restored in light of increasing environmental variability. The International Year of the Salmon will also stimulate an investment in research and leave a legacy of knowledge, data/information systems, tools and a generation of scientists better equipped to provide timely advice to inform rational management of salmon. The countries who are participating include the U.S., Canada, Norway, EU, Russia, Japan and Korea. Planning, promotion and outreach has begun and will continue through 2018. An international science symposium will launch the International Year of the Salmon in the fall of 2018. Over 2018 – 2022, research will be conducted, analyzed, results published and then findings disseminated through an international dénouement symposium. The proposed research themes for the International Year of the Salmon include the Status of Salmon, Salmon in a changing “salmosphere”, New Frontiers, Human Dimensions and Information Systems. We will provide more information on how the International Year of Salmon is an opportunity to connect with others, share the research that scientists are doing to a wider audience and contribute to the collective international research effort.
*Calandrino, Mila1, Andrea Bogomolni2, Michelle Staudinger3. Spatio-temporal movement of individual Gray Seals (Halichoerus grypus) hauled-out on Duck Island, ME.
1University of Massachusetts Amherst, Amherst, MA, 2Woods Hole Oceanographic Institute, Woods Hole, MA, 3Northeast Climate Science Center, Amherst, MA
Gray Seals (Halichoerus grypus) are increasing in numbers on Duck Island, a unique, mixed-species haul-out ite that serves as a potential stop-over between large populations in Canada and on Cape Cod. Individual seal sighting data has been collected on photographic mark-recapture surveys of seal abundance in the summers of 2011-2016. The specific ledges on which the seals were seen, as well as the date they were seen were recorded, and every new individual was added to a growing identification catalogue. This study aims to understand the movement and land use of individually identified Gray Seals over the course of the six-year study period. Factors of importance include whether the animals are displaying inter-annual site fidelity, and if certain individuals are arriving and departing around the same date each year. The results of this study will provide insight into the movements and land use of Gray Seals in the entire Gulf of Maine, and help improve the understanding of Gray Seals & relationship to seasonal changes.
*Comb, Dylan1, William Helt2, Jon Grabowski1, Randall Hughes1, Eric Schneider2. Comparing three growth conditions of Crassostrea virginica in Southern New England to better inform restoration science.
1Northeastern Marine Science Center, Nahant, MA, 2RIDEM, Jamestown, RI
Due to anthropogenic influence, a serious decline in populations of the Eastern Oyster Crassostrea virginica has occurred over the last few centuries. The loss of oyster reefs from direct harvesting and habitat alteration is exceptionally evident in New England, where today wild stocks are a fraction of historic abundance. Understanding the critical importance of this foundation species has recently shifted public perception and awareness, resulting in many efforts to restore oyster reefs to recover the ecological functioning and ecosystem services lost. Although several existing studies assess the successes of past restoration projects, few studies compare restored reefs to other growing conditions, and fewer have examined this within New England. This study compares Rhode Island Oysters growing on restored reefs to those on natural reefs as well as individuals grown in aquaculture. To better inform future restoration efforts in the North Atlantic region, we investigated how oysters in these different settings influence growth, condition, and sex ratio. Restored reefs appeared to be severely lacking recruitment, and adult oysters were significantly less dense than on naturally occurring reefs. These findings are interesting when compared to natural reef recruitment, given the proximity of constructed reefs. Further examination assessing this lack of recruitment on restored reefs is needed to ensure restoration success.
*Dangora, Anthony1, Matthew Devine1,2, Allison Roy1,2,3, Adrian Jordaan1, Joseph Zydlewski3,4,5. Evaluating DIDSON as a tool to monitor juvenile River Herring in coastal freshwater lakes.
1Department of Environmental Conservation, University of Massachusetts, Amherst, MA, 2Massachusetts Cooperative Fish and Wildlife Research Unit, 3U.S. Geological Survey, 4Maine Cooperative Fish and Wildlife Research Unit, 5Department of Wildlife, Fisheries, and Conservation Biology, University of Maine, Orono, ME
Anadromous Alewives (Alosa pseudoharengus) are an important forage fish distributed throughout coastal northeastern United States. Alewife are consumed by freshwater and marine predator species and transport nutrients between the ecosystems. Large knowledge gaps exist about the species, particularly for juvenile out-migration densities from freshwater lakes. Currently, monitoring techniques are limited due to financial and logistical constraints, and rarely explore juvenile recruitment. Purse seining in freshwater lakes is a novel approach to pelagic juvenile sampling but this method may be size selective. DIDSON (Dual Frequency Identification Sonar) is an alternative non-invasive method that may overcome this potential bias. This study conducted a comparison between pelagic purse seine and DIDSON measured juvenile Alewives to study potential impacts of gear bias and alternatives. We deployed a DIDSON for one hour intervals at the outlet of two lakes, Upper Mystic Lake (MA) and Winnisquam Lake (NH) in August of 2015. Concurrent with DIDSON, a purse seine was deployed during the same night. Fish length was estimated using DIDSON software (Mark and Measure Tool) and compared with the purse seine lengths. A one-way analysis of variance was used to test for differences in length between methods. Our results indicate that incorporating DIDSON technology into fisheries surveys may help inform our knowledge about stock recruitment dynamics on anadromous Alewives.
*Davis, Amanda1, Michelle Staudinger1,2, Emily Powell3, Steven Mattocks4, Melissa Ocana1, Scott Jackson1. The Massachusetts Wildlife Climate Action Tool.
University of Massachusetts, Amherst, MA, 2DOI Northeast Climate Science Center, 3North Atlantic Landscape Conservation Cooperative, 4MA Division of Fisheries and Wildlife
The Massachusetts Wildlife Climate Action Tool (climateactiontool.org) is designed to inspire local action to protect natural resources in a changing climate. This informative tool provides approachable and current data for a range of local decision-makers, including conservation practitioners, landowners, municipal agencies, and community leaders, who seek to conduct on-the-ground climate change adaptation efforts. The interactive tool uses public-friendly scientific research results with effective visuals to show users how they can: 1) access information on climate change impacts and vulnerabilities of fish and wildlife species and associated habitats; 2) explore adaptation strategies and actions to help maintain healthy, resilient natural communities based on location and area of interest; and 3) find additional resources to help guide decision-making and actions. Content within the tool focuses on fish and wildlife species, aquatic, terrestrial and marine connectivity, land protection, and conservation planning. Although this tool was designed for decision-making in the state of Massachusetts, it provides broadly relevant climate and adaptation information, and can serve as a model for related efforts across the Northeast region. For example, the strategies, actions, and current research that the tool showcases in regard to coastal fish and wildlife conservation, nutrient pollution and coastal resiliency in a changing climate can be implemented across Atlantic coastal socio-ecological communities. This tool has been developed by a diverse team of experts from the Massachusetts Division of Fisheries & Wildlife, the University of Massachusetts-Amherst, the Department of Interior’s Northeast Climate Science Center, and the USGS Massachusetts Cooperative Fish and Wildlife Research Unit.
Davis, Justin1. The rise of the catch-and-release era in Connecticut’s inland fisheries.
1Connecticut Department of Energy and Environmental Protection, Marine Fisheries Division – Old Lyme, CT
Much of traditional fisheries management has focused on managing harvest mortality to achieve a desired outcome. As catch-and-release fishing becomes more prevalent and harvest becomes increasingly insignificant, many traditional management measures may be rendered ineffective. In Connecticut, angler surveys conducted by CT DEEP Inland Fisheries Division (IFD) over the last three decades demonstrate a substantial shift in freshwater angler practices and attitudes related to harvest. Voluntary release rates for most freshwater fish species have increased substantially since the 1980s, and for some species now approach 100 percent. Responses to opinion questions in recent surveys indicate many anglers have low motivation to harvest fish, and commonly self-identify as “catch-and-release only” anglers. This phenomenon reflects changes in angler demographics (e.g. reductions in generalist and/or subsistence fishing), a trend towards specialization (e.g. increased participation in catch & release tournaments), and a pervasive perception amongst anglers that a strict catch-and-release ethic represents a “one size fits all” best practice. Here we illustrate the challenges of managing inland sportfish populations in the face of high angler release rates by describing the CT DEEP Bass Management Lake program, which was initiated in the 1980s, experienced early successes, but then ultimately failed to substantially alter bass sizes structure in management lakes – primarily because of shifts in angler harvest practices.
*Evanilla, Johnathan1 and Stephen Winters-Hilt1. Characterization of fish diversity via EST analysis.
1Connecticut College, New London, CT
While many current fishery stock assessment methods rely on the fish that are brought back to the dock by fisherman, it is important to also have models that represent a fish stock with respect to the total population of that species, not what is being caught. This study focused on the correlation between transcriptome level diversity and the phenotype expression ability of commercially targeted fish. By analyzing the complexity of miRNA/RNAi 7mer-based regulatory capabilities, it is hypothesized that certain assumptions can be made about the current health and abundance of a stock of fish. These assumptions have to do with a less varied group of phenotypes available to use in response to environmental change. Preliminary results have indicated Atlantic Cod (Gadus Morhua) to be lacking this complexity, which appears to be a result of the collapse of the Cod fishery in the Northeast.
Gonzalez, Susan1, Shannon Nardi1. Shifts in demersal fish and macroinvertebrate communities detected by long-term (1976-2015) trawl monitoring in eastern Long Island Sound.
1Dominion Resources Services, Millstone Environmental Lab
Biweekly trawl monitoring conducted in the vicinity of Millstone Power Station has recorded catches of demersal fish and macroinvertebrates since 1976. Multivariate analyses used to examine temporal differences in the integrated fish and macroinvertebrate dataset identified three distinct periods for the assemblages: 1976-1979, 1980-2001, and 2002-2015. The current community structure is characterized by higher abundances of fish with southern affinities like Scup and Black Sea Bass and lower abundances of northern species such as Winter Flounder and American Lobster. Overall, this analysis of four decades of trawl data provides valuable information on fish and macroinvertebrate populations in eastern Long Island Sound and is consistent with results of regional studies documenting shifts in species distribution as a response to a natural rise in seawater temperatures.
*Grasso, Kyle D.1,2, Matthew Devine1,2, Allison Roy1,2,3, Andrew Whiteley4, Julianne Rosset1,2,5, Meghna Marjardi1,2,6, Adrian Jordaan1. Testing for differences in juvenile growth rates of anadromous Alewife and Blueback Herring.
1Department of Environmental Conservation, University of Massachusetts-Amherst, Amherst, MA, 2Massachusetts Cooperative Fish and Wildlife Research Unit, 3U.S. Geological Survey, 4Department of Ecosystem and Conservation Sciences, University of Montana, Missoula, MT, 5New England Field Office, U.S. Fish and Wildlife Service, Concord, NH, 6Ohio State University, Columbus, OH
Alewife (Alosa pseudoharengus) and Blueback Herring (Alosa aestivalis), collectively known as River Herring, are important anadromous forage fish distributed along the northeast coast of the United States. Currently, both species are managed together due to geographic overlap in range and difficulty in identification to species level. Until now, most species level divergence is equated to small differences in preferred temperature and migration timing, although there is substantial overlap in these characteristics and both species co-occur during the period of freshwater habitat use. Little is known about differences in growth rates of juvenile Alewife and Blueback Herring. This study aims to fill these data gaps by investigating individual growth rates for the two species. Fish were collected from four coastal lakes (Great Herrin, Upper Mill/Walkers, Santuit, and Coonamessett) in Massachusetts. Individual fish of approximately the same length were genetically identified to species and their sagittal otoliths were imaged and aged using ImagePro Software. Age and total length were used to calculate growth rates. Although we do not expect to see differences in growth rates between species, species-specific assessments of growth are critical for developing appropriate management targets for mortality and understanding the variation in responses to environmental conditions. The results of this study will contribute to our understanding of life history traits that are selected for through evolution, may help predict early life history responses to climate change, and facilitate development of restoration strategies.
*Greene, Danielle1, Lucas Nathan1, Jason Vokoun1. Landscape correlates of hybridization between hatchery and wild Brook Trout (Salvelinus fontinalis).
1University of Connecticut
Brook Trout (Salvelinus fontinalis) is one of the few native salmonid species in Eastern North America. Once widely distributed throughout the region, sensitivity to land use changes and habitat degradation now restrict many Brook Trout populations to small, isolated headwater streams where conditions remain suitable. Their popularity among anglers as a sport fish has led to the raising and stocking of hatchery fish to provide enhanced recreational fishing opportunities in ponds and streams across Southern New England. The practice of stocking hatchery fish, however, can have unintended consequences when stocked individuals survive and reproduce with wild individuals creating hybrids and the potential for population genetic introgression. Although a conservation concern for wild Brook Trout, little is known about the prevalence and spatial distribution of introgression at the landscape scale. The objective of this study was to identify where hybridization and introgression had recently occurred in Connecticut populations of Brook Trout as well as identification of predictive correlates for introgressed streams. We collected tissue samples from over 100 headwater locations and hatchery individuals and then used a series of individual based analyses to identify evidence of hybridization and introgression. Locations with and without hybrids were modeled against a suite of watershed variables to identify those characteristics most commonly associated with hatchery introgression. This assessment will be used to aid in decision making processes of best management practices for future stocking efforts to reduce alterations to the genetic composition of wild trout populations.
Haas-Castro, Ruth1, Molly McCarthy2, Mark Renkawitz1. Effects of Inter-analyst and Intra-fish Scale Feature Measurement Variation on Back-calculations of Atlantic Salmon Smolt Lengths-at-First-Annulus Formation
1Northeast Fisheries Science Center, Woods Hole, MA, 2University of Alaska Anchorage, Anchorage, AK
Scale pattern analysis (SPA) and estimates of back-calculated lengths-at-age events provide important information to better understand Atlantic Salmon ecology. Sources of variation that may influence back-calculation results have been identified but have not been fully evaluated. In this study, two sources of potential variation were examined: intra-fish scale feature variation, and inter-analyst transect selection/scale measurement variation. Two analysts conducted SPA on 5 scales from 10 age 2 smolts (n = 50, size range 151 to 225 mm) to examine the degree of intra-fish variability in circulus number, inter-circulus width, focus-radius distance, and focus-freshwater annulus distance. Analysts were then compared to examine inter-analyst variability. The magnitude of influence that variation in SPA measurements exerted on back-calculated length-at-life-stage was then evaluated. While intra-fish scale feature variation was low (all p > 0.072), intra-fish back-calculated lengths varied significantly (F9, 49 = 40.07, p <0.001), were in some cases up to 16 mm different. SPA measurement variability between analysts was also significant for 2 variables; inter-circulus width (p = 0.010) and focus-freshwater annulus distance (p < 0.001). Measurement variability was insignificant for circulus number (p = 0.697) and focus-radius distance (p = 0.428). These differences also had a significant influence on back-calculated lengths (F1, 73 = 30.14, p <0.001) resulting in greater back-calculated length by one analyst in 33 of 37 cases. Inter-analyst differences were the most influential sources of variation in this study indicating that uniformly trained analysts are important for the consistency of SPA measurements, data quality, and accurate back-calculated length-at-age estimates.
*Izzo, Lisa K.1,2, Donna L. Parrish1,2, Gayle B. Zydlewski3, Chet MacKenzie4. Feasibility of estimating Lake Sturgeon abundance using side-scan SONAR on a river delta in Lake Champlain.
1Vermont Cooperative Fish & Wildlife Research Unit, 2Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, VT, 3School of Marine Sciences, University of Maine, Orono, ME, 4Vermont Fish & Wildlife Department, Rutland, VT
While Lake Champlain once supported a small commercial fishery for Lake Sturgeon, Acipenser fulvescens, the species was listed as endangered in Vermont in 1972. Spawning has been confirmed in three of the four historic spawning tributaries to the lake, but information on the abundance of Lake Sturgeon in Lake Champlain is currently lacking. Low numbers and sampling conditions have made gillnet-based mark-recapture surveys challenging in spawning tributaries. A potential alternative is the use of hydroacoustic methods, which can allow for sampling of endangered populations without physical handling of individuals. Recent acoustic telemetry of Lake Sturgeon that spawned in the Winooski River indicate that they may aggregate on the adjacent Winooski River delta during the winter months. In the winter of 2016 – 2017, we initiated side-scan SONAR surveys in an attempt to visualize wintering Lake Sturgeon on the river delta. These surveys will be used to develop sampling protocols to estimate Lake Sturgeon abundance in the area. Information gained from this work will aid managers in tracking population recovery over time in Lake Champlain.
*Liu, Chang1, Geoffrey Cowles1. Developing and validating a GPU-accelerated geolocation method for groundfish using particle filter.
1School for Marine Science and Technology, UMass Dartmouth, New Bedford, MA
Geolocation methods have been applied to electronic tagging data to estimate locations of groundfish species. Such information can improve stock assessments and fishery management plans that account for population structure, including movements across stock boundaries. Many popular geolocation methods have limitations including low horizontal resolution, flawed land boundary treatment, and long computational time. The particle filter is a state-space approach that has been applied to localization problems and addresses the aforementioned problems. We present a geolocation method based on the particle filter that is accelerated with the graphics processing unit (GPU). The geolocation method involves the comparison of the tag-recorded depth and temperature to the same variables from an unstructured grid oceanographic model. The geolocation output of each tagged fish include the most probable track and associated uncertainty distribution. The speedup for geolocation computation using the GPU implementation is compared with the CPU (central processing unit) implementation. Validation of the geolocation estimates was performed using stationary tags and through double-electronic-tagging (archival and acoustic tags) studies of Atlantic Cod. This work is expected to provide a geolocation method of deriving reliable movement information from electronic tagging data in a time-efficient manner.
*Markowitz, Emily1, Michael Frisk1, Skyler Sagarese2, Janet Nye1. Distribution shifts associated with changing environmental parameters in two demersal species Summer Flounder (Paralichthys dentatus) and Black Sea Bass (Centropristis striata).
1School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY, 2NOAA NEFSC SWFSC, 75 Virginia Beach Drive, Miami, FL
Shifts in fish population distributions are a growing concern for fishermen and fisheries management scientists. Temperature has been implicated as the main driver of poleward distributional shifts in many marine fishery stocks, including two abundant and commercially valuable fish along the Northeast US coastline: Summer Flounder (Paralichthys dentatus; SF) and Black Sea Bass (Centropristis striata; BSB). Other environmental drivers may also influence their abundance and distribution in the Northeast US. These drivers may be different for different age and size classes within a species. Juvenile SF and BSB may be expected to select for different aspects of their environments and may be found at a wider and warmer range of temperatures than have been experimentally found to support positive growth in adult conspecifics. This study will use fishery-independent Northeast Fisheries Science Center bottom trawl survey data to develop cumulative distribution functions, generalized additive models, and habitat suitability models to determine what parameters (surface and bottom temperature, surface and bottom salinity, bottom depth, rugosity, and distance from nearest bay) are selected for by SF and BSB and influence their distribution in different length classes in winter, spring, and fall. We will also assess whether these factors change the availability of SF and BSB to the Northeast Fisheries Science Center bottom trawl survey in such a way that impacts estimates of stratified-mean biomass and abundance.
McBride, Richard S1. Binomial model selection for estimating fish age and size at maturity: an application with different stocks of Winter Flounder (Pseudopleuronectes americanus).
1Northeast Fisheries Science Center, Woods Hole, MA
Logistic regression is most commonly used to fit maturity data in fisheries research, but there are other binomial link functions, notably the probit, Cauchit, and complementary log-log. This poster addresses how these different link functions compare in terms of model uncertainty and parameter estimation using data for a regional flatfish species. The logit and probit links were indistinguishable between each other, in terms of fitting the certainty of the data (i.e., AIC < 1), and they predicted realistic maturity estimates across their respective ogives. In my experience, the logit is most commonly used, and these results suggest this is well deserved. The probit link may fit a particular dataset better than the logit, but if historic (or future) modeling efforts use the logit, then differences in median or other estimates of maturity could be confounded by model choice alone. The other two link functions (Cauchit, log-log), which are not commonly used to fit maturity data, were not suited to these data nor have they done well with some other data simulations (see https://rpubs.com/fishmcbride).
Pavey, Scott A.1. New ecological genomic tools in Atlantic Canada.
1Canadian Rivers Institute
Recent rapid technological advances in genetic tools have ushered in a new era of genomics. Genomics is different from genetics because entire genomes in multiple individuals and populations to assess genetic diversity, delineate population structure, or identify genes important to local adaptation. Though these topics represent the main thrust of Ecological Genomics, there are a number of other smaller cost effective tools that may be of high interest to managers. These include using genetic barcodes to identify species, mixed stock analysis, parentage analysis to determine the success of fisheries supplementation. Part of the Canadian Rivers Institute, CRI Genomics is a new lab at University of New Brunswick Saint John. It has state-of-the-art genomics infrastructure. We are very interested in new collaborative projects with regional fisheries biologists. We offer at-cost fee-for-service pricing.
*Rich, Tiffany1, Elizabeth A. Fairchild1. Using otolith microchemistry to identify natal origins of Winter Flounder (Pseudopleuronectes americanus).
1Department of Biological Science, University of New Hampshire, Durham, NH
Chemical signatures of Winter Flounder (Psuedopleuronectes americanus) are being utilized to identify the natal areas of adult fish caught from offshore locations. Pilot studies indicate there are discernable differences in young-of-the-year otolith trace metal compositions between estuaries. These signatures are site specific, in a range of 5-10 km. As otoliths are biologically inert, the otolith core signatures of adult fish could be compared to signatures of a known nursery to identify an individual’s origin. For this study, both young-of-the-year specimens from 15 estuaries ranging from New Jersey to Maine and adults of an unknown natal origin caught in multiple offshore locations in the GOM and SNE/MA management areas prior to spawning seasons are being examined. Right sagittal otoliths are being analyzed for elemental composition. Left sagittal otoliths are being analyzed for age verification and stable isotope analysis of 13C and 18O. Using the signatures from Bailey et al.’s 2012 study, annual variability of natal estuarine signatures will be checked. After assessing the annual variability from the pilot study signatures to newly collected samples, temporal variation and trends may be identified in some estuaries and used to identify the sources of adults. If successful, the natural, lifelong available natal signature can be used to identify which estuaries yield better recruitment and from which specific year classes. This information can in turn be used for a variety of stock management methods such as protecting successful estuaries or providing mitigation and recovery efforts to less successful estuaries.
*Valenti, Jessica L.1, Thomas Grothues1, Kenneth W. Able1. Fishes of a temperate estuary: temporal and sub-habitat influences on species composition and abundance.
1Rutgers University Marine Field Station, Tuckerton, NJ
An inventory of the fishes inhabiting Barnegat Bay, a lagoonal estuary in New Jersey, was based on a survey of the fish community within the bay using otter trawl sampling which occurred yearly (2012-2014) in April, June, August, and October. We sampled at 49 stations encompassing four different habitats: open bay, submerged aquatic vegetation (SAV), upper marsh creek, and marsh creek mouth. Throughout the sampling duration, 1,731 tows were performed and 33,993 fish comprising 72 species were collected. The fish fauna consisted of both resident (e.g. Oyster Toadfish, Opsanus tau) and transient (e.g. Summer Flounder, Paralichthys dentatus) species. Composition and abundance of the fish fauna varied seasonally with certain species only collected in a particular month (e.g. Pollock, Pollachius virens in April), whereas others were present within the estuary during all months sampled (e.g. Lined Seahorse, Hippocampus erectus). For many of the species collected, a majority (50% or greater) of their catch was collected in a single habitat (e.g. Fourspine Stickleback, Apeltes quadracus in SAV), whereas others were ubiquitous (e.g. Bay Anchovy). This data set provides a baseline from which long-term stability, improvement, or decline in the Barnegat Bay fish community can be assessed.
*Weston, Ashley1, Gavin Fay1, Carey McGilliard2. Identifying robust model selection tools for including environmental links to recruitment in North Pacific groundfish stock assessments.
1School for Marine Science and Technology, University of Massachusetts Dartmouth, Fairhaven, MA, 2Alaska Fisheries Science Center, NOAA Fisheries, Seattle, WA
Environmental and climate drivers have been linked to the recruitment success of groundfish in the Gulf of Alaska. Stock assessment models for these species have the ability to include recruitment linkages to environmental processes, but the robustness of model selection tools and harvest policies for these types of relationships are not definitive. We simulation tested the ability of Akaike’s Information Criterion (AIC) and Mohn’s retrospective statistic for choosing among models that correctly and incorrectly include a recruitment-environmental linkage. Uncertainty also surrounds the current and future implications of mis-specified recruitment-environmental linkages on population parameters. Using Stock Synthesis we tested operating models that differ in their inclusion of a single recruitment-environmental linkage on unfished recruitment within the Gulf of Alaska flathead sole assessment. Results showed neither AIC or Mohn’s retrospective statistic were able to consistently choose the correctly specified model. Mis-specified models led to greater bias in estimates of catch at maximum sustainable yield, but not for current spawning stock biomass. Model selection tools that incorrectly choose amongst models may misguide stock assessment development and application. Further research will evaluate the implications of including alternative recruitment-environmental linkages in population forecasts with respect to uncertainty associated with climate change, and compare the expected