Volume 55, Issues 1-4, 2003

Influence Of Brackish Water On Survival And Growth Of The Juvenile White Grouper, Epinephelus Aeveus

Peduel, Adi; Ron, Benny — Wed, 01 Jan 2003 00:00:00 GMT

The natural habitat of the white grouper, Epinephelus aeneus, is the Mediterranean Sea, which has a salinity of approximately 35 ppt. As fish species vary in their tolerance of environmental conditions, potential production in specific conditions must be determined empirically. The growth, survival and cortisol level of 1.7 g grouper juveniles grown in diluted sea water (4 ppt) or brackish water (4 ppt) from the Tsofar well in the Arava (southeastern Negev, Israel) was com- pared to the growth of similar fish in sea water (43 ppt). Survival in all treatments was 100%. During the first ten days, the fish grown in brackish water grew significantly less (p<0.01) than the fish grown in full-strength or diluted sea water. There were no significant differences between the treatments during the second growth period or in the final weight (approximately 9 g). Total cortisol concentrations ranged 2.7-4.5 ng/l and did not significantly differ between treatments. Results indicate that the white grouper can flourish in water with salinity as low as 4 ppt and that there are no detrimental chemical factors in the brackish water from the Tsofar well.

Marine Recirculating Systems In Israel-Performance, Production Cost Analysis And Rationale For Desert Conditions

Wed, 01 Jan 2003 00:00:00 GMT

A semi-commercial 100 m3 marine recirculating system (RAS) was designed, based on the results of a 5 m3 experimental system. The system was stocked with gilthead seabream (Sparus aurata). After 200 days, the fish in the semi-commercial system had a similar weight (about 330 g) and density (78 kg/m3) and identical survival (99%) and FCR (1.8) as similar fish grown in a flow-through system (FAS). Annual production in the RAS was calculated as 90 kg/m3. Seawater consumption was 3.5-4 m3 per kg fish produced, resulting in an average water exchange rate of 80% of the system volume per day. While this is relatively high compared to freshwater RAS, the marine RAS required only 10% of the sea water consumed in an FAS. Since sea water is an inexpensive input, water consumption was a minor component of the total production costs in the RAS (approximately 6%). The economical analysis for a theoretical 500 ton/y farm showed that the main capital investment components would be the rearing volume (fish tanks) and the biofiltration unit, representing over 60% of the total investment. The highest production costs would be feed, fingerlings and return on the investment, in that order, representing over 50% of the production costs. CO2 stripping may limit further intensification because the limited surface area of the tank limits the number of paddlewheels that can be used. Also, the DO/TAN ratio may be a factor limiting achievement of a higher nitrification rate and reduction of the biofilter size. Based on the results of this study, a 100 ton/y pilot plant is currently being designed as a model farm.

Defining Energy And Protein Requirements Of Gilthead Seabream (Sparus Aurata) To Optimize Feeds And Feeding Regimes

Lupatsch, Ingrid; Kissil, George Wm.; Sklan, David — Wed, 01 Jan 2003 00:00:00 GMT

Energy and protein requirements of growing fish can be quantified as the sum of the amounts of energy and protein retained as growth plus the amounts simultaneously lost from the body. The requirement for dietary gross energy and protein can be calculated using the respective effi- ciencies of utilization. Growth of gilthead seabream as a function of body weight and tempera- ture was predicted by the equation: y = 0.024 x BW0.514 x exp0.060T (where y = daily weight gain in g/fish, BW = body weight in g and T = temperature in °C). The gain was determined in fish ranging 1-470 g. The energy content of the fish depended on fish weight and rose from 4.7 to 11.0 kJ/g body mass as the fish grew whereas the protein content was constant at 176 mg/g regardless of fish weight. The efficiencies of utilization of digestible energy (DE) and digestible protein (DP) for maintenance and growth were determined by feeding the fish at increasing feed- ing levels from zero to the maximum voluntary feed intake. The daily requirement of DE for main- tenance was dependent on temperature and determined as (16.6kJ x exp0.055T)/BW in kg0.82. The maintenance requirement for DP was independent of temperature and equaled 0.62g/ BW in kg0.70. The relationship between DE intake and energy gain was linear, constant at kDEg = 0.67 and independent of feed intake and temperature. Efficiency of protein utilization for growth var- ied between 0.33 and 0.80 depending on the DP/DE ratio in the diet. The optimal protein uti- lization for protein deposition was estimated at kDPg = 0.47. Using these values allows optimiza- tion of feeding for seabream culture.

Key Factors Influencing Juvenile Quality In Mariculture: A Review

Koven, William — Wed, 01 Jan 2003 00:00:00 GMT

Environmental (temperature, salinity) and nutritional (DHA, EPA, ArA, vitamin A, phospholipids, iodine) factors during larvae rearing largely dictate the successful transformation of larvae to juveniles during metamorphosis which, in turn, determines juvenile quality. Studies on Atlantic halibut, turbot and Japanese flounder report higher metamorphic success, in terms of pigmen- tation, eye migration and general development, when copepods, rather than enriched Artemia, were fed to larvae. Copepods have higher levels of vitamin A, which is required for the synthe- sis of rhodopsin in the retina, a critical visual pigment in the rods necessary for vision at low light intensities. Deficient rhodopsin affects neural transmission from the retina via the central nervous system that triggers pituitary production of melanophore stimulating hormone leading to reduced melanin synthesis and pigmentation deficiency. DHA, an abundant PUFA in copepods, is also vital to vision as it provides the membrane fluidity necessary for rhodopsin to function when stim- ulated by light. The essential fatty acids EPA and ArA are more involved in eicosanoid synthe- sis. These highly potent metabolites are thought to regulate the mechanisms involved in the release of melanophore stimulating hormone and pigmentation. Thyroid hormones play a major role in regulating many developmental processes that occur during metamorphosis. Immersing different age marine fish larvae into various concentrations of thyroid hormone has been shown to synchronize and shorten the duration of metamorphosis in a dose dependent manner in species such as grouper. However, the effect of this immersion on survival varied with the type of thyroid hormone, dose and timing of application. In some species, such as the European seabass (Dicentrarchus labrax), females grow up to 40% faster than males. However, when this species is intensively cultured, masculinization can result in a 70-90% male population. A num- ber of studies have shown that manipulating temperature and salinity during larviculture can result in higher quality juveniles, i.e., a higher percent of faster growing females.

Parental Effects On Sex Ratios In Progeny Of The European Sea Bass (Dicentrarchus Labrax)

Wed, 01 Jan 2003 00:00:00 GMT

In European sea bass (Dicentrarchus labrax), females grow 20-50% faster than males. Therefore, they are more in demand than males for commercial farming, generating much inter- est in the development of female monosex populations. Whereas most current research focus- es on the influence of temperature on sex determination, the present experiments aimed at studying parental effects on sex ratios in progeny. The study analyzed progeny resulting from a diallel crossing (2 x 2 type or a complete bi-factorial mating design), reflecting both maternal and paternal genetic relatedness among progeny. The proportion of females varied significantly among families (20.7-68.2%). There were significant maternal and paternal effects on the pro- portion of females among the progeny. The effect of the parental interaction on the sex ratio in the progeny was also significant. Parents had a significant effect on total length and body weight. Sexual growth dimorphism, in favor of females, was evident in all the full-sib families and varied significantly between families. Among offspring at 9-9.5 months (68.9±23.7 g), females were 26.6% heavier than males. It is concluded that in addition to temperature manipulation in sea bass, as proposed in earlier studies, selection of parents will probably result in an improved ratio of female to male progeny.

Mariculture in Israel

Gordin, Hillel — Wed, 01 Jan 2003 00:00:00 GMT

Israel is a long narrow country occupying 180 km of the eastern shore of the Mediterranean and 12 km of the shore of the Gulf of Aqaba/Eilat, Red Sea. More than half of the country, the southern half, is desert and receives less than 200 mm of rain annually. Therefore, the country suffers from a chronic shortage of fresh water and it is not surprising that governmental agencies encourage the development of food production systems using sea water. Governmental activities began in the early 1970s with the establish- ment of the National Center for Mariculture (NCM) in Eilat, as part of the Israel Oceanographic and Limnological Research Institution (IOLR).

Hatchery And Growth Performance of Two Trout Pure Breeds, Salvelinus Alpinus And Salmo Trutta Fario, And Their Hybrid

Aras-Hisar, Sukriye; Yanik, Telat; Hisar, Olcay — Wed, 01 Jan 2003 00:00:00 GMT

An allelic cross between Salmo trutta fario and Salvelinus alpinus was carried out under con- trolled hatchery conditions. Survival to the eyed stage was significantly lower for the hybrid than for both purebreds. There were significant differences in survival in the eyed and yolk sac stages and from fertilization to the first feeding (p<0.05) between the hybrid and the purebreds, while the differences between the purebreds were not significant (p>0.05). The hybrid did not display heterosis with respect to any hatchery property. During the first 45 days of nursing, there were significant differences between the purebreds and the hybrid in terms of weight gain, survival, feed conversion ratio and specific growth rate (p<0.05) with no significant differences between the purebreds (p>0.05). The hybrid was slightly heterotic (+1.69) with respect to survival how- ever no heterosis was observed in any other property to the first feeding stage.

Replacing Fish Meal In Rainbow Trout (Oncorhynchus MyKiss) Diets

Yanil, Telat; Dabrowski, Konrad; Bai, Sungchul C. — Wed, 01 Jan 2003 00:00:00 GMT

The effects of Ohio State University (OSU) meal (a mixture of blood meal, meat and bone meal, poultry by-products and feather meal), as partial or total replacement of fish meal was investi- gated. Thirty-two fish tanks, each containing 30 rainbow trout (initial mean weight 1.93 g), were fed one of 10 diets (the control had only two replicates) containing a different quantity of OSU meal for 14 weeks. The trout fed the diets containing 20% or 40% OSU meal grew similarly to the trout fed the fish meal based diet. Total replacement of the fish meal caused a significant reduction in growth (p<0.05) only at the 47% protein level and not at the 36%. The results of this study suggest that diets containing up to 75% OSU meal and 25% fish meal are sufficient for good growth in rainbow trout fry.

Cryopreservation Of Rainbow Trout (Oncorhynchus Mykiss) Semen

Tekin, Necmettin; Secer, Selçuk; Akcay, Ergun; Bozkurt, Yusuf — Wed, 01 Jan 2003 00:00:00 GMT

Rainbow trout semen was diluted in one of three extenders (1:3 v/v) containing egg yolk (7-10%) and 10% DMSO as cryoprotectants. The diluted semen was packaged in 0.5 ml straws and frozen in liquid nitrogen (LN2) vapor. For thawing, the straws were immersed in a water bath for 30 sec at 30°C. The best post-thaw motility and fertilization results, 56.67±5.77% and 80.5±16.01% respectively, were obtained when a glucose based extender was used.

Feeding Frequency And Feed Intake In The African Catfish Clarias Gariepinus (Burchell 1822)

Pantazis, Panagiotis A.; Neofitou, Christos N. — Wed, 01 Jan 2003 00:00:00 GMT

Triplicate groups of subadult catfish (Clarias gariepinus; 102.18±30.48 g) were fed a purified diet to satiation twice or three times a day during the daylight hours for 26 days. Fish fed twice a day consumed 1.42±0.49% of their body weight per day. Those fed three times a day consumed 1.27±0.27%. The fish fed twice a day exhibited better growth and food conversion. Despite the use of purified diets, performance indices for the group fed twice per day were good, compared to previously reported data. The specific growth rate was 1.24±0.08%, the weight gain was 38.51±2.96% and the food conversion ratio was 0.72±0.13.

Growth And Production In Long-Line Cultivated Mediterranean Mussel (Mytilus Galloprovincialis) In Sinop, Black Sea

Wed, 01 Jan 2003 00:00:00 GMT

One-year rope-grown mussels (Mytilus galloprovincialis Lam.) with a mean length of 37.6±0.52 mm and live weight of 5.02±0.28 g were collected from fish farm mooring ropes and cultured in cotton or nylon socks in a long-line system in Sinop, Black Sea. The growth of the mussels, water temperature, salinity, chlorophyll a, seston and particulate organic matter were monitored from July 1997 for eleven months. Shell length and live weight were high from May to October when the temperature was 13oC-25oC. Growth decreased during late autumn and winter due to the low temperature and food availability. A significant and positive relationship was found between particulate organic matter, shell growth and live weight. At the end of the experiment, shell length reached 59.89±0.93 mm in the cotton socks and 57.81±0.88 mm in the nylon socks, while live weight reached 19.42±0.91 g in the cotton socks and 16.89±0.76 g in the nylon. Harvestable production was lower in the cotton (4.1 kg/m) than in the nylon socks (8.7 kg/m). Meat yield was high during spring and early summer and significantly and positively correlated with chlorophyll a, particulate organic matter and seston. In the light of these results, recom- mendations for mussel culture in the long-line system are given.

Effects Of Meal Frequency On Growth And Reproduction In The Ornamental Red Swordtail, Xiphophorus Helleri

James, Raja; Sampath, Kunchitham — Wed, 01 Jan 2003 00:00:00 GMT

Experiments were performed to investigate the influence of meal frequency on growth, gonad weight and fertility in an ornamental fish, the red swordtail Xiphophorus helleri. Five groups of uniform-sized 30-day juveniles (0.04±0.01 g, 13.10±0.61 mm) were fed either one meal in 3 days (1/3), one meal in 2 days (1/2), one meal a day (1/1), two meals a day (2/1) or three meals a day (3/1) for 210 days. Group 3/1 had the highest mean body weight throughout the experiment, fol- lowed successively by groups 2/1, 1/1, 1/2 and 1/3. The growth rate was higher in all groups before breeding began and drastically declined afterwards; the significant reduction might have been due to the diversion of assimilated food energy to fry production. The gonad weight and gonadosomatic index (GSI) increased with the increase in meal frequency and as the rearing period progressed. Fish in groups 1/1, 2/1 and 3/1 began to develop gonads on day 42 and reached the breeding stage on day 70; fish in 1/2 and 1/3 began to develop gonads on days 70 and 98 and reached the breeding stage on days 98 and 112, respectively. The increase in meal frequency significantly reduced the interbrood interval and fertility. Fish in group 3/1 produced the highest number of fry (704). Those in groups 2/1, 1/1, 1/2 and 1/3 released 450, 372, 70 and 8 fry, respectively. Groups 3/1, 2/1, 1/1, 1/2 and 1/3 bred four, three, three, two and one times, respectively. Based on the present study, three meals a day is optimum for X. helleri growth and reproduction in a culture system.

Inheritance Of The White-Red (Kohaku) Color Complex In Ornamental (Koi) Carp (Cyprinus Caprio L.)

Gomelsky, Boris; Cherfas, Nina; Hulata, Gideon; Dasqupta, Siddhartha — Wed, 01 Jan 2003 00:00:00 GMT

Color variability was investigated in three normal (amphimictic) and three meiotic gynogenetic progenies obtained from white-red (kohaku, according to Japanese classification) koi parents. All the amphimictic and gynogenetic progenies consisted of three color types – white, white-red and red. The ratio of colors depended on the relative coverage by red patches in the kohaku parents. The lowest percentage of red fish and highest proportion of white fish were recorded in progeny obtained from kohaku parents with relatively weak development of the red color. The percent coverage by red patches was measured in a sample of thirty or sixty white-red fish from each amphimictic progeny and the distribution of color classes within the sample was determined. The distribution of the sample, together with the white:white-red:red ratio in the total progeny, was used to estimate the color class distribution in the entire progeny (including the solid white and solid red individuals). In two of the amphimictic progenies, the fish clearly divided into two groups: non-red (solid white and white-red) and solid red fish. Appearance of these groups might be explained by the existence of some major color-determining gene(s), which determine(s) the background color (either white or red) of the individual fish. It is also suggested that the devel- opment of red patches in fish with a white body background is controlled by many genes with alleles that either maintain the white color or induce the appearance of red patches.

Effects of Chloramine-T And CuSO4 On Enzyme Activity Of Glucose 6-Phosphate Dehydrogenase From Rainbow Trout (Oncorhynchus Myskiss) Erythrocytes In Vitro An In Vivo

Çiltas, Abdulkadir; Erdogan, Orhan; Hisar, Olcay; Çiftçi, Mehmet — Wed, 01 Jan 2003 00:00:00 GMT

Traditional treatments of parasitic and bacterial diseases are based on chemotherapeutic com- pounds such as chloramine-T and CuSO4. Although many compounds are used in fish treat- ments, their undesirable effects are not known. In this study, glucose 6-phosphate dehydroge- nase (G6PD) was purified from rainbow trout (Oncorhynchus mykiss) erythrocytes by hemolysate preparation, ammonium sulfate precipitation and 2', 5'-ADP Sepharose 4B affinity gel chromatography in a single day. The enzyme, with a specific activity of 14.51 EU/mg protein, was purified 906.8-fold with a yield of 70.38%. To check the purity of the enzyme, SDS poly- acrylamide gel electrophoresis was performed, which showed a single band. The effects of chlo- ramine-T and copper sulfate (CuSO4) on the G6PD were investigated in vitro. Chloramine-T and CuSO4 had inhibitory effects on the enzyme. I50 values of the chemotherapeutic compounds were determined by plotting percent activity and Ki values, and types of inhibition were deter- mined for each compound by means of Lineweaver-Burk graphs. In vivo studies showed that G6PD in rainbow trout erythrocytes was significantly inhibited by CuSO4 in one hour but not inhibited by chloramine-T.

Growth And Feed Consumption Of Young Rainbow Trout (Oncorhynchus Mykiss) Exposed To Different Photoperiods

Ergün, Sebahattin; Yigit, Murat; Türker, Ali — Wed, 01 Jan 2003 00:00:00 GMT

A feeding experiment was carried out in a brackish water (18 ppt) flow-through system to deter- mine the effects of different photoperiods (light hours/dark hours; L/D) on feed intake and growth performance of young rainbow trout (Oncorhynchus mykiss). Duplicate groups of fish (35.32 g avg body wt) were exposed to a natural photoperiod, a long photoperiod (16L/8D) or a continu- ous photoperiod (24L/0D) for 60 days and fed to satiation twice a day. The growth rate, daily feed intake and feeding rate in the natural photoperiod were significantly lower (p<0.05) than in the long and continuous photoperiod groups. Growth was highest in the continuous photoperiod, but did not significantly differ from the long photoperiod. The feed conversion ratio, feed efficiency and gross efficiency in the long and continuous photoperiods were slightly better (about 5-7%) but did not significantly differ (p>0.05) from the natural photoperiod. Survival was not significantly (p>0.05) affected by the treatment. For better growth and a lower food conversion rate, the long photoperiod is recommended for young rainbow trout.

The Influence of Multiple Meals On The Gastric Evacuation Rate In Rainbow Trout (Oncorhynchus Mykiss)

Tekinary, Ahmet Adem; Güner, Yusuf; Akbas, IIhan; Baysal, Hüsnü — Wed, 01 Jan 2003 00:00:00 GMT

Rainbow trout, Oncorhynchus mykiss (mean weight 70.8±1.0 g SEM) raised in the Sea of Marmara (Turkey), were used for a preliminary gastric evacuation study. After being starved 72 hours, three groups of 110 fish, each, were fed ad libitum once, twice or three times in a single day. Ten fish from each group were withdrawn and killed in an anesthetic solution during each sampling at 0, 3, 6, 9, 12, 15, 18, 21, 24, 27 and 30 hours following the last feeding. Gastric material was removed from the fish and dried for gastric evacuation modelling. Gompertz and logistic models (with fixed asymptotes) best explained the data. The gastric emptying rate of the trout offered a single meal (Group A) was faster than those fed two (Group B) or three (Group C) meals while the emptying patterns of Groups B and C were similar to each other. The time required to evacuate 95% of the gastric material from the first meal was estimated as 54.3, 68.0 and 67.8 h for Groups A, B and C, respectively, according to the Gompertz equations (with a fixed asymptote).

The Gut Contents Of Grass Carp, Ctenopharyngodon Idella, Drug Nursing In An Earthen Pond

Kirkagaç, Mine Uzbilek — Wed, 01 Jan 2003 00:00:00 GMT

Grass carp fry (0.04±0.01 g avg wt; 1.48±0.03 cm total length) were stocked into an earthen pond in June. Every week for twelve weeks, fifteen fish were sacrificed and the content of their guts was examined. At the first week, animal material represented 74% of the gut contents. From the second week onwards, plant material was higher (mean value 79%). In the seventh week, when grass carp reached 4.83±0.09 cm, filamentous algae were replaced by macrophyte frag- ments. Besides the macrophytes, animal material such as the rotifers Monostyla and Lecane and the cladoceran Bosmina were found and the proportion of animal material in the gut varied 11-26%.

Food Competition In Small Groups Of Juvenile Gilthead Sea Bream (Sparus Aurata)

Goldan, Oded; Popper, Dan; Karplus, IIan — Wed, 01 Jan 2003 00:00:00 GMT

Four groups of single-size and four groups of mixed-size gilthead sea bream (Sparus aurata) were raised in small observation cells for 16 days. Each group consisted of four individually marked juveniles. Agonistic behavior, motor activity and feeding behavior were monitored on days 1, 4, 10 and 16. At the end of the study, the weight gain was measured. Aggressive interactions occurred almost exclusively during feeding. A linear dominance hierarchy stabilized sooner in the mixed groups than in the single-size groups. Rank in the hierarchy had a profound effect on the behav- ior and growth of all group members. The dominant fish in each group carried out more aggres- sive acts and bit at food particles more often than the other group members. The dominant fish also had the highest relative specific growth rate. Direct competition for food is probably the major social mechanism regulating growth in small groups of juveniles of this species when food is lim- ited and defendable. The relevance of these findings for the commercial culture of this species is discussed.

Thermal And Hormonal Feminization Of All Male YY Nile Tilapia, Oreochromis Niloticus L.

Karayücel, Ismihan; Penman, David; Karayücel, Sedat; McAndrew, Brendan — Wed, 01 Jan 2003 00:00:00 GMT

Hormonal and thermal sex reversal of YY male Oreochromis niloticus were compared. While similar percentages of females (34% and 32%, respectively) were produced, a significantly high- er percent of intersex individuals (18.5%) was produced in the heat (36oC) treatment than in the group treated with diethylstilbestrol (DES; 1.6%). The heat-treated groups had 62.6% survival, compared to 97.0% and 97.3% in the control and DES-treated groups, respectively. Our results demonstrate that a high temperature treatment can be an alternative to hormonal sex-reversal treatments for YY male O. niloticus. Although the low survival and high occurrence of intersex individuals may limit its use, it can be used to produce large numbers of YY male broodstock in countries where hormone use is illegal and/or consumer reaction to hormonally-treated fish is negative.

Carbon Dioxide Removal Rate By Aeration Devices In Marine Fish Tanks

Eshchar, Micha; Mozes, Noam; Fediuk, Michael — Wed, 01 Jan 2003 00:00:00 GMT

A procedure for measuring the transfer coefficient KLa for the removal rate of carbon dioxide by aeration devices in fish tanks was developed in the National Center for Mariculture in Eilat, Israel. The KLa for a paddlewheel and a submerged aerator were calculated, following experi- ments in which the aeration devices were used simultaneously for both carbon dioxide stripping and oxygenation. The paddlewheel was more efficient, with a transfer rate up to 1,200 g CO2 per hour and a stripping efficiency of 1.2 kg CO2 per kWh. In intensive sea bream culture, the cal- culated maximum feed load that a single paddlewheel aerator can support is 43.6 kg feed per day with an energy requirement of about 1.0 kWh per kg fish produced.