Iranian Scientific Fisheries Journal
Year:2009 | Volume:18 | Issue:2|Papers Count:22

We studied effects of different feeding deprivation periods on the growth and feed utilization indices of rainbow trout. The study lasted for eight weeks. Four treatments with three replicates including a control group without feed deprivation and treatments 1, 2 and 3 with 1,2 and 3 week(s) of feed deprivation, respectively, were set up. Fish were fed ad lib for five weeks from week four up to the end of week eight, twice daily. The initial weight was (44.01±0.19g±S.E).  At the end of the deprivation period (day 21 of the experiment), starved fish including treatments 1 (46.96±2.74g), 2 (46.04±1.21g)and 3 (41.04±0.22g) had significantly lower weights (P<0.05) than the control group (64.00±5.60g). At the end of week eight, treatments 1 (93.00±3.95g), 2(83.06±3.87g) and 3 (93.85±5.60g) and the control group (82.87±9.53g) showed no significant differences in the final body weight (P>0.05, weight after starvation as covariate). From day 21 to day 33, treatments 2 (3.11±0.09% BW/day) and 3 (3.13±0.14% BW/day) had significantly higher feed intakes than the control group (1.77±0.29a) and treatment 1 (2.60±0.0) (P<0.05, weight after starvation as covariate). Meanwhile, there were no significant differences in FCR in the given period among the treatments. From day 33 to 55, FI and FCR were similar among the treatments (P>0.05). PER and PPV but not LPV for fish with starvation were higher in value, but did not differ statistically (P>0.05). Different body components were not significantly different among the treatments at the end of the starvation period (P>0.05). Results indicated that the rainbow trout with average weight of 44.01±0.19g could tolerate the starvation and could finally compensate for the final body weight.

Feeding behavior in Acipenser persicus and Acipenser stellatus in summer and winter was studied from 2004 to 2006 simultaneously with the marine survey for sturgeon stock assessment. Bottom trawls (9m) on board the research vessel Sisara 2 (50 hsp) were used to collect specimens at depth below 10m, while specimens at depths more than 10m were collected using bottom trawls (24.7m) on board the Guilan Research Vessel (1000 hsp). Examination of stomach contents of 135 A. persicus and 80 A. stellatus specimens revealed that the food spectrum was composed of bony fishes (Neogobius sp., Atherina sp., Clupeonella cultriventris), invertebrates belonging to the family Ampharitidae (polychaeta worms including Hypanai sp. and Nereis diversicolor), various crustaceans (Gammarus sp. and Paramysis sp.) and the bivalved mollusc, (Abra ovata). Significant differences were detected in the frequency of prey items in the different seasons studied. Also significant differences (P<0.05) were also detected between prey frequency and length at 95% confidence level with the greatest differences recorded in the <50cm and in the 50-100cmlength classes. It is evident from the results obtained that specimens belonging to the 50- 100cm length class showed the highest diversity in food items in all the seasons studied. Highest frequency of food items was consumed by A. stellatus in the <50cm and in the 50- 100cm length class, which were not significantly different (P<0.05) in the two seasons studied. In the present study no significant differences were recorded in the main food items consumed by A. persicus and A. stellatus in the <100cm length class and both species fed on (Ampharitidae) worms at depths less than 10m  (P>0.05).

Effects of pH, Na, K, ci2+ and Mg2+ ions on characterization of sperm motility (duration of motility and percentage of motility) of wild carp (c. carpio) were investigated. After determination of optimum pH, its interaction effect with Na, K, Ca2+ and Mg2+ was studied. Maximum motility (duration of motility and percentage of motility) was observed at pH=8.5. Effects of different treatments of Nacl on sperm motility was significantly different (P<0.05). Maximum motility was observed at 50mM of Nacl. Effects of different treatments of Kcl and Cach on sperm motility were not significantly different (P>0.05) while that of the Mgch was significantly different (P<0.05). Maximum motility was observed at 20mM of Mgch but the percentage of motility was not significantly different (P>0.05). In general, it is concluded that movement of spermatozoa of wild carp is influenced by high concentration of ions.

Complementary feedstuff extract from Laminaria digitata and Ascophylum nodossum containing 1% alginic acids as stimulator of immune system in Litopenaeus vannamei for controlling WSSV was used in this study. The test shrimps, Litopenaeus vannamei, in larvae stage (Z1-PL1), post larvae stage (PL1 –PL10) and juvenile (from day 30 to 40) were fed by complimentary feedstuff as the other test conditions in the test and control group were the same. Both groups were exposed to WSSV after 40 days by oral inoculation. The clinical signs and mortality were recorded for 10 days. The results showed the survival rate of the test group was higher than the control group and it was significant (P<0.05). The results also showed that the mortality in the test group occurred 48 hours. Later than the control group. This study can lead us to new methods for controlling White Spot Disease.

In this study, 180 Beluga (Huso huso) weighing 120±0g each with a stocking density of 12 fish per tank were adapted with synthetic diet and then fed with different levels of AFBI (0, 25, 50,75 & 100ppb/kg of diets) under controlled conditions (T=18±2°C,DO=7.3ppm). The fish were fed 3% of their body weight four times a day for three months. Prevalence of skin lesions evaluated through clinical observations monthly. With regard to toxin concentration and time of exposure to AFB1 in experimental fish, different degree of skin lesions (simple hemorrhage to progressive wounds) were observed in different parts of body especially in vent, caudal peduncle, fins, and head. "Yellow sores" on head and trunk regions were considerable and led to deterioration of appearance. Prevalence of skin lesion in different treatments was 8-53.3%. After feeding with toxic diets was stopped, 16-24% healing was observed in the fish.

We examined the possibility of replacement of the live food (rotifer) with a vmicroencapsulated diet (MED) from first feeding in yellow fin seabream larvae by utilizing compound feeding technique during the first two weeks of larval life. The experiment consisted of five treatments and a control group (100% rotifer), which was fed live food during experimental period (regime A), three experimental treatments which received MED supplementing with reduced rations of rotifer including 75, 50 and 25 percent of rotifer in the control treatment (regimes B, C and D, respectively), and finally a treatment received exclusively MED throughout the experiment (regime E). At the end of the experiment results indicated that the regimes A, Band C did not differ significantly for total lengths, final survival and stress test resistance (P>0.05). In terms of dry weight, there was no significant difference between 100% live food treatment (A) and that received 75% live food in control treatment (B) (P>0.05). The solely MED treatment showed significantly lower growth and survival than other treatments receiving rotifer (P<0.05). The results revealed that complete replacement of live food with MED are still not possible in Acanthopagrus lotus larval rearing. Nevertheless, a substantial 50% reduction in the daily supply of live food can be achieved with a combination of microencapsulated diet and live food.

In this study, 945 Specimens of bivalve Solen dactylus were biometrically assessed from April 2007 to March 2008 in two transects of Golshahr coast in Bandar Abbas, Persian Gulf. Physical and chemical  factors of water like temperature, pH, salinity, dissolved oxygen, coast's sediment, diversity and abundance of phytoplankton were studied monthly during the clam sampling. The mean clam length and total weight were 67.5±17.13mm and 6.3±4.04g, respectively. The relationship between clam length-width, total weight-dry weight and clam length-dry weight were significant (r2 = 0.91, r = 0.83 and r2= 0.86, P<0.05). The mean allometric coefficient (b) for relationship between clam length and dry weight was 2.8±0.12 and showed a negative allometric growth style (t-test, P<0.05). No significant relationship between different dimensions of clam with diameter and depth of the canals where clams lived was found (P>0.05). The maximum value of Gonado Somatic Index (GSI) in the first and second transect were 11% and 16%, respectively in January (reproductive cycle). The minimum value of GSI in both transects was zero from April to September. Gonado Condition Index (GCI) was synchronous with the GSI during the year of study. GSI and GCI showed a negative relationship with temperature and a positive relationship with dissolved oxygen.

Caspian sand goby, Neogobius jluviatilis pallasi belongs to Gobiidae family. Because of their abundance in Caspian Sea, they have important role in the sea food chain in this area. This study was conducted from October 2005 to September 2006 in southwest coasts of the Caspian Sea in Guilan province. Samples were collected monthly from four stations (Astara, Anzali, Chamkhaleh and Chaboksar coasts) from coastal areas to waters 15meters deep using bottom trawl. Result of differential function analyses on corrected morphometric statistic showed three functions 51.3%, 28.4% and 20.3%, respectively, and sum of differentiative function percentage was 80% which proved difference among groups. The functions showed that samples in Astara station were completely different from other regions while they were similar to Anzali station only in some sampling points. Chamkhaleh and Astara stations were the same but Chaboksar station was a separated group. Analysis of differential functions for studied characteristics included on average 86.3% of the population with most of it belonging to Astara station (93.3%) and Anzali (90%). The minimum amount belonged to Chamkhaleh with 79.3%. The results showed that Neogobiusjluviatilis pallasi probably has three different populations in Astara, Anzali, Chamkhaleh and Chaboksar populations.

Culture of beluga (Huso huso) in new conditions such as inland brackish water necessitates studying nutritional requirements and effects of different diets on gonadic and somatic growth as well as physiological condition. In this research 74 beluga each 4 years old cultured in brackish water of earthen ponds in Bafgh Fisheries Research Station, were selected and distributed in 8 circular cement ponds. Feeding was done in 4 formulated diets with fixed protein level and 4 energy levels (400, 425, 450, 475kcal/100g). Samples were biopsied at the start and the end of the experiment to determine sexuality and stage of maturation. To study gonad tissues, the hematoxylin-eosin method was used. Results indicated that somatic and gonadic growth indices were affected by diets. Somatic growth overlapped in both sexes. Sexual maturation stages were not the same in males and females and trarisition from stage II in males was more rapid than females. Considering the results in this study, diet treatments influenced on somatic growth in both sexes and gonadic growth in females. We conclude that somatic and especially gonadic growth in brackish water is suitable. Therefore, inland brackish water environment can be regarded suitable for beluga cultivation.

The Caspian Sea has a high ecological and biological value due to harboring important commercial bony fishes and sturgeons. There are more than 15 species of bony fishes (excluding kilka) which are harvested by 135 fishing cooperatives in Iranian coastal waters of the Caspian Sea and 10000 fishermen are involved in exploitation of these fishes. Annually, between 20 to 24 thousand tons of commercial bony fishes as Caspian kutum, mullets, bream, pikeperch, European carp, Caspian salmon, shads and other fish species are caught in Iranian coastal waters of the Caspian Sea. Strengths, weaknesses, opportunities and threats (SWOT) in exploitation of the bony fishes have been surveyed. SWOT results were analyzed considering the long-term development plan of the Iranian Fisheries Organization for sustainable and responsible exploitation of bony fish species. The effective strategies including rehabilitation of spawning grounds in the rivers, restocking of endangered species, controlling illegal fishing and decreasing the number of beach seine fishing cooperatives were determined as required in Iranian coastal waters of the Caspian Sea.

Caspian Sea macrobenthos was surveyed every two months from December 2007 to October 2008, in the west, east and central parts of Mazandaran province waters. Each area was sampled with 3 replicates at 2 depths of 5 and 10m by Van Veen grab. Five different classes were recognized, including Polychaeta (52.7%), Oligochaeta (27.8%), Bivalvia (12%), Crustacea (7.5%) and Insecta (0.07%). Total mean (±SD) abundance and biomass were 2727±1303 individuallm2 and 88.9±22.93, respectively. The Polychaeta demonstrated the highest abundance and Bivalvia had the highest biomass. The highest abundance of macrobenthos was found in eastern and the highest biomass in western coasts of Mazandaran. In August 2008, macrobenthos abundance showed higher values. In October, remarkable difference was observed between the abundance of Polychaeta and other macrobenthos organisms. According to Kruskal-Wallis test, abundance and biomass of the entire macrobenthosclasses except Insecta, showeda significant difference between sampling months (P<0.05). Macrobenthos biomass had no significant difference among the three areas whereas abundance demonstrated a significant difference within these areas (P< 0.05).

We studied the relationship between physical and chemical properties of frozen kilka with weight loss for packed and unpacked products during storage at -18°C. Statistical analysis of the results including variance, Duncan test and ANOVA showed relationships existed between changes in Total Volatile Nitrogen (TVN), Peroxide Value (PV), pH, moisture, organoleptic properties of frozen packed and unpacked kilka with product weight losses during cold storage at -18°C. The statistical treatment of the results showed that weight losses for packed samples in comparison to unpacked one at the level of P<0.01 was significant. The weight losses, changes of TVN, PV, pH and moisture losses for unpacked samples were 1.5, 1.35, 4.5, 1.32 and 1.32 times more in comparison to the packed one, respectively. Also, the statistical analysis of the results showed a correlation between weight losses in unpacked samples of frozen kilka and the measured factors. The results of chemical and physical properties measured for packed samples of frozen kilka during cold storage and their statistical analysis showed a significant correlation P<0.01 between weight losses and the changes in TVN from 7 to 28mg/100 gr,PV from 2.28 to 6.01meq/kg, pH from 6.08 to 6.37 and 1.72% loss in the moisture of the samples. According to these results and the organoleptic tests, the shelf life for packed and unpacked frozen kilka in cold storage at -18°C, is recommended 60 and 30 days, respectively.

During 2 months (from April to June, 2008) we studied the suitable quantity of Highly Unsaturated Fatty Acids (HUFA) for desirable fecundity and egg diameter of female broodstock of white leg shrimp (Litopenaeus vannamei). Similar dry food containing Isonitrogeneous material (31.5% protein) and Isolipid (6.9% lipid) was used but with different levels of HUFA (1, 2 and 3%). Also, the HUFA of natural foods (Perinereis worm, melalis bivalvia and cuttlefish) was analyzed. We compared the effects of four levels of dietary HUFA (1, 2 & 3 % HUFA of dry diets and the average HUFA of natural diets) on fecundity and egg diameter of female broodstock of white leg shrimp. The fecundity and egg diameter of natural diet and HUFA 3% were not significantly different (P>0.05). The fecundity of natural diet and HUFA 3% was significantly higher than the other two treatments (P<0.05) and also the egg diameter of HUFA 3% and natural diet was significantly higher than the other two treatments (P<0.05). According to the results of fecundity and egg diameter measurements, both natural and HUFA 3% diets are suggested as suitable for white leg shrimp breeding.

In this study, effects of concentration and length of enrichment of rotifer Brachionus plicatilis fatty acid composition and its population profile by cod liver-oil emulsion were tested. Rotifers pre-fed on yeast (Saccharomyces cerevisiae) were enriched with cod liver oil emulsion at three different concentrations (4, 8 and 12%). Rotifers were sampled after 0, 3, 6, 12 and 24 hours of enrichment. Considering total lipid present in rotifers as a function of the enrichment period, the increase was significant for 3 hours treatment while the same was not observed when raising the oil concentration (P<0.05). Increasing the enrichment period rather than the amount of oil present in the medium was found to be more efficient in increasing the n-3 highly unsaturated fatty acids (n-3 HUFA) level in rotifers. Rotifers showed a better incorporation of Eicosapentaenoic acid (EPA, 20:5n3) than Docosahexaenoic acid (DHA, 22:6n-3), regardless of the ratio between the two fatty acids in the emulsion.

The aim of the project was to assess production per hectare and other growth indices of Fenneropenaeus merguiensis and F. indicus in Zarabzy farm in earthen ponds of Tiab area, Hormozgan province. We used two treatments, one for each species three replications each. Post larvae of the species were stocked at density 20 ind/m2. Shrimp were fed by imported pellet on the basis of standard feeding table. In order to obtain the growth rate and calculate daily feeding status, the shrimp were biometrically assessed twice a month. We also measured physic-chemical factors of water including pH, temperature, dissolved oxygen and salinity twice a day. The recorded mean results of survival rate in treatment 1 and 2 were 10% and 64%, respectively. Final product and mean body weight in treatment 1 and 2 were 337.5 and 1526Kg/ha and 16.97 and 11.44g, respectively. The result of final product, survival rate and F.C.R. were above standards. The result of physico-chemical tests showed the parameters were higher than standard which had negative impact on production in both treatments. The results showed that propagation of F. merguiensis is feasible and it can be cultured provided that the suitable food is made available. 

Regulation of water temperature is a major factor affecting the embryonic development of fish species. We examined effects of five temperatures, from 13°C to 23°C on three embryonic phases including cleavage, neurolation and hatching in Persian sturgeon (Acipenserpersicus) from March to May 2006. After obtaining mature Persian sturgeon (five females and three males) transport them to the Aquaculture Center of Aghghala in Golestan province. The temperature effects on the three embryonic period's cleavage, neurolation and hatching keeping other physical and chemical factors constant were examined. The maximum hatching was in 15°C and the minimum abnormality was in 15°C and 16°C and also, the maximum mortality was seen in 21.5°C. It is concluded that temperatures between 15°C to 18°C are the upper limit of the thermal optima for Persian sturgeon embryos. Abnormalities observed in this research included edema of the pericardial cavity, notochord curved downwards (lordosis) or upwards (kyphosis) which affected mobility of the hatching embryo.