Journal of the World Aquaculture Society

Published by Wiley
Online ISSN: 1749-7345
Publications
Article
The nature of the animal taxa that are the most probable candidates for an intensive, commercial aquatic animal husbandry industry is considered. A characterization is presented of those biological criteria that lend the species the necessary physiological and genetic malleability to be adapted and molded into a domesticated race. The animal cultivated must be amenable to intensive management in high-density confinements such as those now being engineered for high-yield aquaculture. Atributes considered are discussed in the context of the various aquacultural ecosystems in which the specific biotype is expected to achieve satisfactory growth and survival. Correlative with bionomic criteria, economic requirements are posed and evaluated in an effort to define a socially and financially profitable agribusiness system. Investment requirements and operating costs are considered in terms of expected returns. However, since production alone is insufficient to sustain an enterprise — i.e. the product must be sold — production costs must be judged against market values. Therefore, ultimate use or consumer acceptance criteria are incorporated into the list of essential requirements for a candidate species for aquafarming.
 
Article
For some years, crustacean mariculturists have been aware of the effectiveness of “green water” in enhancing survival and growth of larvae, but its mode of action has not been known. Because fatty acids have been shown to be excellent biochemical tracers in food-web studies, this class of compounds was selected to assess the possible nutritional role of algae in promoting metamorphosis, growth and survival of Macrobrachium rosenbergii larvae. Larvae, fed Artemia salina nauplii, were provided with supplements of Pseudoisochryois paradoxa, Dunaliella tertiolecta or Phaeodactylum tricornutum for 32 days. Fatty acid analysis of the algae showed that each species of alga contained unusual fatty acids, not normally present in larvae, which might be expected to appear in the larval lipids if the algae contribute to larval nutrition. P. paradoxa contain 18:5ω3 (4.5%); D. tertiolecta, 16:4ω3 (18.2%); and p. tricornutum, 16:3ω4 (13.3%). Fatty acids of the larvae from the different dietary treatments were remarkably similar and none of the unusual algal fatty acids were observed. These results provide additional evidence that algae are not utilized as a supplemental food by the larvae. However, the possibility that the larvae have an active “species-oriented” lipid metabolism and do not retain algal fatty acids, as has been demonstrated in the oyster, cannot be ruled out.
 
Article
Juveniles from all possible crosses among USDA 102. USDA 103, and Norris channel catfish Ictalurus punctatus strains were compared for: 1) survival and mix-Edwardsiella ictaluri antibody after exposure to live E. ictaluri bacterium (isolate 597-458); 2) antibody level after injection with formalin-killed E. ictaluri (597-458); and 3) pre-stress. post-stress, and stress-recovery serum Cortisol levels. Purebred and crossbred USDA 102 strain fish had higher survival (mean of five genetic groups = 87%) and lower anti- E.ictaluri antibody (mean optical density (OD) of five genetic groups = 0.167) 30 d after live E. ictaluri challenge than purebred Norris and USDA 103 strains and their crosses (means of four genetic groups = 60% survival and 0.210 OD antibody level). Significant general combining ability, line effects, and heterosis indicated that the USDA 102 strain contributed additive and dominance genetic effects for increased survival and lower antibody level after live E. ictaluri challenge. Antibody response to formalin-killed, intra-peritoneally injected E. ictaluri was not different among genetic groups (overall mean = 0.198 OD). Serum Cortisol was measured prior to (pre-stress), immediately after (post-stress), and 2 h after (stress-recovery) a standard stressor. Serum Cortisol level was highest in post-stress fish (35.8 ng/mL), intermediate in stress-recovery fish (10.9 ng/mL), and lowest in pre-stress fish (6.5 ng/mL), but was not different among genetic groups within a stress time period. Results indicate diat differences exist among genetic groups of channel catfish for survival and antibody production after live E. ictaluri challenge, but these differences were not related to antibody response to killed E. ictaluri or serum Cortisol levels.
 
Article
A study of added feed utilization by pond grown shrimp was done using seven feeds with different 13C/12C ratios, as expressed by δ13C. The pond shrimp did not track the δ13C value of the feed to the extent that tank grown shrimp did. For the seven pond experiments the δ13C data indicate that the added feed supplied between 23 and 47% of the growth carbon. This implies that between 53 and 77% of the growth is due to the grazing on pond biota. It is suggested that this experimental approach can be used to evaluate the relative contribution of presented dried feeds versus natural productivity in ponds as an aid to developing pond management strategies and optimum feeds.
 
Article
The objectives of this study were to investigate: 1) the pharmacokinetics of dietary icosapentaenoic acid (EPA) in the plasma using 13C-labeled EPA ([13C]EPA); 2) the bioavailability of [13C]EPA with different chemical forms; and 3) an effective plasma EPA level for normal growth of the Japanese flounder Parachthys olivaceus. [13C]EPA was biosynthesized using the Chlorella Nannochloropsis oculate, and 1-myristoyl 2-[13C]icosapentaenoyl phasphatidyl-choline ([13C]EPA-PC) and [13C]EPA ethyl ester ([13C]EPA-EE) were chemically synthesized from [13C]EPA. Free [13C]EPA ([13C]EPA-FREE) dissolved in 0.5% tragacanth gum-polye-thyleneglycol (3:1, V/V) was administered to the Japanese flounder at dosages of 2.8, 5.6, and 16.8 mg/kg by a single oral administration. [13C]EPA-PC (44.8 mg/kg) and [13C]EPA-EE (18.3 mg/kg), equimolar to 3.0 mg [13C]EPA-FREE (16.8 mg/kg), were administered to the fish in a similar manner. In [13C]EPA-FREE dosed fish, the kinetics of the mean plasma [13C]EPA were linear with respect to dose. [13C]EPA-FREE and [13C]EPA-PC were more efecient in maintaining high plasma EPA levels than [13C]EPA-EE in the Japanese flounder. [13C]EPA was distributed in plasma, blood cell, eyeball containing the orbital fat, liver, stomach, intestine, skin, brain, heart and muscle in three [13C]EPA derivatives studies. The effective plasma EPA level for normal growth of the Japanese flounder is estimated to be 307 to 937 μg/mL for EPA-FREE administration, and from 286 to 815 μg/mL 6.3 to 38 mg/mL for the EPA-PC administration.
 
Article
The objectives of this study were to investigate: 1) the pharmacokinetics of dietary docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA) using 13C-labeled fatty acids; 2) the interorgan transport of DHA in the red sea bream by monitoring the DHA level of several organs; and 3) the relationship between the plasma DHA level and optimum dietary DHA level in the plasma of the red sea bream Chrysophrys major. For this purpose, a mixture of 38.5% of [13C]DHA, 8.5% of [13C]DPA, and 4.2% of [13C]palmitic acid were given to the red sea bream at dose level of 8.0, 16.0, and 47.9 mg/kg by a single oral administration. For [13C]DHA, the maximum plasma concentration (tmax) occurred at 2.00–3.00 h after the oral administration. The peak plasma concentration (Cmax) and the area under the plasma concentration-time curve to 24 h (AUC0-24 for [13C]DHA level linearly increased with respect to dosage. [13C]DHA appeared in each organ (plasma, erythrocyte and the fat body of the orbit, liver, intestine, skin, brain, heart and muscle) at 0.5 h and was observed until 24 h. From the values determined for the pharmacokinetic parameters, the range of the effective plasma DHA level for normal growth of the red sea bream was suggested to be between 21.0 and 40.3 μg/mL. For [13C]DPA, the AUC0-24 and Cmax values also linearly increased with the dosage, but tmax did not depend on it.
 
Article
This experiment was carried out in two groups of coho salmon (Oncorhynchus kisutch) hatched in early 1982 in Brittany (France). The biggest fish (group 1) had been kept in freshwater, although smoltification had been evident during autumn 1982. The smallest fish (group 2) had not smoltified. In April 1983, fish of group 1 resembled smolts (average weight about 300 g) again while those of group 2 looked like parr (average weight about 40 g). At that time, injections of U 14C glutamate were made intraperitoneally and measurement of the incorporation of 14C into protein, glucose and lipids of plasma, liver and muscle was performed after 2, 3 or 5 hours. This operation was repeated in June on batches of salmon out of group 1 that were transferred, either into seawater (SW) or freshwater (FW) tanks. At that time, the fish were either fully adapted to SW or “desmoltified” in FW. The results show in groups 1 and SW very clear modifications of the use of glutamate as compared with groups 2 and FW: gluconeogenesis is enhanced; apparent protein anabolism is enhanced in liver, but depressed in muscle. Apparent lipogenesis from glutamate is sharply decreased; therefore preparation for, and adaptation to, seawater induces clear changes in the intermediary metabolism. A second experiment was carried out in October 1983 in fish, where gill ATPase was measured to confirm that the modifications were due to smoltification itself. The effects of autumn smoltification are, however, very different from those observed in spring.
 
Article
— Controlled reproduction of penaeid shrimp requires a better utilization of males by sperm quality monitoring and sperm quality improvement. Spermatophores of white shrimp Penaeus vannamei were improved, in terms of increased sperm count, spermatophore weight, and a reduced incidence of sperm abnormalities by a single injection of 17α-methyltestosterone at 0.01 or 0.1 μg/g body weight. 17α-hydroxyprogesterone did not induce a significant improvement in spermatophore quality. These findings indicate that a steroid injection program should be evaluated as a practical way of improving spermatophore quality in commercial operations.
 
Article
The effects of 17α -methyltestosterone (MT) treatment and withdrawal on relative daily gain (RDG), protein gain (PG), productive protein value (PPV), and maximum efficient protein gain (MEPG) of juvenile rainbow trout fed practical diets varying in protein to metabolizable energy (P:ME) ratio were examined over an 18 week period. Two commercially available practical feeds with additions of dextrin and codliver oil were used to formulate diets containing 48% and 32% protein at approximately 320 kcal ME/100 grams with and without 2.0 mg MT/kg of dry diet. MT treated fish were fed hormone supplemented diets for 10 weeks (Phase 1) and hormone free diets for the final eight weeks (Phase 2) of the experiment. Control fish were fed hormone free diets for 18 weeks. MT treatment increased all growth and efficiency factors of fish during Phase 1. The increase in MEPG values due to MT treatment was more pronounced for fish fed the diet containing 48% protein than for fish fed the diet containing 32% protein. Hormone withdrawal reduced growth and efficiency values of fish to below the level of controls during Phase 2. Greater declines occurred for MT treated fish fed the diet containing 32% protein. No difference was observed between final mean RDC, PG, and MEPG values of fish initially fed MT and control fish calculated for the entire 18 weeks. Hormone withdrawal negated MT stimulated increases in empty carcass (EC) fat and whole body (WB) protein and decreases in EC and WB water contents that occurred in Phase 1. EC ash content was increased due to MT treatment and remained high through the period of withdrawal.
 
Article
Effects of feeding 17--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.
 
Article
To produce a monosex female population of European sea bass Dicentrarchus labrax, fry were fed dry diets containing dosages of 12.5, 25, and 50 mg/kg food of either the natural estrogen estradiol-170β(E2) or the synthetic estrogen 17α-ethynylestradiol (EE2) for 60 d starting at 88 d post-hatch (dph). A complete feminization (100%) was achieved in all E2-treated groups at the age of 11 mo (330 dph). All affected fish had ovaries similar in size and histological structure to those of control females. In the E2-treated groups, feminized fish were heavier and longer than untreated controls (males and females combined). In control groups females exhibited significantly higher body weight and total length than males. Untreated females from control groups and females from the group treated with E2 at 12.5 mg/kg food had similar body weight, suggesting that in sea bass growth is related to phenotypic sex. In the Entreated groups, survival rates were similar to those of the control fish. A relatively high percentage of females was obtained in the EE2-treated groups (from 38.6 to 96.5%). However, the gonadal development in these fish was significantly suppressed and a dose-dependent reduction of gonadal sizes was evident. Treatments with the EE2 (12-5, 25, and 50 mg/kg food) resulted in many fish having abnormal (2.9-5.4-39.8%, respectively) and sterile (0.6-6.0-21.6%, respectively) gonads. Effects also included significantly lower weight and shorter length when compared with controls. Furthermore, fish fed with EE2 at the dosage of 50 mg/kg food had high mortality rate. A simple protocol was developed for the complete feminization in sea bass in which the fry (80-100 dph) were fed to satiation two times daily with a diet containing 12.5 me of E2/ks food for a period of 60 d.
 
Article
Fingerling red tilapia (Oreochromis mossambicus±O. niloticus) were orally administered 17--methyltestosterone (MT) under a warmwater (27.0 ± 0.5 C) and coolwater (21.5 ± 0.5 C) thermal regime. In the warmwater experiment, fish received either 0, 1, 5, 10, 30, 60, or 100 mg MT/kg feed for 75 days. In the coolwater experiment, fish received 0, 10, or 60 mg MT/kg feed for 75 days followed by a 34 day withdrawal period. After 75 days, fish receiving 60 mg MT/kg feed (best treatment) in the warmwater and coolwater experiments exhibited significantly higher growth rates than controls by 35.3 and 45.8%, respectively. Likewise, feed conversion among groups receiving 60 mg MT/kg feed in the warmwater and coolwater experiments were significantly better than the controls (1.14 versus 1.30 and 1.44 versus 1.77, respectively). During the withdrawal period, no significant differences in growth rates or feed conversion were observed between the control and treatment groups. MT treatment significantly affected the body composition (whole body and empty carcass) of the red tilapia in both experiments, elevating percent moisture and protein values, but depressing percent fat values. Results demonstrated that incorporation of MT into fingerling diets offers potential for extending the period when tilapias actively feed and grow in temperate climates.
 
Article
Two consecutive feeding trials were used to examine optimum dietary protein to metabolizable energy (P:ME) and ME needs of juvenile rainbow trout fed semipurified diets supplemented with 2.0 mg 17α-methyltestosterone (MT)/kg of dry ingredients. In trial 1, five diets containing 80,100, 120, 140, and 160 mg protein/kcal ME of dry diet at a constant 390 kcal ME/100 g of dry diet were used. In trial 2, four diets were prepared with 300, 340, 370, and 390 kcal dietary ME at a P:ME ratio of 100. Diets were prepared with and without MT and fed for 8 weeks to 5.4 g initial weight fish in trial 1 and 3.7 g initial weight fish in trial 2. Proximate composition of the whole body (WB) and empty carcass (EC = an eviscerated whole body) of fish was measured at the end of both trials. In trial 1, maximum efficient protein gain (MEPG) values of MT treated fish were correspondingly higher than the values obtained for controls at all dietary P:ME ratios fed except for those fish fed at a P:ME ratio of 80. The optimum P:ME ratio for MT treated fish was 100 and for control fish was 120. In trial 2, all MT treated fish fed diets containing 340 kcal ME/100 g and above had a higher MEPG value than all control fish. The diet containing an ME level of 340 kcal was considered optimum for growth of MT treated fish fed a dietary P:ME ratio of 100. MT treatment increased EC, but did not change WB fat content of fish in both trials.
 
Article
Tuna, Thunnus spp. (Linnaeus, 1758), is the most valuable finfish aquaculture product currently recognized around the world, with two main methods of farming presently employed. The most common is the fattening process where fish are kept in captivity for 6-10 months ; a method in wide use in the Mediterranean, Australia, Mexico and Japan. In the Adriatic Sea however, smaller specimens are caught and reared for a longer period of time (up to 3 years), in order to gain 50-80 kg of weight for marketable sale. Differences in the rearing technology are implicated in the isolation of different pathogen groups, as well as the diseases’ etiology. Between 2003 and 2006, parasitological examination was done on newly caught tuna specimens, fish reared for one or two years, harvested tuna and occasional mortalities. Bacteriological examination assessed by the incubation of bacterial colonies on different media and API system, and diagnosis of β nodavirus by immunohistochemistry, was done only when fish suffered elevated mortalities. The total number of isolated parasite species was 23, composed mostly of didymozoid digeneans, and showing variable impact on general tuna health. Secondary bacterial infections were contracted seasonally caused by Photobacterium damselae subsp. piscicida, to whom the highest losses were attributed during the spring epizootic outbreaks. During the study period, no nodavirus infections were diagnosed in fish suffering mortalities. Based on four years of findings, we argue that the major risk factor for the propagation of known and introduction of new pathogens in reared tuna is strongly related to the feeding methods employed. Imported frozen or fresh local baitfish represents a potential source of different pathogens, or if of poor quality, acts as a trigger for development of secondary bacterial diseases.
 
Article
This work reports on the effects of intertidal planting heights upon the growth and survival of the northern quahog, Mereenaria mercenaria (L.) and the Atlantic sod clam, Spisula solidissima (Dillwyn), in the castal waters of Georgia. Quahogs (N = 100 per cage) at 19.5 mm in shell length were planted in replicate cages (N = 3) placed at the spring (SLW), mean (MLW), one (+1), two (+2), and three (+3) hours above mean low water mark. Surf clams (N = 200 per cage) at 41.5 mm in shell length were placed in replicate cages (N = 3) deployed, as above, in all sites except +3. Quahogs grown at the SLW mark after 15 months were significantly larger than clams planted at other tidal heights. Quahogs planted at the MLW mark were significantly greater in shell length than those planted at the +3, +2, and +1 marks. Clams at the upper three sites were not significantly different in size. An inverse relationship between clam growth and intertidal planting height was evident among surf clams. Surf clams grown at the SLW mark for six months were signplificmtly larger than those at the MLW mark which were larger than those grown at the +1 above MLW mark. No significant differences in quahog survival were detected between intertidal planting sites. There was no significant difference in surf clam survival between SLW (77.5%) and MLW (61%) marks, but there was significantly lower survival at the +1 mark (15%) and no survival at the +2 mark.
 
Article
Sex reversal of early life stage tilapia (approximately 7–12 d post-hatch, total length averaging 9–11 mm, and total weight averaging 10–15 mg) is used commonly to produce populations of fish comprised of > 5% phenotypic females. The synthetic androgen, 17α-methyl testosterone (MT), is used to effect sex reversal in tilapia. This paper evaluates environmental impact and human food safety aspects of MT use for tilapia sex reversal based on a review of the scientific literature and on dilution models of farm discharge. Effect of MT treatment on human food safety was evaluated by regression analysis of radioactivity depletion data and by dilution through growth analysis. Results show that the proposed use of MT for sex reversal of early life stage tilapia presents no negative effects on human food safety. Regression analysis of available depletion data from tilapia shows that whole-body concentrations of MT and metabolites in tilapia attain levels of <100 pg/g after 8 to 40 d of withdrawal, and that achievement of <10 pg/g of MT and metabolites in carcass tissue occurs after 6 to 50 d of withdrawal. These concentrations are attained well before completion of the FDA-required 120-d withdrawal period following MT treatment. Standardized calculations were made to estimate MT concentration in effluents based on stocking rate and water exchange. Guidelines are provided for management of farms to ensure that effluent MT concentration remains < 1 μg/L. Given the expected concentration of MT in any farm effluents, the rapid dilution of effluent MT to very low levels in receiving waters, the sensitivity of MT to photo-oxidation, the expected rapid bacterial degradation of MT, and the limited total use of MT in the United States, we concluded that the use of MT-treated feed according to the proposed protocol will not cause significant adverse environmental effects.
 
Article
—Experiment was conducted to ascertain the effect of l-carnitine on growth and body composition of Cirrhinus mrigala fry (0.342 ± 0.03 g) using five different concentrations (0.25, 0.50, 0.75, 1, and 0%) of l-carnitine-incorporated diets for 120 d. At the end of trial, weight gain, feed conversion efficiency, and protein efficiency of fishes fed with 0.25% l-carnitine diet were observed to be significantly higher. Poor growth was recorded in the fry fed diet with no carnitine, while intermediate growth was observed when fed with 0.50, 0.75, and 1% l-carnitine-incorporated diets. The analysis of body composition of C. mrigala fry indicated that there is no significant difference (P > 0.05) in moisture, protein, and ash contents, but significant difference (P < 0.05) was found in body lipid content of fry, fed with different concentrations of l-carnitine. Decrease in viscerosomatic and hepatosomatic indices were observed in fishes fed with l-carnitine-incorporated diets. Results of this study indicated that diet containing 0.25% l-carnitine can promote higher growth in C. mrigala fry.
 
Article
This work presents the embryonic, larval, and postlarval development of Lithopoma undosa (L. undosa) (20 ± 2 C and the effect of natural inducers on the larval metamorphosis. Embryonic development until hatching of the trochophore larva took 15 h. Early veliger larvae with well-developed shell were after 24 h. At 48 h, the operculum was completely formed. Cephalic tentacles were visible after 72 h. Larvae reached competence 6 to 7 d after fertilization, and was characterized by the presence of branched cephalic tentacles. The effect of natural inducers was evaluated. The percentage of metamorphosis with diatoms and adult mucus was 94% and 58% respectively, differing from the 25% without inducer. When was repeated, the metamorphosis was 100%, and 16% with benthic diatoms. The initial mean size of the postlarvae was 0.316 ± 0.02 mm. After 264 d the juveniles had attained a mean size of 5.98 ± 0.16 mm. These results will not only be of use in the evaluation of the culture of L. undosa, but also in studies on the characterization of inducers.
 
Article
Reproductive performance of unilateral eyestalk ablated and unablated wild and pond reared Penaeus semisulcatus was compared in a series of experiments in Eilat, Israel. Tagging techniques were used to study the maturation and spawning of individual females. The average numbers of spawns and eggs per ablated females were more than double those produced by unablated females, although fewer eggs per spawn were produced by ablated females. There were no significant differences in spawn quality, as measured by the percent fertility, hatch, and metamorphosis to zoea 1, between ablated and nonablated females. Egg production of ablated females was consistent for 70 to 80 days after which a decline was observed. The average rate of egg production of nonablated shrimp was more erratic with an apparent decline only after 100 to 110 days. No significant differences were found in spawn size or spawn quality between the first three spawns of ablated and nonablated females. A significant reduction in spawn size was apparent over the molt cycle although the percent fertility remained constant. Spermatophore transfer rates of 84 to 92% were achieved with female to male rations of 1.8:1 to 2.5:l. A reduction in fecundity was observed for successive generations of pond-reared brood stock. Eyestalk ablation was used to stimulate spawning of P. semisulcatus in captivity with no significant reduction in brood stock survival or in spawn quality.
 
Article
The freshwater snail Pomacea patula catemacensis is a fishing resource that is endemic to Lake Catemaco, Veracruz, Mexico. Due to overfishing and other anthropogenic factors, its capture has decreased in recent years. Various research projects have been conducted to support its recovery, although many aspects of its basic biology are as yet unknown. This study evaluated how the snail's growth and reproduction are affected when it is fed the cultivated cyanobacteria Calothrix-sp. (C), in comparison to a diet elaborated with pellet-shaped carp food (P). Experimentation was carried out in two closed-recirculation systems (RS1 and RS2) for a period of 181 d. In RS1, 80 3-mo-old juveniles were distributed, as opposed to 144 6-mo-old adults in RS2. In RS1, the weight gain was 3.98 g with diet C and 3.44 g for juveniles fed P; 74 and 68 egg masses were produced in RS1 with C and P, of which 64.9 and 67.7% turned out to be fertile, respectively. In RS2 average weight increase was 0.74 and 1.14 g for C and P; 117 and 92 egg masses were produced, of which 39.3 and 28.3% were fertile for adults fed C and P, respectively. The number of organisms that hatched was independent of egg mass weight. Fecundity was linked to snail size, and diet had a significant effect on fertility in each system. It was established that, in general, Calothrix was superior to pellet carp food, as the former demonstrated that it can be efficiently consumed as food for P. patula catemacensis in laboratory conditions.
 
Article
The genus Callinecres is ecologically important in the coastal lagoon region of the Gulf of Mexico. This study was conducted to test the feasibility of raising these crabs in a system of floating cages and to measure their scope for growth in a tropical coastal lagoon of the Gulf of Mexico. The equation P = As - (R + E + N) was used to estimate the scope for growth (P) for C. rathbunae under experimental conditions for 21 days. Ingested food was 3% of body weight. Assimilation (As) was 73% of assimilated energy, 21.4% was channeled to respiration (R), 2% to excretion (N) and 0.16% to exuvia (E). The remainder of the energy was channeled to growth at a net efficiency of 76%. Significant differences were not found between the calculated scope for growth and the growth achieved in the culture system (P > 0.05). These results support the energy balance equation and suggest that the cultivation of C. rathbunae in floating cages is possible.
 
Article
Ectoparasite infections can cause death or a decline in the general health of farm-raised finfish. This paper reports the findings from two studies conducted to evaluate the efficacy of hydrogen peroxide as a therapeu-tant for the control of infections of Amyloodinium sp. on cultured Pacific threadfin Polydactylus sexfilis (locally called “moi”). Threadfin with amyloodiniasis collected from a commercial farm were used in both trials. Prior to the trials, and following hydrogen peroxide treatment, the extent of infection was determined by a gill biopsy procedure. An initial trial was conducted in the laboratory to assess the response of juvenile threadfin and Amyloodinium sp. trophonts to hydrogen peroxide exposure at four dosages: 0, 75, 150, or 300 mg/L for 30 min. In a trial on a commercial farm, a hydrogen peroxide treatment at 75 mg/L for 30 min was applied to juvenile threadfin in a grow-out tank. In both trials, hydrogen peroxide was immediately flushed from the culture system with sea-water after the 30 min exposure period. In the laboratory trial, treatment with 300 mg/L hydrogen peroxide resulted in 100% mortality of the exposed group of fish. However, single treatments with hydrogen peroxide at concentrations of 75 or 150 mg/L eliminated Amyloodinium sp. trophonts without causing loss of fish. In the field trial, a single treatment with 75 mg/L hydrogen peroxide greatly reduced levels of Amyloodinium infestation, and a second treatment 6 d later reduced Amyloodinium trophonts to a nondetectable level. These findings suggest that hydrogen peroxide is a suitable chemical for the treatment of amyloodiniasis of cultured, juvenile Pacific threadfin.
 
Article
This paper describes the reproductive performance of Penueus schmitti kept under controlled conditions in a maturation facility of a commercial shrimp farm. A total of 369 females and 368 males of wild P. schmitti were used to form 9 broodstock groups. Unilateral ablation was performed on females only. Although females were not tagged, the total number of mated females (N = 533) indicates that rematuration of the ovaries did occur. Only 9 mated females (1.69%) did not spawn and only 22 mated females (4.20%) of the remaining 524 cases did not produce viable spawns. These results indicate that a large number of viable spawns (94.18%) can be expected from P. schmitti. A minimum latency period of 6 days for the ovaries to attain full development was observed twice. The highest mating frequency occurred between the 46th and 60th days after unilateral ablation, but mating frequency remained above 2% until the 90th day. The average number of nauplii/female/spawn was 78,961 (N = 524) and the average fertilization rate of the eggs was 73.12% (N = 297). Usually when the pair of the spermatophores is dislodged from the thelycum of the mated female, a small sperm mass still remains between the third pair of walking legs. This condition did not show any negative effect on the fertilization rate of the eggs and nauplii production. Mating behavior displayed by P. schmitti is also described and includes three distinctive phases: a) chasing, b) mating and c) post-mating chase.
 
Article
Grass prawn (Penaeus monodon) culture in Taiwan started more than 300 years ago as a by-product of milkfish (Chanos chanos) culture. Since 1968, however, with the success achieved in larval rearing, prawn farming has developed into a major aquaculture industry. Fifty farmers were interviewed and the information obtained from them was compiled for this presentation. Prawn hatcheries have achieved a state of overproduction today, as postlarvae prices have been driven below cost due to the high number of commercial hatcheries now in operation. The evolution of culture ponds has also gone from a primitive lowdensity type to a well designed high-density type. Formulated feed, its use and its role in the continuing development of the prawn industry, harvesting techniques and processing procedures are discussed. Prawn diseases remain a problem for some farms and this investigation suggests that further research is required in this area. An economic analysis of cost and profit of both family-run and commercial farms is presented. A list of fixed and variable costs for operating all types of farms is provided and the relationship between each cost and the final profit is evaluated. The problems facing the grass prawn industry in Taiwan today as well as some future prospects are also discussed.
 
Article
Effective indefinite prolonged treatments with 20 ppm formalin for the external protozoa, Scyphidia sp. and Trichodina spp. (Ciliata) of eight species of fishes, and 0.25 ppm Dylox for 24 hours for the polyopisthocotylean monogenetic trematode, Bicotylophora trachinoti, from the gill filaments of pompano (Trachinotus carolinus) are discussed. These treatments were successfully employed during 4 years of mariculture experiments at Dauphin Island, Alabama. A prolonged treatment for cymothoid isopods of pompano is discussed. Subsequent testing of the treatment was not possible. Toxicity of Dylox to pompano in saltwater is presented.
 
Article
On January 20, 1986, at the annual meeting of the World Mariculture Society in Reno, Nevada, Dr. Guido Persoone, President, announced that the name of the World Mariculture Society would be changed to World Aquaculture Society. Eightyeight percent of voting members favored the change. What follows, then, is an historical account of the World Mariculture Society, 1969–1986. We have used as references archives promulgated in the Proceedings and Journals, newsletter materials, and our own first hand knowledge.
 
Article
Pond cultur̀e experiments were conducted with brown shrimp (Penaeus aztecus) and white shrimp (P. setiferus) in 0.1 ha ponds. All ponds were stocked with juvenile shrimp trawled from the Barataria Bay area. In 1969, there were several types of feed used; in 1970, stocking rates were varied; and in 1971, the feeding rate was varied. The shrimp were fed a specific percentage of their body weight daily. Feeding rates were calculated after a weekly sample of 50 shrimp was taken from each pond, weighed and returned to the pond alive. Results obtained from 44 experiments are compared and discussed. Production ranged from 104 to 931 kg/ha and feed conversion values ranged from 1.1 to 12.6. The heads-on weight of recovered shrimp ranged from 4.4 to 16 g. Mortalities ranged from 1.6 to 100%.
 
Article
Population structures of Malaysian prawns, Macrobrachium rosenbergii, reared in earthen ponds in South Carolina are presented and various pond management strategies discussed. Sex ratios were generally biased toward females and overall, the total biomass of females was 20.6% greater than the total biomass of males. Mean sizes of males and females at harvest were usually similar (within one gram); however, their respective population structures showed distinct and characteristic differences. In general, females exhibited unimodal approximately normal distributions over a relatively narrow size range whereas the male populations exhibited markedly skewed, bi- or multimodal distributions over a comparatively broad size range. The size distributions of prawns produced in the 15 grow-out studies were influenced by prawn size at stocking, stocking density, and duration of grow-out (4 to 6 months). Of these, initial prawn size was clearly the most important factor controlling size distribution. Stocking juveniles resulted in shifting the prawn biomass at harvest into the larger size classes and the lower the stocking density or longer the rearing period, the more pronounced was this shift in biomass distribution. In contrast, regardless of density (8.4–20.1 m-2) and grow-out time (137–181 days), the stocking of postlarvae resulted in 46 to 96% of the harvested biomass being contained in the small (<15.0 g), less valuable size category. Although stocking juveniles results in a more valued crop, the cost of producing these juveniles may offset much of this economic gain. Our data suggest that an alternative stocking strategy which consists of stocking a mixture of postlarvae and juveniles may in fact result in a greater net return. Pilot-scale demonstrations coupled with economic analyses are needed to test this pond stocking strategy.
 
Article
The feasibility of growing Macrobrachium rosenbergii commercially in ponds is under investigation in South Carolina, USA. Laboratory-reared prawns (mean size, 0.006 to 2.66 g) were stocked into earthen ponds (0.02 to 0.25 ha) at densities ranging from 29,400 to 166,600 prawns/ha surface area. Mortality was generally low, with survival rates to 81.2% even when new postlarvae were stocked. Excellent growth was observed among some male prawns which grew from a mean size of 0.7 g to 100.6 g in five months in a brackish water (mean salinity 7.2 ppt) pond. Maximum gross production (equivalent to 1,660 kg/ha surface area) was achieved in 1974 when larger juveniles were reared for 146 days. Gross production in 1975 ranged from an equivalent of 572–1,499 kg/ha (mean, 904 kg/ha) during the 131 to 160-day grow-out studies. Feed conversions of 2.1–7.5 (mean, 4.4) in 1974 and 2.6–4.9 (mean, 3.6) in 1975 were obtained with an extruded ration, Ralston Purina Marine Ration 20. Duration of grow-out season and the possibility of rearing prawns in brackish water were also examined. Outdoor culture season in South Carolina varies from about 5 to 6.5 months depending on site selection. Results from a brackish water study indicate that many coastal areas can be considered for farming M. rosenbergii.
 
Article
Studies were conducted seasonally from 1975–1977 in 0.08 ha, brackish water ponds at the Claude Peteet Mariculture Center on monoculture of Florida pompano (Trachinotus carolinus), brown shrimp (Penaeus aztecus), and white shrimp (P. setiferus), and on polyculture of pompano with pink (P. duorarum) or brown shrimp. Three methods of stocking polyculture ponds were investigated. Pompano production from monoculture ponds manages eeasonally for 95 to 191 days averaged 564 kg/ha with mean survival of 42%, mean feed conversion of 3.0, and mean weight of 156 g. During one growing season in 1977, consecutive 75- to 81-day crops of brown and white shrimp produced mean yields of 349 and 600 kg/ha, survivals of 69 and 96%, feed conversions of 4.0 and 2.3, and weights averaging 8.3 and 10.0 g, respectively. The optimal method of stocking polyculture ponds with pompano and shrimp produced mean yields of 593 and 222 kg/ha, survivals of 30 and 53%, feed conversion of 2.6, and weights averaging 185 and 13.5 g, respectively. Although one season's highest yield (949 kg/ha, mean) was from 2 successive crops of penaieds and the maximum yield of pompano (760 kg/ha) was in monoculture, polyculture of shrimp and pompano demonstrated both technical and economical potential.
 
Article
The University of Delaware Project is working toward development of commercial, closed-cycle, controlled environment shellfish mariculture. As the result of several years' effort, the technical feasibility of raising bivalve molluscs from egg to market size in a recirculating system on a diet of cultured algae has been demonstrated. System optimization and cost reduction efforts are leading to an economically feasible system. Progress toward this goal has been made in several areas, including improved oyster growth rate, reduction in make-up nutrient cost, and incorporation of a foam fractionation device for water quality maintenance and waste removal.
 
Article
White shrimp (Penaeus vannamei), blue shrimp (P. stylirostris), and Florida pompano (Trachinotus carolinus) were reared in 0.08-ha, managed nursery and monoculture and polyculture production ponds in coastal Alabama. In Trial I during 1978, a white shrimp nursery pond culled for production stock then continued for 140 days produced 2,331 kg/ha of shrimp averaging 12.0 g with a feed conversion of 1.2. Yield of white shrimp from 3 monoculture production ponds stocked at 25,000 shrimp/ha and managed for 63 days averaged 193 kg/ha with 63% survival, 3.8 feed conversion, and 11.9 g mean weight. Yield of pompano from 2 monoculture production ponds stocked at 4,925 fish/ha and maintained for 33 days averaged 23 kg/ha with 38% survival, 5.5 feed conversion, and 15 g mean weight. In polyculture, yield of white shrimp and pompano averaged 265 kg/ha with 0.9 feed conversion. The shrimp averaged 11.2 g with 90% survival, and the pompano averaged 14 g with 21% survival. In Trial II during 1979, a blue shrimp nursery pond stocked at 500,000 postlarvae/ha and managed for 47 days produced 864 kg/ha of shrimp averaging 1.8 g with 96% survival and 2.1 feed conversion. Yield from one nursery pond stocked at 165,025 fish/ha with graded pompano and maintained for 55 days was 601 kg/ha of pompano averaging 5.1 g with 71% survival and 3.0 feed conversion. Yield of blue shrimp from 3 production ponds stocked at 82,813 shrimp/ha and managed for 149 days averaged 904 kg/ha of shrimp averaging 16.0 g with 70% survival and 4.5 feed conversion. Yield of pompano from 3 monoculture pompano ponds stocked at 10,000 fish/ha and managed for 106 days averaged 741 kg/ha with 67% survival, 3.9 feed conversion, and 106 g mean weight. In polyculture, yield of blue shrimp and pompano averaged 1,285 kg/ha with 3.0 feed conversion. The shrimp averaged 14.1 g with 63% survival, and the pompano averaged 75 g with 74% survival. Crops of blue shrimp in monoculture and blue shrimp and pompano in polyculture had positive economic returns.
 
Article
Results of 32 collection cruises for Penaeus setiferus adults over a 3-year period in the northwestern Gulf of Mexico are reviewed to document incidence of capture of mature females, mating incidence by time of day of capture, and larval production from natural and artificial inseminations. Mean number of eggs per spawn by year for natural inseminations ranged from 197,000–309,000 (n=160) and for artificial inseminations, 136,000–300,000 (n=174) for females averaging 38–45 g. Mean percent hatch for natural inseminations ranged from 35.3–72.8, and for artificial inseminations, 14.7–77.8. The percentage of females captured from 0900–1600 hours which were mated ranged from 0–13%, while 9–42% of those captured from 1600–2200 hours were mated. The strongest diurnal increase in mating activity occurred from 1600–1800 hours. Three mated conditions, characterized by 1) a complete compound spermatophore; 2) the “wings” or anterior portion of the spermatophore only; and 3) a sperm mass only, represented 28.4%, 38.3%, and 33.3%, respectively, at time of capture. A significant relationship was found between spermatophore stage and hour of capture (P < 0.149), suggesting there may be a sequential breakdown of the spermatophore prior to spawning.
 
Article
During 1981, pond culture trials with prawns, Macrobrachium rosenbergii, were conducted with 7 private farmers in order to obtain information on the potential for prawn farming in South Carolina. Some farmers were able to control water quality while other farmers had little or no ability to modify pond environmental conditions. Seed stock, feed, management, and harvesting assistance were provided by research personnel, while daily monitoring of pond conditions and feeding were the responsibility of the farmers. Eight ponds (size range 0.04-0.41 ha) were stocked with small juvenile prawns (mean weight 0.29 g) at densities of 4.3/m2 (43,000/ha) or 6.5/m2 (65,000/ha). An additional pond, containing hung webbing to increase habitat area, was used in a high density rearing trial and stocked at a density of 19.5/m2. Growing periods ranged from 125 to 173 days during which time most farmers encountered some serious problems (predators, competitors, low dissolved oxygen levels, etc.). In the lower density trials (4.3 and 6.5/m2) production averaged 573 kg/ha (range 155–900 kg/ha) while survival averaged 44.2% (range 13.4–67.9%). Feed conversions ranged from 1.84 to 7.40 and averaged 3.34. The high density trial resulted in a production rate of 1,902 kg/ha, a survival rate of 51.2%, and a feed conversion of 2.4. Disposition of the prawn crops included: 1) direct sales to customers; 2) marketing through a farmer-owned restaurant; and 3) retention of a portion or all of the production to substitute for the purchase of marine shrimp. Direct sales to consumers offers a number of advantages and may be the most suitable market for the predicted near-term level of production.
 
Article
The culture of penaeid shrimp in grow-ponds in Ecuador is expandin: at a rapid rate. Coastal, low lying, salt flats adjacent to estuarine waters, unsuited for classical agriculture, are being transformed into productive shrimp farming areas. Currently, post-larval “seed” shrimp must be collected from the wild to stock the ponds. The Ecuadorian Government is concerned, however, that this practice may affect production from the trawl fishery.A hatchery facility with the capacity of producing 5 million postlarval shrimp per month is planned by the Ecuadorian government. This should help eliminate part of the demand for post-larval shrimp from the wild stock. Also, an extension service is being developed to aid the shrimp farmers.An on-site visit and description of Ralston Purina's hatchery facilities in Panama, Central America, is also included.
 
Article
The National Agricultural Statistics Service surveyed by telephone and mail in January and February 1997 all known producers of channel catfish letalurus punctatus to acquire current information about wildlife-caused losses in calendar year 1996. Many producers tried to prevent wildlife-caused losses of their catfish by shooting (57%), vehicle patrol (55%), or frightening (36%), at an estimated cost of >$5 million. Yet, 69% of catfish producers cited some wildlife-caused losses. Birds were most frequently cited as a cause of losses, and double-crested cormorants Phalacrocorax auritus was the species cited most frequently (53%). The next most frequently cited birds were herons Ardea spp. (48%), egrets Egretta spp. (16%), and pelicans Pelecanus spp. (8%). Muskrats Ondatra zibethicus were cited by 10% of producers, primarily for damaging dikes and roads. The main problems caused by wildlife were feeding on catfish (67%), injuring catfish (40%) or disturbing feeding patterns of the catfish (23%). The total estimated cost of losses was $12 million. Overall, wildlife damage and damage prevention may have cost catfish producers > $17 million, about 4% of the total $425 million of catfish sales in 1996. Of the 44% of all catfish producers who were familiar with Wildlife Services (WS), 51% had ever contacted WS for assistance, 55% used methods suggested by WS to reduce their losses, and 40% received direct assistance from WS in 1996. Mississippi producers, who most frequently received direct assistance from WS, had proportionately lower wildlife-caused losses.
 
Article
— The aim of this study was to compare the levels of docosahexaenoic acid (DHA, 22:6n-3) in three different bisexual and one parthenogenetic strains of Artemia after enrichment. Freshly-hatched nauplii from A. franciscana (Great Salt Lake, USA), A. sinica (Yimeng, P. R. China), A. persimilis (Argentina), and A. parthenogenetica (Tanggu, P. R. China) were enriched with a purified lipid emulsion containing 95% DHA ethyl esters (% total fatty acids) and subsequently starved. All strains had very low initial DHA levels (< 0.3 mg/g dry weight). Initial eicosapentaenoic acid, 20:5n-3 (EPA) levels were high in A. parthenogenetica (18.2 mg/g dry weight) as compared to those in the other strains (4.6-8.5 mg/g dry weight). After 24-h enrichment, A. sinica contained the highest DHA level (37.0 mg/g dry weight) as well as the highest DHA/ EPA ratio (3.7). The lowest DHA enrichment levels were found in A. franciscana and A. parthenogenetica (26.3 and 22.7 mg/g dry weight, respectively). During the subsequent 24-h starvation period, the contents of DHA decreased rapidly in all strains, whereas EPA levels remained relatively stable. This indicates the high catabolism of DHA for energy production, the relative conservation of EPA, and possibly a partial bioconversion of DHA to EPA during the starvation period in each species.
 
Article
A study of polyculture was initiated at the Aquaculture Research Center, Texas A&M University, using Macrobrachium rosenbergii and monosex Tilapia aurea. These species were selected because of their current popularity in aquaculture and because their food preferences and patterns of behavior indicated no reason to expect serious competition. Shrimp were stocked at 11,000 per ha with or without fish (2000 per ha) for observation from June 1 to October 15. The effect of pre-treatment of ponds with inorganic fertilizer was also studied. Each pond was supplied with equal amounts of Experimental Marine Ration 25 (Ralston-Purina Co.). Mean survival of fish and shrimp was 96 and 95.7%, respectively. Fish grew to a mean weight of 182 g while shrimp in polyculture grew to 24.5 g and 27.5 g in monoculture. Average daily growth increments were 1.37 g for fish and 0.21 g for shrimp. Neither growth nor survival of fish or shrimp were influenced by pre-treatment of ponds with fertilizer in this study.
 
Article
Shipping trials were conducted with adult Penaeus setiferus to determine the effect of 24 hour closed shipments on water quality, to evaluate methods of reducing water quality deterioration and to maximize packing density (biomass). Other trials were undertaken with juvenile P. setiferus and adult P. vannamei for comparison. The method utilized 8 L seawater chilled to 18–19 C, inside doubled polyethylene bags held in a Styrofoam box (42 × 42 × 23 cm deep). Gaseous O2 was injected into the water to 8 ppm (for standardization) and into the space above the water. Super-saturation of dissolved oxygen (>20 ppm for 24 hours) had no adverse effect on survival. Initial trials resulted in increased ammonia (from 0.1 to 4–6 ppm NH4-N), increased carbon dioxide (from <2 to 80–100 ppm), increased temperature (from 18–19 to 25–26 C) and decreased pH (from 8.0 to 6.0–6.4). Increases in shipping density (number or biomass of shrimp per L seawater) further intensified water quality deterioration. Carbon dioxide (with concomitant pH decline) is implicated as the major limiting factor during 24 hour closed shipment. Ammonia accumulation was reduced or totally eliminated with addition of AmQuelΘ (Kordon, Inc, Hayward, California),† depending on the dosage used. The buffer, Trizma® 8.3 (Sigma Chemical Co, St. Louis, Missouri),† limited CO2 buildup and reduced pH decline. Maintenance of low temperature over 24 hours was enhanced with addition of a frozen cold pack placed over the shipping bags. However, the control of ammonia, pH and carbon dioxide by the addition of AmQuel and Trizma did not increase survival, possibly due to toxic effects of the chemicals.
 
Article
A 10-wk growth comparison trial of two strains of channel catfish Ictalurus punctatus was conducted in 40 120-L flow-through aquaria using a 2 ± 2 × 2 factorial experiment design. The three factors evaluated were: strain (Norris and NWAC103), dietary protein level (28% and 32%), and feeding rate (restricted and satiate). Average initial weight (× SD) for the Norris strain was 3.0 ± 0.08 g/fish, while that of the NWAC103 strain was 4.7 ± 0.13 g/fish. The feeding rate for the satiated group was adjusted based on feeding observations. The feeding rate for the restricted group was adjusted to about 2/3 of the satiate level. For both satiate and restricted feeding regimens, the NWAC103 strain consumed more feed than the Norris strain. Fish of Norris strain fed the 32% protein diet consumed more feed than fish fed the 28% protein diet; however, there were no differences in feed consumption in the NWAC103 fish fed the two protein diets. Regardless of feeding rate, the NWAC103 fish gained more weight and converted feed more efficiently than the Norris fish. Fillet composition was not affected by fish strain. Fish fed the 28% protein diet had a lower level of fillet protein than fish fed the 32% protein diet. In fish fed to satiation, a 32% protein diet resulted in a lower fillet fat level than a 28% protein diet, but no differences were observed in fillet fat levels between fish fed the two dietary protein levels for the restricted group. Results from the present study demonstrate that under laboratory conditions, the NWAC103 strain of channel catfish is superior to Norris strain in feed consumption, growth rate, and feed efficiency. Our data also indicate that either a 28% or 32% protein diet can be fed to either strain of channel catfish whether they are fed to satiation or fed a restricted ration with no detrimental effects on growth.
 
Article
Channel catfish Ictalurus punctatus were vaccinated at 12 d of age (post-hatch) by a 2-min bath immersion with attenuated Edwardsiella ictaluri RE-33 at doses of 2.5 × 105, 2.5 × 106, and 2.4 × 107 colony-forming units CFU/mL of water. Following vaccination, RE-33 was recovered from a greater percentage of fry that were vaccinated at the high and intermediate doses compared to fry vaccinated at the lowest dose. Independent of dose, the greatest percentage of RE-33 positive fry occurred between 1 and 6 d post-vaccination with a significant decrease in positive fry observed on day 12. A significant increase in mortality occurred 6 to 12 d post-vaccination in fry vaccinated at the highest dose. No differences in post-vaccination mortalities occurred between the other treatments. Following virulent E. ictaluri challenge, mortalities of fish vaccinated at doses of 2.5 × 106 and 2.4 × 107 CFU/mL were significantly less than those of fish vaccinated at 2.5 × 105 CFU/mL and sham-vaccinated control fish. These data show that vaccination with RE-33 can offer protection against subsequent virulent E. ictaluri infection.
 
Article
These studies were conducted to evaluate the efficacy of a live attenuated Edwardsiella ictaluri vaccine against enteric septicemia of catfish. In one study channel catfish fingerlings (72 d of age post hatch) were immersed for 30 min in water containing E. ictaluri RE-33 at dosages of 1 × 106, 1 × 107 and 2 × 107 CFU/ML of water. No mortalities were observed following vaccination. Following exposure to virulent Edwardsiella ictaluri the cumulative mortality of fish vaccinated with dosages of at least 1 × 107 CFU/mL were significantly lower than that of non-vacccinated fish in both laboratory and field challenges. Vaccination with 1 × 106 CFU RE-33mL provided some protection during the laboratory challenge but failed to protect fish under field conditions. In a second study, vaccination of 6 full-sib families of channel catfish at a vaccine dosage of 1 × 107 CFU/mL resulted in a relative percent survival among families ranging from 67.1 to 100%. Significant differences in mortality were found among families and between vaccinated and unvaccinated groups, but there was no family by vaccine interaction. Families with the highest mortality after vaccination were also shown to have the highest mortality without vaccination (r = 0.82; P= 0.04).
 
Regression analysis of mean growth (g) for channel catfish fry fed a 36%-animal protein diet or a 36%-all plant protein diet. There were no statistical differences (P > 0.05) in growth rate for the two diets.
Experimental diets for evaluation of channel catfish fry growth and mortality with all plant proteins or animal and plant proteins. a
Article
The basic nutrient requirements for channel catfish, Ictalurus punctatus, are well known, with anecdotal evidence suggesting that catfish fry grow faster and have better survival when fed an animal protein diet. However, the ability to grow channel catfish as small as 11 g on all plant diets and a lack of published data showing the superiority of fish or animal proteins compared to nutritionally equivalent plant proteins for catfish fry indicates that it may be possible to raise channel catfish fry on diets with only plant protein sources. Therefore, an experiment was conducted to compare the effects of 36 and 45% animal protein diets and 36 and 45% all plant protein diets on catfish fry growth and survival. Experimental diets were formulated to contain: 36% all plant protein (primarily from soybean meal); 36% animal and plant protein (≥45% of crude protein as fish meal); 45% all plant protein (primarily from soy protein concentrate and soybean meal); and 45% animal and plant protein (≥60% of crude protein as fish meal). The catfish were fed at a rate of 20% of body weight daily for 28 d using 24-h automated feeders. Mean ending weights and lengths of catfish fry were not significantly different (P > 0.05) for any treatment. Mean mortality was also not significantly different (P > 0.05) among diets. Regression analysis of growth rate and analysis of variance of final weights revealed that there was no significant difference in growth rate for any of the four diets. These results indicate that growth is not limited in channel catfish fry fed all plant protein diets, and that there is no apparent advantage to the inclusion of animal protein in diets for channel catfish fry.
 
Article
The swimming and feeding behavior of striped mullet (Mugil cephalus), 40–60 mm SL, was observed in 37.8-liter aquaria. Five of the most frequently observed behavioral acts were then chosen as representatives of “normally” occurring behavior under these experimental conditions. These behavioral acts were subsequently counted in the 37.8-liter aquaria with population densities of 3, 6, 18, 30 and 60 mullet per aquaria, during swimming and feeding observations. More food bites were taken at densities of 18 and 30 than at the other densities. Mullet kept at a density of 30 per tank exhibited the lowest mean number of long traverses (a distance of more than one-half the aquarium front). Perhaps at a density of 30 mullet per aquarium (0.79 mullet/liter or 231 mullet/m2), food was assimilated into biomass and less was burned for energy. Obtaining data in aquaria in this manner may prove an invaluable tool since it is less expensive than stocking ponds experimentally and can provide a useful basis for deciding efficient stocking densities for any size fish.
 
Article
The occurrence of off-flavors in farm-raised channel catfish is a major burden to the catfish culture industry, causing millions of dollars worth of market-ready fish to be rejected each year. Off-flavors are believed to be the result of exposure and subsequent accumulation of certain volatile microbial metabolites such as 2-methylisoborneol. In this study, the uptake and elimination of [14C]-2-methylisoborneol equivalents were examined in juvenile and mature channel catfish. The described method is presented as a simple and inexpensive procedure for comparing treatment effects on off-flavor elimination rates. In addition, the effects of the cytochrome P4501A inducing agent 3-methylcholanthrene on 2-methylisoborneol depuration was studied in juvenile fish. Uptake was determined during a 24–h static exposure to waterborne 2-methylisoborneol (7.6 ± 3.7 μg/L). Uptake equilibrium had been established in all groups by 12 h, with total uptake higher in juvenile fish. Depuration rates were not different between untreated groups (t½ a = 12.r122.4 h; t½β= 91.3–143.7 h); however, the depuration half-lives for 3-methylcholanthrene treated juveniles were significantly longer than those of controls.
 
Article
Approximately 100 species of abalone are known to exist in the world and commercial abalone fisheries have been established in at least 6 countries. In Japan, 5 species of abalone provide an annual catch of 5,000 metric tons (whole weight with shell) which sells for 6,000/kg (US$27/kg). To increase productivity of coastal waters, juvenile abalone “seed” (10–30 mm) are produced at government operated Fish Farming Centers. Production has increased from 200,000 seed in 1970 to more than 10.7 million in 1978. Survival of artificially reared abalone from larvae to 20 mm averages 1%. Problems still exist in providing the quality and quantity of food required by postlarvae and older juvenile abalone. Twenty millimeter seed is sold by the farming centers to fishermen at a price of $0.10-0.12 each, which represents only 1/2 to 1/4 of the production costs. Seed is placed in coastal waters for grow-out to 11–12 cm in 3–5 years. Recapture rates may exceed 10%. Production costs at the only private abalone hatchery in Japan are estimated to be $0.018/mm of shell length. Based on Japanese methods for seed production, an assessment of production costs for an abalone hatchery in the USA is presented. With an annual production of one million abalone (20 mm each) the production cost is estimated to be $0.022/mm of shell length or $0.44/20 mm abalone. The success of abalone production in the USA will be determined by cost effective hatcheries and a strong market for the abalone produced.
 
Article
Application of the floating laboratory concept to hatchery culture of abalones and rock scallops was tested in 1975–76 using a mono-hull pleasure craft. Successful experiments prompted construction of a larger vessel consisting of a deck and laboratory superstructure supported by pontoons. The facility has been in operation since early 1978, moored in a marina cove near the entrance to Mission Bay. Seawater is delivered to tanks in the laboratory when currents and tides bring offshore water into the cove. Use is made of inexpensive materials and equipment wherever possible. This paper describes the laboratory, relates successes in spawning and rearing young of the green abalone (Haliotis fulgens) and the purplehinge rock scallop (Hinnites multirugosus), and compares culture conditions and success with those at the nearby La Jolla laboratory of the National Marine Fisheries Service.
 
Article
— The European abalone Haliotis tuberculata, a valuable macroalgivore, was introduced and acclimated for culture in a land-based facility at Eilat, Israel, on the Red Sea (Gulf of Aqaba). Large quantities of high-protein seaweed (Ulva lactuca) are produced there in biofilters used in fish mariculture. Although high water temperatures (25–27 C) inhibited summer growth, and in spite of the high salinity (41 ± 1 ppt). four groups of abalone of different sizes grew more in 1 yr than reported in their natural habitat. This fast growth is attributed to the long period (8 mo, from fall to spring) in which temperatures in Eilat waters are within the optimal range for this species, and to the high protein content of the seaweed. Winter timing of maximal growth as well as reproduction in Eilat was reversed compared with Europe, where they occur in summer. Gametogenesis began in December, and the gonads in most broodstock were spent by May. Haliotis tuberculata appears to have excellent potential for intensive mariculture in Israel.
 
Top-cited authors
Claude E. Boyd
  • Auburn University
Menghe Li
  • Mississippi State University
Delbert M. Gatlin
  • Texas A&M University System
Donald Allen Davis
  • Auburn University
James H. Tidwell
  • Kentucky State University