IJA Volume 57, Issue 3, 2005
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ItemEffect of short-term preservation of mirror carp (Cyprinus carpio) semen on motility, fertilization, and hatching rates(Israeli Journal of Aquaculture - BAMIGDEH, 2005)Mirror carp (Cyprinus carpio) semen was collected by hand stripping for short-term preservation. Two groups of pooled semen were diluted with one of two extenders; a control group was undi- luted. The three groups were stored at 4oC for 72 h. During preservation, spermatozoa motility (%) and duration of spermatozoa movement (s) were determined every 12 h. Following preser- vation, fertilization was carried out using the dry fertilization technique at 1 x 105 spermato- zoa/egg. The highest fertilization rates were 21±3.60% in May and 16.67±2.08% in June, both significantly higher than in the control. The highest hatching rates, 69.60±11.86% in May and 89.13±10.75% in June, did not significantly differ from the control.
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ItemThe first pasteurellosis case in cultured sea bass (Dicentrarchus labrax l.) at low marine water temperatures in Turkey(Israeli Journal of Aquaculture - BAMIGDEH, 2005)The first observed pasteurellosis outbreak at a low marine water temperature (18-19oC) is here- by reported. The disease was identified in three sea bass farms in the Aegean near Bodrum, Turkey. Diseased fish, Dicentrarchus labrax (L.), were characterized by lethargy, loss of appetite, darkened skin color, exophthalmia, abdominal swelling, pale gills, and hemorrhages over the operculum and ventral part of the body. Some diseased fish had hemorrhages on the head and opaque eyes. There were whitish nodules in the liver, the spleen varied in size (0.5-4 mm), and both organs were pale. Morphological, physiological, and conventional biochemical tests were used to determine the phenotypic properties of pure cultures of isolated colonies in samples taken from internal organs. Mono-Pp agglutination kit and API 20E were used to con- firm the identified bacteria. The isolated strain was Photobacterium damselae subsp. piscicida. The sensitivity of the Aquarapid-Pp kit, which produced positive results in all diseased fish, was 0.91 and the specificity was 0.95. The principal histological changes were depletion of hemo- poietic tissue and multiple round small or large necrotic and lytic areas in the spleen, vacuole degeneration and diffuse hemorrhagie in the liver, and peritubular vacuole degeneration and tubular necrosis in the kidney. Treatment with flumequine in the feed at 50 mg/kg body weight/day for seven days controlled mortality.
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ItemEffect of salinity on gestation period, fry production, and growth performance of the sailfin molly (Poecilia latipinna lesueur) in captivity(Israeli Journal of Aquaculture - BAMIGDEH, 2005)Breeding and growth trials were carried out with Poecilia latipinna in different salinities (0.5, 10, 15, 25, and 35‰) and effects on gestation period, fry production, and fry growth (75 days) were examined. Results showed that while P. latipinna successfully spawned in all salinities, there was a significant difference in fry production among treatments. The minimum gestation period was 28 days in all salinities except fresh water (0.5‰); the maximum fry production was obtained in 25‰. Fry growth was highest in 10‰ and significantly differed (p<0.05) from the rest of treat- ments in terms of weight gain, specific growth rate (SGR), and feed conversion ratio (FCR). Maximum SGR was 3.35% per day in 10‰ salinity. FCR ranged 4.28-5.67. The results suggest that the optimum salinities for breeding and rearing P. latipinna are around 25‰ and 10‰, respectively.
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ItemEffect of restricted feeding regimes on compensatory weight gain and body tissue composition in Cirrhinus mrigala (Hamilton) fry.(Israeli Journal of Aquaculture - BAMIGDEH, 2005)An experiment was conducted to examine the effect of restricted feeding on compensatory weight gain and body tissue composition in Cirrhinus mrigala fry. The control group was fed to satiation twice a day throughout the 8-week experiment. Feed for the other three groups was restricted for one, two, or four weeks. When reinstated, feed was given to satiation. Fish deprived of feed for two weeks had significantly (p<0.05) higher body weight (5.40±0.20 g) and lower FCR (3.40±0.20) than those of the control (4.55±0.10 g and 6.75±0.02, respectively). At the end of the re-alimentation period, there were no significant differences in dry matter, protein, lipid, or ash contents except that protein content in fish deprived of feed for four weeks was significant- ly (p<0.05) lower than in fish of other treatments.
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ItemEffects of natural and synthetic pigments in diets on flesh coloration and growth of rainbow trout (Oncorhynchus mykiss W.)(Israeli Journal of Aquaculture - BAMIGDEH, 2005)The desired pink to red color of rainbow trout flesh (Oncorhynchus mykiss W.) can be obtained by adding carotenoids to the fish diet. This study was conducted to determine the effects on growth and color retention of natural pigments (30 ppm red pepper meal, 60 ppm red pepper meal, 30 ppm shrimp by-products meal, 60 ppm shrimp by-products meal), synthetic carotenoids (30 ppm astaxanthin, 60 ppm astaxanthin), and a control group (no added pigment). Duplicates of each of the seven treatments were reared for three months. The best specific growth rates were obtained with 30 ppm astaxanthin (0.83%) and 60 ppm red pepper meal (0.84%); the low- est was in the control (0.54%). The lowest food conversion ratio was obtained with 30 ppm astax- anthin (1.38) and highest in the control (2.23; p<0.05). Visual coloration values ranged from 14.46±0.23 in the 30 ppm astaxanthin group to 11.55±0.25 in the control. Retention coefficients ranged from 6.63 in the 30 ppm astaxanthin group to 1.79 in the 60 ppm shrimp by-products meal (p<0.05). Tristimulus chromometer a values ranged from 0.87±0.47 in the control to 6.96±0.47 in the 60 ppm astaxanthin treatment, b values from 10.94±0.27 in the control to 12.90±0.27 in the 60 ppm red pepper meal treatment, and L values from 46.81±0.50 in the 60 ppm astaxanthin group to 54.57±0.26 in the control (p<0.05).
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ItemEffects of feeding raw soybean meal to fry of indian major carp, Catla catla, on growth, survival, and protein digestibility(Israeli Journal of Aquaculture - BAMIGDEH, 2005)Effect of feeding raw soybean meal on growth, nutrient utilization, and amylase and protease activity of Indian major carp (Catla catla) fry was studied in a 70-day feeding trial. Five isocaloric (1568 kJ/100 g diet) and isonitrogenous (45 g crude protein/100 g diet) semi-purified diets had varying levels of soybean meal (0, 5, 10, 20 or 30%). Ninety C. catla fry (0.94±0.02 g) were dis- tributed into the five treatment groups with three replicates of each treatment. The weight gain, SGR, and PER of groups receiving diets with soybean meal were significantly (p<0.05) lower than in the control group that contained no soybean meal. Trypsin inhibitor units in the diets neg- atively correlated with weight gain (r = -0.7557), protein digestibility (r = -0.9541), trypsin (r = -0.9087) and protease activity (r = -0.8596), and positively correlated with carbohydrate digestibility (r = 0.8140) and amylase activity (r = 0.7802). An increase of trypsin inhibitor units resulted in increased hypertrophy of pancreatic, kidney, and liver tissues. Inclusion of as little as 5% soybean meal depressed the growth rate. Hence, although the soybean diets did not result in mortality, inclusion of raw soybean meal in the diet of C. catla fry should be discouraged.
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ItemEffects of photoperiod on growth and feed utilization of juvenile Black Sea turbot (Psetta maeotica)(Israeli Journal of Aquaculture - BAMIGDEH, 2005)A study was conducted to determine the effect of different photoperiods on the growth and sur- vival of juveniles of the Black Sea turbot (Psetta maeotica). Juvenile turbot (32.17±0.1 g) were reared under one of three experimental photoperiod regimes: natural, continuous light, or extended light (18 h light:6 h dark). The turbot were held in sea water (18 ppt) at 15-24°C from May 27 to July 29, 2004. The maximum growth rate, feed efficiency, and specific growth rate were recorded in the fish exposed to the extended light period (p<0.05). Continuous light may have acted as an irritant, inducing stress, suppressing growth, and reducing feed intake.
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ItemEvaluation of organic tilapia culture in periphyton-based ponds(Israeli Journal of Aquaculture - BAMIGDEH, 2005)The introduction of hard surfaces in the water column to induce the growth of biofilms and peri- phyton on these surfaces is a method used to increase natural productivity of the water body and food for cultured aquatic organisms. In periphyton-based systems in Africa and Asia, substrate introduction and consequent periphyton development positively affected water quality and pro- duction of the target species. In Israel, this technology is being evaluated in the culture of organ- ically produced tilapia. Among other restrictions imposed by organic standards, fish stocking densities must be low and only organic feeds and manures must be supplied. Organic pelleted feeds cost twice as much as regular aquaculture feeds. Since feed constitutes the major pro- duction expense, economic viability is hampered by using costly organic feeds. An experiment was performed at the Dor Aquaculture Station to explore methods of improving natural food pro- duction for tilapia and reducing added feeds. Submerged plastic surfaces equivalent to 40% of the pond surface area were immersed in polyculture ponds containing 85% hybrid tilapia (Oreochromis niloticus x O. aureus), together with a reduction of 40% of the amount of pelleted feed. The treatment improved nitrification and saved 40% of the feed costs, with only a 10% reduction in the tilapia growth rate and yield. These results indicate that periphyton-based aqua- culture is an appropriate technology for reducing production costs and allowing economically viable organic tilapia production.