bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen Budget for the Rotifer Brachionus plicatilis
Authors: Tanaka Yoshiaiu
Published: April 2007

Nitrogen ingested by the rotifer, Brachionus plicatilis (S type) is balanced by gain in body nitrogen (including reproduction), soluble excreted nitrogen, and nitrogen as egested feces. Every term in the budget was estimated independently, and measured as directly as possible. A comparison of the observed and calculated nitrogen as egested feces yielded a satisfactory result.

The nitrogen ingested by the rotifer was distributed as follows: 15.6% for growth and reproduction, 42.0% for metabolic excretion, and 42.4% as feces. From these results, it was concluded that a large proportion (84%) of the nitrogen ingested by the rotifer is transferred to water in various forms and may cause deterioration of the water quality.
Artificial Spawning of Tilapia Eggs1
Authors: Myers James M. , Hershberger William K.
Published: April 2007

A stripspawning methodology was evaluated for tilapia (oreochromid) species. This technique achieved an average hatching success of 68.6 ± 3.6% (N= 31). Female fecundity and spawning frequency were dependant on both genetical and husbandry factors. Egg yields for Oreochromis niloticus, O. mossambicus, and O. niloticus±O. mossambicus hybrids averaged 4.54, 10.86 and 10.36 eggs/g female/spawn, respectively. Female broodstock that were adapted to an intensive spawning regime exhibited a significant increase in fecundity. Additionally, egg survival was not affected by hydration for up to 15 minutes prior to fertilization. Results suggest that the strip spawning of tilapia species may be an efficient method of providing viable gametes for hatchery purposes.
Toxicity of Un‐ionized Ammonia and High pH to Post‐larval and Juvenile Freshwater Shrimp Macrobrachium rosenbergii
Authors: Straus David L. , Randall Robinette H. , Heinen John M.
Published: April 2007

Post‐larval and juvenile Macrobrachium rosenbergii were exposed for 72 h at 29 C to four pH levels (8.5, 9.0, 9.5, 10.0) and four concentrations of un‐ionized ammonia‐nitrogen (0, 1, 2, and 3 mg/L NHj‐N). Results indicated potentiation between NH3 and high pH. Juveniles were more tolerant of high pH and NH3 than post‐larvae.

For post‐larvae, estimates of 72 h LC50 for pH were 9.43, 9.21, and 8.71 at 0, 1, and 2 mg/L NH3‐N, respectively; 72 h LC50 estimates for NH3‐N were 2.18 and 1.45 mg/L at pH levels of 8.5 and 9.0, respectively. For juveniles, estimates of 72 h LC50 for pH were 9.91, 9.56, 9.04, and 8.76 at 0, 1, 2, and 3 mg/L NH3‐N, respectively; 72 h LC50 estimates for NH3‐N were 2.02 and 0.54 mg/L at pH 9.0 and 9.5, respectively.

In pond culture of M. rosenbergii, high pH levels can cause mortality at stocking. The 72 h data can be used as an indication of safe stocking levels of pH and ammonia. These data suggest that post‐larvae should not be exposed to pH > 9.0 nor to NH3‐N > 1 mg/L in the pH range 8.5–9.0 and juveniles should not be exposed to pH > 9.5 nor to NH3‐N > 0 mg/L at pH 9.5, > 1 mg/L at pH 9.0, or > 2 mg/L at pH 8.5.
Reproductive Performance of Pigmented and Albino Female Channel Catfish Induced to Spawn with HCG or Ovaprim
Authors: Goudie Cheryl A. , Simco Bill A. , Davis Kenneth B. , Parker Nick C.
Published: April 2007

Reproductive performance of albino and pigmented channel catfish (Ictalurus punctarus) females was compared when spawning was induced with HCG (human chorionic gonadotropin) or Ovaprim3 (domperidone and [d‐Ala6, Pro9 NEt]‐luteinizing hormone‐releasing hormone). In 1985, only HCG was used to induce spawning. Albino females required more injections, had a longer latency period from time of first injection to spawning, and had lower spawning success (30%) than pigmented females (77%). No differences were observed between albino and pigmented females for time‐of‐day of spawning, number of eggs obtained by manual stripping, and number of eggs/kg body weight. In 1988, HCG, Ovaprim, and saline (control) were used to induce spawning. HCG induced spawning in 80% of albino and 71% of pigmented females. Ovaprim induced 67% of pigmented females to spawn, but only 2 of 5 albino females spawned. One of four pigmented females injected with saline spawned. Albino females yielded 40–50% fewer eggs/kg body weight than pigmented females. Other performance characteristics for albino and pigmented females were similar whether injected with HCG or Ovaprim. High temperatures encountered during the 1985 spawning season my have had a differential effect on albino and pigmented fish and may account for some differences in spawning success.
Impact of Double‐Crested Cormorant Depredations on Channel Catfish Farms
Authors: Stickley Allen R. , Warrick Gordon L. , Glahn James F.
Published: April 2007

Resurgent wintering populations of double‐crested cormorants in the past 10 years have caused serious depredation problems for commercial channel catfish (Ictalurus punctarus) growers in Mississippi. Catch rates of catfish by cormorants were found to average 5 catfish per cormorant‐hour. Catfish taken averaged 12 cm in length. However, cormorants took fingerling catfish at rates as high as 28 per cormorant‐hour. The average number of cormorants found feeding on a single pond in this study was 30.5. If this number (but not necessarily the same individuals) fed all day in an 8 ha pond stocked at 51,000 fishlha, the fish population would be halved in 30 days. Further, using this example, the cost of harassment patrols on a 200 ha catfish farm complex over a 5 month period would be exceeded in 22 days by the losses in this one pond. Wild gizzard shad (Dorosoma cepedianum) occurred in some ponds, and seem to be preferred by cormorants over caffish.
Recent Advances in Lumpfish Cyclopterus lumpus and Ocean Pout Macrozoarces americanus Larviculture
Authors: Brown Joseph A. , Somerton Donna C. , Methven David A. , Watkins John R.
Published: April 2007

The aquaculture of marine finfish in Newfoundland presents a challenge due to the cold‐water (<0 C) conditions which occur over a four to five month period. As part of a continuing research program on the culturing of cold‐water marine finfish species we report on preliminary results of two “new” aquaculture species. The lumpfish and the Ocean pout both occur along the coast of Newfoundland and are adapted to a cold‐water environment. Lumpfish have been reared from egg masses collected from the wild or from eggs stripped in the hatchery. Eggs and larvae are relatively large and larvae are well developed at hatch. Larvae will feed on day‐old Artemia nauplii after four to six days. Survival over the first eight weeks is high but declines over the first year. Lumpfish cultured in the laboratory become sexually mature and produce eggs (roe) at the end of their second year. Ocean pout have been cultured only from egg masses collected from the wild. Eggs and larvae are extremely large compared to other marine finfish currently being cultured. Larvae hatch during the cold‐water period, absorb the yolk‐sac within 24 hours and are ossified at hatch. Juveniles feed on Artemia nauplii within two days at very low temperatures. Survival is comparatively high (75–80%) over the first year. Initial results are encouraging but more research is required before commercial production of these species would be feasible.
Marine Fish Larvae Feeding: Formulated Diets or Live Prey?
Authors: People Le Ruyet Jeannine , Alexandre Jean Claude , Thébaud Laurence , Mugnier Chantal
Published: April 2007

In the rearing of larval marine fish, any diet that reduces dependance on live prey production is of technical and economic interest. Weaning juveniles with a completely developed digestive tract to a conventional diet, (i.e., “late weaning”) can be successful in any marine fish species. For example, weaning one‐month‐old sea bass (20 mg) to the study's reference diet, Sevbar, resulted in over 85% survival (40% from hatching) and 1.25 g fish at day 90 (at 19 C)

In contrast, “early weaning” of larvae to special microdiets during the first month is still difficult. The best way to reduce live prey utilization in sea bass is to wean larvae at about 3–4 mg in size (day 20). If weaning could be accomplished 15 days earlier, Artemia savings could be as high as 80%. However, this introduces risks relative to growth retardation (30% weight loss) and lower juvenile quality, including greater size variability and skeletal abnormalities. Similar results have been obtained with commercial microparticles (Fry Feed Kyowa) and experimental microbound diets (MBD) made from raw materials (alginate MBD) or preferably from freeze‐dried protein sources (zein MBD).

Total replacement of live prey is still impossible in marine fish. Sea bass larvae fed formulated diets exclusively from first feeding (0.3 mg larval wet weight), or even from their second week of life onwards, exhibited low survival and poor growth. Better results can be obtained when formulated diets are used in combination with live prey from first feeding, although the optimal ratio of live prey to formulated diet is still to be specified.
A Review of Cannibalism and its Implications in Fish Larviculture
Authors: Hecht Thomas , Pienaar Anthony G.
Published: April 2007

A review of cannibalism is presented with particular emphasis on the role that this phenomenon plays in applied larviculture. Cannibalism is more ubiquitous than previously assumed and its implications under larviculture conditions are significant. The review is focused primarily on the two principal causes of sibling cannibalism. These are genetic and behavioral, the latter being influenced directly by environmental factors. Cannibalism is regarded as an alternative feeding strategy, more likely to be adopted by larvae and early juveniles which are carnivorous, when resources become limiting. Agonistic behavior induced mortality, the causes of which are identical to those of cannibalism, is also dealt with. Experimental results on the effects of several important environmental factors are presented and evaluated, and suggestions are made to reduce mortality rates under larviculture conditions.
Preliminary Comparisons of the Native Penaeus setiferus and Pacific P. vannamei White Shrimp for Pond Culture in South Carolina, USA
Authors: Sandifer Paul A. , Hopkins J. Stephen , Stokes Alvin D. , Browdy Craig L.
Published: April 2007

Two pond experiments were conducted at the Waddell Mariculture Center to compare production characteristics of the native Penaeus setiferus and Pacific P. vannamei white shrimp in South Carolina. In 1985, 7–9 day old postlarval P. setiferus were stocked in one 0.1 and one 0.25 ha ponds, while P. vannamei of the same age were stocked in one 0.1 and one 0.25 ha ponds, while P. vannamei of the same age were stocked in one 0.1, one 0.25, and one 0.5 ha ponds. Both species were stocked at 12 shrimp/m2. The shrimp were fed a 25% protein commercial food and harvested by draining after 147 d. Sarvival in all ponds was > go%, but growth and production of the P. setiferus were considerably lower than values obtained for P. vannamei: 12.8 g and 1,555 kg/ha/crop for P. satiferus versus 19.7 g and 2,477 kg/ha/crop for P. vannamei. In 1989, duplicate 0.1 ha ponds were stocked with P. setiferus and P. vannamei at 60 shrimp/m2, and two additional 0.1 ha ponds were stocked with P. setiferus at 40/m2. The P. setiferus postlarvae were produced at the Waddell Center from captive‐reared and wild South Carolina brood stock. Rearing procedures involved paddlewheel aeration (10 hp/ha), regular water exchange (averaging 16–21%/d in all ponds), and use of a 40% protein feed. Due to the availability of postlarvae, the various treatments were stocked at different times. Both P. setiferus treatments were reared for 145 d, while the P. vannamei were reared for 165 d. P. setiferus at the 40/m2 density attained mean size, survival, and standing crop biomass at harvest of 13.5 g, 97.5% and 5,259 kg/ha/crop, respectively. The 60/m2P. setiferus treatment was stocked 2 wk earlier and yielded 15.2 g mean weight, 87.5% survival, and 7,995 kg/ha/crop at harvest. The P. vannamei 60/m2 treatment, which was stocked 3 wk earlier than any of the P. setiferus, produced mean size, survival and standing crop biomass at harvest of 17.1 g, 69.5% and 7,187 kg/ha/crop. Both survival and production levels would have been higher had not one replicate experienced a partial mortality due to a feeding accident. The 1989 study yielded what is thought to be the highest production levels yet achieved with P. setiferus in pond culture. These results suggest that P. setiferus may be a viable alternative to P. vannamei for intensive cultivation in the continental U.S. when P. vannamei are unavailable. Further evaluation of this potential is needed.
The Effects of Water Exchange on Production of Metapenaeus macleayi and Water Quality in Experimental Pools
Authors: Allan Geoff L. , Maguire Greg B.
Published: April 2007

Two experiments in 4 m diameter, plastic lined pools were conducted nt two densities, 20 shrimp/ m2 and 47 shrimp/m2, to determine the effects of water exchange rate on the production of the penaeid shrimp Metapenaeus macleayi (Haswell) and on water quality variables. Water exchange rates ranged from 0–40%/d for the 9 wk low density experiment and 0–20%/d for the 8 wk high density experiment. With the exception of mass mortality after prawns escaped from one pool (0% water exchange) on the last day of the high density experiment, shrimp performance indices (survival, weight gain, biomass gain and food conversion ratio) were not significantly affected by water exchange rate. During both experiments water exchange significantly reduced the concentrations of phosphorus and plant pigments (chlorophyll a, b and c and pheophytin) but had no significant effect on pH or the concentration of ammonia or nitrite plus nitrate. Data from this study suggest that while production ponds should not be managed for extended periods without water exchange, simply increasing daily water exchange rates may not necessarily increase shrimp growth or survival. Water exchange can reduce nutrient concentrations and phytoplankton densities but most of the reduction occurs at water exchange rates of between 0–5%/d.
The Cost of Production of Giant Clam Seed Tridacna gigas
Authors: Tisdell Clement A. , Thomas William R. , Tacconi Luca , Lucas John S.
Published: April 2007

The costs of providing giant clam seed in Australia are examined for alternative annual volumes of production. Considerable economies of scale in production are available, both in relation to labor costs and non‐labor costs (mostly capital costs). The fall in per‐unit cost of producing giant clam seed is considerable when annual production is expanded from 100,000 to 500,000 seed clams per year. At 10% rate of interest, the unit cost per clam seed falls from $1.43–$2.04 at a production level of 100,000 to $0.41–$0.55 at a production level of 500,000. Per‐unit operating costs also fall. They decline from $1.01–$1.22 to $0.29–$0.35. This suggests that there are likely to be cost economies in having large centralized hatcheries.
Combined Effects of Diet and Salinity on European Sea Bass Larvae Dicentrarchus labrax
Authors: Barnabé Gilbert , Guissi Abderrafie
Published: April 2007

Effects of diet, salinity, and consumption of endogenous reserves on the growth, survival and swim bladder inflation of European sea‐bass larvae were studied. Primary inflation of the swim bladder occurs in 7‐day‐old larvae. Inflation is synchronized with the absorption of endogenous reserves. The kinetics of the consumption of these reserves varies with the diets tested, and is the slowest at higher salinity (28.7 and 37.7‰). Best results were obtained with larvae fed on Artemia nauplii. Larvae raised at lower salinity (19.7 and 10.7‰) had the highest proportion of inflated swim bladders. Larvae raised at 28.7‰ salinity had the best survival rate, while those raised at 38.7‰ had the best growth rate. Larval mortality was associated with inappropriate functioning of the swim bladder. Larvae exposed to decreasing salinity during rearing showed very high survival rates and normal swim bladder inflation.
Riboflavin Requirement of Fingerling Red Hybrid Tilapia Grown in Seawater
Authors: Lim Chhorn , Leamaster Brad , Brock James A.
Published: April 2007

Red hybrid tilapia Oreochromis mossambicus×O. niloticus fingerlings were fed diets containing 0, 2.5, 5.0, 10.0, 20.0 and 40.0 mg/kg, and 0, 2.5, 5.0, 7.5, 10.0 and 20.0 mg/kg of riboflavin in separate 8 and 12 wk feeding studies, respectively. The dietary riboflavin level required to provide maximum growth and survival, and prevent deficiency symptoms in red hybrid tilapia fingerlings was found to be approximately 5 mg/kg of diet. In both trials, fish fed the diet devoid of supplemental riboflavin exhibited anorexia, reduced growth and nervous symptoms after 4–6 wk. Mortality began to occur after the sixth week. None of these abnormalities were observed during the first 6 wk in fish fed the riboflavin supplemented diets. However, by the seventh week, fish fed the diet supplemented with 2.5 mg/kg of riboflavin showed reduced appetite and growth rate. In both experiments, short body dwarfism was observed during week 8 for fish fed the diet without riboflavin supplementation. In experiment 1, fish fed the riboflavin‐deficient diet had lens cataracts at week 8. This deficiency sign was not observed in experiment 2. Histological studies of liver, kidney, spleen, lateral muscle, gill and gastrointestinal tract revealed no major histopathological changes.
Early Larval Growth of Pacific Halibut Hippoglossus stenolepis
Authors: Liu Han Wu , Stickney Robert R. , Dickhoff Walton W. , McCaughran Donald A.
Published: April 2007

Growth of Pacific halibut Hippoglossus stenolepis larvae was studied in the laboratory during 1989 and 1991. Larvae increased in length from 6.3 mm at hatching to 9.9 mm 20 d post‐hatch. The average daily length increment was 0.17 mm. Dry weight of the larvae increased from an average of 210 μg at hatching to 570 μ g on day 20, providing a specific growth rate of 4.99. During the same period, mean yolk sac weight decreased from 1,390 μ g to 646 μ g, resulting in a yolk to body conversion efficiency of 48.5%. At hatching, the larval body made up only 13% of total dry weight. On day 20, the larval body made up 46.9% of the total weight. Larvae started feeding at a length of 12 mm after about 90% of their yolk sac had been absorbed.
Food Value of Indigenous Zooplankton from the South China Sea on the East Coast of Peninsular Malaysia
Authors: Lokman Shamsudin
Published: April 2007

Zooplankton samples were collected from the shallow waters of the South China Sea, situated in the east coast of Peninsular Malaysia during the dry monsoon (May to August 1990) and the wet monsoon (September and October 1990). Copepods comprised more than 65% of the total zooplankton with Paracalanus (especially P. parvus, P. aculeatus and P. nanus) being the dominant species. The zooplankton lipid content ranged from 0.18 to 1.09% wet weight (1.04 to 4.99% dry weight) with higher values during the dry monsoon. The polyunsaturated fatty acid (PUFA) contents showed high concentrations of eicosapentanoic acid (20:5ω3) and docosahexanoic acid (22:6ω3) with moderate amounts of linoleic acid (18:2ω6). Total polyethylenic acid contents were higher than monoethylenic acids whereas the C18 PUFA components were minor constituents. As ratios of ω3 to ω6 PUFA were high, the zooplankton are regarded as desirable food for the rearing of larval fish.
Tolerance of Juvenile Red Drum Sciaenops ocellatus to Rapidly Decreasing Water Temperatures
Authors: Whitehurst Andrew , Robinette H. Randall
Published: April 2007

This study assessed the potential mortality of pond‐reared juvenile red drum Sciaenops ocellatus subjected to rapid declines in water temperature simulating cold front activity. Fish acclimated in an earthen pond at ambient temperature and photoperiod were introduced into a recirculating aquarium and biofiltration system when pond water temperatures decreased to 20, 18, 16, 14, 12, and 10 C. Fish were stocked according to size group into 10 aquaria containing filtered pond water at 9 ± 1‰ salinity and temperature matching the acclimation temperature. Fish were acclimated to the aquaria for 3 d, subjected to a 6 C decrease over 24 h, and then held for 72 h. No mortalities were observed in any trial. The results suggest that if juvenile red drum are maintained in water with salinity around 9‰, they should survive the passage of most cold fronts.
Phosphorus Fractions in Soil and Water of Aquaculture Ponds Built on Clayey Ultisols at Auburn, Alabama
Authors: Masuda Kiyoshi , Boyd Claude E.
Published: April 2007

Phosphorus fractions in soil and water were determined for a 22‐year‐old, 400m2 fish pond constructed on clayey Ultisols at Auburn, Alabama. This pond had been used in pond fertilization and fish feeding experiments each year. Total phosphorus concenlrations in bottom soil were greater in deep water than in shallow water areas. Highest concentrations of phosphorus occurred in the 5–10 cm soil layer, but phosphorus had accumulated above its original concentration to depths of 20 to 45 cm (x= 36.8 cm). The soil phosphorus accumulation rate was 2.68 g/m2 per year. Less than 1% of the total phosphorus in soils from three ponds was extractable in distilled water or 0.5 M NaHCO3. Sequential extraction with 1 M NH4Cl, 0.5 N HCl, and 0.1 N NaOH removed less than 25% of the total phosphorus. The loosely‐bound phosphorus fraction (1 M NH4Cl extractable) was 0.4 to 5.2% of the extractable phosphorus. The ability to adsorb phosphorus decreased and the capacity to release phosphorus increased in pond soils as total phosphorus concentration increased. After 22 years of aquacultural production, phosphorus adsorption sites in a pond soil were only about half‐saturated. Although soluble phosphorus accounted for 37% of the phosphorus in pond water, only 7% of the total phosphorus in pond water was soluble reactive phosphorus. The phosphorus pool in pond soil was over 500 times greater than that of pond water, but most of the soil phosphorus was strongly adsorbed and unavailable.
Effects of Aeration, Alum Treatment, Liming, and Organic Matter Application on Phosphorus Exchange between Soil and Water in Aquaculture Ponds at Auburn, Alabama
Authors: Masuda Kiyoshi , Boyd Claude E.
Published: April 2007

Application of readily‐oxidizable organic substrate to laboratory soil‐water systems and fish ponds caused anaerobic conditions in bottom soil and water, and concentrations of soluble reactive phosphorus (SRP) increased. Aeration of ponds increased total phosphorus (TP) concentrations by suspending soil particles in the water, but SRP concentrations declined because of increased oxy‐ genation of bottom water and soil, Alum [Al2(SO4)3·14H2O] treatment of ponds reduced SRP and TP concentrations in ponds, but the low concentration of alum used, 20 mg/L, had little residual effect on phosphorus concentration. Application of agricultural limestone at 0.2 kg/m2 to ponds with soil pH of 5.5 and Ca2+ concentration of 5 mg/L did not affect SRP and TP concentration. Unless pond soils were anaerobic at their surfaces, a condition not acceptable in thermally‐unstratified fish ponds, soils released little phosphorus to the water. Strong adsorption of phosphorus by soils in intensive ponds with feeding is beneficial, because removal of phosphorus by aerobic soils is a control on excessive phytoplankton growth. In fertilized ponds, phosphorus must be applied at frequent intervals to replace phosphorus removed from the water by soils.
Performance of Larval Walleye Cultured Intensively in Clear and Turbid Water1
Authors: Bristow Brian T. , Summerfelt Robert C.
Published: April 2007

Experiments were conducted to determine the performance of larval walleye (Stizostedion vitreum) reared in clear, 0.2 nephelometric turbidity units (NTU), and turbid water, 20 or 50 NTU, on formulated feed. Larvae were cultured for 21, 28, or 30 days posthatch in four trials with 3 or 4 replicate tanks per treatment (clear and turbid) in each trial. Duration of each trial was dependent on the arrival of newly hatched larvae for subsequent trials. The desired turbidity levels were obtained by pumping a solution of clay to the culture tanks every 20 (trial 1) or 30 min (trials 2, 3 and 4). Other than turbidity, all environmental conditions (dissolved oxygen, alkalinity, pH, total ammonia, un‐ionized ammonia, nitrate, nitrite, chloride, and hardness) and rearing techniques were similar between treatments. Larvae were stocked at 20/L and fed formulated feed (Fry Feed Kyowa B‐400 and B‐700) every 3 to 7 min, 24 hours per day. Significant differences in feed acceptance and total length between larvae in the clear and turbid water were observed as early as 7d posthatch. Larvae in turbid water began eating the formulated diet one to two days before those in clear water. In all trials, survival, final length, and final weight of larvae reared in water of high turbidity were significantly greater than for larvae reared in clear water. Mean survival (±SE) for all four trials was 27.7 ± 5.6% in high turbidity water and 5.9 ± 1.3% in clear water. At the end of the trials, mean total length of the larvae reared in turbid water was at least 3.2mm (15%) greater than that in the clear water. Mean final weight of the larvae from turbid water was 2.25 times greater than larvae from clear water over the four trials. In two of the four trials, gas bladder inflation (GBI) of larvae reared in high turbidity was significantly greater than for fish reared in clear water, but the difference in GBI was not significant in the other two trials. In this study, performance of larval walleye was greatly enhanced by water with a turbidity of at least IS NTU.
Effects of High‐Protein “Finishing” Feeds on Performance and Fat Content of Channel Catfish
Authors: Robinson Edwin H.
Published: April 2007

A study was conducted to evaluate the effects of using high‐protein “finishing” feeds on production and fat content of channel catfish. Fish were fed either: a 32% protein feed for 150 days; a 28% protein feed for 150 days; a 28% protein feed for 90 days and then a 38% protein feed for 60 days; a 28% protein feed for 90 days and then a 35% protein feed for 60 days; a 28% protein feed for 120 days and then a 38% protein feed for 30 days; or a 28% protein feed for 120 days and then a 35% protein feed for 30 days. The study was conducted in earthen ponds stocked with channel catfish at a rate of 14,826 fish/ha (35 g initial weight) and fed once daily to satiation. There were no significant differences in either feed consumption, weight gain, final weight, feed conversion ratio, survival, or percentage visceral fat of catfish regardless of treatment. Fillets from fish fed the 28% protein feed for 150 days contained more fat than fish on other treatments. There was no advantage of finishing channel catfish on high‐protein diets as compared to feeding either a 28 or 32% protein feed for the entire grow‐out period.
Antibiotic Resistance of Bacterial Fish Pathogens
Authors: Dixon Beverly A.
Published: April 2007

Antibiotic resistance by bacterial fish pathogens has been reported in all areas of aquaculture from warmwater to coldwater, and freshwater to marine environments. Decreased efficacy has been documented in many antimicrobial drugs regardless of their mechanism of action. Resistance emerges by two known genetic mechanisms, mutation on the bacterial chromosome, or extrachromosomal transfer mediated by plasmids. Alternatives to the currently used antimicrobial therapies are being evaluated for use in aquaculture, particularly the new fluoroquinolones and the third generation cephalosporins.
Indoor Intensive Red Drum Aquaculture: A Stochastic Sensitivity Analysis
Authors: Thacker Sayra G. , Griffin Wade L.
Published: April 2007

This research uses stochastic sensitivity analysis to examine an indoor intensive red drum aqua‐culture facility. Important biological and economic factors are varied one at a time to determine the chance of survival and the chance of success. Results indicate that this type facility is very stable since all but one scenario had a 100% chance of surviving. This stability occurs because harvesting is spread uniformly through the year. Chances of being an economic success range from 0 to 100% depending on the investor's required rate of return and the assumed level of biological and economic factors considered in this analysis. An investor's interest in red drum farming will depend on his individual required rate of return, his management capabilities, the market conditions and his willingness to take a risk. It is certain, however, that a 0% chance of economic success will occur for a red drum farm under poor management.
Oocyte Growth in the Striped Mullet Mugil cephalus L. Maturing at Different Salinities
Authors: Tamaru Clyde S. , Lee Cheng‐Sheng , Kelley Christopher D. , Miyamoto Garret , Moriwake Aaron
Published: April 2007

Profiles of oocyte growth were obtained from female striped mullet Mugil cephalus L. held in salinities ranging from fresh water to seawater during two consecutive spawning seasons (1988–1990) in Hawaii. Females underwent vitellogenesis at all salinities (i.e., 32–35, 13–20, and 0%‰) tested. Females maturing in fresh water exhibited a slower rate of oocyte growth, and a significantly lower number completed vitellogenesis. All females were induced to spawn in full seawater. The number of fertilized eggs per spawning was highest from females maturing in brackish water. More females were able to be induced to spawn twice in brackish water during the 1989–1990 season than in fresh or seawater. The results from the current investigation suggest that salinities ranging from 13–35 ppt are adequate for ovarian maturation in captive striped mullet females.
An Epizootic of Vibriosis in Ecuadorian Pond‐Reared Penaeus vannamei Boone (Crustacea: Decapoda)
Authors: Mohney Leone L. , Lightner Donald V. , Bell Thomas A.
Published: April 2007

A massive ephtic of vibriosis, named “sindroma gaviota” (or sea gull syndrome = SGS) by local shrimp fanners, began in November 1989 and continued through May 1990 in nursery and grow‐out ponds in a number of shrimp farms located in the Gulf of Guaynquil near Cunyaquil, Ecuador. The level of cumulative mortalities ranged from slight in some ponds to more than 90% in others. Examination of affected shrimp, Penaeus vannamei Boone, led to the isolation of several closely related Vibrio species. The predominant species were identified as Vibrio parahaemolyticus, V. vulnificus, and V. alginolyticus using the API‐NFT system. Several of the strains exhibited a transient luminescence and some were positive for urease, an unusual trait for these species. Comparisons of the antimicrobial sensitivity patterns between farm and hatchery isolates from 1989–1990 and hatchery isolates from 1987–1989 indicate that the 1989–1990 pond isolates were not of hatchery origin. The epizootic coincided with the second year of a severe drought in Ecuador. Thus, the discharge of fresh water by the Guayas River was reduced and salinities and relative nutrient concentrations were elevated in the Gulf of Guaynquil. These environmental conditions were ideal for the increased growth of the causative vibrios in the estuarine waters and are believed to be factors that contributed to the 1989–1990 SGS epizootic.
Economic Feasibility and Risk Analysis of Australian Red Claw Crayfish Cherax quadricarinatus Aquaculture in the Southeastern United States
Authors: Medley Paul B. , Nelson Robert G. , Hatch L. Upton , Rouse David B. , Pinto Gerard F.
Published: April 2007

Australian red claw crayfish Cherar guudricurinutus are receiving increased attention from aqua‐culturists, but have not been extensively investigated in terms of economic feasibility. In this study, research data from small pond experiments were combined with cost and return data to evaluate prospects for commercial production (50 ha scale) in the southeastern United States. Production data were derived from density experiments involving three initial stocking rates: “low” (l/m2), “medium” (3/m2) and “high” (5/m2). Experiments were conducted in nine 0.02 ha earthen ponds.

Risk analysis was used to simulate the range of potential outcomes that might be faced by producers. Results indicate that economic potential is most sensitive to the cost of juveniles, the percentage of the harvest biomass in the larger size classes, the price these classes receive, and the length of the growing season.
Induced Spawning of the African Catfish Clarias gariepinus Using Non‐Piscine Pituitary Extracts
Authors: Salami Adekunle A. , Fagbenro Oyedapo A. , Edibite Leo , Fagbemiro Sunday O.
Published: April 2007

Acetone‐dried hypophyses from the common toad and bullfrog administered intramuscularly was an effective inducing agent for spawning the African catfish Clarias gariepinus held in cisterns. A dosage schedule of 4–6 mg dry gland/kg female catfish applied in two installments (equal doses) is recommended. Toad and frog hypophyses were as good as or better than human chorionic gonadotropin or homoplastic injection to induce spawning of C. gariepinus under ambient temperature conditions (28–30 C).
Changes in Serum Steroid Hormones and Vitellogenin Levels in Cultured Female European Eels Anguilla anguilla during Artificially Induced Ovarian Development
Authors: Chiba Hiroaki , Iwatsuki Kenji , Hayami Kazuo , Hara Akihiko , Yamauchi Kohei
Published: April 2007

Changes in serum concentrations of estradiol‐17β, testosterone, 17α,20βdihydroxy‐4‐pregnen‐3‐one, and vitellogenin were investigated during ovarian development induced by injection of a salmon pituitary extract in cultured European eel Anguilla anguilla. Vitellogenesis was induced with a weekly dose of 50 mg pituitary extract/kg body weight. In eels receiving that dose, gonadsomatic indices ranged from 20–43% after the 10th–11th weekly injection. Body weights were relatively stable during vitellogenesis, but increased dramatically during final maturation. Serum estradiol‐17β levels increased slightly during vitellogenesis and peaked at an average of 6.95 ng/mL at final maturation. The profile of serum vitellogenin followed that of estradiol‐17β which increased markedly from an average of 0.36 to 20.72 mg/mL. Control levels of vitellogenin were undetectable throughout the study. Average serum levels of testosterone increased to a peak of 17.74 ng/mL in the early stage of vitellogenesis, followed by a sharp drop to initial levels (3.86 ng/mL) in the late stage of vitellogenesis, and then increased again to an average of 8.84 ng/mL at the final maturation stage. Serum 17α,20β‐dihydroxy‐4‐pregnen‐3‐one was not detected (<50 pg/mL) throughout the experiment. Profiles of serum estradiol‐17β, testosterone, and vitellogenin observed during ovarian development appear different from those found in salmonids and other teleosts. This study indicates, however, that cultured European eels are a useful model for study of gonadal maturation in the eel.
Standardization of Ultraviolet Irradiation of Channel Catfish Sperm
Authors: Christensen J. Michael , Tiersch Terrence R.
Published: April 2007

Gynogenesis is a naturally occurring phenomenon in lower vertebrates in which offspring receive two sets of chromosomes from the female (Dawley 1989). This occurs when development is activated by sperm, but genetic material from the male is not incorporated into the embryo. Normally, haploid offspring result that do not survive to hatching, although in certain instances suppression of meiosis II or first mitosis can result in diploid gynogenetic offspring (Purdom 1993). Artificially induced gynogenesis has been used in the breeding and genetic study of several fishes, including salmonids (Chourrout 1982; Allendorf et al. 1986), tilapia (Don and Avtalion 1988), and channel catfish (Liu et al. 1992). Gynogenesis has been applied to production of monosex populations, isogenic populations, and inbred lines of fish (Ihssen et al. 1990; Tave 1993). Gynogenesis can be induced artificially by irradiating sperm with ultraviolet (UV) radiation to inactivate genetic material. Eggs are fertilized with the irradiated sperm and shocked by temperature or pressure change to restore diploidy.
Kinetics of Nitrogen Excretion by Cultured Flounder Paralichthys olivaceus
Authors: Tanaka Yoshw , Kadowaki Shusaku
Published: April 2007

This study was undertaken to quantify the rate of nitrogen excretion by the cultured Japanese flounder as a function of body weight and water temperature. Measurements of the did rate of nitrogen excretion for the cultured flounder were made at mean water temperature of about 16, 19, and 23 C. The excretion rate of nilmgen was estimated by adding the nitrogen excreted in the forms of ammonia and urea nitrogens. The diurnal pattern in the excretion rate of nitrogen was governed mainly by the feeding time. The proportions of excreted ammonia to total nitrogen were 77.9% at 16 C, 84.5% at 19 C, and 83.2% at 23 C. The average was 81.9%. The relationship between the body weight and excretion rate of nitrogen (EN, mg N/fish per h) is expressed as EN=α,.W', where α, = nitrogen excretion rate at temperature 0. The parameter α, is dependent on water temperature, such that α, =α20 Q01(0–200) where α20= nitrogen excretion rate at 20 C, and Q01, = temperature coefficient. The values of the kinetics parameters for the cultured flounder were found to be γ= 0.57, α20= 0.060, and Q01= 1.12.
Impact of Great Blue Heron Depredations on Channel Catfish Farms
Authors: Stickley Allen R. , Glahn James F. , King Junior O. , King D. Tommy
Published: April 2007

With the growth of channel caffish Ictalurus punetatus production in the Delta Region of Mississippi over the last 30 years have come concurrent depredation problems caused by great blue herons Ardea herodias. Biomass in stomachs from herons collected at catfish farms averaged 41% catfish, 38% sunfish Lepomis sp., 17% shad Dorosoma cepedianum, and 4% gambusia Gambusia sp.; whereas observations of herons foraging indicated that 45% of the prey taken were gambusia. Our observational data indicate that herons take an average of 12 10‐cm catfish fingerlings daily. The diurnal density of foraging herons on catfish ponds averaged 0.17 herons/ha in 1990, which means that the average 127‐ha farm supports approximately 22 herons. Nocturnal foraging, especially on dark nights, appears to be minimal. If our data are approximately correct, the average catfish farm could be losing $30/ha per yr to herons, assuming that this catfish fingerling mortality can be attributed solely to heron depredation.
Potential for Asexual Propagation of Several Commercially Important Species of Tropical Sea Cucumber (Echinodermata)
Authors: Reichenbach Norman , Holloway Steve
Published: April 2007

Six species of tropical sea cucumbers (Echinodermata) of high to moderate commercial value were evaluated as to their potential for being propagated asexually by induction of transverse fission. The species considered were Thelenota ananas, Holothuria fuscogilva, Actinopyga mauritiana, A. miliaris, Stichopus chloronotus, and S. variegatus. Rubber bands placed midbody on the sea cncumbers provided an effective yet simple technique to induce transverse fission. Although fission could be induced in all six species, only T. ananas and S. chloronotus had the ability to regenerate both anterior and posterior parts into whole animals. Other species showed no or low potential for regeneration (H. fuscogilva, A. mauritiana) or regeneration of only the posterior part into whole animals (S. variegatus, A. miliaris). Both T. ananas and S. chloronotus had survivorship of nearly 80% or greater. S. chloronotus regenerated anterior and posterior parts into whole animals within 3 mo. In contrast, T. ananas regenerated the posterior part into a whole animal within 5 mo while the anterior part was regenerated within 7 mo. Consequently, weight recovery began earlier with S. chloronotus relative to T. ananas.
Temporal Variation in Egg and Larval Productivity of Eyestalk Ablated Spawners of the Prawn Penaeus monodon from Cook Bay, Australia
Authors: Hansford S. W. , Marsden G. E.
Published: April 2007

This paper reports on the variability in spawner performance and viability of the eggs and larvae of Penueus monodon from a single geographical region (Cook Bay, Australia). Data is presented from seven separate experiments spawning eyestalk ablated P. monodon conducted between Sep tember 1992 and July 1994. These experiments used 200 spawners from which 290 spawns were assayed. Total egg and larval (Nauplius, and ha,) production values per prawn were calculated and were significantly different (P < 0.05) between experiments. Spawner weight and number of spawns per prawn also varied significantly between experiments and, although these factors afiected egg and larval productivity, they accounted for only a small percentage of the observed variability. The cause of this variation is unknown but it may be due to differences in the age of the spawners and to seasonal environmental effects. The variation in reproductive success of wildcaught spawners probably reflects differences in overall condition of the spawners and/or their nutritional status at different times. Understanding the causes of variation in productivity is important if hatcheries are to improve the reliability of supply of larvae for the prawn farming industry.
Food Selection by Larval Paddlefish Polyodon spathula Supplied with Rice Bran to Promote Production of Live Foods, with Prepared Diets, or with their Combination in Earthen Ponds
Authors: Mims Steven D. , Clark Julia A. , Williams John C. , Lovshin Leonard L.
Published: April 2007

Food selection of larval paddlefish Polyodon spathula was evaluated by gut analysis in nine 0.02‐ha ponds either fertilized with rice bran (RB) to promote zooplankton production, supplied with prepared diets (PD), or with a combination of rice bran and prepared diet (CB). After 40 d, mean fish yields in RB and CB ponds were significantly higher (P < 0.05) than fish yield in PD ponds, but there was no significant difference (P > 0.05) in survival among treatments. Cladocerans were the main Live food items selected by paddlefish in RB and CB ponds. Chironomid larvae were the main food items selected by paddlefish in PD ponds. Less than 10% of the food found in paddlefish guts was prepared diets in PD and CB ponds. Prepared diets apparently were not as available to the fish or were not as preferred by the fish as Live foods. Levels of un‐ionized ammonia were significantly greater in CB and PD ponds than that in RB ponds. Decomposition of uneaten high‐protein diets in PD and CB ponds probably led to production of ammonia. Elevated un‐ionized ammonia levels during week 5 caused abnormal swimming behavior and some paddlefish mortalities in PD and CB ponds. Based upon these results, use of RB or other organic fertilizers to promote zooplankton production is recommended over direct feeding or a combination of fertilization and feeding for larval paddlefish in earthen ponds.
Production Management of Double‐Net Tilapia Oreochromis spp. Hatcheries in a Eutrophic Tropical Reservoir
Authors: Costa‐Pierce Barry A. , Hadikusumah Herri
Published: April 2007

Abstract.— A floating, double‐net hatchery system for a red tilapia hybrid Oreochromis spp. was developed and tested in a eutrophic reservoir in West Java, Indonesia. Objectives of the studies were to test the effects of different male and female broodstock rotation times on fingerling production and compare production of the double‐net system with other studies using a multiple regression model. Two experiments (EXP1 and EXP2) were conducted in four separate double‐net hatchery systems comparing three broodstock rotation times over 12 spawning periods in EXP1 and 21 in EXP2. In both experiments, shorter broodstock rotation times (14–16 d in EXP1 or 10–15 d in EXP2) produced significantly (P < 0.05) higher numbers of fingerlings (6.24 in EXP1 and 14.52 fingerlings/female per d in EXP2). A multiple regression model was developed to summarize results of six studies which included 31 spawning periods. A significant (r2= 0.651, P < 0.05) relationship was found between tilapia seed production in net hatcheries as the dependent variable and initial female broodstock densities (−), initial female body weight (−), female/male stocking ratio (−), and feed protein content (±) as independent variables.
Weight Gain and Survival of Juvenile Australian Crayfish Cherax quadricarinatus Fed Formulated Feeds
Authors: Meade Mark E. , Watts Stephen A.
Published: April 2007

Abstract.— Weight gain and survival were examined in newly‐hatched juvenile Australian crayfish Cherax quadricarinatus fed formulated crustacean feeds. Crayfish cultured using several Argent specialty feeds, including brine shrimp flakes, freeze‐dried krill, powdered spirulina, and hatchfry encapsulon, exhibited high mortality (>90%) and little or no weight gain. After ten weeks of culture, crayfish fed AB crayfish feed (AB) exhibited the highest weight gain with nearly 100% survival. Weight gain of crayfish fed other formulated feeds, such as Zeigler post‐larval feed (ZPL), Zeigler shrimp grower (ZSG), Burris Mill crayfish feed (BM), Rangen shrimp grower (RSG), and a formulated CNStacean feed (CRUS) were significantly lower. Survival of crayfish cultured using these feeds was also significantly lower, ranging from 40% (CRUS) to 72% (BM). Mortalities associated with these feeds occurred both during the intermolt period and during the molt. Recovered biomass was approximately half of that observed for crayfish cultured using AB feed, further indicating the inadequacy of these formulated feeds for use in crayfish cultures. These data suggest that many commercially available feeds do not provide the nutritional requirements for juvenile Australian crayfish.
Survival and Growth of White Bass Morone chrysops Reared at Different Salinities
Authors: Heyward Louis D. , Smith Theodore I. J. , Jenkins Wallace E.
Published: April 2007

Abstract.— Juvenile white bass Morone chrysops (age 158 d, 110.4 mm total length) were reared at salinity levels of 0, 4, 8, 12, 16, and 20 parts per thousand (ppt). Fish (10/tank) were stocked in 64‐L tanks with four replicates/treatment (N= 40heatment) and fed a pelleted feed daily. Fish were sampled semimonthly for 70 d. Fish reared at salinities of 12 ppt and below were significantly (P≤ 0.05) larger (mean = 151.5 mm total length; range 146.8–155.7 mm) than fish reared at salinities of 16 and 20 ppt (mean 133.7 mm total length; range 131.5–135.8 mm) after 70 d. Survival was also higher (P≤ 0.05) among fish reared at salinities of 12 ppt or lower (mean 85.6%; range 77.5%–92.5%) compared to those reared at the two highest salinities (42.5% survival at 16 ppt; 5.0% survival at 20 ppt). Thus, although typically found in freshwater habitats, white bass can survive and grow in brackish water.