This thesis was partitioned into three studies. In the first study, striped bass, Morone saxatilis, (n = 16) were monitored over a 13 month period to examine the efficacy of ultrasound to determine sex and to monitor sexual maturation. Four observers reviewed all ultrasound images (n = 208) of striped bass and were able to sex male and female striped bass with 99 and 95% accuracy, respectively throughout an annual reproductive cycle. Egg diameter was highly correlated with average (r = 0.89) and maximum (r=0.92) ovarian diameter as measured by ultrasound. Spenniating males exhibited larger maximum testicular diameters (23.5 mm) than non-spermiating males (13.1 mm). Fully mature female and male striped bass exhibited maximum ovarian diameters > 30 mm and testicular diameters > 20 mm as measured by ultrasound. The results of this study indicate that ultrasound is an effective and non-invasive method that aquaculturists can use to quickly scan, sex, and assess the sexual maturation of adult male and female striped bass year-round. In the second study, photothennal manipulation was used to induce spawning out-of season and to increase the frequency of spawning in striped bass, Morone saxatilis. Forty adult striped bass, held in five environmental chambers, were exposed to compressed 6- and 9- month cycles and a 12-month reference cycle. Maximum egg diameters increased with cycle length, averaging 845 urn, 946 urn, and 1,073 um for females held on the 6-, 9-, and 12-month cycles,respectively. Females held on the 6-month cycle had smaller ovarian diameters (19.6 mm) than those held on the 9-month (27.4 mm) and 12-month (24.5 mm) cycles. Ovary diameter was highly correlated with egg diameter (r = 0.91). Spawning success (percent of females spawning) increased with cycle length, averaging 38%, 86%, and 100% in the 6-, 9-, and 12-month cycles, respectively. However, no differences in latent times, fecundity, or fertility were detected between cycles or between tank-spawned and strip-spawned females. Males held on the 6-month cycle had smaller testicular diameters (16.2 mm) than those held on 9-month (23.6 mm) and 12-month (19.2 mm) cycles. Testicular diameter of spenniating males (15.7 mm) was significantly larger than that of non-spenniating males (6.9 rnrn) in all cycles. Mortality increased with cycle length, averaging 28%, 38%, and 88% for fish held on the 6-, 9-, and 12-month cycles, respectively. Maturation and spawning were advanced by five and three months for fish held in the 6- and 9-month cycles, respectively when compared to a natural 12-month reference cycle. Fish held on the 6-month cycle matured twice within a year. However, the relatively low number of spawning females and diminished egg, ovarian, and testicular diameter of fish held on the 6-month cycle suggest that an abbreviated cycle length « 9 months) may inhibit maturation and constrain spawning success. / Master of Science

Thesis (M.S.)--North Carolina State University, 2002. / Title from PDF t.p. (viewed on Dec. 15, 2005). Includes vita. Includes bibliographical references.

Striped bass larvae, native to the Shubenacadie River, catch invertebrates in darkness using mechanoreception via lateral line neuromasts. The neuromast total increased from 17 at first feeding (5 to 7 dph) to 135 by the juvenile stage (27 dph). A 5 mM neomycin dose ablated neuromasts, confirmed by fluorescent and confocal microscopy. In feeding trials, larvae with and without functional neuromasts were offered Artemia salina in darkness or light. To identify ontogenetic changes in feeding, experiments were repeated at 10, 13, 17, and 20 dph. In darkness, neomycin treated larvae caught fewer prey (~5 Artemia h-1 at all ages, p<0.05) than larvae with intact neuromasts (10 dph, 16 Artemia h-1; 20 dph, 72 Artemia h-1). In light, neomycin did not affect feeding, indicating no deleterious side-effects. Neomycin did not damage olfactory or taste cells judged by FM1-43FX and calretinin staining. The results support the contribution of mechanoreception to non-visual feeding. / Master's thesis

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 109-117). Also available via the Internet.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 64-75).

Thesis (M.S.)--University of North Carolina Wilmington, 2008 / Title from PDF title page (viewed May 26, 2009) Includes bibliographical references (p. 31-33)

Since 1995, California State Fish Hatcheries (Feather River, Nimbus, and Mokelumne) and Coleman National Fish Hatchery have raised approximately 29 million 4 fall run Central Valley Chinook salmon (Oncorhynchus tshawytscha) per season for stock enhancement. From April through June, fish are acclimated in net-pens prior to release at one of three sites: the Carquinez Strait at Conoco Phillips (CP), the mouth of the Napa River at Mare Island (MI), and the San Joaquin River at Jersey Point (JP). Striped Bass, Marone saxatilis, are known to congregate at the release location to feed on the hatchery fish as they enter the Delta and Bay, and are suspected to be reducing numbers of Chinook recruitment. Dual-Frequency Identification Sonar (DIDSON) was used to capture video-like images to enumerate and estimate sizes of potential predators in the area. Stomach analysis was used to obtain consumption rate data and a simple model was used to estimate predator impacts on the hatchery fish. Data was collected in 2011 and 2012. In 2011 the striped bass population at CP was significantly larger than MI (p=0.009) and JP (p=0.038) and in 2011 , and MI (p=0.046) in 2012. Predators were significantly smaller (range 11.8-61.7 em, mean 34.6 em in 2011 ; 21-67 em, 42.9 in 2012) atJP (p<0.001). Average size predator at MI was 47.3 em (range 31-59 em) in 2011 and 50.9 em (range 33-73 em) in 20 12; and at CP was 48.3 em (range 16-77 em) in 2011 and 52.7 em (range 31-78 em) in 2012. On average an estimated 2.2% of hatchery fi sh are consumed each year by striped bass and predator impacts are greatest at CP (p<0.001). Changing the release site often could improve salmon survival by decreasing predator attraction to the site and reducing immediate predator-prey encounters.

The early life history dynamics of stocked, fingerling striped bass (Morone saxatilis) were evaluated in Smith Mountain Lake, Virginia, from 1994-96 and incorporated into an individual-based model to assess various stocking strategies in terms of their largest percent increases in first-year growth, overwinter survival, and recruitment to age 1. Age-0 striped bass exhibited dissimilar patterns of dispersion and size-dependent spatial distribution as a result of differences in habitat availability between stocking sites and water temperature preferences. Although size increased over the growing season, a bimodal length distribution developed by fall during both 1994 and 1995; this distribution consisted of large-mode juveniles (> 180 mm TL) that weighed several times more than small-mode fish (<140 mm TL). Differential growth was attributed primarily to size-dependent differences in food habits and diet quality: small-mode striped bass maintained a mixed, low quality diet of invertebrates and small, age-0 cyprinids, while large-mode juveniles consumed only larger, energetically more profitable age-0 alewives. This disparity in food habits, largely due to the inability of small-mode striped bass to consume distributionally- and morphologically-invulnerable age-0 alewives, resulted in size-dependent differences in physiological well-being as large-mode juveniles had amassed greater absolute energy stores than small-mode fish by the end of the growing season. Spring sampling revealed that the bimodal length distribution had become unimodal and was comprised almost entirely of large-mode juveniles. Because the few surviving small-mode striped bass collected during spring were extremely emaciated, it appears that this size group exhausted their energy stores and, consequently, starved over the winter. Individual-based model simulation results indicated that stocking juvenile striped bass at a median total length of 52 mm on 08 June, while maintaining the current stocking density at 300,000 fingerlings, would result in the largest percent increases in first-year growth, survival, and number of age-1 recruits. This strategy was also less sensitive to perturbations in alewife population parameters and water temperature regime, and was more robust to these variations than the existing stocking scheme (300,000 fingerling striped bass with a median total length = 42 mm introduced on 15 June). / Ph. D.

As aquaculture continues to contribute high quality protein to a greater proportion of the worlds growing population, fish producers have been pressured to increase overall production. However, associated with elevated production is greater stress due to crowding, reduced water quality, and other factors. These stressors impact the health and welfare of the farmed animal which has become of increasing concern to a more environmentally aware and health conscious consumer. New strategies must therefore be developed and adopted by the aquaculture industry to counteract negative consumer perceptions of industrial fish production while also stabilizing the industry. Better nutrition may enhance disease resistance of farmed fish, while fillet accumulations of specific health-related nutrients may simultaneously add value to the final product. This thesis summarizes research undertaken in an effort to enhance the nutritional value of fish by increasing fillet levels of selenium (Se). In addition, various biomarkers of fish health (lysozyme, ceruloplasmin and glutathione peroxidase (GSH-Px) activities), were examined to determine whether dietary Se supplementation had a positive impact upon fish immunocompetence. Moreover, the effect of vaccination was also examined using lysozyme and growth as indicators of fish performance. Hybrid striped bass (HSB), the fourth most valuable farmed fish and fifth in tonnage produced in the United States, were employed as a model animal. Se, an essential component of the antioxidant enzyme, glutathione peroxidase with many established health benefits was supplemented to HSB diets at various concentrations but was found to be without effect upon serum immune proteins or GSH-Px activity. This finding likely reflected the use of fishmeal within the dietary formulation, which possessed relatively high Se levels, together with sufficient storage of tissue Se within the experimental animals. Nevertheless, these studies determined that organic sources of Se were more efficiently accumulated in HSB muscle than traditional inorganic sources. A linear response occurred up to the highest dose used (3.2 mg kg⁻¹) over a 6 week study. Fillet Se accumulation (r²=0.95) proved to be a better indicator than the liver (r²=0.87).Se enhanced fish therefor appear to offer a route of entry for fish producers into the lucrative designer food market - especially since many hundreds of millions of people worldwide are believed to be Se-deficient. Studies undertaken with Se-deficient HSB confirmed findings from the aforementioned research and also indicate that Se-enhanced fillets might be produced using a finishing feed containing 1.5 mg Se kg⁻¹ 6-8 weeks prior to harvest. Accumulation of Se using this strategy resulted in a 100g portion of HSB fillets containing between 33-109 µg Se, amounting to a dietary intake of between 25-80 µg Se; a level that would satisfy present daily intake recommendations. Vaccination of HSB with a Streptococcus iniae oil-in-water vaccine was examined for its potential negative impacts upon HSB production performance. Vaccinated fish did not exhibit any significant reductions in growth but microarray studies revealed that together with many hundreds of genes, four immune-related genes were impacted by this procedure. This thesis discusses the results obtained with regard to their practical implications to the industry and welfare of cultured fish. / Master of Science

Smith Mountain Lake, Virginia supports a successful put-grow-take striped bass fishery. Empiric analysis of striped bass stocking has shown an inverse relationship between number of fingerling striped bass stocked and survival to age 1. Potential causes for this inverse relationship include largemouth bass predation on fingerling striped bass and mortality resulting from stocking stress. Cage studies performed in 1994 and 1995 quantified percentage of fingerlings lost due to hauling/handling stress. Mean mortalities ranged from 1.78% for Phase I fingerlings in 1994 to 99.5% for Phase II fingerlings (reared in a recirculating aquaculture system for increased size at stocking) in 1994. Mortality rates varied greatly and were probably directly related to length of transport and inadequate thermal tempering prior to stocking. Highest mortality occurred at transport times in excess of six hours and when receiving water was 5° C warmer than transport water. A trial in which Phase I fingerlings were caged without transport or temperature change resulted in no mortality. Predation mortality by largemouth bass was also considered as a source of poor first-year survival of striped bass in Penhook and Waterwheel stocking coves at Smith Mountain Lake. It was necessary to estimate largemouth bass population size, diet composition, and daily consumption (bioenergetic modeling) to determine the total number of striped bass lost to predation. Diet analysis revealed that age-0 striped bass made up a maximum of 2.5% of largemouth bass diets in the month following stocking; adult alewives constituted more than 60% by weight. The estimated number of striped bass lost was only 360 (0.1%) in 1994 and 3062 (1.2%) in 1995. Bioenergetic simulations demonstrated that predation could become significant in the unlikely event that the contribution of striped bass to largemouth diets increased to 10% or more. Based on results from diet analysis and a prey preference laboratory study, alewives appear to buffer predation of age-0 striped bass during the month after stocking. In 1994 and 1995, neither stocking stress associated with the typical Phase I fingerling stocking procedure nor largemouth bass predation resulted in substantial mortality of stocked fingerling striped bass. / Master of Science