Striped Bass Research Articles

Salinity Has Limited Influence on Sedation of Sunshine Bass with AQUI-S 20E (10% Eugenol)

AbstractWe evaluated sedation and recovery of juvenile sunshine bass (male Striped Bass Morone saxatilis × female White Bass M. chrysops) exposed to AQUI-S 20E (10% eugenol; 60 mg/L) in freshwater or increasingly brackish salinities (nominal salinities of 0, 5, 10, 15, 20, and 25 g/L). Induction and recovery times were significantly affected by salinity, but the magnitude of the effects was relatively small. Induction was fastest (0.90 min) among fish tested at 25 g/L salinity and slowest (1.07 min) among those tested at 0 g/L salinity, but this was the only significant difference observed in induction times between treatments. Recovery was also faster among fish that were tested at higher salinities and slower among fish that were tested at lower salinities (range = 2.63–3.91 min), but significant differences were not noted for each pairwise comparison. Most fish (65%) exhibited slight agitation and gasping or piping at the surface during sedation, but these behaviors were less common among fish held at ...

The Misunderstood Striped Bass of the Saint John River, New Brunswick: Past, Present, and Future

AbstractThe Striped Bass Morone saxatilis of the Saint John River, New Brunswick, is an enigma, having now existed in a state of uncertain species status for more than four decades. Despite a well‐established historical record of adult occurrence in large numbers, the available literature, historical accounts, and status reports contain no evidence for the persistence of a native, reproducing Striped Bass population. In 2012, the Committee on the Status of Endangered Wildlife in Canada listed the Saint John River Striped Bass as endangered as part of the Bay of Fundy designatable unit. This listing lacked current peer‐reviewed literature and based its conclusions predominately on restatements of findings and opinions from the 1970s and 1980s. After the apparent failure of Striped Bass spawning in the 1975, the decline of native Saint John River Striped Bass was accredited to many factors ranging from chemical pollutants to overfishing to the installation of a sizeable hydropower facility. Modest attempts to locate eggs and juveniles of the native species have been taken; however, the results have been inconclusive due to ineffective, infrequent, and poorly timed sampling. Here we reviewed all available information, literature, reports, and data to effectively describe the Saint John River Striped Bass population in an effort to help manage and recover (if required) this apparently missing population.Received March 8, 2016; accepted September 14, 2016Published online January 24, 2017

Quantifying Site-Specific Physical Heterogeneity Within an Estuarine Seascape

Quantifying physical heterogeneity is essential for meaningful ecological research and effective resource management. Spatial patterns of multiple, co-occurring physical features are rarely quantified across a seascape because of methodological challenges. Here, we identified approaches that measured total site-specific heterogeneity, an often overlooked aspect of estuarine ecosystems. Specifically, we examined 23 metrics that quantified four types of common physical features: (1) river and creek confluences, (2) bathymetric variation including underwater drop-offs, (3) land features such as islands/sandbars, and (4) major underwater channel networks. Our research at 40 sites throughout Plum Island Estuary (PIE) provided solutions to two problems. The first problem was that individual metrics that measured heterogeneity of a single physical feature showed different regional patterns. We solved this first problem by combining multiple metrics for a single feature using a within-physical feature cluster analysis. With this approach, we identified sites with four different types of confluences and three different types of underwater drop-offs. The second problem was that when multiple physical features co-occurred, new patterns of total site-specific heterogeneity were created across the seascape. This pattern of total heterogeneity has potential ecological relevance to structure-oriented predators. To address this second problem, we identified sites with similar types of total physical heterogeneity using an across-physical feature cluster analysis. Then, we calculated an additive heterogeneity index, which integrated all physical features at a site. Finally, we tested if site-specific additive heterogeneity index values differed for across-physical feature clusters. In PIE, the sites with the highest additive heterogeneity index values were clustered together and corresponded to sites where a fish predator, adult striped bass (Morone saxatilis), aggregated in a related acoustic tracking study. In summary, we have shown general approaches to quantifying site-specific heterogeneity.

Evaluating Ecosystem‐Based Reference Points for Atlantic Menhaden

AbstractImplementation of an ecosystem approach to fisheries management (EAFM) for forage fish requires methods to evaluate tradeoffs associated with competing management objectives that focus on supporting fishery yields or providing food for predators. We developed an Ecopath with Ecosim ecosystem model of the U.S. Northwest Atlantic continental shelf (NWACS) for the period 1982–2013 to inform an EAFM for Atlantic Menhaden Brevoortia tyrannus. The model (with 61 trophic groups and 8 fishing fleets) was parameterized and fitted to time series using data from stock assessments, surveys, and literature. Fifty‐year simulations evaluated how Atlantic Menhaden fishing mortality rates (F) influenced different ecosystem indicators, including population biomasses, fishery yields, prey‐to‐predator ratios, and the proportion of trophic groups that were positively or negatively affected. We quantified tradeoffs associated with a range of alternative ecosystem‐based reference points for Atlantic Menhaden F and biomass (B), including F for maximum sustainable yield (FMSY), 0.5FMSY, proxies for current single‐species F reference points, 75% of virgin unfished biomass (B0), and 40%B0. Striped Bass Morone saxatilis were most sensitive to increases in Atlantic Menhaden fishing, largely due to their strong dietary reliance on this prey species, but other higher‐trophic‐level groups (birds, highly migratory species, sharks, and marine mammals) were also negatively impacted. Other commercially important predators of Atlantic Menhaden (e.g., Bluefish Pomatomus saltatrix and Weakfish Cynoscion regalis) had moderate to negligible responses at the highest levels of Atlantic Menhaden F. The alternative reference points considered resulted in (1) variable Atlantic Menhaden biomasses (40–75% of B0) and yields (54–100% of MSY), (2) up to a 60% decline in Striped Bass B and yield, (3) negative impacts on the B of ≤13% of modeled groups, and (4) positive impacts on the B of ≤6% of modeled groups. Simulations demonstrated the varied responses, potential winners and losers, and tradeoffs resulting from alternative management strategies for Atlantic Menhaden. These results and the NWACS model can help to advance an EAFM for Atlantic Menhaden and other fishes.

Tissue localization of piscidin host-defense peptides during striped bass (Morone saxatilis) development

Infectious diseases are a major cause of larval mortality in finfish aquaculture. Understanding ontogeny of the fish immune system and thus developmental timing of protective immune tissues and cells, may help to decrease serious losses of larval fishes when they are particularly vulnerable to infection. One component of the innate immune system of fishes is the host-defense peptides, which include the piscidins. Piscidins are small, amphipathic, α-helical peptides with a broad-spectrum of action against viral, bacterial, fungal, and protozoan pathogens. We describe for the first time the cellular and tissue localization of three different piscidins (1, 3, and 4) during striped bass (Morone saxatilis) larval ontogeny using immunofluorescent histochemistry. From 16 days post hatch to 12 months of age, piscidin staining was observed in cells of the epithelial tissues of gill, digestive tract, and skin, mainly in mast cells. Staining was also seen in presumptive hematopoietic cells in the head kidney. The three piscidins showed variable cellular and tissue staining patterns, possibly relating to differences in tissue susceptibility or pathogen specificity. This furthers our observation that the piscidins are not a monolithic family of antimicrobials, but that different AMPs have different (more specialized) functions. Furthermore, no immunofluorescent staining of piscidins was observed in post-vitellogenic oocytes, embryos, or larvae from hatch to 14 days post hatch, indicating that this critical component of the innate immune system is inactive in pre-hatch and young larval striped bass.

Feeding Habits of Young-of-Year Striped Bass, Morone saxatilis, and White Perch, Morone americana, in Lower James River, VA

Feeding Habits of Young-of-Year Striped Bass, Morone saxatilis, and White Perch, Morone americana, in Lower James River, VA

Zebra mussel (Dreissena polymorpha) affects the feeding ecology of early stage striped bass (Morone saxatilis) in the Hudson River estuary

Variability in the feeding ecology of young fishes over short and long time scales in estuaries is likely to affect population dynamics. We studied 14 years of early stage Striped Bass feeding ecology in the Hudson River Estuary over a 25-year time span, including years in which invasive zebra mussels markedly altered energy flow within the estuary. We predicted that feeding success would be low and that diet composition would be altered during years of high zebra mussel impact, particularly in upriver locations where mussels occur. Feeding success in the short term was indicated by volume of gut contents and in the long term by dry mass at length, i.e. condition; these measures were positively intercorrelated and varied significantly year to year. We tested for associations between condition and multiple biotic and abiotic environmental variables. There was a strong negative effect of zebra mussel grazing rate on condition in upriver locations and a weak positive effect in downriver locations. In upriver locations, condition was 33% higher when local salinity was high and zebra mussel grazing rates were low, whereas in downriver locations, condition was 35% higher when zebra mussel grazing rates and copepod abundance were high and local dissolved oxygen was low. Copepods, amphipods, mysids, and Leptodora constituted the highest prey-specific index of relative importance throughout the estuary. There was no evident effect of the zebra mussel invasion on diet composition. This long-term study corroborates the inferences of earlier studies that zebra mussels reduced early-stage striped bass growth rate.

Movement patterns of striped bass (Morone saxatilis) in a tidal coastal embayment in New England

Striped bass (Morone saxatilis) are important in commercial and recreational fisheries along the western Atlantic coastline. Although there is a good understanding of their seasonal migration patterns, less is known about the short-term movements of striped bass once they have reached New England coastal embayments during the summer months. Movement patterns were assessed by tagging 35 striped bass (38.5–80.5cm TL) with acoustic transmitters and tracking them within a fixed array (n=34 receivers) in Plymouth, Kingston, Duxbury (PKD) Bay, MA. The majority of tagged striped bass took up residency within PKD Bay for the summer months. Large juvenile through sub-adult (21–46cm) and adult bass (>46cm) remained residents of PKD Bay for periods of 6–75days and appear to use the estuary as a vital summer foraging area before emigrating from the bay for their southward migration. Changes in activity space estimates were significant over the course of the season and increased with water temperature. There was a general increase of activity space preceding emigration where presence of striped bass was significantly related to water temperature and photoperiod. Various environmental factors influence striped bass movement, and it is important to understand individual patterns and behavioral ecology to make the most educated management decisions.

Winter presence and temperature-related diel vertical migration of striped bass (Morone saxatilis) in an extreme high-flow passage in the inner Bay of Fundy

During a multiyear fish tracking study, subadult and adult life stages of Shubenacadie River striped bass (Morone saxatilis) were detected throughout winter in the well-mixed, hypertidal waters of the Minas Passage, Bay of Fundy. Thirty-five percent of the striped bass tagged with Vemco V16 transmitters were detected by two Minas Passage receiver arrays. Transmissions were received on 82% of winter days (December to April) and by all receivers spanning the width of the passage. Tagged striped bass were detected largely within the top 20–40 m during the day. The extent of vertical migration to shallower waters at night showed a strong relationship with water temperature; however, there was no diel vertical movement pattern observed at water temperatures <1 °C. Our results demonstrate overwintering of a portion of the Shubenacadie River striped bass population in high-flow inner Bay of Fundy waters, which extends the northern limit of this species’ winter marine range. This study is also the first to describe the relationship between daily vertical migration by striped bass and low water temperatures. Both findings suggest an elevated potential risk of interaction with an in-stream tidal turbine facility in Minas Passage.

Mechanical properties of striped bass fish skin: Evidence of an exotendon function of the stratum compactum

Teleost fish skin is a multifunctional natural material with high penetration resistance owing to specialized puncture mechanisms of both the individual scale and the intact scaled integument. In this paper, we explore the possible additional role of the skin in fish undulatory locomotion by examining the structural and mechanical properties of the dermal stratum (s.) compactum layer of striped bass (Morone saxatilis) skin. The structure, mechanical response and function of s. compactum was investigated by combining several methods: optical microscopy and histology, tensile tests on descaled skin specimens in different anatomical locations and orientations, puncture tests, and flexural tests on whole fish with disruption of the s. compactum. Local histological features of the s. compactum, such as collagen fiber angle and degree of crimping, were shown to explain corresponding patterns determined for the tensile properties of the skin along the long axis of the fish, including changes in stiffness, strength and locking strain at stiffening. The fish bending tests demonstrated a tendon-like response of the whole fish and a significant contribution of the s. compactum to the flexural stiffness of the fish. Collectively, the findings show that the s. compactum is a strong tissue with a tendon-like nonlinear response, and which provides an appreciable mechanical protection against sharp puncture and lacerations. Our results also support the theory of an exotendon function of the s. compactum in teleost fish skin. These findings may inspire the design of new multifunctional protective and locomotory systems for a variety of engineering applications.

Temporal dynamics of condition for estuarine fishes in their nursery habitats

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 557:207-219 (2016) - DOI: https://doi.org/10.3354/meps11858 Temporal dynamics of condition for estuarine fishes in their nursery habitats R. W. Schloesser1,2,*, M. C. Fabrizio1 1Virginia Institute of Marine Science, College of William & Mary, PO Box 1346, Gloucester Point, Virginia 23062, USA 2Present address: Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, Florida 34236, USA *Corresponding author: rschloesser@mote.org ABSTRACT: The condition of individuals in a year class may contribute to recruitment variability due to differential survival of poor- and well-conditioned fish, but the temporal dynamics of juvenile fish condition are poorly understood. We examined inter- and intra-annual dynamics of condition for juveniles of 3 species collected from estuarine nursery areas of Chesapeake Bay from November 2010 to June 2014. We describe temporal patterns in length-based indices, the hepatosomatic index (HSI), and relative subdermal lipid estimates for juvenile summer flounder Paralichthys dentatus (n = 1771), Atlantic croaker Micropogonias undulatus (n = 3911), and striped bass Morone saxatilis (n = 874). Multiple indices provided a more complete understanding of energy-storage strategies for juveniles because temporal patterns among condition indices were not congruent for a given species. Most juvenile summer flounder and Atlantic croaker migrate from Chesapeake Bay in the fall, and both species exhibited increases in subdermal lipids in the time period prior to migration. For all species, individuals that remained in the estuary during winter exhibited high HSI values, indicating a common energy-storage strategy during winter. Mean condition of juveniles varied among year classes, but differences were inconsistent among indices, suggesting that energy was differentially stored among tissues for these year classes. Density-dependent effects contributed to variation in mean condition for summer flounder and striped bass. Our understanding of recruitment variability may be improved by assessing annual differences in mean condition as revealed by multiple indices. KEY WORDS: Fulton’s K · Hepatosomatic index · Subdermal lipid · Fish fatmeter · Juveniles · Bioenergetics · Recruitment Full text in pdf format PreviousNextCite this article as: Schloesser RW, Fabrizio MC (2016) Temporal dynamics of condition for estuarine fishes in their nursery habitats. Mar Ecol Prog Ser 557:207-219. https://doi.org/10.3354/meps11858 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 557. Online publication date: September 28, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

Biochemical Characterization and Comparison of Pancreatic Lipases from the Pacific Bluefin Tuna, Thunnus orientalis; Totoaba, Totoaba macdonaldi; and Striped Bass, Morone saxatilis

AbstractLipolytic activity from pancreatic crude extracts from the Pacific bluefin tuna (PBT), Thunnus orientalis; totoaba, Totoaba macdonaldi; and striped bass, Morone saxatilis, were biochemically characterized to detect possible differences in the digestive capacity of each fish. The maximum activity was at temperatures ranging from 35 to 45 C and at pH 8.0; the activity decreased significantly at a pH lower than 7.0. Lipases from PBT and totoaba showed an increase in activity with the presence of sodium taurocholate (NaTC; 6 mM). However, no increase in activity could be observed when a mixture of bile salts or natural bile extracts was used in the reaction mixture, which was observed in the presence of NaTC. In contrast, the lipase activity from striped bass increased accordingly when NaCl was added at different levels (0–1.5 M). Calcium was not required in the reaction mixture for any of the fish species tested. We concluded that all three lipases have different physicochemical properties and ionic strength and emulsifier requirements to obtain their maximum activity. Striped bass was far too sensitive to NaCl, while totoaba and PBT were sensitive to NaTC. The differences in activity shown here suggest the possibility of studying the use of different additives on feed formulations to maximize lipase efficiency.

Gutsy genetics: identification of digested piscine prey items in the stomach contents of sympatric native and introduced warmwater catfishes via DNA barcoding

A major focus of ecology is understanding trophic relationships and energy flows in natural systems, associated food web dynamics and changes in food webs due to introduced species. Predator-prey interactions are often assessed by examining stomach contents. However, partially digested remains may be difficult to accurately identify by traditional visual analysis. Here we evaluate the effectiveness of DNA barcoding to identify digested piscine prey remains in invasive Blue Catfish Ictalurus furcatus, non-native, but established Channel Catfish Ictalurus punctatus and native White Catfish Ameiurus catus from Chesapeake Bay, USA. Stomach contents were examined and piscine prey items were scored as lightly digested, moderately digested or severely digested. A 652 base pair region of the cytochrome c oxidase subunit I (COI-5P) mitochondrial DNA gene was sequenced for each prey item. Edited barcode sequences were compared to locally-caught and validated reference sequences in BOLD (Barcode of Life Database). A large majority of prey items were sufficiently digested to limit morphological identification (9.4 % to species and an additional 12.1 % to family). However, overall barcoding success was high (90.3 %) with little difference among the digestion classifications. Combining morphological and genetic identifications, we classified 91.6 % of fish prey items to species. Twenty-three fish species were identified, including species undergoing active restoration efforts (e.g., Alosa spp.) and commercially important species, e.g., Striped Bass Morone saxatilis, White Perch Morone americana, American Eel Anguilla rostrata and Menhaden Brevoortia tyrannus. We found DNA barcoding highly successful at identifying all but the most heavily degraded prey items and to be an efficient and effective method for obtaining diet information to strengthen the resolution of trophic analyses including diet comparisons among sympatric native and non-native predators.

Draft Genome Sequences for Seven Streptococcus parauberis Isolates from Wild Fish in the Chesapeake Bay.

Streptococcus parauberis is a pathogen of cattle and fish, closely related Streptococcus uberis and Streptococcus iniae. We report the genomes of seven S. parauberis strains recovered from striped bass (Morone saxatilis) in the Chesapeake Bay. The availability of these genomes will allow comparative genomic analysis of Chesapeake Bay S. parauberis strains versus S. parauberis cultured from other animal hosts and geographic regions.

Prey selection of larval and juvenile planktivorous fish: impacts of introduced prey

Changes in the abundance and composition of zooplankton resulting from species introductions may be contributing to a decline in the abundance of planktivorous fish in the San Francisco Estuary (SFE). To examine how changes in the prey assemblage may translate into feeding success of planktivorous fish, we quantified the relative consumption of native and introduced copepods by larval and juvenile delta smelt, Hypomesus transpacificus, and larval striped bass, Morone saxatilis, in laboratory feeding experiments. Larvae ≤20 days post-hatch (dph) of both fish consumed the copepodite stages of ~1 mm calanoid copepods, native Eurytemora affinis and introduced Pseudodiaptomus forbesi, and the smaller (~0.5 mm) introduced cyclopoid copepod, Limnoithona tetraspina, in approximately the same proportion as their abundance in the assemblage. Conversely, prey selection of larvae >20 dph shifted towards the larger calanoid species, E. affinis and P. forbesi. The timing of this shift differed between fish species, occurring earlier in striped bass, and varied between calanoid species, occurring later for P. forbesi than E. affinis. These data suggest that the impacts of introduced prey on planktivorous fish depend not only on the prey being introduced, but also on the resident predators. Additionally, even small differences in size and behavior between native and introduced prey can influence prey selection of planktivorous fish. Changes in prey selection of planktivorous fish resulting from species introductions could directly impact fish recruitment. As a result, species introductions could significantly alter food web function in the SFE and other invaded aquatic ecosystems.

Long‐Term Dynamics in “Trophy” Sizes of Pelagic and Coastal Pelagic Fishes among California Recreational Fisheries (1966–2013)

AbstractIn California, recreational fisheries contribute a significant amount to coastal economies, with pelagic and coastal pelagic species constituting a principal set of target species during summer and fall. Although traditional catch frequency (landings) data sets exist for these species, size‐specific information is limited, especially for the largest size‐classes. We digitized weekly records of trophy catch reported in the “Whoppers of the Week” section of the Western Outdoor News, a California fishing and hunting newspaper published since 1953. The resulting database contained catch records that described the largest fish caught at each sportfishing landing site along the California coast during 1966–2013. We then assessed the temporal dynamics in trophy size of the top‐15 pelagic and coastal pelagic species, with a combined total of 21,440 individual catch records. Among the 15 pelagic and coastal pelagic species examined, the Yellowfin Tuna Thunnus albacares and Striped Bass Morone saxatilis were the only species that showed clear long‐term declines in trophy size over the study period, whereas the Pacific Bluefin Tuna Thunnus orientalis, White Seabass Atractoscion nobilis, and Yellowtail Jack Seriola lalandi exhibited long‐term increases in size. In general, the trophy sizes of pelagic species were more variable than those of coastal pelagic species and were not as consistently correlated with oceanographic conditions; both findings likely reflect the fact that oceanography drives the availability but not necessarily the size of pelagic species catch. In contrast, coastal pelagic species demonstrated trends in trophy sizes that were more consistently responsive to both oceanography and fisheries management. Our results suggest that oceanographic processes, natural history characteristics, fishing, and fisheries regulations each play a role in trophy size dynamics, but their relative influences vary among species.Received December 12, 2015; accepted April 26, 2016Published online August 3, 2016

The effects of bupropion on hybrid striped bass brain chemistry and predatory behavior

Increased use of antidepressants has led to an increase in their detection in final treated wastewater effluents and receiving streams. Antidepressants are intended to modify human behavior by altering brain chemistry, and because of the high functional conservation of antidepressant target receptors in vertebrates, aquatic organisms may be at risk. The antidepressant bupropion is designed to alter brain norepinephrine and dopamine concentrations in humans. The objective of the present study was to understand if alteration of dopaminergic neurotransmitter concentrations in the hybrid striped bass (Morone saxatilis × Morone chrysops) brain by bupropion would alter this predator's ability to capture prey. The authors exposed hybrid striped bass to bupropion in a static system for 6 d, followed by a 6-d recovery period. During the present study's 12-d experiment, each hybrid striped bass was fed 4 unexposed fathead minnows every 3 d, and the time it took the hybrid striped bass to consume each of those 4 fathead minnows was quantified. After each feeding event, hybrid striped bass brains were harvested and analyzed for changes in several brain neurotransmitter concentrations, including serotonin, norepinephrine, dopamine, and many of their metabolites. Although bupropion altered the concentration of dopamine and many of the dopaminergic neurotransmitter metabolite concentrations in the brains on day 3 of the exposure, it did not alter the time to capture prey. This suggests that alteration of dopaminergic neurotransmitter concentrations in the hybrid striped bass brain does not alter a predator's ability to capture prey. Environ Toxicol Chem 2016;35:2058-2065. © 2016 SETAC.

Generation of Quantitative Polymerase Chain Reaction Detectability Half‐Lives and Comparison of Sampling Protocols for Genetic Diet Studies of San Francisco Estuary Fishes

AbstractSeveral factors affect the probability of genetic analyses to detect prey in predator gut contents, including biological differences in the prey and predator species as well as differences in sampling and laboratory methodologies. Understanding these biases allows researchers to more appropriately put genetic prey detections in an ecological context. In this study, we determined the detectability half‐lives of DNA from two prey species in the guts of two predators. The half‐life detectability of juvenile Chinook Salmon Oncorhynchus tshawytscha in Striped Bass Morone saxatilis was 66.2 h, and that of larval Delta Smelt Hypomesus transpacificus in Mississippi Silverside Menidia audens was 26.4 h. Additionally, we performed a series of laboratory trials to examine the effects of variables in sample collection and preservation methodologies on the detectability of prey. Differences between methodologies were minimal, providing confidence that laboratory analyses will not be greatly affected by inconsistencies in field sampling procedures. Injecting a 95% solution of ethanol into the stomach via the esophagus immediately following collection and placing the fish on ice in the field prior to freezing at −20°C in the laboratory is a protocol readily applied in the field that will provide consistent results.Received August 19, 2015; accepted December 3, 2015 Published online April 11, 2016

Quantifying Striped Bass (Morone saxatilis) Dependence on Saltmarsh-Derived Productivity Using Stable Isotope Analysis

Each winter, populations of striped bass (Morone saxatilis) migrate north from the coastal mid-Atlantic region of the US to the coastal waters of New England. During this migration, striped bass spend significant time in estuaries and saltmarshes, presumably to forage. However, the extent to which saltmarsh productivity supports striped bass remains unresolved. We used a three-isotope Bayesian mixing model to determine the relative contribution of three primary producers [C4 saltmarsh cordgrass (Spartina spp.), phytoplankton, and benthic diatoms] to striped bass tissue. Phytoplankton (51 % contribution) and Spartina-derived sources (44 % contribution) are the primary sources of production to striped bass, while benthic diatoms made a relatively small contribution (5 %). Our results highlight the importance of saltmarshes to striped bass by showing that primary producers unique to saltmarsh ecosystems support a large proportion of striped bass production.

Spawning and Larval Rearing in Hybrid Striped Bass (Morone chrysops ♀ X Morone saxatilis ♂) in Turkey

This study is the first spawning and larval rearing of the F1 hybrid striped bass (Morone chrysops ♀ X M. saxatilis ♂) grown in culture conditions in Turkey. The F1 Hybrid striped bass was fed with commercial pellet feed in floating net cages. They reached the sexual maturity at two years old. Female brood fish were given 30 µg/kg of LHRH-a (Lutenizing hormone releasing hormone analogue) and male fish given 10 µg/kg; of CHP(Dried carp pituitary), 4 mg/kg was used for the female and half that amount for the male for induced breeding. The fish injected LHRHa were successfully induced to both strip spawning and tank spawning by a single hormone injection. However, fish injected CPH and saline, untreated control did not spawn. Latency period was found to be 20.41±0.91 hour. In term of fertilization rate, larval deformity rate no significant difference was found between tank spawning and strip spawning (p>0.05).Fertilization rates ranged from 56.3% to 85.4% and hatch rates were between 0.99% and 46.88%, whereas the level of larval deformities ranged between 81.25% and 100%. Hatched larvae were placed into 400-liter rectangular tanks with water discharge of 4 liter/minute at a stocking density of 30 larvae/liter. After larvae hatching, they were given artemia nauplii for 5-19 days. Trout granule feed (300-500 micron) also started to be given in addition to artemia nauplii afterwards. Granule feed was started eating completely 24 th days. The larvae obtained from a single hatch in the production season reached 2.87 cm length in 32 days with 2.7% survival rate. Of this study was terminated due to white spot disease (Ichtyophthirius multifilis) arising from sudden change in water temperature. The F2 progenies were not deemed to be available for aquaculture due to poor fertilization, poor hatching, low survival rate and high deformity rate. For the progenies of the hybrid striped bass that grow in natural water, it was suggested that their ecology in waters in Turkey be first studied and brought into aquaculture afterwards.