JOURNAL OF FISHERIES SCIENCE AND TECHNOLOGY (JFST)
Year:2013 | Volume:2 | Issue:3|Papers Count:7

The effect of Artemia urmiana nauplii enriched with flaxseed oil on growth performance, survival and fatty acid composition of severum, Cichlasoma severum, larvae (0.3 mg initial weight) was investigated through a completely randomized block design with two treatments, viz., (1) larvae fed with plain nauplii, (2) larvae fed with nauplii enriched with flaxseed oil, in three replications. Results of the first biometry (day 18th), showed a significantly higher survival rate in treatment 1 (81.87±0.29%) than treatment 2 (68.83±1.62%) (P<0.05), but there were no significant differences in the specific growth rates, the average weight and length gains between treatments (P>0.05). At the end of the second period of the experiment (day 36th), significant differences in growth performance and survival rate was recorded between treatment 1 (97.82±1.09%) and treatment 2 (91.16±1.34%) (P>0.05). The larvae was also found to convert n-3fatty acids to EPA and DHA.

Separate or combined effects of inulin and mannan oligosaccharide supplements on the growth, survival, body composition and salinity resistance of kutum roach (Rutilus frisii kutum) fry (410±19 mg) were investigated for 45 days in 40-liter tanks containing 30 individuals. Fish were fed 7 to 12% body weight with a commercial diet (35% protein and 12% lipid) supplemented with 0 (control), 5 g kg-1 inulin, 5 g kg-1 MOS and 2.5 g kg-1 inulin+2.5 g kg-1 MOS in a totally randomized design trial in triplicate. A general enhanced growth performance and feed efficiency were observed in fish fed on diet containing 5 g kg-1 MOS (p<0.05). There were no significant differences in survival rate among treatments (p>0.05). NO significant difference was observed in body composition, but protein and lipid contents in the whole body increased in fish fed with 5 g kg-1 MOS and control group. In general, the fish fed 5 g kg-1 MOS had the highest survival index after 48 hours exposed to salinity stress (15 ppt). Results showed 5 g kg-1 MOS could improve growth performance, survival and salinity stress resistance of kutum fry.

The gill Structure and localization of Na+, K+-ATPase were examined through branchial arches of the Persian sturgeon, Acipenser persicus larvae (25 days-post-hatched, 417.3 mg). Studies were conducted through light microscopy (H&E Staining) and immunofluorescence for Na+, K+-ATPase. Results showed each gill consisted of four complete holobranches and opercular hemibranch. Each filament carried rows of lamellae consisting of a network of interconnecting blood lacunae, which were lined by pillar cell flanges. Pavement cells covered the outermost layer of the lamella and blood cells were found in lacunae. High density of ionocytes (529.73 per mm2 of the gill tissue) was found at the base of the lamella, in the interlamellar regions, on the filaments and the septums. Ionocytes possessed large size and round basal nuclei. Ionocytes possessed strong immunofleurescence in their cytoplasm, especially in the basolateral sides because of high concentration of the enzyme. The results showed that the main structures of the gill has already been formed at this developmental stage of the Persian sturgeon, and along with its respiratory and excretory roles, it also plays an important role in osmoregulation.

In this study, the human health risk of mercury due to consumption of croaker (Otolithes ruber) in Mahshahr, the Persian Gulf, was evaluated using atomic absorbtion spectrophotometer) and cold vapor techniques to measure the mercury concentration in muscle samples of 30 fresh croakers. A. Result showed the average concentration of mercury in croaker muscle was 0.354±0.09 mg/ g of fresh wet weight, which was less than the allowable amount for human consumption determined by the international organizations such as USFDA and WHO, but more than the allowable amount for human consumption determined by MAFF and the USEPA. HQ Index was above 1 (1.18). In addition, the calculations indicated that daily and weekly mercury uptake for the Iranian consumers, according to Statistical Yearbook of Iran Fisheries organization (the amount consumed per capita), is lower than the guideline values (PTWI and PTDI) provided by WHO, USFDA and more than USEPA. Therefore, the consumption of the croaker might be associated with some threat to the consumer’s health particularly pregnant women, fetuses and children from mercurybut consumption permitted rate of 20gper dayand138 gper weekis recommended for other people.

Having the Five Year Development Plans (FYDP) of the fisheries sector (Shilat) in mind, and based on the resources documentation and content analysis of two scenarios of the “continuation of the current trend” and the “optimal situation”, this research provides the future opportunities and threats and also suggestions towards improving the situation and relevant decision making. The assessment of production indices demonstrated that in each of the plans, except the third one, not a so-logical growth rate was envisioned for the fisheries development. Of 5% predicted growth in fisheries sector within 23 years, only 4.5%, or 90.3% of the goal, has been realized, which means the policies and programs have not been completely performed. Although possessing the world ranking of 21st in aquaculture and 32nd in fishing, potential and capacities in Iran indicate a far higher exploitation and utilization possibilities from the present resources, which require better policies and approaches as well as a large and targeted investment by the government.

The effect of the antioxidant extracts on the quality indices of rainbow trout fillet stored at refrigerator (4±1ºC) for 15 days was investigated. The fillets in 3 treatments, including salted in 10% brine, salted in 10% brine plus 1% nettle leaf extract, and salted in 10% brine plus synthetic antioxidant BHT were evaluated at every 3 days interval, using the quality indices including the free fatty acids (FFA), thiobarbituric acid (TBA), peroxide (PV), moisture content, pH levels and sensory characteristics. The results showed that TBA and FFA values increased significantly (p<0.05), but PV significantly decreased in all treatments during the course of storage (p<0.05). Samples containing antioxidants had significantly lower TBA, PV and FFA values in comparison with the control sample throughout the storage. Also, the methanol extract from nettle leaves (at 1% balance) controlled the TBA, PV and FFA indices and entirely replaced the synthetic BHT antioxidants (at 1% balance). Since the sensory evaluation (smell, texture, taste and after taste elements) showed no significant differences between the two antioxidants, both are recommended to preserve the quality of rainbow trout fillet. The nettle leaf extract was found to be more efficient on shelf life extension the fillet.

Length-weight relationship, age range and fecundity of 40 specimens of the Russian sturgeon, Acipenser gueldenstaedtii, collected from two fishing stations in the southeastern Caspian Sea, were determined. Average length (TL) and weight were 129.5 cm and 12.7 kg for males and 145.8 cm and 22.15 kg for females, respectively. Absolute fecundity was 184000 in average and condition factor calculated 0.58 and 0.7 for male and females, respectively. Average age for males and females was 12.7 and 14.6 years, respectively. All these factors were lower than previous records from the Volga river estuary. Length-weight relationships results demonstrated isometric growth pattern with average slope of 2.978 and 2.822 for males and females respectively. These values were not statistically different between sexes (p>0.05), but using this relationships for each sex separately will be useful for more reliable results especially in broodstock studies.