IJA Volume 57, Issue 4, 2005

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    Effect of low salinity on the survival of postlarvae of the blue shrimp, at different stages
    (Israeli Journal of Aquaculture - BAMIGDEH, 2005) Xinhong, Su ; Changchun, Shen ; Zhangwu, Yang ; Yayou. Zheng
    The development of low salinity culture techniques is the major factor that facilitated the wide- spread cultivation of the white shrimp Litopenaeus vannamei in China. Similarly, adaptation to fresh or low salt water is critical for the commercial farming of a related species, the blue shrimp L. stylirostris. To determine the effects of low salinity on L. stylirostris development, the survival of postlarvae was investigated at different levels of salinity at the Haichang Jinhaian Shrimp Breeding Farm and Gulangyu Breeding Farm for Aquatic Animals of the Fisheries Research Institute of Fujian during 2002-2003. Results showed that both salinity and the age of the post- larvae significantly affected survival (p<0.01). The minimum seawater salinity for young postlar- vae was 10-14 ppt and survival rates increased with age. When the post-larvae were 9 days old or older (≥P9), survival did not significantly differ in the low salinity treatments from that of the control (P12). The first hour was the most critical period. If larvae survived the first hour, they usually survived the whole study period (24 h) or longer.
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    Effects of molting on the growth of primary cultured muscle cells from and Short Communication
    (Israeli Journal of Aquaculture - BAMIGDEH, 2005) Wang, Wei-Na ; Wang, An-Li ; Nu, Dong-Hong ; Liu, Yi-Chen ; Sun, Ru-Yong
    This study examined the effects of molting stage on the growth of primary-cultured cells from the shrimps Macrobrachium nipponense and Penaeus vannamei. Muscle cells in different molting stages were cultured in L-15 medium, supplemented with 1g/l glucose,1g/l MgCl2,1 g/l CaCl2,100 IU/ml penicillin, and 100 μg/ml streptomycin. Results showed that cells cultured in the early postmolt stage grew best. They had an unfolding cell shape, a compact monolayer, a high rate of coverage, and the highest RNA:DNA ratio. Differences among early postmolt, premolt, and intermolt cells were significant (p<0.05).
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    Atypical aeromonas infection in cultured sea bass in the Black Sea
    (Israeli Journal of Aquaculture - BAMIGDEH, 2005) Karatas, Süheyla ; Candan, Akin ; Demircan, Didem
    The Black Sea, an inland sea, has contributed about 70% to the total fish production of Turkey for many years. Because of its low salinity and appropriate water temperature, both freshwater and marine fish such as salmon, trout, and sea bass can be cultured in the Black Sea. The aim of this study was to identify the etiological agent of mortality that occurred in sea bass in the Black Sea during July 2002. Bacteria isolated from kidneys and livers of infected fish were iden- tified as Aeromonas salmonicida achromogenes according to morphological and biochemical characteristics, API 20NE results, and an agglutination test for A. salmonicida. The diseased fish had petechial hemorrhages on the bottom of the fins and lesions on the lateral and ventral sides of the body. Cumulative mortality was approximately 20%. This is the first report of A. salmoni- cida achromogenes associated with sea bass in Turkey.
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    Effect of restricted feeding regimes on compensatory weight gain and body tissue in fry of the Indian major carpHamilton, 1822)
    (Israeli Journal of Aquaculture - BAMIGDEH, 2005) Singh, Ravendra Kumar ; Balange, Amjad
    An 8-week experiment was conducted to examine the effect of restricted feeding on compen- satory weight gain and body tissue changes in fry of the Indian major carp, Cirrhinus mrigala. During the period of feed restriction, the control group was fed to satiation twice a day while feed for the three other groups was completely withheld for 1, 2, or 4 weeks. During the subsequent re-alimentation period, all groups were fed to satiation. At the end of the experiment, fish deprived of feed for two weeks had a significantly (p<0.05) higher body weight (5.40±0.20 g) and lower FCR (3.40±0.20) than the control group (4.55±0.10 g and 6.75±0.02, respectively). At the end of the experiment, there were no significant differences in dry matter, protein, lipid, or ash contents among groups, except that fish deprived of feed for four weeks had a significantly (p<0.05) lower protein content than fish in the other treatments.
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    Effects of flow velocity on growth of juvenile cobia
    (Israeli Journal of Aquaculture - BAMIGDEH, 2005) Yu, Shyi_Liang ; Ueng, Ping-Sheng
    The objective of this study was to investigate the growth rate and feed conversion ratio (FCR) of juvenile cobia, Rachycentron canadum, in different flow velocities. In experiment A, fifteen groups of fish with an initial mean weight of 14.35 g were reared for 28 days in one of five flow velocities: 0, 5, 10, 15, and 20 cm/s. In experiment B, fifteen groups of fish with an initial mean weight of 30 g were reared for 21 days in the same velocities as in experiment A. In experiment C, fish weighing an average 77 g were raised for 21 days in 0, 10, 20, 30, and 40 cm/s. The opti- mal velocities in terms of growth rate were 10 cm/s for fish of 10-30 g (experiment A), 20 cm/s for fish of 30-60 g (experiment B), and 23 cm/s for fish of 60-200 g (experiment C); the optimal velocity increased as the fish weight increased. FCR and specific growth rate (SGR) also signif- icantly (p<0.05) corresponded to the flow velocity for the different sized juveniles with the opti- mal FCR and weight gains occurring at 10-23 cm/s. FCR rapidly increased when the velocity exceeded 35 cm/s, regarded as the maximum flow velocity for fish growth.
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    Nitrogen excretion patterns and postprandial ammonia profiles in Black Sea turbot under Controlled conditions
    (Israeli Journal of Aquaculture - BAMIGDEH, 2005) Yigit, Murat ; Erdem, Muammer ; Aral, Orhan ; Karaali, Burcu
    Measurements of the rate of nitrogenous excretion were carried out in two batches of young Black Sea turbot (small 42 g, large 72 g) at 12±1°C under natural light conditions (10 h light:14 h dark and 13 h light:11 h dark, respectively). The ammonia nitrogen excretion rates of fish starved for 48 hours were 0.20±0.05 mg-N for the small fish and 0.18±0.09 mg-N/100g fish/h for the large. Fish were then fed a pellet diet containing 8.3% nitrogen at average rations of 0.67% and 0.59% of the body weight, respectively, for four days. On the fourth day, ammonia nitrogen excretion rates were evaluated. In both batches, the rates were 2-3 times higher immediately after feeding than in the starved fish, reaching a peak 3-6 hours after feeding and declining after- wards. For the small and large fish, respectively, 21% and 20% of the consumed nitrogen was excreted as ammonia nitrogen, 6% and 7% as urea nitrogen, and 8% and 4% as feces nitrogen within 24 hours after feeding.
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    Induction of ovulation and spawning in the Mediterranean red porgy, by controlled delivery and acute injection of GnRHa
    (Israeli Journal of Aquaculture - BAMIGDEH, 2005) Kokokiris, L. ; Canario, A. ; Mylonas, C. ; Pavlidis, M. ; Kentouri, M. ; Divanach, P.
    Gonadotropin-releasing hormone analogue (GnRHa) in the form of saline injections or sus- tained-release microspheres was used to induce oocyte maturation, ovulation, and spawning in captive red porgy (Pagrus pagrus). Individually tagged vitellogenic females (n = 9 or 10) were treated at the beginning of the spawning season (March) with 20 μg/kg body weight (bw) GnRHa-loaded microspheres, a single injection of 20 μg/kg bw dissolved in saline, or physio- logical saline (control). Females were placed in tanks (one tank per treatment) connected to overflow egg collectors and monitored for 11 days. In addition to the eggs collected from the tank overflow, eggs were stripped from the fish on a daily basis. Only one spawn was obtained from the control fish, probably from a single female, given the small relative fecundity (700 eggs/kg bw). On the contrary, treatment with a GnRHa injection produced two spawns (9 and 11 days after treatment) and 50% of the fish ovulated. Treatment with GnRHa microspheres induced seven spawns (3 and 6-11 days after treatment) and 100% of the females ovulated. Females did not spawn all the eggs ovulated on a particular day, evident from the significant number of eggs obtained by manual stripping. Egg quality did not significantly differ among treatments, whereas number of spawned eggs and total relative fecundity were significantly higher in fish treated with GnRHa microspheres (ANOVA, p<0.05). The results demonstrate the potential of GnRHa- loaded microspheres to induce spawning in red porgy, as a method of overcoming spawning fail- ures in commercial hatcheries.
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    Mycobacteriosis in European sea bass, l., cultured in Turkey
    (Israeli Journal of Aquaculture - BAMIGDEH, 2005) Korun, Jale ; Olgac, Vakur ; Akgun-Dar, Kadriye ; Colorni, Angelo ; Diamant, Ariel
    A case of mycobacteriosis in European sea bass (Dicentrarchus labrax L.) cultured in Turkey is described. Diseased fish were characterized by lethargy, lingering passively at the water sur- face, pale gills, and exophthalmia. Internally, grayish-white nodules were observed in the liver, spleen, and kidney. In one individual, a granulomatous mass of renal origin protruded into the abdominal cavity. The principal histological feature was the occurrence of characteristic granu- lomas with associated acid-fast, rod-shaped bacteria. This is the first confirmed case of fish mycobacteriosis in Turkey.