bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth and Survival of Intrastrain and Interstrain Rainbow Trout (Oncorhynchus mykiss) Triploids1
Authors: Guo Ximing , Hershberger William K. , Myers James M.
Published: April 2007

Triploid rainbow trout exhibit improved survival and extended growth during sexual maturation, compared to their diploid counterparts. However, there have been few benefits demonstrated prior to sexual maturation. This study was undertaken to investigate the possibility of improving growth and survival parameters in triploids through interstrain crosses. Triploids were induced by heat shocking fertilized eggs from intra‐ and interstrain crosses of two rainbow trout strains. The four triploid groups and their diploid counterpart groups were reared to 233 days post‐hatching and analyzed for growth and survival characteristics.

Compared with diploids, triploids had significantly (P < 0.05) higher mortalities during the first 100 days post‐fertilization, primarily just prior to and after hatching. However, during the remainder of the study triploids exhibited significantly (P < 0.05) lower mortalities than diploids. During the first 50 days of rearing all four triploid groups were significantly shorter and lighter than their diploid counterparts. The growth of the triploid groups later in the study varied considerably. At the conclusion of the rearing phase, one interstrain triploid group was significantly (P < 0.05) longer than its diploid counterpart, although not significantly heavier. The other triploid groups were either significantly smaller than, or equal to the diploids. Analysis of variance indicated that the growth of triploid rainbow trout was significantly affected by maternal strain effects. These results suggest that the use of specific strains and crosses may improve the growth of triploid rainbow trout.
An Evaluation of a Leuteinizing Hormone‐Releasing Hormone Analog to Induce Spawning of Channel Catfish Ictalurus punctatus
Authors: Busch Robert L. , Steeby James A.
Published: April 2007

The leuteinizing hormone‐releasing hormone (LH‐RH) analog, DAla6DesGly10 LH‐RH‐ethyl amide, delivered by intraperitoneal or intracranial injection was an effective agent for the induced spawning of channel catfish (Icrulurus punctatus) held in aquaria. A daily dose of 100 μg LH‐RH analog (LH‐RHa) per kg fish body weight was recommended as the dosage schedule of choice, but daily doses as low as 1 cg LH‐RHa per kg fish body weight induced spawning of channel catfish. LH‐RHa was as good or better than human chorionic gonadotropin or carp pituitary to induce spawning of channel catfish in aquaria. Sham‐injected (control) channel caffish spawned in this study contradicting observations in earlier studies.
Effect of Feeding Rate on Growth and Feed Conversion of Florida Red Tilapia Reared in Floating Marine Cages
Authors: Clark John H. , Watanabe Wade O. , Ernst Douglas H. , Wicklund Robert I. , Olla Bori L.
Published: April 2007

An experiment was conducted to investigate growth, survival and feed conversion of Florida red tilapia reared in floating cages in seawater under different feeding regimens. Twenty‐four cages (1 m3) were anchored in a sea pass on Great Exuma, Bahamas, and each was stocked with 300 juvenile, monosex males (10 g mean weight). Growth was monitored every 14 days for 84 days. Fish were fed daily a floating pelletized diet (32% protein) at 4 programed rates representing 50, 70, 90, and 110% of the estimated satiation rate, ad libitum, and by demand feeders, with each treatment comprised of 4 replicate cages.

Final mean weight was significantly lower for the 50% treatment (94.1 g) than for all other treatments (range = 121.8–155.7 g). Final mean biomass per cage ranged from 24.2 to 39.4 kg/m3, and survival ranged from 98.2 to 99.8%.

Mean specific growth rate was significantly lower under the 50% programed feeding treatment (2.42%/day) than for all other treatments (range = 3.15–3.56%/day) while feed conversion ratios (dry weight/wet weight) were significantly lower under the 50% (1.57) and 70% (1.68) programed feeding treatments than under all other treatments (range = 1.98–2.26). Thus, maximum growth was achieved at feeding rates near satiation while feed conversion was improved at lower feeding rates. Under demand feeding, growth and feed conversion were not significantly different than those of the ad libitum, 100%, and 90% treatments.
Diversification of Crawfish Management Schedule1
Authors: Eversole Arnold G.
Published: April 2007

Six 0.02 ha ponds were used to evaluate crawfish production and standing crop biomass of rice forage in ponds managed on a standard (control) and delayed (experimental) schedule over a two year production cycle. Delayed schedule followed the same sequence of events except the management activities were delayed approximately one month. Control and experimental ponds had statistically similar amounts of forage. No statistical difference was detected in crawfish production between the management schedules or between production years; however, analysis revealed a significant treatment × year interaction. Overall average crawfish production was 986 kg/ha. Variation in crawfish production is explained within the context of annual temperature variations and differences in population density.
Quality Evaluation of Four Sources of Brine Shrimp Artemia spp.1
Authors: Webster Carl D. , Lovell Richard T.
Published: April 2007

A study was conducted to compare fatty acid composition, hatching quality, and size of nauplii from four commercial sources of brine shrimp (Artemia spp.) cyse: China (CH), Colombia (COL), Great Salt Lake (GSL), and San Francisco Bay (SFB). The CH brine shrimp had a comparatively high percentage of 20:5(n‐3) fatty acid (eicosapentaenoic acid or EPA), an essential fatty acid for most Iarval fishes, which was 10.4% of the total lipids. The COL, GSL, and SFB sources of cysts contained comparatively low percentages of EPA, 2.9, 1.2, and 1.6%. respectively. Hatching quality was determined by hatching cysts in salt (NaCl) water with a specific gravity of 1.02 at 27 C for 42 h. The COL cysts had the fastest hatching rate, with 50% of the cysts hatching in 13.4 h, while CH cysts hatched at the slowest rate, requiring 25.6 h for 50% of the cysts to hatch. Total percentage hatch was not significantly different among the SFB, COL, and GSL sources, with an average hatching percentage of 84.5, while CH cysts had a significantly lower total percentage hatch of 67.5. The SFB source produced the greatest number of nauplii (1.6 ± 105 per g of cysts) with the smallest length (382 μm), while CH produced the smallest number (8.7 ± 104) with the greatest length (500 μm). These results indicate that there is great variation in nutritional quality, hatching quality, and size of nauplii among commercial sources of brine shrimp cysts, and each of these criteria should be considered in selecting brine shrimp in a development of a feeding strategy for larval culture of a particular species.
The Economics of Intensifying Catfish Production: A Production Function Analysis1
Authors: Nerrie Brian L. , Hatch L. Upton , Engle Carole R. , Smitherman R. Oneal
Published: April 2007

Yields of channel catfish in the United States have increased as a result of higher levels of stocking, feeding and aeration. A Cobb‐Douglas production function was estimated using survey data from 66 catfish ponds in West‐Central Alabama to determine if further intensification of catfish production in West‐Central Alabama would be profitable.

Feed, capital, stocking rate, and length of production period explained most of the variation in yield. Values of the marginal products for feed, stocking rate and capital were consistently higher than input costs during the study period. Profit‐maximizing levels of input use were higher than the levels of inputs used in West‐Central Alabama during the study period. Results indicated that more intensive use of production inputs would increase yield and profits. However, careful interpretation of these results requires consideration of non‐profit factors such ns cash Row and risk as well as the specific nature of the data used to develop the production relationship. The method utilized in this study can generally be applied to any aquaculture production system, but the recommendation for more intensive input use is specific to the pond data collected for this study.
Principles of Siphons
Authors: Garrett Roger E.
Published: April 2007

A simple siphon raises water over a crest and discharges it at a lower level. As water flows through a siphon, energy due to pressure and elevation is either lost to pipe friction or converted to velocity energy. For most practical siphons, between 50 and 75% of the elevation energy available to drive flow will be converted to velocity energy.

A standpipe covered with a dome will begin to siphon when the standpipe flows full. During siphoning, the flow rate may be several times higher than the flow through an uncovered standpipe of the same size. Furthermore, the covered standpipe can be designed to lower the water level to a point below the top of the standpipe before siphoning is allowed to stop.

Flow into the covered standpipe can be drawn from the bottom of the reservoir by extending the skirt of the dome. A vent tube allows easy adjustment of the elevation at which air enters the dome and siphoning stops. Flow rate and water level required to start the siphon depend on the pipe diameter. Some flow through the standpipe will occur before siphoning begins. Flow into the reservoir must be greater than the flow required to start siphoning. Maximum flow through the standpipe during siphoning depends on pipe diameter and the elevation energy driving the flow.

Adding a trap to the outlet of the covered standpipe eliminates the leakage flow prior to the start of siphoning. When air bubbles out the trap at the end of the standpipe, pressure inside the dome is released suddenly allowing the water level to jump above the critical level needed to start siphoning. For reliable operation, the crest height of the trap should be about equal to one diameter of the standpipe. The vent tube opening must be below the top of the standpipe to prevent premature overflow of the standpipe. Because a trapped outlet siphon has no minimum flow limit, the standpipe can be sized to carry any maximum flow.

While the trapped outlet siphon eliminates low rate leakage flow prior to the onset of siphoning, the height differential between the start and stop of siphoning cannot be as small or as easily adjusted as with a covered standpipe without a trap. The simple siphon is convenient for some applications, but it does not lend itself to automatic cycling operation. The choice depends on the needs of the situation.
Growth and Bone Development in Channel Catfish Fed 17‐α‐Methyltestosterone in Production Ponds
Authors: Gannam A. L. , Lovell R. T.
Published: April 2007

Effects of feeding 17‐α‐methyltestosterone (MT) to channel catfish (Icralurus punctatus) grown to harvestable size in earthen ponds were examined. Channel catfish fingerlings (mean weight, 14.4 g), stocked in 0.04 ha ponds (7,410 fish/ha) were fed diets containing MT at concentrations of 0, 2.5, and 10 mg/kg for 123 days. Weight gain by fish fed the control diet (0 MT) was higher (P < 0.05) than that of fish fed the treated diets. Increasing the dietary concentration of MT reduced weight gain further (P < 0.05). Both male and female fish fed MT had enlarged and thickened heads, and their skins were dark. Their dorsal and pectoral spines were short and the tips, which are normally very sharp, were soft and blunt. Weight of the rib bones per unit of length decreased (P < 0.05) as MT was added to the diet. Breaking strength of the ribs (force required to break the bone at its midpoint) measured by an Instron shear press, was less (P < 0.05) for fish fed MT than for control fish. The ratio of calcium to phosphorus in bones was lower (P < 0.05) in fish fed MT. These results indicate that feeding MT at these doses (2.5 mg/kg or above) to channel catfish suppresses growth rate and reduces size and strength of bones.
Toxicity of Chelated Copper to Juvenile Red Drum Sciaenops ocellatus1
Authors: Peppard Eileen M. , Wolters William R. , Avault James W. , Guthrie Perry W.
Published: April 2007

Acute toxicity of chelated copper to juvenile red drum (x̄= 3.1 g) was determined in a static test at 25 C and 8 ppt salinity. The 12, 24, 48, 72, and 96 h LC50s were 1.90, 0.84, 0.75, 0.64, and 0.52 mg/L copper, respectively. Effects of temperature and salinity on the 96 h LC50 (0.5 mg/L copper) for juvenile red drum (x̄= 5.0 g) were tested at two temperatures, 25 and 30 C, and three salinities, 0.5, 8, and 30 ppt. Temperature significantly affected mortality; mortality in 0.5 and 8 ppt salinities was significantly higher at 30 C than at 25 C. An increase in salinity significantly reduced the mortality of juvenile red drum. Total mortality occurred in 0.5 ppt salinity within 48 h at 25 C and within 12 h at 30 C. Total mortality occurred in 8 ppt salinity within 72 h at 25 C and within 48 h at 30 C. No mortality occurred during 96 h in 30 ppt salinity at 25 C or 30 C.
Optimum Feeding Rate of the Rotifer Brachionus plicatilis on the Marine Alga Nannochloropsis sp.
Authors: Ahmad Abu Talib , Yamasam Shigehisa , Hirata Hachiro
Published: April 2007

The optimum feeding rate of the rotifer Bruchionus plicutilis was investigated to determine the best conditions for growth of the rotifer, and also in order to maintain good water quality of the culture. Fifty rotifers of a large size strain were cultured individually at five food density levels of Nannoehloropsis sp. (0.5 ± 106, 1.5 ± 106, 3 ± 106, 5 ± 106, and 8 ± 106 cells/ml). At each level, daily survival and offspring production were recorded until the death of the final individual. The data obtained were analyzed by the life table method. The maximum value of three growth indices (the net reproduction rate, mean life expectancy at age 0, and intrinsic rate of increase) was obtdned at the food density of 1.5 ± 106 cells/ml. The ration size was calculated to be 325% (dry weight)/ day, which is equivalent to about 70% of the saturated feeding rate. It was suggested that the feeding rate should be controlled to lower than the saturated value for an efficient mass culture.
Spermatophore Generation Times inPenaeus setiferus, P. vannamei, andP. stylirostris
Authors: Leung‐Trujillo Joanna R. , Lawrence Addison L.
Published: April 2007

Spermatophore development times were studied in three species of penaeid shrimp,Penueus setifcrus, P. vannumei, andP. stylirosrris. In the terminal ampoule, the progression of spermatophore formation occurred in 4 stages (I‐IV). The duration of each stage varied with species and ablation state. In unablated males, with spermatophores manually or electrically removed, structnrally complete spermatophores containing high numbers of morphologically normal sperm were formed in 2–4 days forP. vannamei, 4–6 days forP. stylirostrisand 5–7 days forP. setiferus. Unilateral eyestalk ablation ofP. setiferusaccelerated spermatophore production time by approximately 2 days, and significantly increased spermatophore weight and sperm count without affecting sperm quality.

Spermatophore removal techniques had little effect on development time inP. vannamei. However, inP. setiferus, new spermatophores were produced faster in males mating naturally than in those males whose spermatophores were removed electrically.
Evaluation of the Dietary Iron Requirement of Penaeus vannamei
Authors: Davis D. Allen , Lawrence Addison L. , Gatlin Delbert M.
Published: April 2007

Two experiments were conducted to evaluate the dietary iron requirement of juvenile Penaeus vunnamei. Prior to initiation of 28 day (Experiment I) and 35 day (Experiment II) feeding trials, 17–20day‐old postlarvae were fed the basal diet lacking iron supplementation but containing 12 mg Fe/kg for seven days. After conditioning, juvenile shrimp (mean weight: 0.038 g Experiment I, 0.047 g Experiment II) were fed one of four diets supplemented with 0, 20, 40 or 80 mg Fe/kg from ferrous sulfate heptahydrate. Final weight gain of shrimp ranged from 1.03 to 1.28 g in Experiment I and 1.62 to 1.94 g in Experiment II. Although percent weight gain was in excess of 2700% in Experiment I and 3400% in Experiment II, there were no significant differences in growth or survival of shrimp fed the different levels of iron. Iron levels of the hepatopancreas and carapace increased linearly with dietary iron; however, there were no significant differences in the iron content of muscle tissue. Based on these results, the iron content of the basal diet appeared to satisfy physiological needs of the shrimp. Therefore, practical diets containing protein sources of animal origin which are rich in iron should not require iron supplementation.
Economic Effects of Intensification of Baitfish Production
Authors: Pounds Gayle L. , Engle Carole R. , Dorman Larry W.
Published: April 2007

This study analyzed the economic effects of intensifying baitfish production. An economic engineering approach was utilized to develop enterprise budgets for baiffish production that were used to conduct an economic analysis. All indicators utilized, including net returns, internal rate of return, and payback period, indicated dramatic improvement in the economics of baitfish production with yield increases. There were strong economic incentives to increase yield, and minnow production at industry average yield was only marginally profitable under certain scenarios and unprofitable under others. Yields of 600 kg/ha would generate adequate revenue to compete with other aquaculture alternatives in terms of net returns as well as generate M internal rate of return that would outperform current long‐term interest rates.
Enhancement of the Fatty Acid Composition of the Nematode Panagrellus redivivus Using Three Different Medial
Authors: Rouse David B. , Webster Carl D. , Radwin Ismail A.
Published: April 2007

The free living nematode Panagrellus redivivus has shown promise as a live food for marine shrimp and fish. This study evaluated the effect of three media on the fatty acid (FA) profile of nematodes. The media tested were: wheat flour (WF), wheat flour plus yeast (WFY), and wheat flour plus yeast plus fish oil (WFFO).

The total lipid content of nematodes grown on WFFO (14.9%) was significantly higher than the lipid content of nematodes grown on WF (2.7%) and WFY (4.4%). The lipid of nematodes grown on WFFO also contained a higher percentage of n‐3 highly unsaturated fatty acids (HUFA) (11.2%), especially 20:5(n‐3) (7.4%) and 22:6(n‐3) (3.3%), than nematodes grown on WF (4.8%) and WFY (5.7%). Nematodes grown on WFFO medium had similar lipids as Artemia, especially desirable n‐3 HUFA's.

Total daily yield of nematodes was highest on WFY. There was no difference in yields of nematodes on WF and WFFO. This study has shown that the nutritional value of nematodes can be influenced by the media on which they are cultured. With a proper medium, cultured nematodes can provide the inexpensive, consistently nutritious live food that can be considered for larval culture of marine crustaceans and fish.
Effect of Dietary Protein Concentration on Nitrogenous Waste in Intensively Fed Catfish Ponds
Authors: Li Menghe , Lovell Richard T.
Published: April 2007

Channel catfish were fed five diets containing 24, 28, 32, 36 or 40% protein in intensively stocked earthen ponds over a 141 d growing season. Mean standing crop at harvest was 7,559 kg/ha, and maximum daily feed allowance was 105 kg/ha. Dietary protein concentration had a negative linear effect on weight gain. Total ammonia‐nitrogen (TAN) in pond water increased linearly as dietary protein concentration increased and was positively correlated with total protein fed. However, unionized ammonia‐nitrogen (NH3‐N) was not influenced by dietary protein concentration. Dietary protein had a positive linear effect on nitrite‐nitrogen (NO1‐‐ ‐N) concentration, which was positively correlated with total protein fed and TAN. There was no significant correlation between NO2‐‐‐N and fish weight gain, although there was a significant positive correlation between NO2‐‐ ‐N/Cl‐molar ratio in pond water and concentration of methemoglobin in the fish. Results from this study indicate that when the feeding rate is as high as 100 kg/ha/d, or 3,000 kg protein/ha/season, dietary protein concentrations of 36% and above can result in harmful concentrations of NO2‐‐‐N when Cl concentration in the ponds is 2–3 mg/L. Although the NO2‐‐‐N/Cl‐ ratio in the ponds increased to harmful levels with protein concentration of the diets, this might not be the major cause of the reduction in fish growth rate as dietary protein increased because the greatest difference in weight gain occurred at the lower protein concentrations and the greatest difference in NO2‐‐‐N occurred at the higher dietary protein concentrations.
Effect of Salinity on Hatching in Neobenedenia melleni, a Monogenean Ectoparasite of Seawater‐Cultured Tilapia
Authors: Mueller Karl W. , Watanabe Wade O. , Head William D.
Published: April 2007

Laboratory experiments were conducted to determine the effect of salinity on embryonic development and hatching in Neobenedenia melleni, a monogenean ectoparasite of seawater‐cultured (37 ppt) Florida red tilapia (Oreochromis urolepis hornorum × O. mossambicus). Eggs, collected from adult monogeneans at 37 ppt, were exposed to different salinities (0, 6, 12, 18, 24, 30 and 37 ppt) for 48, 72 or 96 h. Varying degrees of post‐treatment development and hatching occurred when natural seawater conditions were restored. Hatching success generally declined with decreasing salinity and increasing duration of exposure. Under all durations of exposure, hatching success remained relatively high (≥ 69.6%) at salinities of 24 ppt and above, but declined markedly (≤ 32.5%) at lower salinities. Hatching did not occur in eggs exposed to fresh water (0 ppt) for 72 and 96 h. The most effective treatments in preventing hatching, other than prolonged exposure to fresh water, were 96 h exposures to low‐salinity brackish water. Percent hatch after 96 h exposure to 6, 12 and 18 ppt was 5.5, 11.9 and 5.8%, respectively.
Evaluation of Naturally‐Occurring Organisms as Food for Juvenile Crayfish Procambarus clarkii1
Authors: Brown Paul B. , Wetzel James E. , Spacie Anne , Konopka Allan
Published: April 2007

Nutritionally important food items for crayfish have been difficult to identify and little information exists for third instar (first‐feeding) crayfish. In this study, three major groups of potentially‐important foods were fed to communally‐reared third instar crayfish (Procambarus clarkii) and weight gain and survival were measured over a 30 day period. Mean weight gain (% increase) of crayfish fed the zooplankton Daphnia magna alone or in combination with other food items, ranged 2, 277–3, 239%, while mean weight gain of crayfish fed unidentified aquatic bacteria, the aquatic macrophyte Myriophyllum spicatus, combinations of bacteria and plant, or a negative control ranged 254–767%. No significant interaction of food items was detected. Bacteria appear to be a utilizable nutritional source for juvenile crayfish, but, using the methods employed in this study, do not support maximum rates of weight gain. Thus, pond management strategies that maximize zooplankton populations at the time of crayfish hatching might be beneficial.
Biology of Idotea baltica in Chondrus Aquaculture1
Authors: Shacklock Peter F.
Published: April 2007

The marine isopod, Idoreu baltica, was studied in conjunction with Chondrus crispus aquaculture to provide information necessary for managing populations of grazers in the biological control of algal weed species. Feeding rates, growth, and reproductive activities varied directly with temperature between 10 C and 20 C. The amount of Chondrus consumed at 20 C was approximately double that at 10 C. Female I. baltica released young at about 16 day intervals at 20 C, 25 days at 15 c and 60 days at 10 C. One female grown at 17 C produced a total of 8 broods of young over a 182 day period. The number of young per brood from this female increased from 84 (1st brood) to 310 (7th brood) as she matured. Ectocurpus, Enteromorpha and Palmaria were grazed preferentially over Chondrus and Gracilaria; a preference for haploid phases of Chondrus over diploid phases was also noted. Cannibalism was prevalent and it is suggested that this behavior might fulfill a dietary requirement.
Experimental Studies of Feeding in Larval Red Drum
Authors: Holt G. Joan
Published: April 2007

The red drum (Sciaenops ocellatus) is the only marine fish species in commercial culture in the US. Red drum can be induced to spawn on demand at any time of the year and the young grown to marketable size in indoor raceways or in ponds. Although many eggs are produced (up to 1 million per spawning pair), grow‐out through the larval stage remains a bottleneck in commercial production. Most larvae for commercial use are grown in outdoor ponds where natural blooms of phytoplankton and zooplankton are induced, but pond production is limited seasonally and geographically since red drum larvae require sea water and are intolerant of temperatures below 20 C.

It is possible to raise larvae indoors in tanks year‐round by controlling temperature and salinity and by culturing live food, but not in sufficient number to supply commercial fish growers. Experimental studies are being carried out to modify the feeding and rearing systems to improve production of post‐larvae. Of utmost importance is the development of a complete diet independent of live foods. Results of studies of highly unsaturated fatty acid requirements, digestive system development and activity levels of digestive enzymes are being incorporated into the development of an improved diet for red drum larvae.
The Development of a Functional Digestive System in the African Catfish Clarias gariepinus (Burchell)
Authors: Verreth Johan A. J. , Torreele Els , Spazier Eljallil , Van der Sluiszen Ad , Rombout Jan H. W. M. , Booms Ronald , Segner Helmut
Published: April 2007

The morphological and physiological development of the intestine, stomach, liver and pancreas of the African catfish, Clarius guriepinus (Burchell 1822), was investigated from hatching until 9 days after the start of exogenous feeding by histological, histochemical and immunohistochemical procedures. During the yolk sac period, lasting 48 hours at 30 C, the digestive system develops from a rather undifferentiated system into a distinct liver and pancreas and a segmented intestine (parts I to III). Insulin and glucagon producing cells were clearly found in the endocrine pancreatic islets from 14 hours after hatching onwards, while at the start of exogenous feeding, the exocrine pancreas showed an intense zymogen colouration. Exogenous feeding started three days after fertilization, i.e., 48 hours after hatching. At that moment, the rearing temperature was lowered to 27.5 C. The first day of feeding was referred to as day zero, changing into day 1 when the first 24 hours of feeding were completed. From the start of exogenous feeding onwards, aminopeptidase, non‐specific esterase and ATP‐ase were detected in the digestive system. Morphologically, the stomach was completed at day 4 of exogenous feeding. Gastric acid secretion started on day 4 and lead to a pH below 3.3 in the stomach on day 5. During the first four days of exogenous feeding, C‐t‐gastrin immunopositive cells were found throughout the gut, including the gastric epithelium. After day 4, the C‐t‐gastrin cells were only detected in the anterior intestine. The completeness of the stomach development was also marked by the appearance of non‐specific esterase activity in the stomach epithelial cells on day 5. All data together clearly indicate that in Clarius gariepinus, the ontogeny of a functional digestive system has been completed on day 5 after the start of exogenous feeding, marking thereby the end of the larval period.
Evaluation of Live Feeds for Larval and Postlarval Mahimahi Coryphaena hippurus
Authors: Kraul Syd , Nelson Alan , Brittain Karen , Ako Harry , Ogasawara Amy
Published: April 2007

Live hatchery feeds were assayed for fatty acids (FA), amino acids (AA), and their ability to support growth and survival of larval and postlarval mahimahi Coryphaena hippurus at two different hatchery stages. Euterpina acuritrons copepods (C), mahimahi yolk‐sac larvae (YSL), Artemia parthenogenica brine shrimp nauplii (BSn), A. parthenogenica juveniles (BSj), and Brachionus plicatilis rotifers (R) were assayed, using several enrichment media. There was little difference in AAs among feeds.

Levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were about 10 times higher in YSL than in their feeds. This explains previous findings where first stage larval survival (0–9 days) was not affected by feed HUFA levels. Second stage survival was significantly higher when larvae were fed copepods. Enrichment with 100 ppm SuperSelco greatly improved the survival of larvae that were fed brine shrimp. The even higher omega‐3 fatty acids found in copepods appear to be important for survival of larvae under more stressful conditions.

Brine shrimp juveniles enriched with SuperSelco are a good food for postlarval mahimahi. Yolksac larvae of mahimahi are an even better food, promoting faster growth at less cost, for large scale mahimahi aquaculturists. Different batches of yolksac mahimahi larvae varied by a factor of 10 in their concentration of DHA, but always had the highest level of DHA as much as 40% of total fatty acids (FAs). These “high HUFA” batches of YSL also had the highest levels of EPA and total fatty acids. The data suggest that climate and broodstock age may have considerable influence on larval nutrition.
Evaluation of the Dietary Zinc Requirement of Penaeus vannamei and Effects of Phytic Acid on Zinc and Phosphorus Bioavailability
Authors: Davis D. Allen , Lawrence Addison L. , Gatlin Delbert M.
Published: April 2007

Experiments were conducted to determine the dietary zinc requirement of Penaeus vannomri and evaluate the effects of phytate on zinc bioavailability. Prior to initiation of the growth trial, 20‐day‐old P. vonnamei postlarvae (mean weight 0.0032 g) were fed a casein‐gelatin based semi‐purified diet lacking zinc supplementation but containing 18 mg Zn/kg diet for one week. Subsequently, juveniles (mean weight 0.058 g) were fed one of seven diets containing either supplemental zinc (0, 15, 30, 60 mg/kg diet) without phytate or supplemental zinc (0, 60, 200 mg/kg diet) with 1.5% phytate for 33 days. Weight gain was greatest in shrimp fed 15 mg supplemental Zn/kg diet. In the absence of dietary phytate, zinc concentrations in the hepatopancreas of shrimp were maximized when zinc was supplemented at levels greater than or equal to 15 mg Zn/kg diet (33 mg total Zn/ kg). Supplementation of 1.5% phytate to the diet did not have a significant effect on growth or zinc concentrations in the carapace; however, it did depress zinc levels in the hepatopancreas. Supplementation of 200 mg Zn/kg diet was required to overcome the depressed bioavailability of zinc caused by the presence of dietary phytate and return zinc levels of the hepatopancreas to that observed when phytate was not present. Based on apparent digestibility values phytate phosphorus was unavailable to the shrimp and the presence of phytate depressed the bioavailability of phosphorus and zinc.
Evaluation of Beef Liver, Fruits, and Vegetables as Dietary Supplements for Indoor Nursery Culture of Freshwater Prawns Macrobrachium rosenbergii
Authors: Garces Carla L. , Heinen John M.
Published: April 2007

Frozen beef liver fed at dietary levels of 5, 10, 15, 20, and 25% (dry weight) to postlarval Mucrobruchium rosenbergii was evaluated as a supplement to Mna Trout Chow No. 2. Final mean wet weights and yields of prawns fed 15, 20, and 25% beef liver were significantly higher than those of prawns that received 5 and 10% levels. Survival rates and food conversion ratios of dry matter fed to wet biomass produced were not significantly different among treatments. The suitability of 47 fresh and frozen fruits and vegetables as dietary supplements was tested. Fourteen fruits and vegetables sank and were readily consumed by prawns, and seven (fresh orange and sweet potato, and frozen banana, carrot tops, butternut squash, yellow squash, and turnip greens) were tested as supplements (10% dry weight of the total ration) to trout chow and 15% beef liver. There were no significant differences (P < 0.05) in final mean weight, survival, yield, or food conversion ratio. Pigmentation of prams fed carrot tops or turnip greens was enhanced. No significant differences in final mean weight, yield, or survival were found when frozen banana was evaluated at levels of 0, 5,10,15, and 20% as a supplement to trout chow and 15% beef liver. Food conversion ratios for prawns fed 15 and 20% levels of banana were not different from those fed 10%, but were significantly higher than for prawns fed the 0 and 5% levels. Thus, a diet of Purina Trout Chow No. 2 plus 15% beef liver gives good results with postlarval M. rosenbergii in aquaria. Largescale testing and an economic analysis are needed to determine if this diet is practical for commercial prawn nurseries.
Evaluation of Distillers Dried Grains with Solubles as an Ingredient in Diets for Pond Culture of the Freshwater Prawn Macrobrachium rosenbergii
Authors: Tidwell James H. , Webster Carl D. , Clark Julia A. , D'Abramo Louis R.
Published: April 2007

Distillers dried grains with solubles (DDGS) were evaluated as an ingredient in practical diets for pond culture of the freshwater prawn Macrobrachium rosenbergii. Juvenile prawns averaging 0.66 ± 0.47 g were stocked into nine 0.02 ha ponds at 19,760/ha. Three isonitrogenous diets (29% crude protein) containing 0, 20, or 40% DDGS were fed to shrimp in triplicate ponds. Average yield, survival, individual weight, and feed conversion did not differ significantly (P > 0.05) among treatments. When averaged over the three diets, results were: yield, 833 kg/ha; survival, 75%; individual weight, 57 B; and feed conversion, 3.1. It appears that DDGS is a suitable ingredient for use in practical diets for freshwater prawns at levels of up to 40% of the total formulation, when prawns are stocked at the densities used in this study.
Substitution of Soybean Protein for Fish Protein in Formulated Diets for Red Swamp Crawfish Procambarus clarkii1
Authors: Reigh Robert C. , Braden Stephanie L. , Laprarie Ralph J.
Published: April 2007

A 10 week laboratory growth trial was conducted with red swamp crawfish Procambarus clarkii to determine the amount of soybean protein that could be substituted for fish protein in formulated crawfish diets without reducing growth. Crawfish received 32% crude protein, isocaloric diets in which protein was supplied by soybean (soy) meal, menhaden fish meal or an isonitrogenous mixture of soybean and fish meal calculated to provide graded levels of each protein source. Dietary protein was provided as: 1) 100% soy protein; 2) 75% soy protein: 25% fish protein; 3) 50% soy protein: 50% fish protein; 4) 25% soy protein: 75% fish protein; and 5) 100% fish protein. Crawfish fed soy protein: fish protein (SP:FP) mixtures or fish protein alone exhibited better (P < 0.05) weight gain than crawfish fed a diet containing soy protein as the only protein source. Diets containing 25% soy protein: 75% fish protein (1:3 ratio) and 50% soy protein: 50% fish protein (1:1 ratio) produced greater (P < 0.05) weight gains than a diet in which fish protein was the sole protein source. Survival, feed efficiency ratio, maturation rate, net protein and energy retention, and body composition of crawfish did not differ (P > 0.05) among diets with SP:FP ratios of 1:3, 1:1 and 3:1. However, maximum (P < 0.05) weight gain occurred in crawfish fed the 1:3 SP:FP ratio. Although crawfish fed SP:FP ratios of 1:1 and 3:1 had lower weight gains in the laboratory than crawfish fed a 1:3 SP:FP ratio, SP:FP ratios of 1:1 and 3:1 might be adequate for supplemental diets fed to pond‐reared crawfish that have access to natural sources of food.
Oxytetracycline Residue in Hybrid Striped Bass Muscle
Authors: Xu Dehai , Rogers Wilmer A.
Published: April 2007

Hybrid striped bass (Morose saxatilis male ×M. chrysops female) were injected with 25 and 50 mg oxytetracycline (OTC) per kg of fish. Rate of elimination of OTC from muscle tissue and inhibition of bacteria by muscle injected with OTC were studied. OTC residue in muscle of fish injected with 50 mg OTC/kg fish was much higher (P < 0.01) than that in fish injected with 25 mg/kg and took a longer time to clear from the muscle. In fish injected at 25 mg OTC/kg of fish, OTC was completely eliminated from muscle in 24 d; the rate of elimination constant (β) was 0.278/day and the half‐life (t1/2) 2.5 d. In fish injected at 50 mg OTC/kg of fish, the OTC was not depleted in fish muscle until 32 d after injection; the rate of elimination constant 13 was 0.265/day and the half‐life was 2.6 d. No statistical difference was found in muscle OTC residue between male and female fish. Size of fish (16.5 to 21.5 cm and 21.6 to 25.5 cm) made little difference in OTC residue in muscle. Muscle removed from fish injected with 25 mg/kg OTC 12 d after injection inhibited the growth of Vibrio anguillarum, V. ordalii and Aeromonas hydrophila in cultures.
An Analysis of Biological, Economic, and Engineering Factors Affecting the Cost of Fish Production in Recirculating Aquaculture Systems
Authors: Losordo Thomas M. , Westerman Philip W.
Published: April 2007

Aquaculture production in recirculating systems has been the focus of research and development efforts for decades. Although considerable resources have been expended on these systems in the private sector, there is a scarcity of data on the economic or engineering performance of commercial scale recirculating production systems. This paper presents the results of a computer simulation of tilapia production in a small recirculating production system. Much of the performance data has been developed at a demonstration facility at North Carolina State University. Given the assumptions of the base case simulation, the cost of producing a kilogram of tilapia in the recirculating system described is estimated to be $2.79 ($1.27/lb). The results of a model sensitivity analysis indicate that while improvements in the performance efficiency of system components did not greatly affect fish production costs, reductions in feed costs and improvements in the feed conversion ratio caused the greatest reduction of production cost of all of the operational variables investigated. The analysis further indicates that the greatest gains to be realized in improving profitability are those associated with increasing the productive capacity or decreasing the investment cost of a recirculating fish production system.
The Isolation and Propagation of Dero digitata Infected with Aurantiactinomyxon Sp.
Authors: Pote L. M. , Bellerud B. , Lin T. L. , Chenney E. F.
Published: April 2007

Techniques were devised to facilitate the collection, isolation, and propogation of the aquatic oligochete Dero digitata infected with actinosporeans for the purpose of studying the causative agent of proliferative gill disease (PCD). Pond mud containing the infected D. digitata was collected using a modified Ekman dredge. The mud was covered with pond water, transported to the laboratory, and aerated at 25 C until further processing. Worms were separated from the mud using an elutriator and screen. Worms were rinsed from the screen, the wash was examined using a dissecting microscope, and all D. digitata were removed. These worms were individually placed into 96 well plates. Wells were checked with a dissecting microscope at 24, 48, and 72 h for the presence of actinosporeans. Those positive worms were placed into petri dishes with sterile spring water and 3–4 grains of sterile wheat and held at 25 C. These techniques allowed large numbers of infected D. digitata to be collected and retained for a year for research purposes.
Bacterial Degradation of Microencapsulated Foods Used in Larval Culture
Authors: Muir P. R. , Sution D. C.
Published: April 2007

Microencapsulated foods are widely used in the culture of larval fish, bivalves and crustaceans. The resistance to bacterial decay of two of these diets was investigated under microbial conditions similar to those found in hatchery cultures of larval penaeid prawndshrimps. A 2–3‐fold increase in total ammonia concentration and a 7–14‐fold increase in total bacterial numbers were detected within 48h when microcapsules were added to larval culture water at a density recommended by the manufacturer for one day of supplementary feeding. Increased dissolved total ammonia and bacterial populations were detected within 1.5h of addition of food to penaeid larval culture water. Scenning electron microscopy indicated that microcapsules were colonized by numerous bacterial cells within 1h. Physical disintegration of microcapsules occurred after 6 to 12h. Only in sterilized penaeid larval culture water did microcapsules remain intact for a significant period. These findings are discussed in relation to development of improved methods of larval culture.
The Effects of Enriching Live Foods With Highly Unsaturated Fatty Acids on the Growth and Fatty Acid Composition of Larval Red Drum Sciaenops ocellatus
Authors: Craig Steven R. , Arnold Connie R. , Holt G. Joan
Published: April 2007

Three experiments were carried out to test the effects of enrichment of live food (rotifers) with varying levels of n‐3 highly unsaturated fatty acids (HUFA) on the growth rate and fatty acid composition of red drum larvae. Additionally, the fatty acid compositions of red drum eggs and day‐1 larvae were compared. The enrichment techniques were successful in that the levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were elevated in the rotifers fed the enrichment diet. Red drum larvae fed the control rotifers produced the highest growth rate of the three experiments. Larvae fed rotifers with no HUFA supplement (NHUFA) had a significantly lower growth rate than the controls for that experiment. The fatty acid compositions of the eggs and day‐1 larvae did not vary significantly and contained high levels of 16:0, 16:1 n‐7 and DHA (22:6 n‐3). Based on these data, the lack of DHA in the diet significantly reduced the growth rates of larval red drum. The 10‐day‐old red drum larvae had similar fatty acid profiles at the end of the experiments regardless of the diet they were fed, indicating that dietary inputs have little effect on the fatty acid composition of larvae during the first ten days of growth. Red drum larvae appear to have the ability, though limited, to bioconvert EPA to DHA since there was a significant increase in the levels of DHA from day 1 to day 10 in the NHUFA larvae. However, the efficiency of this bioconversion is not sufficient for optimal growth and supplemental DHA at least to the level found in the control rotifers (0.3–0.4mg/100mg tissue) is necessary to maximize growth. The exact role of EPA could not be determined from this study due to the inability to produce an EPA‐free rotifer.
Hormones and Egg/Larval Quality in Fish
Authors: Lam T. J.
Published: April 2007

Recent evidence suggests that hormones are passed on to eggs by broodfish. This store of maternal hormones may fill the regulatory needs of fish larvae for growth, development, osmoregulation, stress response and other physiological functions prior to the functional development of their own endocrine glands. Thus the hormonal levels in eggs/larvae may be an important determinant of egg/larval quality.

Thyroid hormones have been best studied in this regard. Both thyroxine (T4) and triiodothyronine (T3) are present in fish eggs and in most cases, the levels decrease as development proceeds until the onset of endogenous thyroid hormone production, which usually occurs before or at around yolk‐sac resorption. Enhancement of T4/T3 levels in newly‐hatched larvae through immersion or maternal injection has been shown to promote larval growth, development and/or survival in several fish species, although overdose causes thyrotoxicosis.

Other hormones such as corticosteroids, sex steroids, growth hormone and prolactin are also being studied, but to a much lesser extent.

The paper reviews the evidence and discusses the practical implications of the various findings for larval rearing in aquaculture.
Effects of Broodstock Size and Source on Ovarian Maturation and Spawning of Penaeus monodon Fabricius from the Gulf of Thailand
Authors: Menasveta Piamsak , Sangpradub Sakon , Piyatiratitivorakul Somkiat , Fast Arlo W.
Published: April 2007

The effects of broodstock source (pond‐reared and wildcaught from shallow waters) and prawn size (large—weight >120 g, and small‐weight < 110 g) on ovarian maturation and reproductive success of Penueus monodon were evaluated. Large females underwent stage IV ovarian maturation and spawned with greater success than did small prawns. Both pond‐reared and wildcaught females of the same size exhibited comparable maturation and spawning success. Large females rematured and spawned more frequently than small ones. Total eggs produced by large prawns was significantly greater than for small prawns; nevertheless, prawn source and size had no significant influence on amount of eggs spawned per spawning event. Egg quality varied greatly in terms of percent fertilization, hatch rate, and metamorphosis to first protozwa stage.
Variability of the Microbial Environment of Rotifer Brahionis plicatilis and Avtemia Production Systems
Authors: Verdonck L. , Swings J. , Kersters K. , Dehasque M. , Sorgeloos P. , Leger P.
Published: April 2007

Samplings were organized in three marine fish hatcheries. Samples were taken at different steps during the production of algae, rotifers and Artemia. There were 233 dominant colony types isolated for further characterization. The isolates were compared to each other and to reference strains of Phorobacrerium, Vibrio and Alreromonas, using cellular fatty acid fingerprints. Fatty acid profiles of the isolates were grouped using principal component analysis. The isolates fell into at least ten major groups, of which two correspond to the genera Vibrio and to Alteromonas, respectively. Some groups seem to be restricted to a particular type of live food or isolation site. Although 43% of the isolates belong to Vibrio, only a minority of them could be readily assigned to known species.
Lordotic Deformation and Abnormal Development of Swim Bladders in Some Hatchery‐Bred Marine Physoclistous Fish in Japan
Authors: Kitajima Chikara , Watanabe Takeshi , Tsukashima Yasuo , Fujita Shiro
Published: April 2007

At many hatcheries in Japan, a high incidence of lordosis is being reported among marine physoclistous juveniles of red sea bream, Japanese sea bass, and amberjack. Extensive studies being conducted since 1975 to tackle this problem have led to the following conclusions, and effective countermeasures are being proposed.

During early larval development in the temporary physostomous stage, fish must be able to gulp air at the water surface for normal development of the swim bladder. The juveniles that fail to gulp air swim upward in an oblique position because of insufficient buoyancy, causing the backbone to curve in a V‐shape.

The managerial solutions proposed are: 1) reduce the strong water current caused by vigorous aeration; 2) provide nutrient‐enriched rotifers to produce healthy swimming larvae; and 3) prevent any oily film formation on the water surface.