Nine, production-scale, recirculating aquaculture systems were utilized to compare the growth parameters between all-female and mixed sex yellow perch stocks. Each system was stocked with 455 fish m⁻³ and contained one of three different biofilter types: a rotating biological contactor, a trickling filter or a bead filter. The all-female fingerlings (S1) used were originally derived from Lake Mendota, Wisconsin. The mixed-sex fingerlings (S2) used were originally derived from Lake Erie. Temperature and photoperiod (23°C, 16H-L) were maintained at levels for optimal growth. Absolute growth rates ranged from 0.27-0.48 g/day. Mean final density within treatments was 42.8 kg/m³ and ranged from 37.2-50.2 kg/m³. The main effect of stock did not have a significant effect on growth (p > .1). All-female treatments exhibited more uniform growth. The main effect of filter type did have a significant effect on fish growth (p < .01), with fish in tanks containing trickling filters exhibiting significantly higher growth. Total feed conversion averaged 1.61 across all treatments and ranged from 1.38-1.78. S1 treatments consumed a significantly higher percent body weight per day than S2 treatments (p < .05). Analysis of PIT tagged individuals revealed that the mean relative growth rate was significantly higher in S2 individuals (513.9%) compared to S1 individuals (315.3%: p < .01). S2 females (597.8%) grew 1.9 times faster than S1 females (315.3%: p < .01). Within S2 individuals, females (597.8%) grew 1.5 times faster than males (395.2%: p < .05). For all individuals, 33.6% of the variation in final weight was explained by the variation in initial weight. Differences in the geographic strain or culture history of these stocks may have had a larger overall effect on growth than sexual classification (all- female or mixed sex). Dress percentage of skin-on butterfly fillets was examined in 20 individuals per stock and in six groups of 20 individuals per stock. Within S2 individuals, 73.7% were female. Mean fillet yield was significantly greater in S1 individuals (47.6%) compared to S2 individuals (43.0%: p < .01). Mean GSI in S1 individuals (1.01%) was significantly higher than S2 individuals (0.54%: p < .05). Within S2 individuals, mean GSI was significantly higher in females (0.70%) when compared to males (0.08%: p < .05). Fillet yield was significantly greater in S1 groups (47.2%) compared to S2 groups (44.9%: p < .01). Within each stock fillet yield increased with size. The difference in fillet yield demonstrated between these stocks may be a result of differences in strain of origin. The identification of superior yellow perch strains or strain crosses with regard to growth rate and fillet percentage is of considerable importance to the industry. / Master of Science

Thesis (MPhil (Animal Sciences. Aquaculture))--University of Stellenbosch, 2005. / In recent years there has been a renewed interest in the commercial culture of African Sharptooth Catfish. Its robust characteristics and its air breathing capabilities makes the African catfish a good candidate for culture in intensive recirculating systems. In light of the size variation in offspring spawned from undomesticated fish, that may eventually increase cannibalism, suitable methods for the quantification of some production performance parameters such as growth and health measurements need to be established for application in intensive catfish culture. In fish the condition factor (CF) reflects information on the physiological state of the fish in relation to its welfare. This factor is expressed as Fulton’s condition index, or the K-factor. African Sharptooth Catfish fry with average weight of 1.9g ± 0.7867 and average length of 59.375mm ±8.812 were equally allocated into ten 1000L-recirculating tanks. The fish were fed a commercial feed to apparent saturation at a frequency of 5 times per day. Sixteen fish were sampled out of each treatment. Weight (g) and length (mm) of each fish were recorded every seven days over a trial period of 175 days from which Fulton’s condition index K was calculated. Results were analysed for significant differences using one-way ANOVA and Tukey’s pair wise comparison test for the various parameters. Growth parameters (a = -5.083, b = 3.004, R2 = 99.4%) derived from the logarithmic relationship between body weight (W) and standard length (L) indicated an isometric growth through the duration of the trail. No significant differences (P>0.05) in condition factors between treatments were found at the beginning of the trail. Significant differences (P<0.05) were found at the end of the trail for weight between ponds and condition factor between treatments. No significant difference (P> 0.05) between length and treatments were found at the end of the trial. Mean condition factor was 0.856 ± 0.187. By using this information on condition factor for African catfish a K-factor calculation chart for African catfish could be calculated, to be used as a practical measurement tool to measure performance goals on catfish farms.

Thesis (MPhil)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: 60-day growth experiment was conducted to investigate the effect of dietary Lcarnitine supplementation on the production performance parameters of Mozambique tilapia, Oreochromis mosambicus. A number of approximately 140 tilapia fry with average weight of l.4g ± 0.71g were stocked in each of 40 fine-meshed hapas (I mx 1mx 1.5m) submerged within a complete recirculation pond system. During the first 30 days of the experiment water temperatures ranged from 19 to 23°C where after it decreased to 16-20°C for the consecutive 30-day period. Dietary treatments consisted of 8 replicates of 5 levels of L-carnitine supplementation labelled as Co, C250,C500, C750 and C 1000represented Omg, 250mg, 500mg, 750mg and 1000mg L-carnitine supplementation per kg feed respectively. Results were analyzed for significant differences using one-way analysis of variance (ANOVA) and Tukey's pairwise comparison test for growth rate, feed intake (FI) and feed conversion efficiency. After completion of the trial 8 fish from each hapa were sacrificed and analyzed for cephalosomatic index (CSI), dress out percentage (viscera, gills and head excluded), viscerosomatic index (VSI) and hepatosomatic index (HSl). Poor production performance results were generally observed as water temperatures were sub-optimal, especially during the second 30-days period. Results from the trial indicate no significant differences (P>0.05) between treatments for weight gain, FCR, FI and VS!. A negative trend was observed for FCR with increasing level of L-carnitine supplementation for both the first 30-day period (1.50±0.07, 1.53±0.08, 1.58±0.09 and 1.61±0.17 for C250,C50Q,C750and C 1000)as well as for the consecutive lower temperature 30-day period (2.22±0.10, 2.25±0.ll, 2.27±0.28 and 2.29±0.2l for C250, C500, C750 and C 10(0)'Although statistically not significant, fish fed the C250showed better performance in dress out percentage weight either than the control or the higher levels. The increasing trend for head weight with increasing level of L-carnitine supplementation were significant (P<0.05) from Co and C250with and above C500.The decreasing trend for liver weight with increasing level of L-carnitine supplementation became significant (P<0.05) with and above C750.The results of the current study showed a trend in the improvement of L-carnitine on the production performance parameters. However, the natural content of L-carnitine in the basal diet impaired with the inclusion levels, thus further research at lower inclusion levels is recommended. / AFRIKAANSE OPSOMMING: 'n Proef oor 'n tydperk van 60-dae is onderneem om die effek van L-karniten aanvulling op produksie prestasie parameters van Mosambiek tilapia (0. mosambicusi te ondersoek. 140 tilapia vingerlinge met 'n gemiddelde massa van lAg ± 0.7lg is ewekansig uitgeplaas in 40 eksperimentele hapa-hokkies (lmxlmx1.5m) in "n hersirkulasie sementdam-stelsel. Gedurende die eerste 30 dae van die proef het water temperatuur gewissel tussen 19 to 23°C waarna dit gedaal het na tussen l6-20°C vir die opeenvolgende 30-dag periode. Proef-rantsoen behandelings het bestaan uit 8 herhalings van 5 vlakke van L-karnitien aanvulling, naamlik Co,C250, C500, C750 en CIOOOvir Omg, 250mg, 500mg, 750mg en 1000mg L-karnitien aanvulling per kg voer afsonderlik. Resultate was ontleed vir betekenisvolle verskille deur gebruik te maak van analise van variansie (ANOVA) ontleding en die Tukey se vergelykende toets vir groeitempo, voerinname en voeromsettingsverhouding. Aan die einde van die proefperiode is 8 visse van elke hapa ontleed vir liggaamskomponent-samestelling (kop-, ingewande- en hepatosomatiese indekse. Ondergemiddelde produksie resultate is waargeneem wat toegeskryf kan word aan onder-optimale water temperature, veral gedurende die tweede 30-dag periode van die proef. Proef resultate het geen betekenisvolle verskille (P>0.05) in massatoename, voeromsettingsverhouding (VOV) of visserosomatiese indeks tussen behandelings getoon nie. 'n Negatiewe neiging is waargeneem vir VOV met toenemende vlakke van L-kamitien insluiting vir beide die eerste 30 dag periode (1.50±0.07, 1.53±0.08, 1.58±0.09 and 1.61±0.17 for C250, C500, C750 and CIOOO) sowel as vir die opvolgende 30-day periode nie (2.22±0.10, 2.25±0.11, 2.27±0.28 and 2.29±0.21 for C250, C50o, C750 and CIOOO). 'n Toenemende neiging vir kop-massa met toenemende L-kamitien insluiting was betekenisvol (P<0.05) vanaf Co en C250 met en hoër as C500. 'n Dalende neiging vir lewermassa met toenemde L-kinsluiting was betekenisvol (P<0.05) met en hoër as C750. Resultate van die proef dui oor die algemeen op 'n neiging tot verbeterde produksie prestasie parameters van tilapia vingerlinge met toenemde insluiting van Lkamitien. Verdere navorsing word aanbeveel om die invloed van natuurlike Lkamitien in die proteïen-bronne van die basaalrantsoen te op die gebrek aan betekenisvolheid van hierdie neiging te verklaar.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Elasmobranch fishes use electroreception to detect electric fields in the environment, particularly minute bioelectric fields produced by potential prey. A single elasmobranch family (Potamotrygonidae) is composed of obligate freshwater stingrays endemic to the Amazon River. A freshwater existence has imposed morphological adaptions on their electrosensory system due to life in a high impedance medium. Because their electrosensory morphology differs from their marine relatives, freshwater stingrays may demonstrate corresponding differences in behavioral sensitivity. The objective of this study was to quantify behavioral sensitivity of the obligate freshwater stingray Potamotrygon motoro to prey-simulating voltage. The voltage produced by common teleost prey of P. motoro were measured and replicated for behavioral trials. The best response was 10.62 cm, and the smallest voltage gradient detected was 0.005 mVcm-1. This sensitivity is reduced compared to marine species. The conductivity of the medium, more so than ampullary morphology, may dictate sensitivity of the elasmobranch electrosensory system. / by Lindsay L. Harris. / Thesis (M.S.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

An Investigation Into the ecology of benthic macro-invertebrates in earthen ponds subjected to intensive trout (Salmo trutta L.) culture practices at Howletoun, Central Scotland, was conducted between May 1984 and January 1986. Soil and water quality, seasonal changes in benthos, its role in the trout diet and the Interaction between fish and benthos were studied. Pond benthos mainly comprised 6 major groups including Oligochaeta. (10 species), Chironomldae (18 species), Molluscs and Hirudinea (2 species each) and an asellid and a sialid species. Oligochaeta formed 78 to 90% of benthic fauna, dominated by Tubifex tubifex. Limnodrilus hoffmeisteri, L. udekemianus and Psammoryctides barbatus, with an average population density of 68,400 - 191,200 worms mˉ², and exhibited peaks in summer and late autumn corresponding to two major breeding periods. The principal species of Chironomidae were Chironomus spp., Procladius spp. and Prodiamesa olivacea, with a population density of 5,400 to 14,900 ind. mˉ² and forming 7 to 13% of the total benthos with peaks in spring and autumn. Dry biomass of total benthos varied from 24-59 g mˉ² in the cultured ponds with oligochaetes accounting for 14-49 g mˉ² and chironomids 4-7 g mˉ². The mean annual dry weight production of total benthos varied from 130-215 g mˉ² in the cultured ponds, with oligochaete production of 94-160 g mˉ² and chironomid production of 20.6-33.5 g mˉ². An investigation into the ecology of benthic macro-invertebrates in earthen ponds subjected to intensive trout (Salmo trutta L.) culture practices at Howietoun, Central Scotland, was conducted between May 1984 and January 1986. Soil and water quality, seasonal changes in benthos, its role in the trout diet and the interaction between fish and benthos were studied. Pond benthos mainly comprised 6 major groups including Oligochaeta (10 species), Chironomidae (I8 species), Mollusca and Hirudinea (2 species each) and an asellid and a sialid species. Oligochaeta formed 78 to 90% of benthic fauna, dominated by Tubifex tubifex. Limnodrilus hoffmeisteri, L. udekemianus and Psammoryctides barbatus, with an average population density of 68,400 - 191,200 worms mˉ², and exhibited peaks in summer and late autumn corresponding to two major breeding periods. The principal species of Chironomidae were Chironomus spp., Procladius spp. and Prodiamesa olivacea, with a population density of 5,400 to 14,900 ind. mˉ² and forming 7 to 13% of the total benthos with peaks in spring and autumn. Dry biomass of total benthos varied from 24-59 g mˉ² in the cultured ponds with oligochaetes accounting for 14-49 g mˉ² and chironomids 4-7 g mˉ². The mean annual dry weight production of total benthos varied from 130-215 g mˉ² in the cultured ponds, with oligochaete production of 94-160 g mˉ² and chironomid production of 20.6-33.5 g mˉ². In an unstocked control pond the total production was 55 g mˉ², 35 g mˉ² of which was accounted for by oligochaetes and 8.06 g mˉ² by chironomids. Analyses of gut contents of the farmed trout showed that 12% of the diet by volume consisted of natural food, mainly benthos. Fish selectively fed on chironomid larvae, Mollusca, Asellus aquaticus and Sialis lutaria. Fish took maximum natural food in the morning and evening. Experimental enclosures to exclude fish from selected areas of the ponds demonstrated that number of species increased outside the enclosures but, except for chironomids, population density, biomass and production generally increased inside the enclosure. The possibility of explaining this result in terms of differential predation is discussed.

No description available.

"August 2004" / Includes bibliographical references. / xi, 108 p. : ill., maps, plates ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / "This thesis extends and summarises Australian data on carp (Cyprinus carpio L.) reproductive biology and early growth. Specifically, it (1) validates the aging of larval and early-juveniles via daily otolith increment counts, (2) provides regression equations to account for shrinkage that occurs upon preservation of young-of-the-year (YOY) carp in 70 and 95% ethanol, (3-4) investigates the timing, frequency and duration of spawning via gonad staging and via a combination of gonad staging and YOY sampling, and (5) investigates relationships between YOY recruitment and nine hydro-climatic parameters, and examines spatial and temporal variation in YOY growth." / Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2004

Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : 50-54).

In Thailand, culture and production of a high value freshwater fish, the marble goby, is dependant upon farm-made feeds using marine and freshwater trash fish as primary ingredients. However, there is lack of nutritional research regarding the use of such farm-made feeds and their impacts on the nutritional status, growth and health of marble goby. The aims of the present study were to evaluate the effects of farm- made feeds on slaughter indices, fish lipid classes and fatty acid profiles, nutrient composition and digestibility. In addition it was intended to improve on-farm feed quality for both current practical feeds as used by farmers and alternative feeds using rice bran and tilapia with reference to biochemical composition, growth performance and haematology of marble goby. Nutritional evaluation of farmed fish compared to their wild counterparts indicated that fatty acid composition of farmed marble goby was markedly influenced by diet. Marble goby appeared to utilize MUFA preferentially as an energy source compared to SFA. Fish muscle was characterised by higher n-6 PUFA; arachidonic acid (20:4n-6, AA) and docosapentaenoic acid (22:5n-6, DPA). Eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22: 6n-3, DHA) comprised the majority of n-3 PUFA found in fish muscle and can potentially be enriched into marble goby muscle through the diet. The significantly higher ratios of neutral liver lipid to polar lipid (NL/PL) indicated the imbalance of dietary lipid and energy of on-farm feeds. Moreover, findings on slaughter indices and lipid peroxidation of farmed fish; higher HSI, VSI, liver TBARS and the pale lipid-rich liver of farmed fish indicated problems with the nutritional quality of lipid in farm-made feeds. Experiments aimed to improve farm-made feeds using supplemental vitamin E in the form of α-tocopherol. These demonstrated that supplementation of α-tocopherol to oxidised diets, both mackerel and tilapia based, did not result in a significant beneficial effect in reducing mortality, and improving growth and haematology in marble goby. However, dietary α-tocopherol supplementation helped in reducing fish muscle peroxidation but was not related to muscle α-tocopherol levels. In mackerel based diets containing lipid peroxidation up to 250-300 µmols MDA g-1, α-tocopherol supplementation appeared not to help in reducing liver peroxidation. The alternative use of tilapia as a feed for marble goby resulted in growth and survival rates similar to those of fish fed mackerel based diets. Tilapia contained intrinsic α-tocopherol levels that appeared to be sufficient to reduce marble goby tissue peroxidation. The synergic effects on antioxidant activities between α- tocopherol supplement and natural E vitamer contained in rice bran helped to reduce tissue TBARS and improve haematology in fish fed combination diets of oxidised tilapia and rice bran. The inclusion of rice bran in farm based diets resulted in decreased tissue peroxidation, an adverse affect on dry matter and protein digestibility; and lower fish feed intake, growth and survival rate when 25% of rice bran was added into practical mackerel based diet. Overall, formulated feeds showed promising growth and survival rate in marble goby but more research on dietary nutrients and energy balances are required.