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Observations of fish behavior can provide insights into habitat preferences and use. Black sea bass, Centropristis striata, are a territorial temperate reef finfish species known for their high commercial and recreational value and association with structured habitat. We used underwater action cameras to record video of black sea bass to assess territorial (agonistic, ambush, displacement) and occupancy (station-keeping) behaviors on shelf and bag style oyster aquaculture cages at a shellfish farm, and on boulders at a natural rock reef near Milford, Connecticut in Long Island Sound, Northwest Atlantic. Black sea bass at a variety of life stages were highly associated with cages, including young-of-the-year, and age 1+ fish. The high abundance of black sea bass observed on cages relative to boulders suggests this species has an affinity for the vertical structure created by aquaculture gear. When behaviors were normalized to the total fish sightings, black sea bass showed no significant difference in frequency of behaviors between habitats, indicating that per-fish rates of behavior were similar on cages and boulders. Demonstration of territorial and occupancy behaviors by black sea bass on, and around cages suggests that aquaculture gear provides structured habitat and ecosystem services for this species similar to natural reefs. These results suggest that essential fish habitat descriptions of manmade structures used by black sea bass could be broadened to include aquaculture gear. Our study provides novel information on behavioral interactions of black sea bass with oyster cages that may support aquaculture permitting and consultation processes. [ABSTRACT FROM AUTHOR]

Objective: The pleated sea squirt Styela plicata (subphylum Tunicata), an invasive marine invertebrate in coastal waters of southeastern North Carolina, was investigated as an alternative protein source to fish meal (FM) in the diet of juvenile Black Sea Bass Centropristis striata. Methods: Six different isoproteic and isolipidic diets were formulated to replace 0.0, 8.3, 16.7, 25.0, 33.3, and 41.6% of FM protein with tunicate meal (TM) protein by supplementing 0, 5, 10, 15, 20, and 25% TM in the diets. The experimental system consisted of eighteen 75‐L tanks supported by a recirculating seawater system in an indoor, climate‐controlled laboratory. Juveniles (average weight = 7.1 g) were stocked at a density of 15 fish/tank (N = 3 tanks/treatment) and were fed the test diets daily to apparent satiation for 55 days. Result: Replacement of FM protein with TM protein caused slight declines in dietary amino acid concentrations (notably arginine, methionine, and tryptophan) at higher replacement levels. At terminal sampling, no significant differences in survival (87–96%), percent body weight gain (157–228%), feed conversion ratio (1.50–1.71), or proximate composition were observed among dietary treatment groups. However, significant positive linear trends were found between incremental levels of TM and final fish weight, body weight gain, and specific growth rate. Whole‐body fatty acid composition reflected dietary levels. Conclusion: Results indicate that TM protein can be used to replace at least 41.6% of the FM protein in the diet for juvenile Black Sea Bass without adverse effects on survival, growth, feed utilization, or whole‐body proximate composition. Impact statementSea squirts (subphylum Tunicata) are suspension‐feeding marine invertebrates. They foul shellfish cages, lines, and the shellfish directly, thus increasing the resource competition experienced by the shellfish. The use of tunicates in aquaculture feed is a possible way to reduce reliance on expensive and unsustainable fish meal protein in aquafeeds. The use of tunicate meal in aquafeeds could be another new cost‐effective alternative protein source with which to develop sustainable feed for aquaculture while reducing the fouling problem in marine shellfish aquaculture. [ABSTRACT FROM AUTHOR]

Observations of fish behavior can provide insights into habitat preferences and use. Black sea bass, Centropristis striata, are a territorial temperate reef finfish species known for their high commercial and recreational value and association with structured habitat. We used underwater action cameras to record video of black sea bass to assess territorial (agonistic, ambush, displacement) and occupancy (station-keeping) behaviors on shelf and bag style oyster aquaculture cages at a shellfish farm, and on boulders at a natural rock reef near Milford, Connecticut in Long Island Sound, Northwest Atlantic. Black sea bass at a variety of life stages were highly associated with cages, including young-of-the-year, and age 1+ fish. The high abundance of black sea bass observed on cages relative to boulders suggests this species has an affinity for the vertical structure created by aquaculture gear. When behaviors were normalized to the total fish sightings, black sea bass showed no significant difference in frequency of behaviors between habitats, indicating that per-fish rates of behavior were similar on cages and boulders. Demonstration of territorial and occupancy behaviors by black sea bass on, and around cages suggests that aquaculture gear provides structured habitat and ecosystem services for this species similar to natural reefs.These results suggest that essential fish habitat descriptions of manmade structures used by black sea bass could be broadened to include aquaculture gear. Our study provides novel information on behavioral interactions of black sea bass with oyster cages that may support aquaculture permitting and consultation processes.

Abstract A reliable and cost‐effective source of fingerlings is essential for the successful commercial aquaculture of black sea bass. This study aimed to determine the effects of nursery tank stocking densities on the growth performance, feed efficiency, survival, tolerance to shipping, and biochemical quality of juvenile black sea bass. In two experiments, different stocking densities were compared for black sea bass at different stages of development. In Experiment 1, intermediate stage juveniles (1.27 g mean wt) were stocked at densities of 4.5 and 6.5 fish per liter of tank volume. Growth performance and biochemical quality were similar between the two density treatments. In Experiment 2, early post‐metamorphic stage juveniles (mean wt. = 0.524 g) were compared using the same stocking densities. While the fish reared at 4.5 fish/L were slightly larger, there were no significant differences in growth performance or biochemical quality between the density treatments. After both experiments, the fingerlings from each density treatment showed high survival rates under acute crowding and simulated shipping conditions. The study demonstrates that high NT densities of 4.5 and 6.5 fish/L did not negatively impact the growth performance and quality of black sea bass fingerlings, providing transport‐ready fingerlings in a relatively short period.

A reliable and cost‐effective source of fingerlings is essential for the successful commercial aquaculture of black sea bass. This study aimed to determine the effects of nursery tank stocking densities on the growth performance, feed efficiency, survival, tolerance to shipping, and biochemical quality of juvenile black sea bass. In two experiments, different stocking densities were compared for black sea bass at different stages of development. In Experiment 1, intermediate stage juveniles (1.27 g mean wt) were stocked at densities of 4.5 and 6.5 fish per liter of tank volume. Growth performance and biochemical quality were similar between the two density treatments. In Experiment 2, early post‐metamorphic stage juveniles (mean wt. = 0.524 g) were compared using the same stocking densities. While the fish reared at 4.5 fish/L were slightly larger, there were no significant differences in growth performance or biochemical quality between the density treatments. After both experiments, the fingerlings from each density treatment showed high survival rates under acute crowding and simulated shipping conditions. The study demonstrates that high NT densities of 4.5 and 6.5 fish/L did not negatively impact the growth performance and quality of black sea bass fingerlings, providing transport‐ready fingerlings in a relatively short period. [ABSTRACT FROM AUTHOR]

Objective: A recent expansion of the northern stock of Black Sea Bass Centropristis striata into the northern Gulf of Maine raises questions about this species' movement and population dynamics in this region. Determining the origin of these fish is essential, as dramatic changes in migration patterns or current population boundaries could have profound effects on stock assessment estimates and subsequent management regulations. Methods: In this study, we measured otolith core concentrations of stable isotopes (δ18O, δ13C) and trace element:calcium ratios (Mg:Ca, Mn:Ca, Cu:Ca, Zn:Ca, Ba:Ca, Sr:Ca) to assess the natal origin of Black Sea Bass that were caught off the coast of Maine. Spawning condition adults from southern New England (SNE) and the mid‐Atlantic Bight (MAB) were used to characterize the chemical fingerprint of these known spawning regions. Result: Unique chemical fingerprints were identified for fish from SNE and the MAB, with high reclassification success using random forest analysis (16% error rate). The classification of Black Sea Bass of unknown origin that were caught in Maine waters indicated that 85% of the samples matched to SNE and 13% to the MAB, whereas one sample remained unclassified. Conclusion: Results from this study support the current management population separation of the northern stock of Black Sea Bass between SNE and the MAB and lends additional information to the understanding of this species' movement into the northern Gulf of Maine. As fish stocks around the world continue to shift into new regions due to climate change, knowledge of their natal origin will be critical to long‐term sustainable management of this species. Impact statementDetermining which population Black Sea Bass located in Maine came from helps scientists understand how these fish migrated there, their potential for success, and their expected growth and maturity. If this species becomes more abundant in the region, this information could help inform regulation surrounding conservation and fishing practices. [ABSTRACT FROM AUTHOR]

Abstract The objective of this study was to optimize nursery diets for post‐metamorphic stage black sea bass by evaluating growth performance, whole‐body proximate and fatty acid composition, and utilization of University of North Carolina Wilmington (UNCW)‐formulated and commercial diets under laboratory conditions. A feeding trial was conducted to compare two UNCW‐formulated diets (D1 and D2) for black sea bass (54% crude protein = CP and 14% crude lipid = CL) and two premium, commercial marine finfish fry diets, Otohime (Reed Mariculture Inc., Campbell, CA, CP = 48% and CL = 14%, CD3) and Gemma Diamond (Skretting, Nutreco, Canada, CP = 57%, CL = 15%, CD4). The UNCW‐formulated diet 1 (D1) contained high fish meal (FM, 40% of diet), whereas UNCW‐formulated diet 2 (D2) replaced 50% FM protein by high‐quality poultry by‐product meal (PBM) protein. Post‐metamorphic stage black sea bass (~0.60 g, d40ph) were stocked in each of sixteen 75‐L tanks at a density of 1 fish per L (75 per tank), with four replicate aquaria per treatment. Fish were fed four times per day (0800, 1100, 1400, and 1600 h) to apparent satiation for 30 days. Final body weight (5.70–5.74), specific growth rate (7.40–7.45%/d), and percent body weight gain (834–848%) of fish fed the UNCW‐formulated D1 (FM‐based) and D2 (FM + PBM‐based) were higher (p

The objective of this study was to optimize nursery diets for post‐metamorphic stage black sea bass by evaluating growth performance, whole‐body proximate and fatty acid composition, and utilization of University of North Carolina Wilmington (UNCW)‐formulated and commercial diets under laboratory conditions. A feeding trial was conducted to compare two UNCW‐formulated diets (D1 and D2) for black sea bass (54% crude protein = CP and 14% crude lipid = CL) and two premium, commercial marine finfish fry diets, Otohime (Reed Mariculture Inc., Campbell, CA, CP = 48% and CL = 14%, CD3) and Gemma Diamond (Skretting, Nutreco, Canada, CP = 57%, CL = 15%, CD4). The UNCW‐formulated diet 1 (D1) contained high fish meal (FM, 40% of diet), whereas UNCW‐formulated diet 2 (D2) replaced 50% FM protein by high‐quality poultry by‐product meal (PBM) protein. Post‐metamorphic stage black sea bass (~0.60 g, d40ph) were stocked in each of sixteen 75‐L tanks at a density of 1 fish per L (75 per tank), with four replicate aquaria per treatment. Fish were fed four times per day (0800, 1100, 1400, and 1600 h) to apparent satiation for 30 days. Final body weight (5.70–5.74), specific growth rate (7.40–7.45%/d), and percent body weight gain (834–848%) of fish fed the UNCW‐formulated D1 (FM‐based) and D2 (FM + PBM‐based) were higher (p <.05) than in fish fed the commercial diets CD3 and CD4 (4.66–5.21 g, 6.80–7.15%/d, and 668–756%, respectively). Feed intake (% body weight/d was significantly lower for fish fed commercial diet (CD4) (3.94) compared with fish fed CD3 (4.20), but feed intake for CD3 was not significantly different compared with the UNCW‐formulated diets D1 and D2 (4.10–4.12). Feed conversion ratios (0.76–0.82) were significantly higher for fish fed CD3 (0.82) than for fish fed D1 and CD4 (0.76). Survival was high (99–100%) in all diet treatments. Final whole‐body crude protein content (15.2 to 15.9% wet basis), moisture (68.9–69.6%), and ash (4.31–4.77%) showed no significant differences; however, whole‐body crude lipid was lower in fish fed CD3 (9.67%) than in fish fed the other diets (9.96–10.22%). Final whole‐body fatty acid composition reflected the diet composition. Higher feed consumption and growth of fish fed the UNCW‐formulated diets were attributed to a more optimal combination of marine (fish, squid, and krill meals), terrestrial plant (soybean meal) protein sources, and the addition of chemo‐attractants, which provided both higher nutritional quality and palatability. The study suggests that the species‐specific starter diets may improve growth performance and fingerling quality and may therefore lower production costs under intensive nursery conditions. [ABSTRACT FROM AUTHOR]

Globally, climate change is inducing range shifts and expansions for numerous species. For commercially exploited species, such as those in directed fisheries, this can cause numerous issues with management and jurisdictions as the species shift and expand into areas at levels previously unseen. The black sea bass (Centropristis striata) fishery has rapidly expanded in the northern Atlantic. Over the past decade commercial landings have more than doubled in the New England and Mid-Atlantic regions. This increase is related to a northward shift in the species’ center of biomass and range expansion. There is a crucial need for increased data in this species’ northern range. Oftentimes, large-scale fisheries data collection is limited by available resources and the difficulty of collecting data at-sea. Citizen science, such as fishing industry-based Research Fleets, represent a cost-effective option to help overcome these limitations and allow for the rapid collection of large amounts of data. The Commercial Fisheries Research Foundation and Rhode Island Department of Environmental Management established the Black Sea Bass Research Fleet in 2016. The Research Fleet is composed of fishers representing a variety of gear types who collect fishery-dependent data on black sea bass at-sea on a custom tablet application. In five years, 20 captains participated in the Research Fleet and collected length, visually-identified sex, and disposition data on 40,939 individual black sea bass throughout southern New England and into the Mid-Atlantic Bight. Catch, effort, and basic environmental data from 2,288 sampling sessions have been collected alongside this biological data. We apply the collaborative Research Fleet approach to a finfish for the first time and evaluate its performance over the first five years of sampling through participant engagement, magnitude of data collection, and interest in collected data. Further, we introduce the next steps being undertaken to incorporate the collected data into the management framework. This project illustrates that a science-industry research collaboration such as the Black Sea Bass Research Fleet can consistently collect large amounts of fishery-dependent data on black sea bass, and highlights a mutual interest among fishers, scientists, and managers to expand the collection of reliable data on this important species.

Abstract Statistical models built using different data sources and methods can exhibit conflicting patterns. We used the northern stock of black sea bass (Centropristis striata) as a case study to assess the impacts of using different fisheries data sources and laboratory‐derived physiological metrics in the development of thermal habitat models for marine fishes. We constructed thermal habitat models using generalized additive models (GAMs) based on various fisheries datasets as input, including the NOAA Northeast Fisheries Science Center (NEFSC) bottom trawl surveys, various inshore fisheries‐independent trawl surveys (state waters), NEFSC fisheries‐dependent observer data, and laboratory‐based physiological metrics. We compared each model's GAM response curve and coupled them to historical ocean conditions in the U.S. Northeast Shelf using bias‐corrected ocean temperature output from a regional ocean model. Thermal habitat models based on shelf‐wide data (NEFSC fisheries‐dependent observer data and fisheries‐independent spring and fall surveys) explained the most variation in black sea bass presence/absence data at ~15% deviance explained. Models based on a narrower range of sampled thermal habitat from inshore survey data in the Northeast Area Monitoring and Assessment Program (NEAMAP) and the geographically isolated Long Island Sound data performed poorly. All models had similar lower thermal limits around 8.5℃, but thermal optima, when present, ranged from 16.7 to 24.8℃. The GAMs could reliably predict habitat from years excluded from model training, but due to strong seasonal temperature fluctuations in the region, could not be used to predict habitat in seasons excluded from training. We conclude that survey data source can greatly impact development and interpretation of thermal habitat models for marine fishes. We suggest that model development be based on data sources that sample the widest range of ocean temperature and physical habitat throughout multiple seasons when possible, and encourage thorough consideration of how data gaps may influence model uncertainty.

External attachment of electronic tags has been increasingly used in fish studies. Many researchers have used ad hoc attachment methods and provided little or no validation for the assumption that tagging itself does not bias animal behaviour or survival. The authors compared six previously published methods for externally attaching acoustic transmitters to fish in a tank holding experiment with black sea bass Centropristis striata (L.). They tracked tag retention, fish growth and external trauma (as a measure of fish welfare) for 60 days. For each of these metrics, the results showed a wide range of responses among tagging treatments. A simple attachment method using a spaghetti tag passed through the dorsal musculature of the fish and tied to the end cap of the transmitter emerged as the preferred option based on high retention, no impact on growth and relatively low detriment to fish welfare. Future field studies using external electronic tagging should consider tag‐related effects that could compromise results when selecting a method for tag attachment. [ABSTRACT FROM AUTHOR]

Statistical models built using different data sources and methods can exhibit conflicting patterns. We used the northern stock of black sea bass (Centropristis striata) as a case study to assess the impacts of using different fisheries data sources and laboratory‐derived physiological metrics in the development of thermal habitat models for marine fishes. We constructed thermal habitat models using generalized additive models (GAMs) based on various fisheries datasets as input, including the NOAA Northeast Fisheries Science Center (NEFSC) bottom trawl surveys, various inshore fisheries‐independent trawl surveys (state waters), NEFSC fisheries‐dependent observer data, and laboratory‐based physiological metrics. We compared each model's GAM response curve and coupled them to historical ocean conditions in the U.S. Northeast Shelf using bias‐corrected ocean temperature output from a regional ocean model. Thermal habitat models based on shelf‐wide data (NEFSC fisheries‐dependent observer data and fisheries‐independent spring and fall surveys) explained the most variation in black sea bass presence/absence data at ~15% deviance explained. Models based on a narrower range of sampled thermal habitat from inshore survey data in the Northeast Area Monitoring and Assessment Program (NEAMAP) and the geographically isolated Long Island Sound data performed poorly. All models had similar lower thermal limits around 8.5℃, but thermal optima, when present, ranged from 16.7 to 24.8℃. The GAMs could reliably predict habitat from years excluded from model training, but due to strong seasonal temperature fluctuations in the region, could not be used to predict habitat in seasons excluded from training. We conclude that survey data source can greatly impact development and interpretation of thermal habitat models for marine fishes. We suggest that model development be based on data sources that sample the widest range of ocean temperature and physical habitat throughout multiple seasons when possible, and encourage thorough consideration of how data gaps may influence model uncertainty. [ABSTRACT FROM AUTHOR]

Abstract Fishes commonly exhibit diel rhythms in movements with consequences to feeding, reproduction, predator evasion, and resting. Such behaviors are conceived as plastic, persisting for phases (days to weeks), and then becoming disrupted, masked, and altered by changed environmental or ecological conditions. In telemetered black sea bass Centropristis striata (family Serranidae), we documented a remarkable 4‐month record of persistent diurnal vertical movements. Within the U.S. Mid‐Atlantic Bight June–October 2019 setting, biotelemetry data of 31 fish were examined through time series analysis and generalized additive modeling. Sun altitude played a dominant role throughout the series, where movements were diurnal. Thermal conditions were uniform until a September hurricane caused a 10°C rise in inhabited waters within the span of six hours, the result of water column mixing. This and other storms caused short‐term disruptions (

Fishes commonly exhibit diel rhythms in movements with consequences to feeding, reproduction, predator evasion, and resting. Such behaviors are conceived as plastic, persisting for phases (days to weeks), and then becoming disrupted, masked, and altered by changed environmental or ecological conditions. In telemetered black sea bass Centropristis striata (family Serranidae), we documented a remarkable 4‐month record of persistent diurnal vertical movements. Within the U.S. Mid‐Atlantic Bight June–October 2019 setting, biotelemetry data of 31 fish were examined through time series analysis and generalized additive modeling. Sun altitude played a dominant role throughout the series, where movements were diurnal. Thermal conditions were uniform until a September hurricane caused a 10°C rise in inhabited waters within the span of six hours, the result of water column mixing. This and other storms caused short‐term disruptions (<2 d) to diel rhythmicity. Daytime vessel traffic, but not dolphin presence, caused ≤1 h refuge‐seeking excursions. The discovery of pelagic behaviors (up to 15 m off the seabed) requires revision to the species' natural history, which was previously conceived as exclusively demersal. Spring‐autumn movement functions included reef recruitment and evacuation, courtship and spawning, and seasonal changes in feeding ecology and predator fields. Throughout these phases, the cycle of daytime movement and nighttime inactivity persisted. We hypothesize that during the nocturnal period these visual specialists become immobile and thus evade predation and mobilize energy toward growth, reproduction, and storage. Because this function does not change from spring through autumn, we speculate that nocturnal quiescence serves as the proximate control for the diurnal activity cycle. [ABSTRACT FROM AUTHOR]

The warming of the world’s oceans has resulted in the redistribution of many marine species globally. As species undergo range shifts, the expanding edge of the population often experiences novel environmental and demographic conditions that may result in the emergence of variation in life-history strategies. The northern stock of black sea bass, Centropristis striata, has recently expanded its distribution poleward, into the Gulf of Maine. Management has struggled to keep pace with this rapid range shift, in part, because very little is known about the expanding population. We compared life-history traits of black sea bass collected from 2013 to 2016 from the northern most point of the historic range of the northern stock (southern Massachusetts) to those from two areas in the newly expanded range (northern Massachusetts and Maine). We found significant differences in size, diet, condition, maturity and sex ratio between black sea bass from southern Massachusetts and the Gulf of Maine. Overall, sea bass in the newly expanded range consumed a less diverse diet and their condition was lower, but they reached maturity at a younger age. We also found greater length- and age-at-maturity estimates from all regions combined compared to the most recent black sea bass stock assessment which includes data from Cape Hatteras, NC to southern Massachusetts. This study represents initial observations of life-history traits of sea bass in its newly expanded range in the Gulf of Maine, and suggests that these sea bass exhibit life-history strategies that differ from their southern counterparts within their historic range. Given these findings, the stock assessment for the Northeast U.S. Continental Shelf black sea bass stock may not be adequate for sea bass in the Gulf of Maine. Studies investigating the expanding edge of economically valuable fishery species are needed to aid in ongoing and future efforts to assess and manage their stocks.

Diel rhythm in activity of antioxidant enzymes, as well as contents of glutathione and lipid peroxides, has been intensively investigated in Mammalia and Aves, however, the relevant studies about fish are few. In the present study, we examined variation in contents of cortisol, glucose and lactic acid in plasma of black sea bass Centropristis striata under natural photoperiod during a 24-h period. In addition, variation in activity of antioxidant enzymes, such as superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), catalase (CAT) and glutathione reductase (GR) as well as contents of total glutathione (T-GSH), reduced glutathione (GSH), oxidized glutathione (GSSG) and malondialdehyde (MDA) in liver and plasma of the fish were also determined. The plasma and liver samples were collected from the test fish at 3 h intervals during a 24-h cycle, with the first sampling time set at 03:00 h. No significant differences were found in glucose content and activities of GSH-PX and GR in plasma, as well as activities of SOD and GR in liver among different sampling times. In contrast, apparent variation was observed in contents of cortisol, lactic acid and MDA in plasma, activities of SOD and CAT in plasma, contents of MDA, T-GSH, GSH and GSSG in liver and activities of GSH-PX and CAT in liver between different sampling times. Moreover, contents of cortisol and MDA in plasma, SOD activity in plasma, and contents of MDA, GSH and GSSG in liver exhibited circadian rhythm, and their acrophases occurred at 06:08 h, 18:38 h, 15:09 h, 09:57 h, 23:36 h and 07:30 h, respectively. The present study indicates that some physiological parameters relating to stress response, such as cortisol and MDA contents in plasma, MDA, GSH and GSSG contents in liver and SOD activity in plasma changed at different time throughout a day in black sea bass. Therefore, caution should be taken when evaluating stress response in fish with these physiological parameters measured at different times. [ABSTRACT FROM AUTHOR]

This study briefly examined the simultaneous use of 2 gear types, single underwater video and hook-and- line, for sampling black sea bass (Centropristis striata) in Mid-Atlantic waters off the Maryland (USA) coast. Fish were sampled from 4 July to 3 August 2012 at two locations with varying bottom habitats ranging from sand and mud to natural hard bottom. First, the relationship between estimates of abundance of black sea bass sampled with the two gear types was examined using least-squares regression analysis. Second, abundance estimates were compared using linear mixed-effects models to determine whether abundance differed between the two sampling locations. In general, positive linear relationships were found between abundance estimates produced by underwater video and hook-and-line sampling methods. Abundance estimates of fish sampled with both gears was also found to be greater for the location with more complex bottom habitat. The results suggest that, if utilized together, both gear types have the potential to provide useful information about the abundance of black sea bass in Mid-Atlantic coastal waters. [ABSTRACT FROM AUTHOR]

The consumptive and nonconsumptive effects of predators on their prey and the indirect effects of these interactions that cascade through food webs have been studied for over half a century. In the northwest Atlantic, the stock of black sea bass (Centropristis striata) steeply declined during the 1980s. While population crashes of fished bivalve species coincided with those of black sea bass, the role of black sea bass in driving trophic cascades that indirectly influence bivalve survival has largely been overlooked. Over the past decade, black sea bass have not only been recovering in abundance but warming water temperatures have been driving a northward expansion of the extent of their seasonal migration, resulting in a particularly strong relative recovery along the south shore of Long Island, New York. To explore whether black sea bass alter the foraging rates of mud crabs (Dyspanopeus sayi) on a species of bivalve, blue mussels (Mytilus edulis), we manipulated the presence and position of sea bass within an array of mesocosm tanks. We found that the presence of black sea bass reduced the proportion of blue mussels consumed by mud crabs. Black sea bass presence indirectly elevated blue mussel survival by as much as 47.7% by reducing mud crab per capita consumption of blue mussels by 57.9%. However, there were limitations to the nonconsumptive effects of black sea bass that appeared to depend on their proximity to mud crabs. While our results are from an experimental setup with a simplified food chain and are context dependent, they emphasize the importance of studying how nonconsumptive effects of specific marine predators influence trophic cascades from both conceptual and applied coastal resource management standpoints. Our results suggest that the recovery of black sea bass may bode well for the population restoration of several species of bivalves within estuaries throughout their range. Further, our study provides evidence that indicates that the nonconsumptive effects of a recovering marine predator can indirectly elevate the survival of a basal food resource species. • Presence of a fish predator produces a trophic cascade that increases bivalve survival. • Crabs reduce their feeding rates when a fish predator is present. • There are limitations to the effects of the presence of a fish predator. [ABSTRACT FROM AUTHOR]

Abstract Distribution shifts poleward are a widespread response to climate change and can result in altered community composition and interactions among species that previously were geographically isolated. The novel communities and species interactions that may arise during range shifts provide an opportunity to study fundamental ecological processes, while also addressing potential conservation issues. Black sea bass (Centropristis striata) historically ranged from the Gulf of Mexico to Cape Cod, but recently have expanded north into the Gulf of Maine. Very little is known about the impact of this range expansion on benthic community structure throughout the coastal waters of the Gulf of Maine. To investigate the effects of sea bass on the behavior of juvenile American lobsters (Homarus americanus), we manipulated the presence of sea bass olfactory cues and quantified shelter use and foraging behavior of lobsters from three regions in the Gulf of Maine with different potential contact histories with sea bass. Sea bass presence increased shelter usage and reduced foraging in lobsters, but contact history influenced the strength of these behavioral responses. Lobsters with no previous contact with sea bass did not significantly increase shelter usage or decrease movement in their presence but did reduce their foraging rate on mussels. This observed reduction in consumption indicates that naïve lobsters recognize novel predators, but the ineffective anti‐predator responses exhibited support the naive prey hypothesis. Meanwhile, lobsters with the longest potential contact history with sea bass significantly increased shelter usage when sea bass were present; however, they exhibited limited movement and foraging behavior in both the absence and presence of sea bass. Finally, lobsters with a short potential contact history with sea bass exhibited increased shelter usage, reduced movement, and reduced mussel consumption in the presence of sea bass, revealing that juvenile lobsters quickly adapt anti‐predator defenses to avoid this novel threat. Overall, these results suggest that prey contact history with novel predators mediates the strength of their nonconsumptive effects, and consequently can influence geographic patterns in predator–prey dynamics.

Autogenic engineers (i.e., biogenic structure) add to habitat complexity by altering the environment by their own physical structures. The presence of autogenic engineers is correlated with increases in species abundance and biodiversity. Biogenic structural communities off the coast of Delaware, Maryland, and Virginia (Delmarva) are comprised of multiple species including boring sponge Cliona celata, various hydroids (i.e., Tubularia sp., Obelia sp., Campanular sp.), northern stone coral Astrangia poculata, sea whips Leptogorgia virgulata, and blue mussels Mytilus edulis. Sea whips are soft corals that provide the majority of vertical height to benthic structure off the coast of the Delmarva peninsula. The mid-Atlantic bight is inhabited by several economically valuable fishes; however, data regarding habitat composition, habitat quality, and fish abundance are scarce. We collected quadrat and sea whip images from 12 artificial reef sites (i.e., shipwrecks) ranging from 10 to 24 m depth to determine proportional coverage of biogenic structures and to assess habitat health, respectively. Underwater video surveys were used to estimate fish abundances on the 12 study sites and determine if fish abundance was related to biogenic coverage and habitat health. Our results showed that higher fish abundance was significantly correlated with higher proportional sea whip coral coverage, but showed no significant relationship to other biogenic structure. Assessment of sea whip condition (as a damage index) showed that sea whip corals on artificial reefs off the Delmarva coast exhibited minor signs of degradation that did not differ significantly among study sites.

Autogenic engineers (i.e., biogenic structure) add to habitat complexity by altering the environment by their own physical structures. The presence of autogenic engineers is correlated with increases in species abundance and biodiversity. Biogenic structural communities off the coast of Delaware, Maryland, and Virginia (Delmarva) are comprised of multiple species including boring sponge Cliona celata, various hydroids (i.e., Tubularia sp., Obelia sp., Campanular sp.), northern stone coral Astrangia poculata, sea whips Leptogorgia virgulata, and blue mussels Mytilus edulis. Sea whips are soft corals that provide the majority of vertical height to benthic structure off the coast of the Delmarva peninsula. The mid-Atlantic bight is inhabited by several economically valuable fishes; however, data regarding habitat composition, habitat quality, and fish abundance are scarce. We collected quadrat and sea whip images from 12 artificial reef sites (i.e., shipwrecks) ranging from 10 to 24 m depth to determine proportional coverage of biogenic structures and to assess habitat health, respectively. Underwater video surveys were used to estimate fish abundances on the 12 study sites and determine if fish abundance was related to biogenic coverage and habitat health. Our results showed that higher fish abundance was significantly correlated with higher proportional sea whip coral coverage, but showed no significant relationship to other biogenic structure. Assessment of sea whip condition (as a damage index) showed that sea whip corals on artificial reefs off the Delmarva coast exhibited minor signs of degradation that did not differ significantly among study sites. [ABSTRACT FROM AUTHOR]

Abstract Many teleost fishes exhibit sequential hermaphroditism, where male or female gonads develop first and later undergo sex change. Model sex change species are characterized by social hierarchies and coloration changes, which enable experimental manipulations to better understand these processes. However, other species such as the protogynous black sea bass (Centropristis striata) do not exhibit these characteristics and instead receive research attention due to their importance in fisheries or aquaculture. Black sea bass social structure is unknown, which makes sex change sampling difficult, and few molecular resources are available. The purpose of the present study was to induce sex change using exemestane, an aromatase inhibitor, and assess gonadal gene expression using sex markers (amh , zpc2) and genes involved in steroidogenesis (cyp19a1a , cyp11b), estrogen signaling (esr1 , esr2b), and apoptosis or atresia (aen , casp9 , fabp11 , parg , pdcd4 , rif1). Overall, dietary exemestane treatment was effective, and most exposed females exhibited early histological signs of sex change and significantly higher rates of ovarian atresia relative to control females. Genes associated with atresia did not reflect this, however, as expression patterns in sex changing gonads were overall similar to those of ovaries, likely due to a whole ovary dilution effect of the RNA. Still, small but insignificant expression decreases during early sex change were detected for ovary-related genes (aen , casp9 , fabp11 , zpc2) and anti-apoptotic factors (parg , rif1). Exemestane treatment did not impact spermatogenesis or testicular gene expression, but testes were generally characterized by elevated steroidogenic enzyme and estrogen receptor mRNAs. Further research will be needed to understand these processes in black sea bass, using isolated ovarian follicles and multiple stages of sex change. Highlights • Exemestane induced the initiation of female-to-male sex change in black sea bass. • Exemestane-exposed females exhibited significantly greater ovarian atresia than control fish. • Males did not exhibit gonadal effects from exemestane treatment. • All testes exhibited elevated steroidogenic enzyme and estrogen receptor mRNAs. • Small decreases in apoptosis-related mRNAs were evident in sex changing gonads. [ABSTRACT FROM AUTHOR]

Abstract Sex differentiation in many lower vertebrates (e.g. reptiles, amphibians, and fishes) can be influenced by environmental factors experienced during sensitive developmental periods. Environmental stressors, acting through cortisol, masculinize some teleost fishes during development by limiting gonadal cytochrome P450 aromatase (cyp19a1a), the enzyme that irreversibly converts testosterone to 17β-estradiol. In this study, we examined the influence of cortisol, cortisol inhibitors and a repeated, acute stressor (net-chasing) on sex differentiation in black sea bass (BSB; Centropristis striata), a protogynous hermaphroditic teleost. Wild-caught, sexually-undifferentiated, BSB juveniles (~90 mm) were collected from Rhode Island waters, raised in recirculating systems and fed diets supplemented with cortisol, a cortisol receptor antagonist (mifepristone), a cortisol synthesis inhibitor (metyrapone), or net-chased twice a week for two min until gonads were differentiated (77–89 days). Long term cortisol administration partially masculinized all female fish, but repeated net-chasing did not alter sex differentiation relative to the control group. Blocking cortisol receptor binding delayed sex differentiation in some individuals, but overall led to increased masculinization compared to control fish. The proportion of treatment fish that developed as males suggests a functionally, diandric protogynous reproductive strategy in this species. We also identified a glucocorticoid response element in the gonadal aromatase (cyp19a1a) promoter, indicating a possible relationship between cortisol and cyp19a1a gene expression. Highlights • Long-term cortisol administration partially masculinized all black sea bass, but repeated acute stressors did not alter sex differentiation. • Blocking cortisol receptor binding, but not cortisol synthesis, delayed sex differentiation in some individuals. • A partial aromatase promotor sequence was identified and contained response elements associated with sex differentiation. • Although black sea bass are protogynous hermaphrodites, 2050% of the fish in all treatments differentiated directly as males. [ABSTRACT FROM AUTHOR]

Alteration and degradation of benthic structure by fishing gear can impede efforts to manage fish stock sustainably. Although the impacts of mobile gear are well known, effects of passive gear (e.g. fish traps) upon structure have been little studied. We modified commercial traps for American lobster Homarus americanus and black sea bass Centropristis striata by attaching GoPro®cameras to ascertain the degree and nature of impacts to seafloor habitats. Customized traps were included within a line of 20 traps, deployed and retrieved according to standard commercial fishing practice. Less than 5% of traps landed directly on bedforms when deployed. However, during retrieval traps dragged along the ocean floor, increasing trap–habitat contact rate to 50%, and causing traps to collide with corals, bryozoans, and other epifauna. Drag time of traps depended on the position in the trap line. Experimentally extending the trap line reduced drag time during retrieval for traps near the distal end of the line. Our results show that impacts of commercial trap fishing can be substantial during trap retrieval, and that the impact depends on their location on a trap line. Fishing practices should be developed that minimize effects of trap retrieval on structural benthic habitat. [ABSTRACT FROM AUTHOR]

Aquaculture of Japanese eel Anguilla japonica relies upon the natural recruitment of their glass eels (juveniles); however, predation that could influence glass eel recruitment remains unknown. In the present study, we aimed to elucidate the proportion of predation on A. japonica glass eels through stomach content analysis of predatory fishes collected in the estuary region of the Tone River system and its vicinity in Japan. Species of the predated glass eels were identified by DNA barcoding. A total of 270 predatory fishes of 15 taxa was collected over 2 years. The overall proportion of predation on glass eels, genetically identified as Japanese eel, was 0.7%, but this rose to 2.0% when data were limited to fishes caught during the peak months of glass eel recruitment. A glass eel was found in the stomach contents of a channel catfish Ictalurus punctatus, an invasive species in this river system, and a blackfin sea bass Lateolabrax latus. These fishes are therefore considered potential predators of A. japonica glass eels. However, as the proportion of predation was low, and the glass eels represented only small proportions of predator stomach contents, further investigation is needed for a better understanding of predation on A. japonica glass eels, and its effects on the early life stages of this endangered species. [ABSTRACT FROM AUTHOR]

Failure to account for time‐varying detection ranges when inferring space use of marine species from passive acoustic telemetry data can bias estimates and result in erroneous biological conclusions. This potential source of bias is widely acknowledged but often ignored in practice due to a lack of available statistical methods.Here, we describe and apply a spatial point process model for estimating individual centres of activity (COAs) from acoustic telemetry data that can be modified to account for both receiver‐ and time‐specific detection probabilities. We use simulation testing to evaluate the suitability of the proposed models for estimating COAs and compare their performance to that of the popular mean‐weighted COA method for a variety of scenarios. We illustrate how the approach can be applied to correct for variable detection ranges by integrating data from moored test tags and demonstrate how accounting for time‐varying detection probabilities can impact space use estimates by fitting the model to data collected from a black sea bass (Centropristis striata) on a receiver array off the east coast of the United States.The proposed model reduced bias in COA estimates, particularly when tagged individuals occurred along the periphery of the receiver array. The test tag‐integrated model largely corrected the bias associated with receiver‐ and time‐specific detection probabilities. When applied to the black sea bass detection data, the model revealed fine‐scale movements not apparent when detection ranges were assumed constant.Spatial management practices for coastal marine species are often based on trends in space use inferred from passive acoustic telemetry data, which can be misinterpreted when factors influencing detection ranges are not accounted for. Our approach provides a general framework for estimating individual COAs that can be modified on a study‐specific basis to ensure resulting patterns of space use reflect a species' movements and behaviour, rather than variation in receiver detection ranges. [ABSTRACT FROM AUTHOR]

Abstract: A feeding trial was conducted to determine the maximum substitution limits of poultry by‐product meal (PBM; 66% crude protein) protein for fish meal (FM; 59% crude protein) protein in the diet of juvenile Black Sea Bass Centropristis striata (family Serranidae). Eight isonitrogenous (44% crude protein) and isolipidic (13% crude lipid) diets were formulated to replace FM protein with PBM protein at 0 (control), 40%, 50%, 60%, 70%, 80%, 90%, and 100% in Black Sea Bass diets. Diets were fed twice daily to triplicate groups of juveniles (initial mean weight = 1.2 g) to apparent satiation for 8 weeks in a recirculating aquaculture system. Final survival was excellent (95–100%) in all diet treatments, with no significant differences. No significant differences in body weight gain (BWG) were observed in fish fed the 40–90% PBM protein diets (1,136–1,357%) compared with the control diet (1,307%). However, BWG of fish fed the 100% PBM protein diet (1,045%) was significantly lower than in the control group. Regression analysis with BWG indicated that PBM protein can replace FM protein in Black Sea Bass diets at levels as high as 81.8%, with no reduction in fish growth performance. For fish fed diets with up to 90% PBM protein, feed conversion (1.08–1.17) and protein efficiency ratios (2.01–2.14) were not significantly different from fish fed a control 100% FM‐protein‐based diet (0.99 and 2.29, respectively). Apparent digestibility coefficients of dietary protein remained high (81.6–87.0%) under all levels of FM replacement with PBM protein. After the feeding trial, whole body and muscle protein content and the concentrations of whole body n‐3 polyunsaturated fatty acids showed no significant differences among the treatments at FM protein replacement levels up to 90%. Poultry by‐product meal is a promising alternative protein source for sustainable diet development in Black Sea Bass. [ABSTRACT FROM AUTHOR]

In this study, we applied systematic adaptive cluster sampling (SACS) to assess the abundance of black sea bass Centropristis striata on hard bottom habitats in the Mid-Atlantic Bight (MBA; USA). We used a remote underwater video system to obtain video recordings of black sea bass from 25 June to 6 August 2013 within a 25-square nautical mile (nmi) sampling region. Data in the form of fish counts were collected from video recordings and used to estimate parameters including sample means and population totals of black sea bass for two adaptive cluster sampling estimators and a single systematic sampling estimator. The precision and relative efficiencies of the parameter estimates were also calculated and compared. In total, two adaptive cluster samples were encountered within the sampling region. Sample means and population totals were largest for the systematic sampling (SS) estimator while the adaptive sampling estimators produced parameter estimates with the lowest variances and highest precision. Our results indicated that SACS was more efficient and advantageous with respect to sampling costs [i.e., sampling time (hours) and travel distance (kilometers)] than SS alone for assessing the abundance of clustered populations of C. striata on hard bottom habitats in the MBA. [ABSTRACT FROM AUTHOR]

Sex change has been widely documented in many commercially and recreationally important fish species, yet the implications of this life history trait are not considered in most stock assessments. This omission can lead to poor estimates of parameters vital to understanding the health of sequentially hermaphroditic stocks. Here, we present a game theoretic approach to model the sex changing behaviour of a stock of protogynous (female first) hermaphroditic fish and produce estimates of maximum sustainable yield (MSY), equilibrium biomass at MSY (BMSY) and sex ratio, then compare these reference points to those from an otherwise identical gonochoristic (non-sex changing) stock. We tested each stock at varying levels of exploitation and with a range of assumptions about how sex ratio impacts fertilization rate. We show that a protogynous hermaphroditic stock with flexible timing of sex change produces similar MSY and slightly higher BMSY than a gonochoristic stock with otherwise identical vital rates. Sex changing stocks were also able to maintain a higher proportion of males in the population than did non-sex changing stocks as exploitation increased. Although sex changing stocks were able to maintain their sex ratio, the age at which females changed sex decreased with increased exploitation, suggesting smaller body size, and presumably lower fecundity, for females in heavily exploited sex changing stocks. Our game theoretic approach to evaluating hermaphroditic stocks can accommodate a wide variety of sex changing cues and behaviours and allows a flexible model for understanding the effects of exploitation on hermaphroditic stocks. [ABSTRACT FROM AUTHOR]

Feeding live prey organisms in a commercial marine fish hatchery requires significant labor and resources. The effects of feeding frequency of live rotifers and Artemia on growth, survival, hyposalinity stress resistance, and Na + /K + ATPase activity in black sea bass larvae Centropristis striata were evaluated. Newly hatched larvae (day 0 post-hatching = d0ph) were stocked (53 larvae/L) into twenty-four 30-L tanks supported by a recirculating seawater (35 g/L) system in a controlled-environment laboratory. Temperature (22 °C), aeration (225 mL/min), light intensity (~ 1000 lx), and photoperiod (18 L: 6 D) were constant. Beginning on d3ph, larvae were fed a prescribed daily ration of live prey (enriched s-type rotifers and/or Artemia nauplii), but distributed at different frequencies: (1) 1 ×/d at 0800 h, (2) 2 ×/d at 0800 and 1600 h, (3) 3 ×/d at 0800, 1200 and 1600 h, and (4) 4 ×/d at 0800, 1200, 1600 and 2000 h, with six replicate tanks per treatment. The daily ration of live prey (maximum of 750,000 rotifers and 90,000 Artemia ) was divided equally among feedings; therefore, prey density at each feeding (i.e., meal size) decreased at higher frequencies. By d31ph, larvae fed 4 ×/d showed significantly ( P < 0.05) greater notochord length and SGR (mean ± s.e. = 7.05 ± 0.20 mm and 20.1 ± 0.467%/d) compared to larvae fed 1 ×/d (6.02 ± 0.11 mm, and 18.1 ± 0.204%/d) or 2 ×/d (6.08 ± 0.12 mm and 18.4 ± 0.399%/d). Feeding frequency had no effect on larval survival (23.8–38.2%) or whole body fatty acid composition. Ability to withstand an acute hyposalinity (10 g/L) challenge on d32ph was significantly poorer in larvae fed 1 ×/d than in those fed 2 ×/d, 3 ×/d or 4 ×/d. Following transfer to a sub-lethal salinity (15 g/L) on d32ph, Na + /K + ATPase activity (μmol ADP/mg protein/h) was higher in larvae fed 3 ×/d (5.61) than in those fed 4 ×/d (5.22) or 1 ×/d (5.20). The largest larvae (4 ×/d treatment) showed reduced Na + /K + ATPase activity (vs 3 ×/d), likely due to accelerated development and a shifting of the Na + /K + ATPase from a global distribution to specialized osmoregulatory sites. The results demonstrated that, for a prescribed total daily ration, feeding lower prey densities (smaller meals) at higher frequencies (3 ×/d or 4 ×/d) improved larval growth and resistance to hyposalinity stress and may increase osmoregulatory ability, without affecting survival. These findings delineate more judicious use of limited live prey resources to maximize larval growth and vitality during hatchery production of pre-metamorphic stage black sea bass. Statement of relevance Live prey (rotifers and Artemia ) are expensive to produce and can limit production of juvenile fish in a commercial marine fish hatchery. The results show that given a prescribed (albeit moderate) total daily ration of prey, feeding lower prey concentrations at higher frequencies optimized larval growth performance and vitality in black sea bass raised from first-feeding through pre-metamorphic stages. [ABSTRACT FROM AUTHOR]

Fish traps were soaked for long (d) and short (min) intervals to examine the relationship between the catch of Black Sea BassCentropristis striataand soak time for traps used in the Middle Atlantic Bight commercial fishery. First, we soaked traps over a 14-d period to examine how catch changes over time and modeled catch as a function of soak time using two three-parameter models from the literature. Maximum catches were obtained after 11 soak days before declining. Models applied to catch and soak time data fit reasonably well and may be used to correct for changes in soak time to develop abundance estimates. Second, we used a modified trap equipped with video cameras to observe fish interactions, including entry and escapement dynamics with traps over short (~60 min) soak times. Out of all the fish that were observed entering the trap, 48 (84.2%) exited while 9 (15.8%) were caught. Patterns for cumulative distributions of entries and exits indicated that entry and escapement behaviors may lead to saturation in Black Sea Bass traps used in the Middle Atlantic Bight. Additional study is needed to examine the dynamics of the saturation process and to elucidate how well trap catches reflect true abundance. Received February 2, 2016; accepted September 7, 2016 Published online December 20, 2016 [ABSTRACT FROM AUTHOR]

A tagging study was conducted off the New Jersey coast to study sex change in Black Sea Bass Centropristis striata as a function of size, age, and spawning season. Throughout 2011–2013, 3,670 fish were measured and 1,498 were tagged from research, charter, and commercial fishing vessels. Of the tagged fish, 437 were recaptured. Size at 50% probability of sex change was 355 mm TL; the proportion of female fish in sexual transition increased with body size from 0.5% at 175–225 mm to 15.7% at 375–425 mm and increased with age from 0.6% at 3 years old to 18.2% at 6 years old. Relatively few females (8 of 107) changed sex during the spawning season, but a larger proportion (8 of 22 females) transitioned between spawning seasons. The proportion of females with transitional gonads was lowest at the start of the spawning season in June (0.2%), slowly increased over the summer, and sharply peaked just after the spawning season in October (9.5%). In addition, a high proportion of young mature fish were male (40% at age 2), which may indicate the presence of primary males. This is the first tagging study to estimate sex change as a function of size, age, and season in a protogynous hermaphroditic fish species. Use of tagging avoids potential problems that are associated with inferring sex change rates from sex ratios based on catch data. [ABSTRACT FROM AUTHOR]

Eight isonitrogenous (46% crude protein) and isolipidic (14% crude lipid) diets were formulated for juvenile black sea bass Centropristis striata to replace menhaden fish meal (FM) protein (59.5% CP) by three cottonseed meal (CSM) proteins: a CSM prepared from glandless seed (GCSM, 50.4% CP), a CSM that had been solvent extracted with acidic ethanol to remove the gossypol (SCSM, 53.8% CP), and a CSM prepared from regular (glanded) cottonseed (RCSM, 45% CP). Three diets replaced 50, 75 and 100% of FM protein with GCSM, and three diets replaced 50, 75 and 100% of FM protein with SCSM. One diet replaced 100% FM protein with RCSM protein. A control diet (0% CSM) was formulated with high FM protein and other practical protein sources. l -methionine and l -lysine were supplemented to the diets to equal the control diet. Fifteen fish were stocked in each of twenty-four 75-L tanks, and each test diet was fed to triplicate groups of fish (mean initial weight = 7.7 ± 0.10 g) for 56 days at 22–24 °C, 32–35 salinity, and ambient photoperiod conditions. Fish were fed twice per day to apparent satiation. Final (day 56) mean body weight (BW, 24.16–31.62 g), body weight gain (BWG, 211.2–311.3%), specific growth rate (SGR, 1.70–2.18%/d), and feed intake (FI, 0.37–0.43 g/fish/d) were not significantly different ( P > 0.05) among the control, GCSM or SCSM treatments, but were reduced ( P < 0.05) for the 100% RCSM treatment (20.09 g, 159.5%, 1.45%/d, and 0.25 g/fish/d, respectively). Lower palatability of the RCSM diet was attributable to the anti-nutrient compound gossypol. No significant differences in survival (84.1–97.8%), feed conversion ratio (FCR, 1.05–1.33), protein efficiency ratio (PER, 1.62–2.08), or whole body protein or lipid composition were observed among the fish fed the low-gossypol diets. Gossypol (25.9 mg/kg) was only detectable in the livers of fish fed the high-gossypol RCSM diet. Fish whole body essential amino acid compositions did not differ significantly among treatments. Whole body n − 3 PUFAs decreased, while n − 6 PUFAs increased with increasing CSM protein in the diets. The apparent digestibility coefficient of protein was high (83.1–87.1%) for all treatments. For juvenile black sea bass, 75% FM in the diet can be replaced with low-gossypol CSM protein prepared by solvent-extraction, and 100% of FM can be replaced with low-gossypol CSM protein prepared from glandless seed with no adverse effects on survival, growth or feed utilization. Statement of relevance Cotton seed flour is an inexpensive agricultural by-product. The results demonstrate successful replacement of fish meal protein with genetically-improved cottonseed flour protein in the diet of black sea bass. These findings may substantially lower aquafeed costs (a key operational cost) for finfish growout operations to boost profitability and accelerate expansion of commercial production of black sea bass and other finfish species. [ABSTRACT FROM AUTHOR]

Fish species that are protogynous hermaphrodites generally have sex ratios skewed toward males at large sizes. These skewed sex ratios at length can make a stock more vulnerable to overexploitation, particularly in fisheries where minimum size is regulated, resulting in the removal of reproductively active males. We developed a length-based population model to test the vulnerability to exploitation of a population with an atypical protogynous life history, in particular the northern stock of black sea bass (Centropristis striata). Black sea bass north of Cape Hatteras, North Carolina, are unusual for protogynous species in that they may undergo prematurational transformation, remain female at large sizes, involve secondary males in spawning, and undertake seasonal migrations. The model was developed to examine the impact of participation by secondary males in population productivity, the influence of size at sex transformation, and the subsequent robustness of the population under exploitation, in comparison with equivalent gonochoristic and typical protogynous populations. Although the model does not capture all the dynamics of a population, such as density-dependent regulation of sex transformation, our results indicate that the northern stock of black sea bass may be more resilient in response to exploitation than would be expected if they were typical protogynous hermaphrodites. [ABSTRACT FROM AUTHOR]

We used fish body depth to predict trap center-to-center mesh sizes that would optimize size selection of black sea bass Centropristis striata for both current and proposed minimum size limits for this species. We fished trap types of five different square mesh sizes/configurations: (1) 38.1 mm mesh, (2) 38.1 mm mesh on five sides and 50.8 mm mesh on one side (back panel trap), (3) 50.8 mm mesh, (4) 57.2 mm mesh, and (5) 63.5 mm mesh. The 38.1 mm mesh trap was the control trap type. Back panel traps are the minimally legal mesh configuration in this region while 50.8 mm mesh traps are commonly used in this fishery to further reduce culling of sub-legal black sea bass by fishers. Two previously untested mesh sizes, 57.2 and 63.5 mm, were evaluated because a previously published morphometric relationship between black sea bass body depth and total length (TL) predicted that the diagonal openings of these two respective mesh sizes would retain black sea bass close to the current (279 mm) and proposed minimum TL limits (305 mm). We estimated size selection of each experimental trap type by comparing catches of control and experimental traps. All but the back panel trap displayed relatively steep selection around the fish length at which 50% of individuals were selected ( l 50 ). Initial size at retention ( l 10 ) by the 57.2 and 63.5 mm trap types were nearly identical to current and proposed minimum fish sizes, respectively. Predictions from the body depth: TL relationship were very similar to estimates of l 10 and l 50 , based on uncompressed body depth and compression to 93%. The 57.2 mm mesh and 63.5 mm mesh trap types maintained catches of legal fish but reduced catches of sub-legal fish compared to the back panel and 50.8 mm mesh trap types. Relative to back panel and 50.8 mm mesh traps, use of 57.2 mm mesh traps would reduce rates of discard and discard mortality given current size limits in this fishery. [ABSTRACT FROM AUTHOR]

Black sea bass (Centropristis striata) migrations are believed to play a role in overwinter survival and connectivity between juvenile and adult populations. This study investigated oceanographic drivers of winter habitat choice and regional differences between populations of juvenile and adult black sea bass. Trends in cohort strength, as a result of juvenile survival, were also identified. Oceanographic and fisheries survey data were analyzed using generalized additive models. Among the oceanographic variables investigated, salinity was the main driver in habitat selection with an optimal range of 33–35 practical salinity units (PSU) for both juveniles and adults. Preferred temperature ranges varied between juveniles and adults, but held a similar minimum preference of >8°C. Salinity and temperature ranges also differed by regions north and south of Hudson Canyon. Shelf water volume had less of an effect than temperature or salinity, but showed an overall negative relationship with survey catch. The effect of winter conditions on juvenile abundance was also observed across state and federal survey index trends. A lack of correlation observed among surveys in the fall paired with a strong correlation in the spring identifies the winter period as a factor determining year-class strength of new recruits to the population. A rank order analysis of spring indices identified three of the largest year classes occurring during years with reduced shelf water volumes, warmer winter shelf waters, and a 34 PSU isohaline aligned farther inshore. While greater catches of black sea bass in the northwest Atlantic Ocean remain south of Hudson Canyon, the species’ range has expanded north in recent years. [ABSTRACT FROM AUTHOR]

Traps are among the most common gears used to capture fish and crustaceans. When traps are deployed in surveys, the data gathered are often used to develop an index of abundance. However, trap catches are known to saturate over time for various reasons, such as space limitation of the gear or intraspecific interactions, and these features can dissociate the catch from local abundance. In this study, we develop a hierarchical state-space model of trap dynamics that is fit to data in a Bayesian framework. The model links trap catch to estimated local abundance, and additionally provides direct estimates of capture probability. For demonstration, we apply the model to data on black sea bass (Centropristis striata), which were collected using chevron traps combined with video cameras to give continuous-time observations of trap entries and exits. Results are consistent with the hypothesis that trap catch is generally proportional to local abundance. The model has potential application to surveys where animals not only enter a trap, but also may exit, such that the apparent trap saturation occurs because the system approaches equilibrium. [ABSTRACT FROM AUTHOR]

Two feeding trials were conducted to investigate the effects of dietary sea salt supplementation on growth and survival of black sea bass Centropristis striata reared under sub-optimal salinity conditions at 15 and 10 g L − 1 . In experiment 1, six iso-nitrogenous (46% crude protein) and iso-lipidic (10% lipid) test diets containing a mineral premix were formulated to supplement graded levels (0, 2.5, 5, 7.5, 10, and 12.5% dry wt.) of natural sea salt (99.9% NaCl). Diets were fed twice daily to juveniles (mean wt. = 8 g) held in triplicate 75-L tanks at a salinity level of 15 g L − 1 under controlled laboratory conditions for 56 days. In experiment 2, six natural salt-based diets as in experiment 1 and another diet with 0% salt and no mineral mix were formulated. Diets (experiment 2) were fed to triplicate groups of fish (mean wt. = 9.37 g) held at 10 g L − 1 salinity for 70 days. In both experiments, final survival was 78–97%, with no treatment differences. At 15 g L − 1 (experiment 1), no differences in weight gain were observed among dietary salt treatments. In contrast, a 5% salt diet significantly (P < 0.05) improved fish growth (vs 0% dietary salt) of fish raised at 10 g L − 1 (experiment 2), a salinity producing lower plasma osmolality (237–285 mOsm L − 1 ) and osmoregulatory stress than at 15 g L − 1 (330–350 mOsm L − 1 ). At the end of experiment 2, fish fed > 5% salt at 10 g L − 1 showed higher survival when challenged with a further reduction in salinity to 4 g L − 1 . Gill Na + /K + ATPase activities appeared to be higher in fish fed the diet with highest level (12.5%) of supplemental salt, whereas intestinal Na + /K + ATPase activity appeared to be maximal at lower levels of dietary salt. Irrespective of dietary salt treatment, black sea bass juveniles maintained good growth and survival and normal whole body electrolyte concentrations at rearing salinities of 10 and 15 g L − 1 , indicating that these fish are good osmoregulators and could be potentially cultured under these low salinities. The results indicate that dietary salt supplementation at 5% improved growth and averted mortality under low salinity conditions. These findings may enable black sea bass to be grown in recirculating aquaculture systems in low-salinity brackish water. Relevance with commercial aquaculture These results indicate that dietary salt supplementation may be used to avert mortality when a producer is faced with adversely low salinity conditions due to weather and tides as may occur in coastal black sea bass fish farms sourcing brackish water from tidal creeks. [ABSTRACT FROM AUTHOR]

Climate change and fishing can have major impacts on the distribution of natural marine resources. Climate change alters the distribution of suitable habitat, forcing organisms to shift their range or attempt to survive under suboptimal conditions. Fishing reduces the abundance of marine populations and truncates their age structure leading to range contractions or shifts. Along the east coast of the United States, there have been major changes in fish populations due to the impacts of fishing and subsequent regulations, as well as changes in the climate. Black sea bass, scup, summer flounder, and winter flounder are important commercial and recreational species, which utilize inshore and offshore waters on the northeast shelf. We examined the distributions of the four species with the Northeast Fisheries Science Center trawl surveys to determine if the along-shelf centres of biomass had changed over time and if the changes were attributed to changes in temperature or fishing pressure through changes in abundance and length structure. Black sea bass, scup, and summer flounder exhibited significant poleward shifts in distributions in at least one season while the Southern New England/Mid-Atlantic Bight stock of winter flounder did not shift. Generalized additive modelling indicated that the changes in the centres of biomass for black sea bass and scup in spring were related to climate, while the change in the distribution of summer flounder was largely attributed to a decrease in fishing pressure and an expansion of the length-age structure. While the changes in ocean temperatures will have major impacts on the distribution of marine taxa, the effects of fishing can be of equivalent magnitude and on a more immediate time scale. It is important for management to take all factors into consideration when developing regulations for natural marine resources. [ABSTRACT FROM AUTHOR]

A pilot-scale finfish mariculture hatchery was established at the University of North Carolina Wilmington. In 2011, research-based hatchery protocols were scaled up to produce 37,000 advanced (1–5 g) black sea bass fingerlings. Based on engineering, biological, and cost data from operating the pilot hatchery, an economic analysis of a hypothetical commercial scale black sea bass hatchery operation was conducted. The financial performance of two alternative facilities that produce 97,200 5-g and 388,800 1-g fingerlings per year over a 30-year project life showed cumulative net present value (NPV) of $445,000, and $3,168,000, modified internal rates of return (MIRR) of 6.52% and 10.52%, and per unit breakeven prices of $1.67 and $0.47, respectively. Sensitivity analyses showed that final stocking density was critical to financial performance. Fingerlings were supplied to startup growers in NC and in VA, and market-size fish from these growout facilities were distributed (live or whole on ice) to premium-value markets on the eastern seaboard. This pilot hatchery is enabling new farmers to access fingerlings, establish growout technology and understand market value and demand. [ABSTRACT FROM PUBLISHER]

Teleost fish exhibit diverse reproductive strategies, and some species are capable of changing sex. The influence of many endocrine factors, such as gonadal steroids and neuropeptides, has been studied in relation to sex change, but comparatively less research has focused on gene expression changes within the brain in temperate grouper species with non-haremic social structures. The purpose of the present study was to investigate gonadotropin releasing hormone (GnRH) and brain aromatase (cyp19a1b) gene expression patterns during reproductive development and sex change in protogynous (female to male) black sea bass ( Centropristis striata ). Partial cDNA fragments for cyp19a1b and eef1a (a reference gene) were identified, and included with known gnrh2 and gnrh3 sequences in real time quantitative PCR. Elevated cyp19a1b expression was evident in the olfactory bulbs, telencephalon, optic tectum, and hypothalamus/midbrain region during vitellogenic growth, which may indicate changes in the brain related to neurogenesis or sexual behavior. In contrast, gnrh2 and gnrh3 expression levels were largely similar among gonadal states, and all three genes exhibited stable expression during sex change. Although sex change in black sea bass is not associated with dramatic changes in GnRH or cyp19a1b gene expression among brain regions, these genes may mediate processes at other levels, such as within individual hypothalamic nuclei, or through changes in neuron size, that warrant further research. [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated that circle hooks modified with an appendage can reduce the occurrence of deep hooking in some fishes. To determine whether this modification affects total catch and deep-hooking rate of Black Sea BassCentropristis striatain a recreational fishery off the coast of Florida, anglers were provided with standardized gear that included one appendaged and one nonappendaged hook. Both hook types were fished equally, and a greater number of Black Sea Bass were caught on appendaged hooks (n= 301) than on nonappendaged hooks (n= 221). There was no significant difference in the mean TL (P= 0.80) of jaw- or deep-hooked fish during the study. Logistic regression was applied to the data using anatomical hooking location as the dependent variable and angler, hook position, and hook type as categorical factors. Hook type was the only significant variable in the final model (P= 0.03) in which fewer fish were deep hooked on appendaged hooks (0.96%) than on nonappendaged hooks (2.11%). Our findings indicate appendaged hooks are capable of reducing deep hooking of Black Sea Bass without reducing catch rates or altering size composition of the catch. Received February 3, 2014; accepted August 14, 2014 [ABSTRACT FROM AUTHOR]