Browsing by Subject "aquaculture"
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Item Evaluation of amino acid supplementation of soybean-meal-based diets for hybrid striped bass(2009-05-15) Savolainen, Lea ChristineHybrid striped bass (Morone chrysops x M. saxatilis) aquaculture is a major commercial enterprise in the United States and internationally. Efforts to decrease diet costs and limit dependence on fishmeal, have led to the development of plant-based diets as an alternative aquafeed. Due to limiting concentrations of amino acids such as methionine, cystine, and taurine in plant meals such as soybean meal, supplementation of these plant-based diets with methionine or other sulfur amino acid compounds is typically required. Therefore, the current study was conducted to evaluate different amino acid supplements in soybean-meal-based diets for hybrid striped bass for possible refinement of diets and reduction of production costs. One feeding trial evaluated methionine hydroxy analog (MHA) and Mintrex? which is MHA containing chelated zinc relative to L-methionine. The second trial evaluated the effects of supplemental taurine or arginine on fish performance and potential health benefits. In the first feeding trial, a basal soybean-meal-based diet (56% soybean meal and 15% fishmeal) marginally deficient in total sulfur amino acids (TSSA) (1.10% methionine and cystine) was supplemented with either L-methionine, Mintrex? or MHA calcium salt and fed to triplicate groups of juvenile hybrid striped bass for 10 weeks. The different methionine supplements provided similar weight gain, feed efficiency ratio (FER) and protein efficiency ratio (PER) values that tended to be greater than observed in fish fed the basal diet. Mintrex? supplementation provided much higher plasma zinc concentrations compared to fish fed the other methionine supplements. In the second feeding trial, soybean-meal based diets which satisfied the requirement for TSAA were supplemented with either taurine or arginine at 1.5% of dry weight. Supplemental taurine or arginine did not provide any improvements in weight gain, FER, PER or survival compared to the basal diet. Thus, taurine or arginine supplementation of soybean-meal-based diets does not appear warranted. However, sulfur amino acid supplementation of plant-based diets is critical, and Mintrex? appears to be an effective supplement to meet the methionine and zinc needs of hybrid striped bass.Item Evaluation of Elevated Dietary Iron and Aluminum on Growth and Survival of Pacific White Shrimp Litopenaeus vannamei(2013-11-19) Morgan, Jessica LeAnneThe need to identify economical applications for the co-products of algal biofuel has led to the evaluation of these co-products as feedstuffs in aquaculture feeds. However, the flocculation of algae often results in co-products with high levels of iron (Fe) and aluminum (Al). Two experiments were conducted to evaluate the effects of high levels of dietary Fe and Al on Litopenaeus vannamei. For the first experiment, a semi-purified basal diet was evaluated using ten diets containing graded levels of either Fe or Al at 200, 500, 1,000, 2,000, or 3,000 mg/kg diet over a 30-day period. In the second experiment, 12 diets with either Fe inclusions of 1,650, 3,260, 4,910, 6,640, 8,290 or 10,044 mg/kg diet or Al inclusions of 670, 1,330, 2,000, 2,702, 3,370, or 4,050 mg/kg diet were evaluated over a 42-day period. The experiments were conducted with post-larval shrimp in 24-L aquaria using a flow-through system. Dissolved oxygen, temperature, and salinity were monitored daily. Automatic feeders distributed diet 15 times daily based on an estimated average growth curve for the duration of both experiments. Feces, molts and uneaten feed were siphoned daily. Survival was not affected in either experiment by the dietary treatments. In the first experiment, growth and biomass increased with each level of supplemental Fe and Al to the 1,000 mg/kg inclusion. At 2,000 mg/kg inclusion of either Fe or Al, growth and biomass decreased significantly. In the second experiment, growth and biomass significantly decreased with increasing inclusion of either mineral (P<0.0001). In both experiments, body tissues were analyzed to determine mineral retention. In the first experiment, tail muscle and whole-body Fe and Al tissue levels did not increase. However, hepatopancreactic levels significantly increased with increasing dietary levels of both Fe and Al. In the second experiment, retention in tail muscle and combined head and carapace tissues increased significantly with increasing dietary inclusion levels of both Fe and Al. Based on data from these experiments, relatively high levels of less than 10,000 mg/kg of Fe and Al in co-products are safe assuming a dietary inclusion level of 10% of the co-product.Item Evaluation of Seafood Processing Wastes in Prepared Feeds for Red Drum (Sciaenops ocellatus)(2012-07-16) Pernu, Benjamin MarkHigh feed costs and increasing demand for fishmeal have intensified the search for alternative protein sources which are needed to allow world aquaculture to continue expanding. A severely underused marine resource is processing wastes of various types of seafood, which are often disposed of at great cost. Therefore, this study was conducted to evaluate three different types of seafood processing wastes as potential feed ingredients for the red drum (Sciaenops ocellatus). The three processing wastes evaluated were heads and shells from Penaeid shrimp, and viscera and skeletal remains from filleted black drum (Pogonias cromis) and channel catfish (Ictaluras punctatus). These wastes were blended with soybean meal in a 40:60 ratio, dry extruded and dried to produce stable ingredients. All three byproduct meals produced had crude protein levels ranging from 45 to 50 percent. Two feeding trials were conducted to evaluate the different processing waste byproduct meals in comparison to menhaden fishmeal. A digestibility trial was conducted with sub-adult red drum which led to the computation of apparent digestibility coefficients (ADCs) for organic matter, protein, lipid and energy for each of the byproduct meals. Each byproduct meal had relatively high ADC values that were generally similar to those of menhaden fishmeal. A comparative growth trial with red drum was then conducted in which experimental diets were formulated with the three byproduct meals replacing menhaden fishmeal on an equal-digestible-protein basis at levels of 65 percent, 80 percent, or 95 percent. Juvenile red drum were fed the various diets for 8 weeks in a brackish (6 plus/minus 1 ppt) water recirculating system after which weight gain, survival, feed efficiency, as well as whole-body proximate composition and condition indices were measured. All three of the byproduct meals could replace up to 65 percent of the protein provided by fishmeal without adversely affecting performance of red drum. However, the shrimp byproduct consistently provided the highest performance values at 80 percent replacement. The catfish byproduct yielded the lowest fish performance at all levels. This study indicates that dry extrusion of seafood processing wastes can be used to replace a considerable amount of fishmeal in feeds for red drum.Item Factors contributing to the effectiveness of newly posted Peace Corps Volunteers in the Rural Aquaculture Promotion Project in Zambia(Texas A&M University, 2004-09-30) Trant, Clay AllenThe Rural Aquaculture Promotion (RAP) project is a vital development initiative by the Peace Corps in Zambia with the goal of increasing the nutritional and caloric intake of rural Zambian farmers in addition to augmenting income (Peace Corps Zambia rural aquaculture promotion, n.d.). Peace Corps Volunteer (PCV) success in achieving the goals of the RAP project is vital, and because PCVs are on site working on projects in the aquaculture assignment area for only 24 months, and as only three generations of PCVs are placed at a given site, it is imperative that they be able to contribute to these projects very promptly after arrival on site. The overriding issue concerning the effectiveness of the Peace Corps development effort is the job performance of the individual PCV which primarily depends on the PCV's ability to transfer learned knowledge and skills to the workplace. Many PCVs are routinely hampered by an inability to achieve significant and continuous contributions to projects within their assignment area. The Peace Corps' fundamental approach to the diffusion of aquaculture in Zambia is centered on the exchange of information between PCVs and rural farmers. Achieving sustainability with the RAP project is essentially based upon the consistency and longevity of this information exchange. PCVs are instructed in very specific technical procedures concerning all aspects of fish farming during pre-service training in order to ensure that they are equipped to diffuse a standardized technical curriculum to project beneficiaries. In addition, volunteers are trained in language and cross-cultural skills, and throughout the pre-service training period are assessed by the training staff for competence in the behavioral areas of motivation, productive competence, and adaptability/social sensitivity. Deficiencies in language and cross-cultural skills, the detrimental psychological effects of culture and role shock, and a lack of agency planning and support were key factors that affected the PCVs' ability to transfer successfully learned skills to the workplace. The lack of language ability was identified as the most substantial factor affecting the Volunteer's on-site job performance. Given the social nature of rural extension efforts, this has serious implications for Volunteer effectiveness.Item Fish for the City: Urban Political Ecologies of Laguna Lake Aquaculture(2013-10-31) Saguin, Kristian Karlo CordovaThe dissertation tells the story of the production of socionatures through the development of aquaculture in Laguna Lake. The state introduced lake aquaculture to supplement fisherfolk livelihoods and improve fish production in part to provide nearby Metro Manila with its fish requirements. Half a century of aquaculture in the lake, however, has transformed ecologies, landscapes and livelihoods. Flows of fish to the city encounter socioecological contradictions in lake production and urban consumption. This dissertation examines these transformations and how state policies, livelihood activities and fish demands produce particular socionatures. Using the urban political ecology concept of urban metabolism, the dissertation frames the production of Laguna Lake socionatures as a city-lake dynamic. It employs qualitative and multi-sited ethnographic methods to follow Laguna Lake fish from sites of production to consumption and to identify actors, relations and practices that shape access to these flows of fish. The state embarked on projects aided by scientific institutions and foreign donors to enable aquaculture production through simplification of complex lake socioecological processes. These resulted in capitalist fishpen aquaculture expansion that transformed lake ecologies and village livelihoods. Capitalist aquaculture continues to confront nature?s materiality in water-based production, which provides constraints and opportunities for aquaculture expansion. Village producers, intermediaries and urban consumers also continually work with the materiality of nature to secure livelihood and sustenance benefits from fish as they flow from the lake to the city. However, the distribution of access to fish flows is uneven, with urban-based fishing corporations that own the largest fishpens and fish market brokers deriving the most benefit as a result of their political and economic power. Other commodity chain actors attempt to gain access to these fish flows through formal and illicit strategies. By following the flows of Laguna Lake fish, the dissertation weaves stories of the urban metabolism as producers, traders, consumers, laborers and the state transform and produce lake and urban socionatures.Item Regional and Local-Scale Population Genetic Structure of a Primitive Teleost, the African Bonytongue (Heterotis niloticus), in Rivers of West Africa(2012-10-19) Carrera, ElizabethThe African bonytongue (Heterotis niloticus), one of two living species of the primitive teleost family Arapaimidae, constitutes an important artisanal and commercial fishery in West Africa. This species has also been proposed for wide aquaculture use in Africa. Despite its importance, information on the levels of genetic differentiation for this fish in Benin is lacking, which can contribute to its conservation and management. In this study, regional and local scale genetic differentiation of the African bonytongue in Benin, West Africa, was examined using six microsatellite markers. In total, 221 H. niloticus individuals were sampled from 12 localities in Benin that include three river basins: Oueme-So (ten localities sampled); Mono (one locality); and Niger (one locality). The results showed a high degree of genetic differentiation between African bonytongue samples from the three river basins, which was expected given the barriers for dispersal for aquatic organisms. For the Oueme-So floodplain, they indicate high and homogeneous gene flow, suggesting that seasonal flooding facilitates gene flow across this region. The information obtained from this study will be useful for defining management units for H. niloticus in Benin, and caution against the translocation of individuals from different basins.Item Social organization of the New Zealand dusky dolphin(Texas A&M University, 2004-09-30) Markowitz, Timothy MichaelSocial organization of dolphins in extensive societies has not been well studied. Off Kaikoura, New Zealand, thousands of dusky dolphins (Lagenorhynchus obscurus) gather, feeding nocturnally on deep scattering layer prey, resting and socializing diurnally. During 1997-2003, interval sampling was used to monitor large assemblages numbering hundreds (n=169), smaller mating groups (mean+s.e.=7+1.6 adults, n=42), mother-calf nurseries (mean+s.e.=13+1.6 adults, 1+0.5 juveniles, 4+0.7 calves and 1+0.4 neonates, n=41), and non-mating adult groups (mean+s.e.= 9+1.3 adults, 1+0.2 juvenile, n=37). Group size, distance from shore (east), ranging along shore (north), traveling, inter-individual distance, and noisy leaping peaked in winter (n=39), with dolphins maintaining closer proximity to each other in smaller, more restful groups, closer to shore during the spring-summer-autumn (n=234) reproductive seasons. Dolphin groups were found closest to shore (west) during early morning, spread out and leaping often. Resting peaked at midday in tight groups. Late in the day, dolphins spread out, moving eastward (offshore) in preparation for feeding. Large groups exhibited coordinated travel, with noisy leaps as a directional signal. "Mating of the quickest" occurred in groups of (median) 6 males chasing 1 female. Leaping rarely occurred in restful nurseries, which at times associated with Hector's dolphins (Cephalorhynchus hectori). Other mixed-species groups included common dolphins (Delphinus delphis), southern right whale dolphins (Lissodelphis peronii), long-finned pilot whales (Globicephala malaena), and bottlenose dolphins (Tursiops truncatus). Killer whales (Orcinus orca) elicited predator assessment and evasion. Whale riding occurred with larger whales. Residence was seasonal, with 1,969+814.9 from a population of 12,626 dolphins spending 103+38.0 days in Kaikoura (mean+s.e., mark-recapture mortality, single-season lagged-ID emigration models, n=153 weeks). Dolphins (n=39) summering in Kaikoura migrated to the Marlborough Sounds in winter, where small, coordinated groups foraged diurnally on schooling fishes in shallow bays, often associated with sea birds and New Zealand fur seals (Arctocephalus forsteri). Aquaculture may threaten dusky dolphin foraging habitat in Admiralty Bay, where an estimated 220 dolphins gathered to feed each winter. Photo-identification research, enhanced by digital techniques, demonstrated a structured fission-fusion society. Dusky dolphins associated with preferred long-term (>1,000 days) hunting companions in Admiralty Bay and non-random casual acquaintances (200 days) in Kaikoura (lagged-association models).