Striped Bass Research Articles

Left out in the cold: the understudied overwintering ecology of striped bass in Canada

Striped Bass in Canadian waters occur at the most northern extent of the species range. At these latitudes, overwintering represents a significant portion of annual activities (Nov- May). During the winter period, Striped Bass generally occupy inland waterways, aggregate densely, feed little, and conduct minimal movements rendering them vulnerable to fisheries exploitation, pollution and habitat alterations. Despite the importance of winter survival to population viability, the winter period remains an understudied aspect of Striped Bass ecology throughout the species range. Here we review what is known as well as the knowledge gaps regarding the overwintering ecology for Striped Bass in Canadian waters. We discuss: all reported Canadian Striped Bass overwintering locations and their characteristics; environmental conditions that may be required for Striped Bass winter survival; environmental cues that may cause Striped Bass to enter overwintering habitats in late fall and depart in early spring; possible threats to overwintering habitat; and we propose numerous research questions necessary for improving Striped Bass conservation and management both within Canada and across the species range.

Non-Native Fish Predator Density and Molecular-Based Diet Estimates Suggest Differing Impacts of Predator Species on Juvenile Salmon in the San Joaquin River, California

The Sacramento-San Joaquin Delta is a major survival bottleneck for imperiled California salmonid populations, which is partially due to a multitude of non-native fish predators that have proliferated there throughout the 20th century. Understanding the diets of salmonid predators is critical to understanding their individual impacts, role in the food web, and the implications for potential management actions. We collected the stomach contents of Striped Bass Morone saxatilis, Largemouth Bass Micropterus salmoides, Channel Catfish Ictalurus punctatus and White Catfish Ameiurus catus sampled from three 1-km reaches in the lower San Joaquin River in 2014 and 2015 during the peak juvenile salmon outmigration period. We tested each stomach (n = 582) for the presence of juvenile Chinook Salmon Oncorhynchus tshawytscha and other prey items using a genetic barcoding technique. Channel Catfish had significantly higher frequency of Chinook Salmon in their stomachs (27.8% of tested Channel Catfish contained Chinook Salmon DNA), compared to the other three predators (2.8% to 4.8%). However, non-native fish species occurred at greater frequencies in the diets of all four predator species than salmon. Using depletion estimation from electrofishing, we were able to generate population densities for Striped Bass and Largemouth Bass in our reaches. Largemouth Bass were evenly distributed throughout all three reaches, at a mean density of approximately 333 (± 195 SE) per km of river. Striped Bass were patchily distributed, ranging from 21 to 1,227 per km. Extrapolating the frequency of salmon detected in stomachs to the predator abundance estimates, we estimate that the population of Largemouth Bass we sampled consumed between 3 and 5 Chinook Salmon per day per 1-km study reach (consumption rate of 0.011 salmon per predator per day), whereas the Striped Bass population consumed between 0 and 24 Chinook Salmon per day (0.019 salmon per predator per day).

Transport Stress Mitigation and the Effects of Preanesthesia on Striped Bass

AbstractThe demand for Striped BassMorone saxatilisas food and sport fish has generated interest in developing effective transport and handling protocols. Studies have shown that anesthetics and elevated salinity can reduce transport stress in Striped Bass, but no studies have compared stress responses among strains or compared and combined treatments to maximize efficacy. In this study, 1‐h transport trials were conducted with subadults produced from wild‐caught (Florida strain) and domesticated Striped Bass. Fish were transported in freshwater (FW; 0‰) or brackish water (SW; 10‰) alone or containing either metomidate hydrochloride (hereafter, “metomidate”; 1 mg/L) or tricaine methanesulfonate (MS‐222; 25 mg/L). After transport, half the fish from each treatment were sampled for cortisol or stocked in a freshwater recirculating system to monitor their health and behavior for 7 d. In preanesthesia trials, Florida‐strain fish were netted and transferred to baths containing a single anesthetic (induction doses; 5‐mg/L metomidate or 150‐mg/LMS‐222), observed for nociception and recovery, and bled 1 h after anesthesia for cortisol analysis. Results from this traditional approach were compared to results for fish that were first exposed to low anesthetic doses (1‐mg/L metomidate or 25‐mg/LMS‐222) added directly to the culture tank prior to netting and then were transferred to baths containing induction doses of the same anesthetic. In transport studies, cortisol was elevated in theMS‐222 andFWtreatment groups compared to the metomidate andSWtreatment groups, respectively. Strain, feed consumption, and health were not correlated with cortisol measured following the transport stressor. In the preanesthesia study, metomidate blocked cortisol synthesis if added prior to or following handling, whileMS‐222 blocked nociception.

Evidence of a Genetically Distinct Population of Striped Bass within the Saint John River, New Brunswick, Canada

AbstractSound management of a species requires, among other things, careful consideration of their distribution and genetic structure throughout their range. Historically, there were three spawning populations of Striped Bass Morone saxatilis occurring within the Bay of Fundy, Canada (Shubenacadie River, Annapolis River, and Saint John River), but today the only known spawning population is found in the Shubenacadie River, Nova Scotia. The last spawning event recorded (albeit unsuccessful) in the Saint John River was in 1975 shortly after the completion of the Mactaquac Dam in 1968. Adult Striped Bass from other rivers frequent the Saint John River during much of the year, making the presence of adults uninformative about the status of spawning. In the absence of direct indicators of spawning, such as eggs and larvae, genomic tools can provide insight into the genetic origin of the juvenile Striped Bass in the Saint John River. Tissue samples were taken from Striped Bass (ages 1–3; 12.2–35.0 cm TL) captured in the Saint John River and compared with samples from the Shubenacadie River, Hudson River, and Chesapeake Bay. A double‐digest RAD‐seq technique was used to identify 4,700 single nucleotide polymorphisms, and population structure was assessed using population differentiation statistics (FST) and genetic clustering algorithms. The FST analysis found significant differences among all sample sites, albeit weak differences between Hudson River and Chesapeake Bay samples, and a global FST of 0.101. Genetic clustering analyses and discriminant analysis of principle components both grouped samples into three clusters: the Shubenacadie River, the U.S. populations, and the Saint John River juveniles. Based on these findings and the current understanding of Striped Bass juvenile dispersal, there is strong evidence of a genetically distinct population of Striped Bass within the Saint John River.

Listeria monocytogenes is inhibited on fillets of cold‐smoked sunshine bass, Morone chrysops × Morone saxatilis, with an edible corn zein‐based coating incorporated with lemongrass essential oil or nisin

Ready‐to‐eat (RTE) foods have been identified as a high‐risk food group because of the number of outbreaks caused by food‐borne pathogens isolated from these products. As these items receive no further processing or heat treatment prior to consumption, bacterial pathogens such as Salmonella, Staphylococcus aureus, Escherichia coli, and Listeria monocytogenes present a serious threat to consumer safety. Of particular concern, L. monocytogenes is resistant to various food storage techniques, including reduced or modified atmosphere packaging, refrigerated storage, and increased salt concentration. Cold‐smoked fishery products have been implicated in a number of listeriosis cases, where it is estimated that between 6 and 36% of cold‐smoked fish is contaminated with L. monocytogenes. Edible coatings incorporated with natural antimicrobials have been suggested to control pathogenic and spoilage bacteria on a variety of meat products. In this study, edible zein‐based coatings incorporated with nisin and lemongrass essential oil (LG) (8%) were evaluated for antibacterial action against L. monocytogenes and spoilage organisms on cold‐smoked, cultured hybrid striped bass, Morone saxatilis × Morone chrysops, under polyvinyl chlorine (PVC) and vacuum packaging for 14 days (PVC) and 42 days (vacuum packaging), respectively, at 4°C. In this study, corn zein‐based edible coatings were found to be an effective carrier for nisin and LG. Nisin‐treated samples were most effective against L. monocytogenes in both PVC and vacuum‐packaged fillets, with a total reduction of 3.5 log and 3.7 log, respectively over the length of the storage time. LG‐treated samples reduced L. monocytogenes cell counts by 2.5 log in PVC and 1.7 log in vacuum‐packaged samples. Only LG‐treated samples packaged in PVC were found to inhibit the growth of spoilage organisms. Because nisin‐ and LG‐treated fillets reduced L. monocytogenes, they may be useful methods to improve food safety in smoked seafood.

Estimating consumption rate of Atlantic salmon smolts (Salmo salar) by striped bass (Morone saxatilis) in the Miramichi River estuary using acoustic telemetry

Differentiating detections of a telemetered fish from those of predators that may have consumed that telemetered fish presents problems and opportunities. Previous efforts to classify predation events quantitatively have had to rely on data from unknown states of fish (i.e., unsupervised learning techniques) with the consequence that model performance cannot be refined or compared with alternate models. We circumvent this limitation by analysing acoustic telemetry track data to differentiate movement patterns of tagged striped bass (Morone saxitilis) from those of Atlantic salmon (Salmo salar) smolts, which were known to not have been predated by striped bass over a 3-year period in the Miramichi River estuary. A random forests classification model (i.e., supervised learning technique) was used to differentiate the movement patterns of these two species and the model was applied to Atlantic salmon smolt movement characteristics to provide an index of striped bass predation-derived mortality. The optimized random forests model inferred that predation rates by striped bass were highly variable between years for two smolt stocks, ranging from 1.9% to 17.5%. Spatial and temporal overlap of the two species is a likely factor defining the between stock and annual variation of predation rate estimates.

Nursery Habitat Quality Assessed by the Condition of Juvenile Fishes: Not All Estuarine Areas Are Equal

High-quality nursery habitats support greater numbers of juveniles that survive to adulthood, but characteristics underlying high-quality habitats remain elusive because their productivity varies spatially and temporally and may be species-specific. Fish condition is an energy-integrative measure of ecological interactions, stress, and activity within a habitat, such that juvenile fish condition is representative of the quality of nursery habitats. We apply spatially explicit models to examine patterns in nursery habitat quality of Virginia estuaries based on nutritional condition for Atlantic croaker Micropogonias undulatus, summer flounder Paralichthys dentatus, and striped bass Morone saxatilis. Environmental factors (water temperature, dissolved oxygen, salinity, and depth) positively influenced the condition of Atlantic croaker but had mixed effects on striped bass and summer flounder condition, despite co-location of these species. Over the observed range of environmental conditions, the potential impact of salinity was 1.7 to 6 times that of other environmental factors. The condition of Atlantic croaker was negatively influenced by conspecific density, indicating local abundance mediates habitat quality. Regional habitat effects on fish condition were apparent after adjusting for broad-scale environmental effects: on average, striped bass condition was 22% greater in habitats near tributary mouths, Atlantic croaker condition was 28% greater in upestuary habitats, and the adjusted mean condition of summer flounder associated with coastal lagoons and the eastern side of Chesapeake Bay was 100% greater than conspecifics from other regions. Not all habitats are equally suitable for juvenile stages of estuarine species, but locations that produce well-conditioned individuals reveal the environmental characteristics associated with high-quality nursery habitats that contribute to species-specific productivity.

Seasonal Movement Patterns of Striped Bass (Morone saxatilis) in Their Nonnative Range

Movement dynamics of nonnative species can change in new environments and differ from native populations. It has been more than 100 years since striped bass (Morone saxatilis) were introduced to the Sacramento-San Joaquin River system in California from the US east coast. Acoustic telemetry from 2011 to 2015 was used to examine striped bass seasonal residence patterns in their nonnative range across three regions—bay, delta and rivers, and the effect of fish length and release river (Sacramento River [SR] vs. Feather River [FR]) on movement. In spring, SR striped bass (n = 52) increased travel speed by 39% and river residence by 63% relative to other seasons, which is consistent with spawning migrations. In summer, SR striped bass spent the most time in the bay (mean = 28.2 ± 30.9 days) relative to other seasons and across regions. In winter, 87% of striped bass were detected in the delta over 42% in the bay and 25% in the river. Release river also affected movement behaviors—FR striped bass (n = 11) spent more time in the river in all seasons compared to SR bass. Striped bass with sufficient tag life (n = 17) traveled farther distances in 365 days (mean = 1248 ± 405 km, range: 641–2212 km) with increasing fish length. Seasonal patterns observed appeared to follow seasonal prey sources throughout the San Francisco Estuary. Individual behaviors, however, were highly variable, and this flexibility may be an important trait that has allowed striped bass to persist in their nonnative range.

Perceptions outweigh knowledge in predicting support for management strategies in the recreational Striped Bass (Morone saxatilis) fishery

Considering that recreational fisheries represent tightly bound social-ecological systems, the development of effective and holistic policy should involve the consideration of stakeholder interests and behaviors. Yet, integrating stakeholders’ input in fisheries management requires understanding and representing their different values, attitudes, and beliefs. Using survey data from recreational Striped Bass (Morone saxatilis) anglers in Massachusetts, this study examined relationships among angler knowledge and perceptions, fishing characteristics, and support for various fishery management measures (e.g., slot limit, reduced bag limits). Results revealed that most anglers underestimated the age at which female Striped Bass reach sexual maturity and the age at which Striped Bass grow to 40” in length. Estimated ages for both metrics increased with fishing experience, but estimates were not influenced by other angler characteristics. Importantly, while precise knowledge of Striped Bass age at maturity (i.e., proximity to actual age at maturity according to the literature) was not correlated with support for more restrictive fishing policies, anglers that believed Striped Bass mature at older ages (i.e., angler perceptions) were more supportive of these policies. Given that a large majority of anglers underestimate Striped Bass age at maturity, initiatives to communicate Striped Bass biology to the angling public could further enhance support. Collectively, these findings illustrate how stakeholder perceptions may influence angler support for fisheries management policies.

Dermal mycobacteriosis and warming sea surface temperatures are associated with elevated mortality of striped bass in Chesapeake Bay.

Temperature is hypothesized to alter disease dynamics, particularly when species are living at or near their thermal limits. When disease occurs in marine systems, this can go undetected, particularly if the disease is chronic and progresses slowly. As a result, population‐level impacts of diseases can be grossly underestimated. Complex migratory patterns, stochasticity in recruitment, and data and knowledge gaps can hinder collection and analysis of data on marine diseases. New tools enabling quantification of disease impacts in marine environments include coupled biogeochemical hydrodynamic models (to hindcast key environmental data), and multievent, multistate mark–recapture (MMSMR) (to quantify the effects of environmental conditions on disease processes and assess population‐level impacts). We used MMSMR to quantify disease processes and population impacts in an estuarine population of striped bass (Morone saxatilis) in Chesapeake Bay from 2005 to 2013. Our results supported the hypothesis that mycobacteriosis is chronic, progressive, and, frequently, lethal. Yearly disease incidence in fish age three and above was 89%, suggesting that this disease impacts nearly every adult striped bass. Mortality of diseased fish was high, particularly in severe cases, where it approached 80% in typical years. Severely diseased fish also had a 10‐fold higher catchability than healthy fish, which could bias estimates of disease prevalence. For both healthy and diseased fish, mortality increased with the modeled average summer sea surface temperature (SST) at the mouth of the Rappahannock River; in warmer summers (average SST ≥ 29°C), a cohort is predicted to experience >90% mortality in 1 year. Regression of disease signs in mildly and moderately diseased fish was <2%. These results suggest that these fish are living at their maximum thermal tolerance and that this is driving increased disease and mortality. Management of this fishery should account for the effects of temperature and disease on impacted populations.

Striped Bass Early Life History in the Macrotidal Shubenacadie River

AbstractThis 9‐year study (2008–2016) on the Shubenacadie River estuary in Nova Scotia yielded new insight into the only confirmed nursery habitat for the Bay of Fundy population of Striped Bass Morone saxatilis. In 7 of 9 years, the initial large spawning episode occurred between May 16 and June 1, after the accumulation of 11 to 20 degree‐days above 12°C. Most of the spawning occurred within about 3 weeks in May and June but could run into July. Egg abundance at river kilometer (rkm) 25 (measured from the estuary mouth) exceeded 1,000 eggs/m3 after the largest episodes due to the narrow estuary and high numbers of spawners. The pelagic eggs and prefeeding larvae were passively transported up and down the estuary by the strong tide, their distribution highly dependent on salinity. The salt front defined the upstream boundary of the nursery habitat, with the eggs and larvae normally distributed between 0.15‰ and 15‰ (above rkm 10). The abundance of first‐feeding larvae (5–7 mm TL) in the upper estuary (above rkm 25) was highest (&gt;500/m3) during years when May–June was warm and dry and saltwater intrusion was high (above rkm 32). Heavy rain after spawning was an important lethal factor, limiting saltwater intrusion to rkm 25 and increasing the risk of advection of eggs and larvae into Cobequid Bay. During June, a lack of copepod prey caused larvae to fail to grow, suggesting that starvation is an important lethal factor. Growth from July onwards was limited by temperature but not food: mysids were highly abundant and an important prey for young of the year (&gt;15 mm TL). By late August juvenile mean total length was &gt;9 cm in warm summers but &lt;5 cm in cooler years. Juveniles were widely dispersed in the estuary and Cobequid Bay through September; their apparent abundance each year was poorly related to larvae abundance.

Exploring Causal Factors of Spawning Stock Mortality in a Riverine Striped Bass Population

AbstractThe recovery of the Atlantic Striped Bass Morone saxatilis stock in the 1990s is an important example of effective natural resources management. Implementation of Atlantic States Marine Fisheries Commission (ASMFC) harvest regulations reduced mortality, protected older and more fecund females, and contributed to the formation of dominant year‐classes in the 1980s and 1990s. However, Striped Bass stocks south of Albemarle Sound, North Carolina, are not subject to ASMFC management plans, and many populations have failed to attain recovery goals. Catch‐curve analyses indicate that the Neuse River Striped Bass population continues to experience spawning stock exploitation rates similar to those implicated in the decline of the Atlantic Migratory and Albemarle Sound/Roanoke River stocks in the 1970s. From 1994 to 2015, Striped Bass instantaneous fishing mortality (F) in the Neuse River ranged from 0.12 to 0.84 and exceeded the overfishing threshold (FThreshold = 0.41) in 12 of 22 years. A global linear model using environmental and exploitation factors accounted for 55% of the variability in spawning stock discrete annual mortality. An information‐theoretic approach was used to elucidate the best linear model for predicting discrete annual mortality. The best model included previous‐year gill‐net effort and same‐year commercial harvest (Akaike weight = 0.64, R2 = 0.50). Model‐averaged coefficients for gill‐net effort and commercial harvest suggested total exploitation impacts that were congruent with other studies of Neuse River Striped Bass. Results indicate that reducing exploitation to target levels will require substantial reductions in gill‐net effort in areas of the Neuse River where Striped Bass occur. Reducing exploitation may increase spawning stock biomass and advance the age structure of spawning females, conferring an increased likelihood of successful recruitment and production of dominant year‐classes during periods of favorable environmental conditions.

Seasonal movements of striped bass Morone saxatilis in a large tidal and hydropower regulated river

Following a failed spawning event in 1975 and the suspected absence of recent spawning by Striped Bass Morone saxatilis in the Saint John River, New Brunswick, the native Striped Bass population has been considered extirpated. Non-native migratory Striped Bass, however, still frequent the river, and a remnant, likely native, population may still exist. To characterize the movements and habitat use of adult Striped Bass still arriving to, and possibly residing within the Saint John River, Striped Bass (n = 40, size range, 40.5–90.9 cm FL) were captured throughout 2010–13 in the lower Saint John River, and surgically implanted with multi-year acoustic transmitters. Striped Bass were passively tracked using an array of 5–33 project specific receivers between 2010 and 14 and augmented by detections from the Ocean Tracking Network from 2011 to 13. Most tag detections recorded during the predicted spawning period occurred near locations suspected to have supported Striped Bass spawning historically. Only six tagged fish (15% of total) were detected outside of the river, five of which only left the river briefly during the spawning period and then returned. Tagged Striped Bass used four overwintering sites within the Saint John River to which individuals demonstrated annual fidelity. Our findings suggest the presence of a local, possibly reproducing Striped Bass population that exhibits multi-annual residency within the river; however, successful spawning remains to be confirmed.

Long-term effect of a tidal, hydroelectric propeller turbine on the populations of three anadromous fish species.

Tidal hydroelectric power has been proposed as one potential solution for sustainable energy sources. The first tidal turbine in North America began continuous operation in the Annapolis River estuary (44 °45'N; 65° 29'W) in June, 1985. The machine is an axial-flow, hydraulic-lift propeller turbine, a type known to cause fish mortality. Anadromous populations of American shad Alosa sapidissima, striped bass Morone saxatilis and Atlantic sturgeon Acipenser oxyrinchus utilize the Annapolis River for spawning and other life history phases. After power generation commenced obvious turbine mortalities of these fishes began appearing downstream of the turbine. Assessments of the A. sapidissima adult spawning runs during 1981-1982 (pre-operation) and 1989-1996 (operational) indicated significant changes in population characteristics after power generation began. Adult length, mass, age and per cent repeat spawners declined and total instantaneous mortality (Z) increased from 0.30 to 0.55. The pre-turbine spawning runs had older fish with numerous adult cohorts whereas by 12 years after operation began runs consisted of younger fish with fewer adult cohorts. During 1972-1987 numerous studies indicated the Annapolis River had an important angling fishery for M. saxatilis, but detailed annual records kept by a fishing contest during 1983-1987 and an elite angler family during the period 1976-2008 demonstrated a rapid decline in the number of fish >4.0 kg after turbine operation began. Pre-turbine catch by the angling family of fish >4.0 kg accounted for 84.1% of total catch, but declined significantly to 39.6% of total catch from 1986-1999, and to none from 2000-2008. The existence of an A. oxyrinchus stock in the Annapolis River was unknown before turbine operation, but during 1985-2017, 21 mortalities were recovered by chance seaward of the turbine. Mechanical strike and cavitation mortalities consisted of juveniles, mature males and gravid and spent females of ages 10 to 53 years found during June to October, the period when this anadromous species returns to its natal river to spawn. The results of the long-term studies at Annapolis indicate managers should realize substantial risks exist for the fish resources of the world's oceans from deployment of instream propeller turbines.

Striped Bass and Atlantic Menhaden Predator–Prey Dynamics: Model Choice Makes the Difference

AbstractA version of multispecies virtual population analysis (MSVPA‐X) had been the sole means of evaluating predation mortality by Striped Bass Morone saxatilis, Bluefish Pomatomus saltatrix, and Weakfish Cynoscion regalis on Atlantic Menhaden Brevoortia tyrannus during 1982–2008. Simplified models may offer a different view of predation, so we developed alternative estimates of predation mortality on Atlantic Menhaden with a simpler biomass dynamic predator–prey (Steele–Henderson or S–H) model. Strongly contrasting predictions of the importance of predation on age‐1+ Atlantic Menhaden, particularly Striped Bass predation, emerged between the MSVPA‐X and the S–H model. Striped Bass selected mostly age‐0 and age‐1 Atlantic Menhaden when modeled by MSVPA‐X, even though large Striped Bass (&gt;40% of biomass after the mid‐1990s) were capable of consuming all ages. Consumption of Atlantic Menhaden by Striped Bass in the S–H model was drawn from aggregated age‐1+ biomass. Combined predation mortality from Striped Bass, Bluefish, and Weakfish was well below fishing mortality for all but the earliest years in the MSVPA‐X but was greater than or equivalent to fishing mortality throughout most of the S–H model time series. Striped Bass were a relatively minor source of Atlantic Menhaden predation mortality with the MSVPA‐X but were the major source since the late 1990s in the S–H model. Annual estimates of Atlantic Menhaden biomass consumed per unit of Striped Bass biomass from the S–H model were roughly five times higher than MSVPA‐X estimates and more consistent with estimates from bioenergetics models and trends of Striped Bass well‐being indicators (tag‐based natural mortality rates and weight at age). Use of an alternative S–H model provided a more complete picture of the potential range of predation pressure.

TỔNG QUAN VỀ VIỆC SỬ DỤNG SELEN (Se) TRONG NUÔI TRỒNG THỦY SẢN

Effects of antibiotics usage in aquaculture on environment and human health has prompted the search for alternative products. Recently, the microelements in organic form have been used as alternative to antibiotics in aquaculture. Se is one of the microelements that have received heightened attention. This report reviews the role of Se in the culture of fishes (cobia Rachycentron canadum L., red sea bream Pagrus major, fingerling channel catfish Ictalurus punctatus, seabass Lates calcarifer, snubnose dart Trachinotus blochii, rainbow trout Oncorhynchus mykiss, common carp Cyprinus carpio L., Atlantic salmon parr Salmo salar, nile tilapia Oreochromis niloticus, african catfish Clarias gariepinus, Senegalese sole Solea senegalensis, grouper Epinephelus malabaricus, gilthead seabream Sparus aurata, Chinook salmon Oncorhynchus tshawytscha, fathead minnow Pimephales promelas, striped bass Morone saxatilis, bluegill Lepomis macrochirus, crucian carp Carassius auratus gibelio) and crustacean (giant freshwater prawn Macrobrachium rosenbergii, white shrimp Penaeus vannamei, marron Cherax cainii, crayfish Procambarus clarkii). Suggestion for further research on the application of Se in aquaculture is also included.

Diet of Striped Bass and Muskellunge Downstream of a Large Hydroelectric Dam: A Preliminary Investigation into Suspected Atlantic Salmon Smolt Predation

AbstractTop predators, such as the Striped Bass Morone saxatilis and Muskellunge Esox masquinongy, can impact food webs and alter ecosystem structure through the regulation of prey populations. Within the Saint John River, New Brunswick, Canada, both predators have long been hypothesized to impart significant mortality on smolts of the endangered Atlantic Salmon Salmo salar. As a consequence, current management practices entail euthanizing Muskellunge (an introduced species) that enter fish passage facilities along the Saint John River. Furthermore, the recovery and protection of a native Striped Bass population have largely been ignored. To assess seasonal diet, gastric lavage was performed on Striped Bass (n = 244) and Muskellunge (n = 96) captured in the downstream proximity of the Mactaquac Dam from April to November 2016. Clupeids dominated the stomach contents by number (92% for Striped Bass; 49% for Muskellunge) and mass (71% for Striped Bass; 96% for Muskellunge). Other prey species included White Perch Morone americana, Yellow Perch Perca flavescens, American Shad Alosa sapidissima, and American Eels Anguilla rostrata. No Atlantic Salmon smolts or other regionally recognized recreational fish species were identified in any of the stomach samples (n = 340) examined. Concurrently, this study observed little temporal overlap between the smolt migratory period and the arrival of Striped Bass to the Mactaquac Dam. Some Striped Bass (n = 33) were observed to be in spawning condition, releasing eggs and milt when handled, although reproduction by this species in the Saint John River was thought to have ceased long ago.

Modeling the Effects of Vital Rate Manipulation and Management Scenarios to Predict the Population Impact of Restoration Programs on an Unrecovered Coastal Population of Striped Bass

AbstractStriped Bass Morone saxatilis have supported important fisheries along the Atlantic coast of North America. However, the species experienced major declines due to overharvest, water quality degradation, and dam construction. Restoration efforts have been successful for specific stocks but unsuccessful for the Striped Bass population in the Neuse River of North Carolina. Ongoing research programs have estimated stage‐ and source‐specific mortality rates to identify mechanisms associated with the lack of recovery of the population. These demographic data are useful; however, they give little insight into the effectiveness of potential restoration programs. To develop effective management strategies, we used estimated mortality rates from the literature to build an age‐structured population model. We estimated that if vital rates remained constant, the Neuse River adult Striped Bass population would consist of 18,457 individuals (95% credible interval = 8,176–34,314). We then conducted a life stage simulation analysis to determine the adult population abundance and age structure that would result from a 50% decrease of the following: juvenile and adult natural mortality, recreational discard and harvest, and commercial discard and harvest. Finally, we simulated the potential impacts of six possible management scenarios on population abundance and age structure. We determined that the abundances of adults (age 3+) and older adults (age 6+) were most sensitive to natural mortality of juveniles and adults and next most sensitive to commercial harvest and discard. We further estimated that eliminating all fishing mortality would have the greatest impact on the population and would result in a 26‐fold increase in abundance of age‐6+ adults. Our results suggest that high mortality rates are preventing the development of a sufficient abundance of adult spawning stock. We recommend that managers use this model to identify the most effective management scenario—given specific goals and constraints—to help increase Striped Bass abundance in the Neuse River.

Edible Corn‐zein‐based Coating Incorporated with Nisin or Lemongrass Essential Oil Inhibits Listeria monocytogenes on Cultured Hybrid Striped Bass, Morone chrysops × Morone saxatilis, Fillets During Refrigerated and Frozen Storage

AbstractListeria monocytogenes presents a serious threat to consumer safety because it is resistant to various food storage techniques, including reduced or modified atmosphere packaging, refrigerated storage, and increased salt concentration. Edible coatings incorporated with natural antimicrobials have been suggested to control pathogenic and spoilage bacteria on a variety of meat products. In this study, edible zein‐based coatings incorporated with nisin and lemongrass essential oil (LGEO; 8%) were evaluated for antibacterial action against L. monocytogenes and spoilage organisms on fresh, cultured hybrid striped bass, Morone saxatilis × Morone chrysops, under two storage conditions (refrigerated or frozen) and two packaging types (polyvinyl chloride [PVC] and vacuum packing) over time. Corn‐zein‐based edible coatings were found to be an effective carrier for nisin and LGEO. Fillets coated with nisin showed the largest decrease in L. monocytogenes cell counts in both PVC and vacuum‐packaged samples in both refrigerated and frozen product, while fillets coated with LGEO showed intermediate inhibition of L. monocytogenes cell counts, with the strongest LGEO antibacterial effect being found in frozen product regardless of packaging. Both nisin and LGEO treatments were most effective in PVC‐packaged fillets compared to vacuum‐packaged fillets, but the difference in bacterial loads between packaging methods was minor. Bacterial loads on refrigerated product tended to increase slightly after 5‐d storage regardless of coating treatment or packaging, whereas bacterial loads on frozen product remained stable or decreased with time up to 60 d regardless of coating treatment or packaging. Data from the present study indicate that application of edible coatings incorporated with essential oils not only promotes food product safety but also may satisfy the preferences of consumers.

Strain evaluation of striped bass (Morone saxatilis) cultured at different salinities

Striped bass (Morone saxatilis) and their hybrids have been well studied and are widely cultured in freshwater ponds as food and gamefish. Recent industry expansion has generated an interest in strain-specific broodstock development for marine netpen and pond culture. In this effort, Atlantic and Gulf coast striped bass strains were cultured in recirculating aquaculture systems (RAS) at different salinities for up to two years and production and morphometric parameters (specific growth, feed conversion, fillet yield, condition factor and stripe patterns) were compared. Striped bass juveniles produced from wild-caught broodstock from rivers in Nova Scotia, Delaware, Virginia, North and South Carolina, Florida, Texas and a selected, domesticated strain were reared in triplicate fresh (0 ppt), brackish (5 ppt) and saltwater recirculating (30 ppt) systems. After one year of age, a subset of fish were implanted with passive integrated transponder (PIT) tags, combined into a larger, “common-garden”, saltwater, recirculating system and monitored over an additional year. Parental broodstock and cultured offspring were fin-clipped and genotyped to identify juvenile family origin. Final weights of fish after one and two years averaged approximately 0.5 and 2.5 kg, respectively and did not differ by water salinity. Growth rates and condition factors differed by strain, but condition factor was not correlated with fillet yield. Consistent with other studies, juvenile fish from South Carolina and Nova Scotia were found to be slow growing compared to migratory Atlantic and Gulf strains. Mixed model analyses showed that family, and family by strain interactions were significant, but accounted for less growth variance than strain alone. These results indicate that family-based selection by strain may be useful in striped bass broodstock development programs.