Winter Flounder Pseudopleuronectes Americanus Research Articles

The Role of Fishery‐Independent Bottom Trawl Surveys in Providing Regional and Temporal Context to Offshore Wind Farm Monitoring Studies

AbstractBottom trawl surveys are commonly used to examine potential effects on fishes and invertebrates from offshore wind (OSW) farms in Europe and in the northeastern United States. Because OSW surveys typically occur over a limited spatial footprint, comparison of OSW monitoring results to long‐term fishery‐independent surveys may provide a regional and temporal context for OSW data sets. We compared results of the Block Island Wind Farm (BIWF) bottom trawl survey (2013–2019) to three fishery‐independent bottom trawl surveys (Northeast Area Monitoring and Assessment Program, Northeast Fisheries Science Center, and Rhode Island Department of Environmental Management [RIDEM]) using catch rates of 12 federally managed species. We evaluated temporal trends in annual residual catches for each species calculated within each survey as the difference between the mean annual biomass per trawl and the long‐term mean. Regional consistency in relative catches was apparent for species exhibiting synchronous interannual variability among surveys (Black Sea Bass Centropristis striata, Scup Stenotomus chrysops, Summer Flounder Paralichthys dentatus, and Winter Flounder Pseudopleuronectes americanus) or a decreasing trend in residual catch rates across the 7‐year study period (Little Skate Leucoraja erinacea, longfin inshore squid Doryteuthis pealeii, and Winter Skate L. ocellata). For other species, catches among surveys were asynchronous (Atlantic Herring Clupea harengus, Butterfish Peprilus triacanthus, and Windowpane Scophthalmus aquosus) or anomalous catches in a single year affected the results (Red Hake Urophycis chuss and Silver Hake Merluccius bilinearis). Monitoring of BIWF occurred during a period with lower‐than‐average historical catches in a 32‐year RIDEM data set for Atlantic Herring, Butterfish, Little Skate, longfin inshore squid, Red Hake, Silver Hake, and Winter Flounder and higher‐than‐average catches for Black Sea Bass, Scup, and Summer Flounder. There was no evidence that variation in catches near BIWF differed from regional trends in a way consistent with a detrimental impact of OSW farm operation. The regional context provided from multiple bottom trawl surveys varies by species and thus may be limited for interpreting OSW monitoring results.

The Relative Influence of Age Structure, Predation, and Temperature on Stock–Recruitment Dynamics: A Case Study of Southern New England/Mid‐Atlantic Winter Flounder

AbstractStock size estimates used in stock–recruitment models often assume that reproductive output per individual is equal despite evidence that larger, older spawners contribute diverse spawning behaviors and disproportionately more to reproductive output. This is concerning since depleted population states often coincide with a compromised age structure and increased control of extrinsic forces (environmental conditions or predator–prey dynamics) on stock productivity. In this study, parameterizations of the stock–recruitment relationship for Winter FlounderPseudopleuronectes americanus, which incorporated covariate metrics describing age structure, temperature, and predation, were compared to identify primary drivers across area‐specific data sets that are included in recent regional stock assessments. Four of the six data sets resulted in a top‐ranked model that incorporated an age structure metric; however, the age structure metric model was alone in the pool of top‐ranked models for only two of these scenarios. In addition, one data set resulted in a base Ricker model, and one resulted in a model that incorporated a predator index. Finally, wavelet analysis identified significant coherence between fishing mortality rate (F) and spawning stock biomass (SSB) for Winter Flounder, which switched from an out‐of‐phase state to an in‐phase state during the 1990s. If the relationship between these model‐derived estimates ofFand SSB reflects dynamics of the Winter Flounder population, it would have strong implications for management efforts.

Flatfish habitat use near North America's first offshore wind farm

Use of offshore wind power as a renewable energy source is underway in North America with the construction of the pilot, five wind turbine, Block Island Wind Farm, off Rhode Island, USA. Demersal trawl monitoring was conducted in two reference areas and near the wind farm that allowed an examination of whether flatfish abundances, size, and condition differed between baseline, construction, and operation time periods. Seven flatfish, (American plaice Hippoglossoides platessoides, fourspot flounder Paralichthys oblongus, Gulf stream flounder Citharichthys arctifrons, summer flounder Paralichthys dentatus, windowpane flounder Scophthalmus aquosus, winter flounder Pseudopleuronectes americanus, and yellowtail flounder Pleuronectes ferruginea) were collected in the study area. Winter flounder, windowpane and fourspot flounder accounted for 83% of all flatfish collected. Flatfish exhibited spatial and temporal variation in abundance, size, and condition, but this variation was not consistent with either positive or negative effects of wind farm construction or operation. Lower winter flounder abundances during the pile-driving time period and higher abundances during the cable-laying time period in the reference and wind farm areas suggest regionwide population fluctuations occurred. Although noise from pile driving may have been detectable in the reference areas, other flatfish abundances were not lower during this time period. Although no artificial reef effect was found for flatfish, negative impacts from construction activity and wind farm operation also were not evident.

Seabed Habitat Determines Fish and Macroinvertebrate Community Associations in a Subarctic Marine Coastal Nursery

AbstractFish exhibit habitat‐specific distributions in heterogeneous landscapes. Many sampling techniques are limited to specific seabed types and have limited utility in comparisons of fish abundance among multiple habitats. We measured the relative abundance and the composition of fish communities in four naturally occurring coastal marine seabed types (sand–pebble, cobble, bedrock, and eelgrass) and one anthropogenic habitat type (wharf) in Newman Sound, Newfoundland, Canada, by using baited video cameras. Fish and macroinvertebrate communities were significantly different among habitat types. Winter Flounder Pseudopleuronectes americanus, Atlantic Cod Gadus morhua, and Shorthorn Sculpin Myoxocephalus scorpius were significantly more abundant over sand–pebble substrate compared with bedrock and wharf sites. Cunners Tautogolabrus adspersus and Greenland Cod Gadus macrocephalus ogac were most abundant at wharf sites. Atlantic rock crabs Cancer irroratus and American lobsters Homarus americanus avoided sand–pebble seabeds, and American lobsters were almost exclusive to bedrock sites. Cunners, Winter Flounder, and Atlantic Cod were more abundant in summer, whereas Greenland Cod and Atlantic rock crabs were more abundant during autumn months. In paired comparisons of eelgrass habitats, the community sampled by two methods was different. Relative abundance estimates from baited video cameras matched beach seine estimates for abundant predatory species (e.g., Cunner, Greenland Cod, and Atlantic rock crab), but other species, including age‐0 Greenland Cod, Shorthorn Sculpin, and White Hake Urophycis tenuis, were better represented in beach seine samples. We demonstrated substrate preferences by common coastal marine fish and crab species, which have proven difficult to enumerate via active sampling techniques in the past. Our findings will facilitate comparative studies for these species among habitat components. For species that are well sampled by using baited video cameras, this technique will advance our ability to plan for their management in the nearshore.

Indications of Offshore Spawning by Southern Gulf of Maine Winter Flounder

AbstractThis is the first study to document quantitatively that Gulf of Maine (GOM) Winter Flounder Pseudopleuronectes americanus spawn offshore. Three sites (southern Jeffreys Ledge, Bigear [an area southwest of Tillies Bank], and a portion of Stellwagen Bank National Marine Sanctuary) were sampled during spring 2016 to determine whether Winter Flounder are spawning in non‐coastal, deep waters in the southern GOM. In total, 1,384 Winter Flounder were caught by trawl, measured, sexed, and assessed for reproductive stage during the peak spawning season (March–May). These fish showed clear signs that spawning was occurring either at or very near to all three sites surveyed. In all sites, a shift from prespawn to postspawn females occurred. Running ripe females were caught at both Jeffreys Ledge and Stellwagen Bank on multiple occasions, and ripe and recently spawned females were caught at Bigear. Given that these sites are over 15 km from the coast, it is not energetically likely that fish in such advanced reproductive condition are migrating to shore to spawn. Essential fish habitat (EFH) for GOM Winter Flounder is categorized as waters with depths of 5 m or less. The present study clearly shows that this depth range is incomplete and thus inaccurate for southern GOM Winter Flounder. Although it is irrefutable that GOM estuaries and shallow bays are important as nursery grounds for juvenile Winter Flounder and as postspawn feeding grounds for adults, the current GOM EFH designation warrants reclassification.

Habitat Use in a Depleted Population of Winter Flounder: Insights into Impediments to Population Recovery

AbstractThe distribution and demographics of a population of Winter Flounder Pseudopleuronectes americanus were examined for changes related to habitat quality over a fishery‐independent survey period of 29 years, encompassing an 82% decline in abundance. We tested for spatial and temporal variation in indicators of fitness to determine whether they revealed likely processes that resulted in the observed patterns of habitat use. We also assessed temporal changes in fitness and inferred changes in habitat quality associated with population decline. We focused on the condition of postspawn (resting) mature and immature fish of both sexes during a critical period of spring feeding prior to summer migration. Analysis of variance of individual condition indices (log10[length]–log10[weight] regression residuals) by sex/maturity group and time period identified consistent and significant differences among six survey strata. Highest condition indices were observed for fish that were captured in shallow (<18‐m) mud, sand, and transitional bottom sediment and deep (>18‐m) mud areas, collectively classified as high‐quality habitat. The proportion of the population that occupied high‐quality habitat remained unchanged at approximately 60% over the time series. As abundance decreased, condition decreased in mature females, increased in immature fish of both sexes, and was mixed in mature males. Additionally, the proportion mature at length shifted significantly upward for both sexes, the back‐calculated lengths at ages 2 and 3 increased for mature individuals, and the estimated winter growth declined for age‐3 mature and immature females. The results suggested increased competition for prey among mature fish and increased predation pressure on smaller fish. This Winter Flounder population may be responding to an increase in the abundance of competing mid‐Atlantic species, which was brought about by increasing water temperature. These second‐order effects may have chronically hindered Winter Flounder reproduction and therefore stock rebuilding, especially in areas of low‐quality habitat.Received September 23, 2015; accepted July 18, 2016 Published online September 30, 2016

Life on the bottom: the chemical and morphological asymmetry of winter flounder (Pseudopleuronectes americanus) sagittae

We observed that paired winter flounder (Pseudopleuronectes americanus) sagittae are not morphologically or chemically identical. Statistically significant (p < 0.05) chemical asymmetry was detected between the sagittae in five of eight elements (with three other elements, Sr, I, and Sn not statistically different). The blind-side otolith exhibited higher mean concentrations of Ba, Mn, Mg, Cu, and Zn trace elements than the eyed-side otolith. These asymmetries may be due to blind-side otoliths absorbing higher concentrations of transitional elements, partly as a result of environmental heterogeneity caused by redox reactions emanating from the sediments. Metamorphic transformation and the subsequent shift to the benthos by fully formed fish may also account for element concentration levels that were significantly different between juveniles and both sub-adults and adults. Our results also suggest that chemical uptake in a pair of winter flounder sagittae is an asynchronous event, and that each otolith potentially records the chemical history of its environment independent of the other. The physiological pathway for entry into winter flounder otoliths is uncertain and warrants further testing. Overall, our results have implications for other flatfish genera as well, and demonstrate the need for standardization of methodology when conducting otolith chemistry on flatfishes.

Influence of mussel aquaculture on the distribution of vagile benthic macrofauna in îles de la Madeleine, eastern Canada

AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 6:175-183 (2015) - DOI: https://doi.org/10.3354/aei00123 Influence of mussel aquaculture on the distribution of vagile benthic macrofauna in îles de la Madeleine, eastern Canada Annick Drouin1,2,*, Philippe Archambault2, Brianna Clynick1,2, Karine Richer1, Christopher W. McKindsey1,2 1Institut Maurice Lamontagne, Fisheries and Oceans Canada, 850 route de la mer, Mont-Joli, Québec G5H 3Z4, Canada 2Institut des sciences de la mer, Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L 3A1, Canada *Corresponding author: annick.drouin@gmail.com ABSTRACT: We examined spatial variation in the abundance of 4 benthic vagile species in a lagoon with blue mussel Mytilus edulis aquaculture (inside vs. outside of the mussel lease; among areas with 1 yr old, 2 yr old and harvested mussels; and with distance from mussel lines). American lobster Homarus americanus, Atlantic rock crab Cancer irroratus, common starfish Asterias rubens and winter flounder Pseudopleuronectes americanus were all at least 3 times more abundant in the farm area with 2 yr old mussels, where mussel fall-off is more frequent, than in areas outside of the farm or other areas within the farm. A strong association of lobsters with mussel line structures was observed, where most individuals were observed directly under the mussel lines, close to anchor blocks, in the areas with 1 yr old, 2 yr old and harvested mussels (58, 42 and 57%, respectively). Mussel farms influence the distribution of benthic macrofauna at a number of spatial and temporal scales, and this may be due to a number of mechanisms, depending on the species. An in situ experiment was done to separate the influence of anchor blocks and mussel fall-off on the distribution of lobsters, crabs, starfish and flounders. Results of the manipulative experiment highlighted the importance of shelter structures over a short-term period for lobsters, but not for the other 3 species. Conclusions from the observations and the manipulative experiment suggest that lobster distribution is a function of both physical structure and feeding opportunities, whereas the distribution of the other species was mainly due to trophic effects. KEY WORDS: Mytilus edulis · Homarus americanus · Cancer irroratus · Asterias rubens · Pseudopleuronectes americanus · Spatial variation · Environmental impact Full text in pdf format PreviousNextCite this article as: Drouin A, Archambault P, Clynick B, Richer K, McKindsey CW (2015) Influence of mussel aquaculture on the distribution of vagile benthic macrofauna in îles de la Madeleine, eastern Canada. Aquacult Environ Interact 6:175-183. https://doi.org/10.3354/aei00123 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 6, No. 2. Online publication date: February 04, 2015 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2015 Inter-Research.

Microchemical Signatures in Juvenile Winter Flounder Otoliths Provide Identification of Natal Nurseries

AbstractVariation of otolith microchemical signatures between natal nurseries from young‐of‐the‐year (age 0) Winter Flounder Pseudopleuronectes americanus were evaluated. Fish were collected in summer 2012 from 12 nursery areas from New Jersey to New Hampshire, spanning &gt;500 km. Nursery specific microchemical signatures were developed using element : Ca ratios, which were determined with solution‐based inductively coupled plasma‐mass spectrometry on the whole otolith. Age‐0 flounder microchemical signatures showed significant nursery‐specific differences and varied on a small spatial scale (about 12 km) based on elemental (Li, Na, Mg, Mn, Sr, Cd, and Ba) ratios. Via quadratic discriminant function analysis, fish were classified back to natal nursery areas with 73% average cross‐validation classification accuracies. Based on this preliminary study, otolith microchemistry has the potential to be an effective tool to assess the connectivity between the inshore nursery areas and the offshore adult populations of Winter Flounder; however, further baseline studies are needed. In particular, between‐year and within‐year variation in the otolith elemental concentrations must be quantified. These elemental analyses need to be linked to specific management needs to be useful to fisheries managers; for Winter Flounder, the ability to rank estuaries by the yield of recruits may help solve estuary‐specific anthropogenic challenges.Received July 11, 2014; accepted October 16, 2014

Growth and Mortality in Coastal Populations of Winter Flounder: Implications for Recovery of a Depleted Population

AbstractWe studied growth, mortality, and settlement distributions of juvenile Winter FlounderPseudopleuronectes americanusin two bays of Long Island, New York, to better understand localized population dynamics of a species experiencing a protracted population decline. Juvenile mortality in Long Island bays ranged between 0.02 and 0.04 per day and was as high as or higher than values reported for other systems. Settlement distributions had multiple peaks (cohorts) occurring between March and late July in 2007 and between February and May in 2008. The presence of multiple cohorts limited the usefulness of field‐derived, length‐based estimates of growth, resulting in unrealistic values compared with otolith‐based measures (field based: −0.05 to 0.25 cm/d; otolith based: 0.05–0.06 cm/d). Thus, we recommend the use of otolith methods or the repeated measurement of individuals to estimate growth of juvenile Winter Flounder. Otolith‐based growth rate was significantly higher for Port Jefferson Harbor during 2007 than for all other year × location combinations. Together with previous research showing genetic differentiation and migratory diversity, our finding of multiple spawning cohorts in Long Island Winter Flounder suggests a degree of isolation, and local management will be needed to support healthy populations. Future research to determine adult spawning, migratory behavior, stock structure, duration of the larval period, and settlement timing is required to unravel the complex behavior of Winter Flounder.Received July 10, 2014; accepted April 10, 2015

Factors Influencing Daily Growth in Young‐of‐the‐Year Winter Flounder along an Urban Gradient Revealed Using Hierarchical Linear Models

AbstractGrowth during early life history plays a key role in the recruitment dynamics of marine fishes; however, the effects of environmental stressors on growth are often difficult to quantify. In this study, increment widths from sagittal otoliths were used as a proxy for daily growth in 102 young‐of‐the‐year Winter Flounder Pseudopleuronectes americanus collected over a 2‐year period from three sites in Long Island, New York. We hypothesized that we would observe different growth patterns among bays due to an environmental gradient driven primarily by contaminant loadings and environmental stressors in our study sites. Hierarchical linear models were utilized to associate individual attributes (ontogeny, condition, and gene expression) to daily growth patterns during each year. As expected, daily growth generally displayed a negative relationship with age and daily average temperature, although the effect of temperature was much more variable. Out of 14 individual attributes, the settlement date, the age at capture, the condition indices Fulton's K and hepatosomatic index, and the expression of genes associated with immune response (pleurocidin), contaminant exposure (cytochrome P5401A), and glucose and glycogen metabolism (glycerol‐3‐phosphate dehydrogenase) were observed to significantly and consistently affect growth. The results provide evidence of differential growth based on the date of settlement and condition, and the molecular indicators of stress suggest that growth is also influenced by habitat quality. There were significantly different relationships between individual attributes and growth among bays, but these did not always reflect the proposed environmental gradient. Together, the results suggest that anthropogenic stressors likely play a role in growth and recruitment processes in Long Island bays and indicate that growth is both spatially and temporally dynamic at multiple scales. Furthermore, this study highlights the utility of hierarchical linear models in analyzing complex daily growth data in juvenile fish, which may be applicable to other species.

Managing a Marine Stock Portfolio: Stock Identification, Structure, and Management of 25 Fishery Species along the Atlantic Coast of the United States

AbstractIn this review, stock identification methods used, resulting stock numbers and boundaries, and assessment and management context were explored for all 25 species managed by the Atlantic States Marine Fisheries Commission (ASMFC). This included invertebrates and vertebrates distributed between Maine and Florida, with a few species ranging across all these states and some ranging into the Gulf of Mexico and the Canadian Maritimes. The effects of larval dispersal or mixing of adults in the marine environment were evident. Marine and catadromous spawners were recognized and treated as a unit stock (e.g., northern shrimp Pandalus borealis, American Eel Anguilla rostrata, Atlantic menhaden Brevoortia tyrannus, Bluefish Pomatomus saltatrix, Tautog Tautoga onitis), a metapopulation (American lobster Homarus americanus, Atlantic Herring Clupea harengus), or two stocks, north and south of Cape Hatteras, a major biogeographic boundary, (Black Sea Bass Centropristis striata, Scup Stenotomus chrysops, Red Drum Sciaenops ocellatus, Summer Flounder Paralichthys dentatus). Estuarine and anadromous spawners were structured and managed at a finer spatial scale (horseshoe crab Limulus polyphemus, Atlantic Sturgeon Acipenser oxyrinchus, American Shad Alosa sapidissima and the river herrings Blueback Herring A. aestivalis and Alewife A. pseudoharengus, and Spotted Seatrout Cynoscion nebulosus). A broad suite of stock identification methods have been applied to ASMFC species and reviewed here in five categories: life history traits, other phenotypic traits, genetic traits, natural marks, and applied marks. An interdisciplinary mix of methods has been achieved for a few species (Striped Bass Morone saxatilis, Winter Flounder Pseudopleuronectes americanus), but only a few or no stock identification methods have been applied to others (Spiny Dogfish Squalus acanthias, Hickory Shad A. mediocris, Spot Leiostomus xanthurus, Spanish Mackerel Scomberomorus maculatus). Clinal phenotypic variation has contributed to several long‐standing debates about stock structure; some of these have been recently reevaluated as a unit stock (Atlantic Croaker Micropogonias undulatus, Weakfish Cynoscion regalis), and others are still debated. For some ASMFC species, other priorities (e.g., bycatch) dominate the uncertainty of the assessment or management process. Otherwise, stock identification remains a research priority for most of these species. Continued research of this subject should consider (1) research priorities tabulated by ASMFC review panels, (2) strategic use of interdisciplinary stock identification methods, (3) use of experiments or reaction norms to separate phenotypes from genotypes, (4) genetic surveys at a seascape scale, (5) demonstration of contingent (nongenetic) structure and its implications for management, and (6) simulation modeling. Obstacles to adopting finer‐scale structure into assessments or management of ASMFC fisheries include: (1) multiple stock units are apparent but boundaries are not clear, (2) monitoring requirements for smaller areas or for mixed‐stock catches are not cost effective, or (3) mixing rates within a metapopulation or across biogeographic boundaries are poorly described.Received May 8, 2013; accepted March 3, 2014

Coastwide Stock Structure of Winter Flounder Using Nuclear DNA Analyses

AbstractMany Winter Flounder Pseudopleuronectes americanus populations have declined dramatically. In U.S. waters, Winter Flounder are managed as three stocks: Gulf of Maine, southern New England–Mid‐Atlantic Bight, and Georges Bank. Historically, it was believed that the spawning of inshore stocks occurs exclusively within natal estuaries. Based on the supposition of estuary‐specific spawning, we hypothesized that Winter Flounder exhibit greater stock structure than predicted by the three‐stock model and, in fact, that they exhibit genetic differentiation at the level of individual estuaries. We tested this hypothesis by conducting microsatellite DNA analysis at 12 loci and single‐nucleotide polymorphism analysis at 4 loci on young‐of‐the year and adult Winter Flounder collected from 27 estuaries from Newfoundland to Delaware as well as from Georges Bank. We found highly significant coastwide genetic stock structure among Winter Flounder; however, there was little evidence of estuary‐specific structure. Pooled collections from north and south of Cape Cod were genetically distinct, as were many individual collections compared between these two regions. However, there was little genetic heterogeneity among estuarine collections within either of these major geographic regions. The two Canadian collections from the Miramichi River and Newfoundland were genetically distinct from those in the Gulf of Maine. Our collection from Georges Bank was marginally distinct from the inshore collections from north and south of Cape Cod. Overall, our genetic results support the three‐stock model used to manage Winter Flounder in U.S. waters and indicate the presence of at least two genetic stocks in Canadian waters (the Miramichi River in the Gulf of St. Lawrence and Passamaquoddy Bay in the Bay of Fundy). Furthermore, our data suggest that the spawning of Winter Flounder in nearshore coastal waters is more extensive than previously thought or that homing is weaker, contributing to the absence of genetic differentiation among populations from proximal estuaries.

Winter flounder (Pseudopleuronectes americanus) estuarine habitat use and the association between spring temperature and subsequent year class strength

Winter flounder habitat use in New York/New Jersey Harbor was examined through a long-term (2002–2010) bottom trawl sampling program (Aquatic Biological Survey) in which 5234 winter flounder were captured in 2069 samples collected at approximately 26 stations throughout the harbor. Interannual variability in catch-per-unit-effort (CPUE) primarily was attributable to fluctuations in Year-1 juvenile CPUE, which was positively correlated with total annual egg abundances from the previous year. Adult male CPUE during the spawning season was positively correlated with total egg abundances of the same year, whereas adult female CPUE was unrelated to annual egg abundances in the harbor. Annual variation in adult male densities in the harbor during the spawning season reflects the intensity of estuarine spawning activity, whereas adult female densities may include non-reproductive, foraging individuals. Seasonal fluctuations in condition indices reflected energy use during the spawning season, with relatively high condition in January, reduced levels in March and April, and elevated condition again in May. Adult CPUE peaked in April, coincident with the critical feeding period that follows spawning. Mean April water temperatures were positively correlated with egg abundances the following year and Year-1 juvenile CPUE two years later. A similar correlation between April temperatures and Year-1 juvenile abundances two years later was demonstrated using published data for winter flounder collected in Niantic Bay, CT. Higher April water temperatures may enhance benthic secondary production during the critical feeding period, and thus increase prey availability for foraging adults that need to restore energy reserves in order to reproduce the following year. A direct examination of benthic secondary production and variation in winter flounder estuarine foraging and subsequent spawning activity is needed to more fully understand this relationship.

Design, Evolution, and Assessment of a Sea Turtle Deflector Dredge for the U.S. Northwest Atlantic Sea Scallop Fishery: Impacts on Fish Bycatch

AbstractBetween May 2006 and November 2009 we tested five sequential dredge modifications during 37 trips on 13 different sea scallop fishing vessels. The testing evaluated the impacts of these modifications on the catch of sea scallops Placopecten magellanicus, the bycatch of fish and sea turtles in the families Cheloniidae and Dermochelyidae, and frame durability. We tested the modified dredges and an original New Bedford dredge (control) by conducting paired, side‐by‐side tows using identical tow parameters. A total of 4,059 paired tows were conducted in which tow data, scallop catch, and bycatch were recorded; data from 44% of the tows were sufficiently sampled for comparisons of bycatch. The dredge catches showed a significant 3% increase in sea scallop catch and significant decreases in the bycatch of many species, including yellowtail flounder Limanda ferruginea (46%), winter flounder Pseudopleuronectes americanus (69%), barndoor skate Dipturus laevis (18%), and winter skate Leucoraja ocellata (20%). The final design, the CFarm turtle deflector dredge, proved effective at guiding turtle carcasses over the top of the dredge by eliminating most of the bale bars and forming a ramp with a forward‐positioned cutting bar and closely spaced struts leading back at a 45° angle. The final design also proved effective in reducing bycatch for a number of nontarget fish species. Flow characterizations in a flume tank provided insight into the cutting bar and frame hydrodynamics that may explain the field trial results.Received February 2, 2011; accepted November 2, 2011

Bacterial colonization of winter flounder Pseudopleuronectes americanus fed live feed enriched with three different commercial diets

The proliferation of bacteria in intensive aquaculture systems may be responsible for poor growth and mass mortality of marine fish larvae. Essential fatty acids provided in the diet could protect larvae by modulation of the immune response via arachidonic acid (AA) and eicosapentaenoic acid (EPA). Winter flounder Pseudopleuronectes americanus larvae were fed rotifers Brachionus plicatilis enriched with three commercial diets containing different fatty acid profiles. Bacterial colonization on the gills and skin and in the intestinal lumen was evaluated at the end of the rotifer feeding period (day 26), and growth was surveyed until metamorphosis. At 26 days post hatching, larvae fed rotifers containing the higher AA content and with a higher docosahexaenoic acid (DHA) to EPA ratio showed better growth and the lowest bacterial colonization of the intestinal lumen compared to larvae fed rotifers with the lowest AA and DHA : EPA levels. AA had been selectively incorporated into the polar lipids of larvae fed the rotifers enriched with the three diets. This is the first study in winter flounder larvae to report a link between different commercial rotifer enrichments and bacterial density in intestinal lumen.

Abundance exchange models of fish assemblages along the Hudson River Estuary Gradient, New York

The spatially explicit abundance exchange model (AEM) was built for four fish species: winter flounder (Pseudopleuronectes americanus), Atlantic silverside (Menidia menidia), eastern silvery minnow (Hybognathus regius), and striped bass (Morone saxatilis) along the Hudson River estuary gradient, New York. The fish and habitat data during 1974-1997 were used to develop and calibrate the AEM; and the fish data during 1998-2001 was used to validate the model. Preference indexes of fish species for dissolved oxygen, salinity, water temperature, and bottom substrates along the gradient were estimated; and these were used to compute habitat preference (HP) of the associated fish species. The species HP was a key variable in the AEM to quantify abundance and distribution patterns of the associated species along the gradient. The AEM could efficiently predict abundance and distribution patterns of all modeled species except striped bass. The model ability for predicting a local distribution range of a fish species with broad tolerance on changing environment like striped bass should be improved.

Effects of the toxic dinoflagellate, Alexandrium fundyense on three species of larval fish: a food‐chain approach

Sublethal behavioural effects of exposure to paralytic shellfish toxins (PST; saxitoxin and its derivatives) from the toxic dinoflagellate Alexandrium fundyense were investigated in newly settled winter flounder Pseudopleuronectes americanus, larval sheepshead minnow Cyprinodon variegatus and larval mummichog Fundulus heteroclitus through an A. fundyense–copepod–fish food chain. Consumption of as few as six to 12 toxin‐containing copepods was lethal to the fishes. After consuming fewer toxin‐containing copepods, all three fish species exhibited sublethal effects from vector‐mediated exposure. Prey‐capture ability of mummichogs was reduced in larvae that had consumed toxic copepods, Coullana canadensis. After consuming toxic C. canadensis or mixed copepods, mummichog larvae had reduced swimming performance. Swimming activity was also significantly reduced in winter flounder after consuming toxic copepods, including time spent in motion and distance travelled. Prey capture and predator avoidance were reduced in first‐feeding sheepshead minnow larvae that had consumed toxic dinoflagellate cells. Adverse effects on prey capture or predator avoidance may reduce larval survival and facilitate the transmission of PST through the food web. This study provides baseline information on sublethal effects of PST exposure on fishes using a novel food‐chain approach with zooplankton as vectors.

Ontogenetic variation in habitat associations for four flatfish species in the Gulf of Maine‐Georges Bank region

Multivariate ordination techniques were used to examine how size classes of four flatfish species, American plaice Hippoglossoides platessoides, winter flounder Pseudopleuronectes americanus, yellowtail flounder Limanda ferruginea and fourspot flounder Paralichthys oblongus, are related to bottom depth, bottom temperature, substratum grain size and temporal factors using a 35 year time series from autumn and spring in the Gulf of Maine‐Georges Bank region. Depth had the most explanatory value during both seasons in most cases, with fish size generally increasing with depth. One exception was yellowtail flounder in the spring for which a temporal factor explained the most variance, reflecting an increase in size over the time series due to changes in fishing pressure. Temperature was secondarily important for yellowtail flounder in the autumn and for fourspot flounder in both seasons. Substratum type was secondarily important for winter and yellowtail flounders in the spring with smaller fish associated with larger substratum types. Seasonal associations with depth, temperature and substratum are related to seasonal spawning migrations, thermal preferences and other ecological factors.

Stock and parental effects on embryonic and early larval development of winter flounder Pseudopleuronectes americanus (Walbaum)

A hierarchical breeding design was used to determine if winter flounder Pseudopleuronectes americanus embryos and yolk‐sac larvae sired by Georges Bank males developed and grew larger than fish sired by Passamaquoddy Bay males, and to examine parental contributions to variations in fertilization success, time to 50% hatch, hatch success and larval morphological development. Significant stock effects were detected for time to hatch and larval development. Eggs fertilized by Passamaquoddy Bay males reached 50% hatch significantly earlier than eggs fertilized by Georges Bank males. Larvae sired by Georges Bank males were significantly larger during larval development for four of the six traits measured at 12 days post‐hatch: head depth, jaw length, myotome height and body area. Embryo and larval development were strongly influenced by maternal contributions; there were significant maternal variance components for the majority of the variables measured. Paternal variance components were significant for fertilization success, time to hatch, larval jaw length and larval head depth, however, they acted principally through parental interactions. This information has important implications for the long‐term sustainable development of winter flounder for aquaculture purposes as well as for understanding winter flounder genetic variation in the wild.