NEW TECHNOLOGIES IN AQUACULTURE DEVELOPMENT (JOURNAL OF FISHERIES)
Year:2008 | Volume:2 | Issue:3|Papers Count:9

Anguilliformes order is one of fish resources in Persian Gulf and Oman Sea. They have ornamental and nourishing value in some species. This research was for revising taxonomic and systematic defects of them. The whole samples were collected from the south coast of Iran included: Chabahar, Bushehr, Bandar Abbas, Bandare Lengeh, and the rest were from museums, universities and research centers in Iran during a year. The whole ichthyology valid published references in this area were considered. The result showed that from among 27 studied samples, only 10 samples presented in this article belong to congridae, Muraenesocidae, Muraenidae, Ophichthidae,and Nettastomatidae; Synaphobranchidae have maximum diversity in this research area. Pseudoxenomystax Albeacens, Muraenesox bagio, Congeresox talabon, Congeresox talabonoides, Gymnothorax lohnsoni, Gymnothorax kidako, Strophidon sathete, Rhinomuraena questathete, Hoplunnis diomedianus, and Synaphobranchus affinis are recorded in Persian Gulf and Oman Sea (i.e. Iranian sea zone) for the first time.

Probiotics are useful microorganisms wich colonized in gut system on animals. The probiotics have useful effects on health and growth performance of the animals. In order to investigate the effects of probiotic and iron supplementation on growth and survival of Rainbow Trout (Oncorhynchus mykiss) larvae, a 30-day feeding experiment was conducted. 2700 larvae (average weight 0.135 g) were used. They were divided into 8 groups and 3 repetitions, groups containing 100 larvae. One control group with 3 replicate was served as well. The first treatment was contained fish larvae fed by 1.6x109 CFU/g, The second treatment was contained by 1.2x109 CFU/g, The third treatment was contained by 7mg iron per kg of feed, The fourth treatment was contained 5mg iron per kg of feed, The fifth treatment was contained by CFU/g and 7mg iron per kg of feed, The Sixth treatment was contained 1.6x109 CFU/g with 5mg iron per kg of 1.6x109 feed, The seventh treatment was contained 1.2x109 CFU/g with 7mg iron per kg of feed, and The eighth treatment was contained 1.2x109 CFU/g with 5mg iron per kg of feed. The sampling for nutritional effects was carried out every 6 days. At the end of the experiment; Weight Gain, Food Conversion Ratio, Specific Growth Rate, Protein Efficiency Ratio in the 1, 2 and 6 treatments were significantly higher than other treatment groups and control group; also weight gain in 9 treatment was the lowest (P£0.05). Total length and survival rate were not significantly affected by the administered probiotic and iron (P³0.05). Protein in whole body of 1 and 2 treatments showed higher rate than in other treatment groups and control group (P£0.05); also fat value of body whole in 1 and 2 treatments showed lower rate than the other treatment groups and control group (P£0.05). The findings in this research support that if probiotic just added to feed (in contrast, that if probiotic and iron both added to feed), growth and nutrition factors of Rainbow Trout larvae would be increased.

Neogobius caspius is a small benthic fish that is native of the Caspian Sea. The importance of this fish is because of its role as a main food resource of the Sturgeon fish. The genetic diversity of N.caspius population in the Caspian Sea was studied using PCR-RFLP technique. A total of 135 samples of N.caspius were collected from costal line in the north Caspian Sea, including specimens from costal of Anzali and Chalus. Genomic DNA was extracted by phenol-chloroform method and then was amplified using a pair primer of cytochrom b gene, 2 tRNA gene and the control region sequences by a thermal cycler.R: D2(5'-CCGGAGTATGTAGGGCATTCTCAC-3')F: CY1(5'-YYTAACCRRGACYAATGACTTGA-3')12 restriction enzyme were used to digest the target gene region including: AluI - Alw26I(BsmAI) - BSeNI(BSRI)- DraI- MboI- RsaI- TasI- HincII- BsuRI(HaeIII) - Bsh1285I - Hin1I- Bsu15I. Digested PCR products were observed by silver staining method followed by polyacrilamid gel electrophoresis (PAGE). The results showed the same pattern among the species. There was no polymorphism and no differentiation in population in the Neogobius caspius fish in the southern coast of Caspian Sea.

The acute toxicity and histopathology of common carp fish exposed to sevin were assessed following the O.E.C.D. Guideline and performed statically in 20±2oC.In acute toxicity experiments the mean body weight of the juveniles was 3.63±0.26 g. The 96h LC50 value of sevin for common carp juveniles was 14.187 mg/l Therefore the MAC value of sevin in natural waters for "Cyprinus carpio" was 1.4187 mg/l. According to the table of sorting the toxicity of insecticides, sevinn was toxic for common carp .The following clinical symptoms were observed in this study consisted of lordosis and neural paralytic syndrom in fish exposed to this pesticide. Some abnormal reactions such as losing the balance and swimming in a half circle , expressive pigmentation mainly on the dorsal part and block of respiration movements were seen in these juveniles. Histopathological experiments performed on control and treatment group of common carp fish with 3.8±0.42 g mean body weight after 96h exposure to sevin in concentration lower than LC50 96h (10mg/l). Samples were taken from tissues of liver, kidney, gills, spleen, gut in both treatmentl and control groups. Sever hyperplasia, edema, inflamation and degenaratin of lamellas were observed in tissues of gills in experimental group. Also vacuolization, necrosis and multifocal hemosiderosis were seen in liver and spleen. More than this lesions, there was kidney's tissue necrosis and enlargement of bowman's capsule In kidney's tissue. The result revealed that, it is concluded that histopathology of these juveniles exposed to environmental contaminants may provide useful information to target organs and mechanism of toxic substance actions.

In this study likely effects of water in oil (w/o) emulsion versus acute administration of gonadotropin releasing hormone agonist (GnRHa) on induction and synchronization of ovulation in rainbow trout were examined. GnRHa was diluted in physiological saline (PS) or propylene glycol (PG) and mixed with equal volume of Freund’s incomplete adjuvant (GnRHa-FIA). All fish received 0.5 ml intraperitoneal injections. Dose of hormone in all groups was 25mg/kg-1 except control fish which received physiological saline. All fish injected with PS diluted GnRHa, combined with adjuvant or in two injections protocol ovulated 10 and 11 days after injection respectively. In contrast only 75% in control fish and 60% of fish with an acute injection of pure GnRHa ovulated up to 36 days after injection. In fish injected with PG diluted GnRHa combined with adjuvant ovulation percentage reached to 87% until the end of experiment compared to 100% ovulation for fish injected twice with PG diluted GnRHa. Fertilization, eyeing and hatching percentages were normal in all treatment groups and did not differ significantly among groups (P>0.05). None of treatments caused any pre or post-spawning mortality. In conclusion, combination of physiological diluted GnRHa with Freund’s incomplete adjuvant (GnRHa-FIA) was effective in advancing the onset of ovulation, synchronizing the ovulation of treated fish and shortening the reproductive period, relative to control or acute GnRHa injected group (P<0.05). GnRHa-FIA did not affect egg quality or cause any mortality in the treated broodstock.

Hilsa shad, Tenualosa ilisha, is an euryhaline, pelagic and anadromous species which is found in marine and freshwater water. It usually migrates more than 100 km to rivers in the breeding season. This survey, carried out from July 2006 to June 2007, included a total of 344 specimens all collected by gill net from the northern Persian Gulf, Bushehr coasts (Deylam waters). As studies show, Hilsa shad is a filterfeeder species and this study demonstrated that they fed on phytoplankton much more than zooplankton.The results indicate that the most abundant phytoplankton species belong to Bacillariophyta. In this phylum, genera Chaetoceros and Cocconeis had the most and the least abundance, respectively. After Bacillariophyta, there was phylum Pyrrophyta. In this phylum, genera Ceratium and Dinophysis had the most and the least abundance, respectively. On the other hand, the most abundant zooplankton species was related to phylum Arthropoda. Class of copepoda was approximately abundant in all months except August 2006 and May 2007. After Arthropoda, phylum Ciliophora with genus Parafavella was located as second food in feeding behaviour of Hilsa shad. Fluctuations between Arthropoda and Ciliophora were observed in comparison with other feeding groups. Abundance of other feeding groups was less than 5% of remainders in alimentary canal (stomach and intestine). The mean RLG was measured about 1.53±0.22 (Range 0.88-2.34). The average (GSI) was measured about 0.752±0.448 (Range 0.04-2.64).

Water molds are assumed as one of the most important injurious microorganisms to fish egg production procedure, while, fungal infection can extensively destroy the fish eggs in hatcheries. The aim of this study was to evaluate antifungal effect of ozone and formalin on prevention of fungal infection on Persian sturgeon (Acipenser persicus) and increasing the hatching ratio. Effects of 0.03, 0.05 and 0.1 ppm of ozone and 1000 ppm of formalin were examined on hatching ratio. Egg disinfection by 1000 ppm formalin resulted in the greatest hatching ratio (74%) among all treatments. Among ozone treatments, 0.1 ppm showed the highest hatching ratio (71.4%) and there was not a significant difference among ozone treatments (P>0.05). Hatching ratio of the control group (without disinfectant) was 56.2%, and there was a significant difference (P<0.05) with other treatments. Ozone is preferred to formalin and can be considered as one of the favorable disinfectants, because of a lower concentration of ozone required to disinfect the culture medium, consequently, environmental pollution will be decreased. Comparison of both disinfectants showed that ozone almost revealed the equal effect on hatching ratio but with the proportion of 1:10000 to formalin (with the dose of 0.1 and 1000 ppm ozone and formalin, respectively).

Rainbow trout is the only species of rearing cold water fish in Iran. One of the main problems in its culture is artificial propagation and production of larva. Among of those, male broods have significant role in propagation process. For this target in the propagation season in 2008 the effect of reproductive performance of different age of male broods on fertilization, eyeing, hatching and survival rates until absorption of yolk sack stage in rainbow trout, were studied. For these studies, 3 groups of male broods (3, 4 and 5 years old) were fertilized with female fish individually. The results showed that in the studied treatments there was significant difference in the mean of fertilization rate, number of fertilized eggs, survival rate to eyeing stage and hatching rate (P<0.05). Further, there was significant difference in milt volume between 3, 4 and 5 years old male broods (P<0.05). The results confirmed that three-year-old males have maximum of espermatocrite rate and differ from four and five-year-old males (P<0.05). The present study showed that the produced eggs from fertilization of four-year-old males milt and mixed females ova have maximum rate in fertilization rate (97%), survival rate until eyeing (97.21%), hatching rate (90.50%) and survival rate until absorption of yolk sack stage (88%).