Hybrid Striped Bass Morone Saxatilis Research Articles

Trophic dynamics of a reservoir fishery following an introduction of a top predator: Insights from stable carbon and nitrogen isotopes

AbstractTrophic dynamics and conceptual niche spaces of top piscivores were assessed using stable isotope analysis following the introduction of hybrid striped bass Morone saxatilis (Walbaum) × Morone chrysops (Rafinesque) into an established reservoir fishery devoid of gizzard shad, Dorosoma cepedianum (Lasueur). Hybrid striped bass were initially stocked into Three Mile Lake, Iowa as an attempt to biologically control pervasive yellow bass, Morone mississippiensis Jordan & Eigenmann, populations. From the analyses, it concluded that hybrid striped bass predominately targeted prey fish located in the littoral habitats of the reservoir and did not selectively consume yellow bass as intended. Bayesian isotope mixing models described the diets of hybrid striped bass to include a variety of prey fish, predominantly consisting of young bluegill Lepomis macrochirus and yellow bass. Food resource overlap among hybrid striped bass, largemouth bass, Micropterus salmoides Lacépède, and walleye, Sander vitreus (Mitchill), appeared substantial based on the isotopic niche overlap model. Results from this case study, in conjunction with the hindsight that yellow bass populations became prolific even with stockings of hybrid striped bass, suggest that their use to control yellow bass populations may not be a viable management strategy in southern Iowa.

Adaptive stocking strategies of Hybrid Striped Bass in a Nebraska reservoir impacted by White Perch

Branched Oak Reservoir is the largest reservoir in eastern Nebraska and provides an important recreational fishery to large urban centers including Omaha and Lincoln. Hybrid Striped Bass Morone saxatilis × Morone chrysops are an important component of the recreational fishery, but this population appears to have been negatively impacted following the introduction and subsequent overabundance of invasive White Perch Morone americana in the mid-1990s. This study analyzed long-term standardized sampling and stocking data from Branched Oak Reservoir to evaluate Hybrid Striped Bass stocking strategies in the presence of White Perch. The spring age-0 stocking era from 1988 to 1997 consisted largely of fry and fingerling stockings. From 1998 to 2015, stockings were adapted to advanced fall age-0s with mean ± SE TL of 146 ± 7 mm. From 2016 to 2019, advanced spring age-1 Hybrid Striped Bass defined the third stocking era with mean ± SE TL of 178 ± 13 mm. Age-1 Hybrid Striped Bass CPUE differed among stocking eras (KW = 9.81, P = 0.007) as mean ± SE CPUEage-1 was 2 ± 1 fish per net night during the spring age-0 era, 1 ± 1 fish per net night during the fall age-0 era, and 3 ± 1 per net night during the spring age-1 era. Hybrid Striped Bass CPUEQP was different among eras (KW = 13.30, P = 0.001). None of the five abiotic factors assessed exhibited significant relationships to Hybrid Striped Bass CPUEage-1, and the strongest relationship (spring temperature) only had an r 2 value of 0.046. Information obtained from this study validates the current management decision to stock spring age-1 Hybrid Striped Bass based on the present White Perch abundances, and observed recruitment of Hybrid Striped Bass.

Immune and histopathologic responses of DNA-vaccinated hybrid striped bass Morone saxatilis ¥ M. chrysops after acute Mycobacterium marinum infection

The post-challenge immune and histopathologic responses of hybrid striped bass vaccinated with a DNA vaccine encoding the Mycobacterium marinum Ag85A gene and subsequently challenged with M. marinum were investigated. Juvenile hybrid striped bass Morone saxatilis x M. chrysops were injected intramuscularly with 25 or 50 microg DNA plasmid and developed significant specific protective responses to live bacterial challenge 120 d post-vaccination. Both vaccine groups demonstrated increased survival, reduced splenic bacterial counts, and reduced granuloma formation compared to the control groups 14 d after challenge with approximately 8 x 10(5) cfu M. marinum g(-1) fish body wt. The vaccine groups also developed more rapidly and significantly increased antibody and lymphoproliferative responses post-challenge compared to control groups, and these post-challenge immune responses appear to be vital against M. marinum infection in vaccinated hybrid striped bass. No significant differences in immune responses were recognized between the 25 and 50 microg vaccination groups, and these groups eventually experienced mortalities, splenic bacterial counts, and granuloma formation 28 d post-challenge comparable to those of the control groups at 14 d post-challenge. Therefore, vaccination of hybrid striped bass with a DNA vaccine encoding the M. marinum Ag85A gene provided significant but limited duration of protection against an acute high-dose M. marinum challenge.

Evidence for widespread distribution of piscidin antimicrobial peptides in teleost fish

Antimicrobial peptides (AMPs) are increasingly recognized as a critical component of the host's defense against infection. Several types of AMPs have been recently identified from mucosal tissues or immune cells of a number of teleosts. Among these are the piscidins, which are 22 residue, alpha-helical AMPs that were originally isolated from mast cells of hybrid striped bass Morone saxatilis male x Morone chrysops female. Using an antibody specific for the conserved N-terminal amino acid sequence of piscidin 1, we used immunohistochemistry to probe skin, gill, and gastrointestinal tract of 39 teleosts representing 7 different orders. Nine fish species were piscidin-positive, with all of these species being in the Perciformes, the largest and most evolutionarily advanced order of teleosts. Piscidin-positive cells were identified in species belonging to the families Moronidae, Serranidae, Sciaenidae, Siganidae and Belontidae. Immunopositive cells were usually most consistent with mast cells, although in some species, the granule appearance and tinctorial properties diverged somewhat from those of a typical piscine mast cell. In addition, rodlet cells were piscidin-positive in one member of the family Cichlidae; to our knowledge, it is the first time that a host-associated chemical biomarker has been identified in rodlet cells. Our data suggest that piscidins are present in many evolutionarily advanced teleosts. Piscidin-immunoreactive cells were most common at sites of pathogen entry, including the skin, gill and gastrointestinal tract. These results strongly suggest that piscidins are a widespread and important component of many fishes' defense against disease.

Pathogenesis of acute ulceration response (AUR) in hybrid striped bass

In a previous study, we discovered that acute confinement stress causes rapid ulceration of the fins of hybrid striped bass Morone saxatilis female x M. chrysops male (Noga et al. 1998. Vet Pathol 35:102-107). In this paper, we report the development of a reproducible model for studying this phenomenon in juvenile hybrid striped bass. We also determined how quickly ulceration could develop in acutely stressed fish and documented the sequential light microscopic and ultrastructural changes associated with this response. When hybrid striped bass were subjected to a standardized confinement protocol, the pathological response was extremely rapid (fin ulceration began to develop within 15 min of confinement). Grossly, the distal edges of the fins became blanched, and melanophores aggregated near the basement membrane and dermis after 15 min of confinement. Microscopically, the earliest detectable change in the fins, which occurred within 15 min of confinement, was swelling and loss of microridges of the outermost epidermal cells; this was followed by epidermal erosion. After 30 min of stress, epidermal ulceration developed at the distal edges of the fins. At this time, both necrotic and apoptotic epidermal cells were present. The middle and basal epidermal layers were severely spongiotic and the dermis and hypodermis were edematous. Over longer periods (up to 2 h), lesions were similar but increasingly more severe, progressing from the distal edge of the fin towards the base. The response to acute stress showed a significant correlation between confinement period and severity of the pathological changes (epidermal degeneration, epidermal ulceration and leukocyte infiltration). Also, we demonstrated that epidermal damage was not restricted to the fins but also affected the body skin and eyes. The ventral area of the body and the corneal epithelium of stressed fish were ulcerated; however, skin on the head and operculum was not affected, suggesting a site-specific mode of damage. In stressed fish, epidermal ulceration was found in 67 to 97% of all fins, 88% of skin on the ventrum, and 67% of corneas, while control fish had only very mild epidermal ulceration in the few fish in which it was present (on 5 to 10% of the fins, but not on the ventral skin or corneas). Due to the widespread damage to epidermal tissues of the body surface, we have named this the acute ulceration response (AUR). Our study indicates that acute confinement can rapidly cause significant damage to epidermal and ocular epithelium. AUR might be a primary cause of morbidity in acutely stressed fish.

Effects of Antenna Placement and Antibiotic Treatment on Loss of Simulated Transmitters and Mortality in Hybrid Striped Bass

Abstract We compared the effects of two antenna placements (trailing and nontrailing) and antibiotic treatments (treated and nontreated) on mortality and transmitter loss in hybrid striped bass Morone saxatilis × M. chrysops (364 ± 28 mm total length, 645 ± 129 g (mean ± SD)) implanted with simulated transmitters and held in the laboratory for 90 d. Although antibiotic treatment significantly increased the time to first mortality in fish surgically implanted with simulated transmitters (by an average of 14 d), we did not detect an effect on cumulative mortality. We also did not detect an effect of antenna type on the time to first mortality, but cumulative mortality was higher in the trailing antenna groups (50%) than in the nontrailing antenna groups (12%). Three transmitters were expelled during the study, all from trailing-antenna treatment groups, indicating a significant effect of antenna placement on the level of transmitter expulsion. Antibiotic treatment appears to be effective in preventing initi...

Intestinal phytase I: Detection and preliminary characterization of activity in the intestinal brush border membrane of hybrid striped bass Morone saxatilis × M. chrysops

While numerous studies have evaluated intestinal phytase activity in terrestrial monogastric species, little work has been conducted investigating the enzyme's activity in finfish. This experiment was conducted to determine if hybrid striped bass Morone saxatilis × M. chrysops possess intestinal phytase activity, and to perform a preliminary characterization of this activity in terms of pH, metal ion dependence and substrate kinetics. Hybrid bass do exhibit low levels of intestinal phytase activity. The activity has an acidic pH optimum between 3.5 and 4.5. Low concentrations of Mn2+ slightly enhance this activity. The divalent cations Mg2+ and Zn2+ were shown to either have no effect on the enzyme activity or to be inhibitory, particularly at high concentrations. The present results indicate that intestinal phytase activity in hybrid bass does follow Michaelis-Menten kinetics, with estimated Km and Vmax values of 2.5 mM phytate and 4.8 units mg−1 protein, respectively. The physiologic significance of the enzyme's presence in hybrid striped bass is questionable due to the low activity as compared to terrestrial monogastrics, the acidic pH optimum and the low affinity the enzyme appears to have for phytate. These observations also raise the question of whether the intestinal phytase activity detected in hybrid bass is merely a manifestation of non-specific acid phosphatase activity. Further investigation is needed to determine the practical significance of phytase activity in hybrid bass in terms of phytate phosphorus utilization. Additional experiments should also be conducted which evaluate intestinal phytase activity in other important aquacultured finfish species.

Fish Community Response to Hybrid Striped Bass Introduction in Small Warmwater Impoundments

Abstract The popularity of hybrid striped bass Morone saxatilis × white bass M. chrysops as sport fish in large reservoirs has increased interest in using these fish to diversify small-impoundment fisheries. We examined the potential impacts that hybrid striped bass competition and predation could have on existing fish communities in farm ponds. Two sizes of hybrid striped bass (phase 2 mean weight = 42.9 g; phase 3 mean weight = 307.2 g) were stocked at a density of 62 fish/ha (40 phase 2 and 22 phase 3) into three ponds (2.4–6.5 ha). Hybrid striped bass diet analyses revealed that piscivory was seasonal and highly size-specific. More than 97% of fish prey recovered from stomachs were larval centrarchids (primarily sunfish Lepomis spp. and black crappies Pomoxis nigromaculatus) less than 15 mm in total length (<0.10 g). Using bioenergetics simulation, we estimated annual fish prey consumption by hybrid striped bass to be 96.9 kg/ha, equivalent to a minimum of 969,000 larval centrarchids (<0.10 g) per hec...

Evaluation of Two Sizes of Hybrid Striped Bass for Introduction into Small Ponds

Abstract Private recreational fisheries in small impoundments provide a potential new market for the growing industry producing hybrid striped bass Morone saxatilis. We estimated growth, condition, and survival of hybrid striped bass (female striped bass × male white bass M. chrysops) in two small ponds with established fisheries for largemouth bass Micropterus salmoides and bluegill Lepomis macrochirus that eventually experienced severe weather-induced fish kills 266 d and 348 d after stocking. Both ponds were stocked with 40 phase 2 (120–169 mm total length, TL) and 22 phase 3 (241–344 mm TL) hybrid striped bass/ha. Growth and condition were monitored from introduction until the occurrence of fish kills. Fish collections immediately following the kills allowed minimum estimates of survival for time at large before each event. Mean growth rates were near 0.35 mm/d for phase 2 hybrids and ranged from 0.13 to 0.21 mm/d for phase 3 hybrids. Mean relative weight (Wr ), which at the time of stocking was optim...

Evaluation of Three Soybean Products in Diets Fed to Juvenile Hybrid Striped Bass Morone saxatilis×M. chrysops

AbstractJuvenile hybrid striped bass Morone saxatilis×M. chrysops were fed practical diets containing graded levels of either solvent‐extracted soybean meal, roasted soybeans, or raw, unprocessed soybeans. Two separate 10‐wk studies were conducted; within each study, there were two separate evaluations of soy products. In the first study, weight gain and feed efficiency of fish fed 45% or higher levels of soybean meal were significantly lower than fish fed the positive control diet, while weight gain and feed efficiency of fish fed 30% soybean meal were not significantly different than fish fed the control diet. Fish fed the lowest level of unprocessed soybean (20%) exhibited significantly depressed weight gain and feed efficiency compared to fish fed the control diet. In the second study, weight gain and feed efficiency of fish fed 40% roasted soybeans were significantly lower than fish fed the control diet, but weight gain and feed efficiency of fish fed 20% roasted soybeans were not significantly lower than fish fed the control diet. In both studies, whole body proximate composition values were significantly different among treatments. Whole‐body lipid concentrations were significantly higher in fish fed certain levels of soy products, but only at levels above those eliciting depressions in weight gain and feed efficiency. A further evaluation of solvent‐extracted soybean meal was conducted with incorporation levels of 20–40% of the dry diet in gradations of 5% with a nutritionally complete mineral premix. Weight gain and feed efficiency of fish fed any level of soybean meal in that study were not significantly different from fish fed a positive control diet. Whole body proximate components were not significantly different between treatments. Unprocessed soybeans apparently have little potential as an ingredient in diets fed to juvenile hybrid striped bass; roasting, or heat treatment, improves their use. Solvent extracted soybean has the potential of supplying the majority of crude protein in diets fed to juvenile hybrid striped bass. Incorporation of complete mineral premixes seems beneficial with higher levels of solvent‐extracted soybean meal.

Initial Disease Report of Streptococcus iniae Infection in Hybrid Striped (Sunshine) Bass and Successful Therapeutic Intervention with the Fluoroquinolone Antibacterial Enrofloxacin

AbstractStreptococcal infection (Streptococcus iniae) was diagnosed sequentially in two tanks of hybrid striped bass Morone saxatilis male ×M. chrysops female (Sunshine bass) grown in a commercial freshwater recirculation facility in western Massachusetts. The pathogen was isolated in the laboratory, biochemically and morphologically characterized, and antibacterial sensitivities determined. Streptococcus iniae‐induced lesions in the Sunshine bass were character at the gross and histopathological levels. Initial treatment with oxytetracycline was unsuccessful. Based on sensitivity results, enrofloxacin‐medicated feed was dosed at 10 mg/kg body weight for 10 d, while a subsequent trial was conducted at 5 mg/kg body weight for 10 d. Mortality of fish subsided promptly following initiation of enrofloxacin therapy, yielding a final mortality in the initial tank of 10.83% (control tank 55.5%) and in the second tank of 16.97% (control tank 39.8%). Tissue enrofloxacin residues, detected via a microbiologic bioassay, revealed greater quantities and longer duration of residues in various tissues from the 5‐mg as compared to the 10‐mg trial, potentially the result of adverse feed palatability. Enrofloxacin appears to have excellent potential as an antibacterial agent for treating susceptible bacterial diseases of Sunshine bass.

Comparative Influences of Abiotic Variables on Seasonal Abundances of Hybrid Striped Bass and White Bass in the Grand Lake Tailwater, Oklahoma

ABSTRACT We sampled hybrid striped bass Morone saxatilis ♀ × M. chrysops ♂ and white bass M. chrysops in the Pensacola Dam tailwater of Grand Lake, Oklahoma, using gill nets at about monthly intervals from January 1988 to July 1989 to assess temporal changes in their abundances in the tailwater and to determine and compare relations between their abundances and changes in selected abiotic variables. Hybrid striped bass and white bass moved into the tailwater during spring and dispersed downstream after the spawning season. Abundances of hybrid striped bass were associated with dam discharge volumes during the month prior to sampling, water temperatures of 15–16°C, and photoperiod intervals of 825–850 min of daylight. Peak white bass abundances were associated with water temperatures of 13°C, photoperiod intervals of 800 min, and dam discharges during the preceding month. Dissolved oxygen concentration had no significant effect on either fish. During periods of peak abundance, both taxa were most abundant ...

Quantifying Responses to Hybrid Striped Bass Predation across Multiple Trophic Levels: Implications for Reservoir Biomanipulation

Top-down effects from piscivores to phytoplankton have been documented in north temperate lakes, thus permitting managers to regulate these food webs. From our review of the literature, reservoir trophic interactions appear less amenable to biomanipulation owing to the presence of a fast-growing, omnivorous planktivore, gizzard shad Dorosoma cepedianum. If reservoir zooplankton can be enhanced by reducing gizzard shad through biomanipulation, this could increase survival of food-limited early life stages of sport fishes dependent on zooplankton and could improve water clarity by reducing phytoplankton. To quantify this potential, we evaluated responses of age-0 gizzard shad, crustacean zooplankton, and phytoplankton to the addition of hybrid striped bass Morone saxatilis × M. chrysops (22 kg/ha) to four of eight 0.4-ha ponds. Hybrid striped bass nearly eliminated age-0 gizzard shad from ponds within 10 d after being stocked, which permitted zooplankton density and size to increase but had no effect on phytoplankton. These pond results independently confirmed the relationships among zooplankton density, zooplankton production, and age-0 gizzard shad density that had been developed previously in 1-m3 enclosures. Only reservoirs with fewer than 10 age-0 gizzard shad/m3 and daily zooplankton production greater than 220 mg/m3 may be amenable to biomanipulation; these conditions occurred in our ponds due to hybrid striped bass piscivory and high zooplankton productivity. About 5% of Ohio reservoirs possess these two characteristics, which makes the potential for improving sport fish recruitment by reducing age-0 gizzard shad abundance a limited option for reservoir managers.

Cage Culture of Hybrid Striped Bass in Indiana and Evaluation of Diets Containing Three Levels of Dietary Protein1

AbstractCulture of hybrid striped bass Morone saxatilis × M. chrysops has been increasing in selected regions of the United States. Because of their thermal tolerance, hybrids may have potential as a new commercial aquaculture species in the Midwest. In these studies, hybrid striped bass were reared in cages located in southern, central and northern Indiana and offered one of three practical diets. Diets contained either 32, 36 or 40% crude protein. Additionally, a preliminary 8 wk laboratory experiment was conducted in which fish were offered the same diets. All diets were formulated to meet the established dietary lysine requirement; optimal levels of other essential amino acids in the diet were predicted by the whole‐body essential amino acid profile of hybrid striped bass. In the laboratory experiment, weight gain of fish fed 36% crude protein was significantly higher than those fed either other level of dietary protein. After 205 days, final average weight gains of fish in the field experiment were not significantly different and ranged from 233 to 426 g with an overall average daily gain of 1.6 g/fish/d. Overall survival was 89.1%. Dress‐out percentages were 81.2, 69.8, and 34.9% for eviscerated, eviscerated and headed, and fillets, respectively. Those values were not significantly different among dietary treatments or sites. Lipid content of fillets from fish fed 32% dietary crude protein was significantly higher than in fish fed 36 or 40% crude protein.

Larval Fish Transport: A Case Study of White Bass

Abstract Larval white bass Morone chrysops resisted downstream transport in the Holston River, eastern Tennessee. Despite a short hydraulic-transport time (<20 hours) through the study area (19.8 km), larvae were not transported downstream and out of this region soon after hatching. Recently hatched larvae were collected near a dam that blocks migration of spawning adults at the upper end of the study area; however, downstream from the dam larvae were significantly larger (and older) than expected if they had been transported passively through the area. Larval white bass probably remain near bottom or in other low-velocity refugia that effectively reduce down-stream displacement. Hybrid striped bass Morone saxatilis x white bass larvae 4 mm and longer oriented upstream in our laboratory flume; they swam vigorously and utilized areas of low current velocity to reduce downstream displacement. Retarded downstream transport found in the rivefine environment, coupled with laboratory observations, implies that ...