NEW TECHNOLOGIES IN AQUACULTURE DEVELOPMENT (JOURNAL OF FISHERIES)
Year:2009 | Volume:3 | Issue:1|Papers Count:12

Long-term duration of ovarian development cycle is an important problem in rearing of sturgeons.This study was done on the probable effects of temperature on the growth and accelerating of maturity in the beluga. For this reason beluga were reared from larval stage to final stage of maturity in 9 years.Results showed underground warm water can decrease duration of ovarian development cycle and fishes reached the maturity when they are 9 years old. Warm water also accelerated growth rate and fish reached to 2.3 kg at the end of the first year and to 4.8 kg at the end of second year. According to our results, beluga need 63540 day-degree to reach maturity in warm water. FCR (food conversation rate) in this experiment for %5, %8 and %11 feeding rate were 3.88, 5.07 and 7.47 respectively. The average of fishes daily growth was 8 g. It can be concluded warm water has an effect an acceleration of growth and maturity of beluga.

This study was conducted in order to consider the effect of water soluble fraction of crude oil on the accumulation of heavy metals (Ni, Pb, Cd & V) in muscle tissue of Lutjanus fulviflammus in the Persian Gulf. The study was carried out in spring 2005 in the Ecology Research Center of the Persian Gulf. Two solutions with 0ppm (Control) and 12 ppm dosages of crude oil were prepared. Then 24 fish from those species which were caught from 6 stations in the northern part of the Persian Gulf were exposed to 12 ppm dosage of crude oil for 8 days in long-term bioassay examination. After 8 days exposed fish were freezed and packed seprately and sent to the laboratory for determination of heavy metals accumulated in their muscle. Heavy metals concenteration measurment was done with Atomic Absorbtion model Philips PU 3400. The result of data analysis shows that the mean (`c ± STD) accumulation amounts of V, Ni, Cd & Pb in tissues of control fish were 0.18±0.03 ppm, 0.41±0.04ppm, 0.01±0.01 ppm and 1.70±0.08 ppm respectively. The mean (`c ± STD) accumulation amounts of V, Ni, Cd & Pb in tissues of fish which were exposed to 12 ppm dosage of crude oil were 0.22±0.05 ppm, 0.65±0.06 ppm, 0.14±0.03 ppm and 1.94±0.13 ppm respectively. According to the conducted T-test we concluded there is a significant difference (P<0.05) between two mentioned dosages of crude oil in muscle tissues of this fish. Also in the fish of both treatments the order of heavy metals accumulation was Pb>Ni>V>Cd that was significant according to the T-test experiment.On the other hand, the high amount of heavy metals in the control fish is due to the pollution of the Persian Gulf. Also, the mean concentrations of Pb, V & Cd in muscle tissue of control fish were below the international guidelines for human consumption.

Histological development of beluga during life stages (1-75 days post hatch) was studied by using light microscopy. Larvae were fixed in bouin’s solution then dehydrated and embedded in paraffin wax. Sections of 5-7mm thick were produced and stained according to standard histological techniques: Hematoxylin-Eosin (HaE), and periodic Acid Schiff (PAS). One-day-old larvae possess a primordial intestine, which is lined by a simple columnar ciliated epithelium. 3 days after hatching, an oblique furrow of the digestive tube wall starts to develop on the dorsal-posterior region of the yolk sac and divides the alimentary canal into two differentiated regions: the future stomach and intermediate intestine. At this time spiral valve starts to differentiate. Granules of embryonic pigment accumulate in the spiral valve lumen forming the melanin plug. 7 days after hatching intermediate gut and spiral gut are lined by a columnar ciliated epithelium. The terminal section of the digestive tract is differentiated into a short rectal duct lined with a cuboidal epithelium. The urinary bladder connects with rectum at this time. 13 days after hatching the number of vacuoles filled with lipid increases in intermediate gut and spiral gut. Between 17-19 days post hatching beluga larvae have a period of mixed nutrition. 25 days after hatching cells of intermediate gut have long microvilli. 36 days after hatching the number of goblet cells increase in spiral gut. 43 days after hatching several intestine glands are visible in connective tissue of intermediate gut which is lined by a simple columnar ciliated epithelium. Between 57-75 days after hatching the number and size of mucosal folds increase in intestine. This information may be useful to improve rearing efficiency of beluga and the other sturgeon.

In this investigation, for caviar processing, the mixture of sodium diacetate and pure salt was used.The usual preservative in this process in Iranian Fisheries is Brox and boric acid. Caviar of Acipenser persicus was processed with 3 doses of Sodium diacetate, 800, 850 and 900mg/kg, then experimental samples and fisheries witness were kept in (-3oC) for 6 months in Anzali port fisheries. During these six months, Chemical changes, organoleptic properties, and bacterial and fungus growth were studied monthly. The result of the meticulous study and comparison of experimental samples with these in the Iranian Fisheries indicated the best quantity for the mentioned preservative in this process is the dosage of 900 mg/kg of deacetate.

Kutum (Rutilus frisii kutum) is a precious and endemic subspecies which is found in the Caspian sea. The study of parasitic infections of Kutum fingerlings was carried out in governmental cultivated ponds in Guilan province in spring and summer 2005. In this survey, 448 specimens of Kutum fingerlings in five weight groups were caught from five sampling areas during weekly samplings in random and they were transferred to laboratory alive. They were measured and weighed. Then various external and internal organs were studied from parasitic infections viewpoint. In the present survey, four species and one genus were separated. Isolated parasites are as follows: Monogenea Dactylogyrus spp. (Prevalence 13.84%, mean intensity 2.65±2.14 and number range 1-16), Digenea, Metacercaria of Diplostomum spathaceum (Prevalence 25.45%, mean intensity 5.33±5.24 and number range 1-43), Cestoda , Bothriocephalus gowkongensis (Prevalence 5.13%, mean intensity 1.35±0.71 and number range 1-4), Nematoda, Camallanus lacustris (Prevalence 0.22%, mean intensity 1 and number range 1)and Crustacea, Argulus foliaceus (Prevalence 0.22%, mean intensity 1 and number range 1). The significant difference between sampling areas was observed from point of intensity of Metacercaria of D.spathaceum (P<0.05). On the other hand, it wasn’t significant for others. Weight groups of 1-2 g and 4-5 g had the highest parasitic diversity whereas the lowest one was related to the weight group under 1g.It must be noticed for the first time in Iran. C.lacustris is introduced on Kutum as a new host.

The use of immune-stimulants is an effective way of increasing protective-ability in fish.Levamisole hydrochloride is a druge which causes regulation immunostimulation and increases fish's white blood cells (Leukocytes). This research was performed to consider the effects of levamisole hydrochloride in activate Persian Sturgeon (Acipenser Persicus) Fry Leukocyte as a mmunostimulator, Two treatment's: 5mg/lit and 10mg/lit levamisole applied on daily bath for 20 min. The results have shown that average W.B.C count of young was 18320, 16740 and 10060 in the 10 and 5mg/lit levamisole treated groups and control respectively. The results of this study demonstrate that levamesole was capable of significantly increasing WBC count.

In this research work the production of fish ball from mullet and the effect of antioxidant on shelf life of the product have been investigated. According to the organoleptic tests, the following formula for production of fish ball has been chosen: Fish meat 50%, Potato 16%, Onion 12%, Soybean 8%, breaded powder 8%, Tomato sauce 2.5%, Lemon juice 1.2%, Salt 1.1%, Garlic powder 0.7% and spices 0.5%. Then three samples were made: the first sample which did not have antioxidant used as blank, the second and third samples were included 0.01% and 0.02% of BHA antioxidant, respectively. These samples were frozen in -18oC and kept in a cold store for 120 day. According to the time schedule, the microbiological, TVN and peroxide test were carried out. The microbiological tests showed that the number of bacteria decreased from 420 colonies after 120 days of storage in -18oC. The results of TVN tests for all samples showed an increase of 9.9 mg/100g to 17 mg/100g after 120 days in -18oC storage. The peroxide test showed an increase of 1.4 meq/kg to 15.6 meq/kg for blank samples after 90 days in -18oC. On the other hand the samples which contained antioxidant showed an increase from 1.4 to 5 mg/kg even after 120 days storage in -18oC. According to these results the shelf life for the blank samples and those which contained antioxidant is suggested 30 and 120 days in -18oC respectively.

An 8-week feeding trial was conducted to evaluate the effect of betafine on growth performance and survival rate on ship fry, Acipenser nudiventris. Betafin were added to commercial diet in four levels (0.5, 1, 3 and 5%) (Biomar) in circular tanks. Each diet was given to three replicate groups of fry ship (initially averaging 1.2±0.32gr). Based on the present results, enhanced growth performance, specific growth rate, feed conversion ratio and survival rate were generally observed in the fish fed with the diets supplemented with betafine 5%.

In this study the filtration rate of nitrogen and phosphorus components by Swan mussel Anodonta cygnea in a recirculation system was investigated. The system was built of a 100 liters main tank and 4 recipients of 2.5 liters each (One of these as control) and one tank for returnin of water. Three treatments of different concentrations of nitrogen (80, 100 and 200 mg/l) and phosphorus (20, 40 and 60mg/l) separately were examined. In all treatments, sampling was repeated 3 times. Results showed that in three treatments during thise time, the filtration rates were reduced. Also an increase in Nitrogen concentration caused filtration rates to be increased. Filtration rates in the first treatment increased from 6.53±0.03 to 7.15±0.02 and then to 8.07±0.05 ml. min-1.gr-1 AFDW from the first to the third treatment respectively. The filtration rates in phosphorus treatment have also increased when the concentration increased. This has been changed from 5.61±0.01 to 6.5±0.04 and 7.58±0.09 ml.min-1.gr-1 AFDW from first to third treatment. Results of filtration rate of nitrogen and phosphorus showed that the performance of Anodonta cygnea in the absorption of nitrogen and phosphorus components is appropriate.