مجله علمی شیلات ایران
سال بیستم شماره 4 (پیاپی 77، زمستان 1390)

The effects of dietary nucleotide (0.2%) on the growth, intestinal morphology as well asfatty acid profile of the whiteleg shrimp, Litopenaeus vannamei was investigated in Bushehr province (Delvar) for a 5-week feeding trial. The experiment was carried out in triplicate in circular PVC tanks of 300L capacity. Each tank was randomly filled with 25 shrimps weighting on average 3.21±0.03g. Added dietary nucleotide significantly improved growth factors such as 10% weight increase, 7.97% increase in specific growth rate (SGR), 11.32% increase in protein efficiency ratio (PER), 9.64% decrease in feed conversion ratio (FCR) and 14:1n5, 20:3n3 and DHA fatty acids. However, no significant differences were evident in survival, carapace length gain, daily feed consumption and saturate fatty acid (SFA), monounsaturated fatty acid (MUFA), poly unsaturated fatty acid (PUFA) content, n-3/n-6 as well as EPA+DHA fatty acids between the two treatments. Intestine epithelium cells height (IECH) in the abdominal first section were significantly higher in shrimp fed by dietary nucleotide.

This study was carried out to identify proper broodstock of Barbus sharpeyi and Barbus grypus using working fecundity indices. For Barbus sharpeyi three female groups were chosen based on previous experiences that included treatment 1: 650±300g, 1±0.5 years, (T.L) 40.68±2.7cm, treatment 2: 1350±350g, 2.5±0.5 years, (T.L) 47.92±4.63cm and treatment 3: 2200±400g, 4±0.4 years, and (T.L) 59.62±3.56cm. The same male broodstock (700±80g) and 2 year old fish were used for all treatments. For Barbus grypus three female groups were chosen using previous experiences that included treatment 1: 2212.5±780g, 2.5±0.5 years, (T.L) 62.68±6.7cm, treatment 2: 4518±780g, 4±1 years (T.L) 79.12±4.36cm and treatment 3: 7712.5±171g, 7.7±1.3 years and (T.L) 92.62±3.13cm. The same male broodstock (1400±100g) and 2 year old fish were used for all treatments. Female broodstock of the two species were injected 3mg/kg of PG hormone two times at an interval of 10 hours and males were injected 2mg/kg. The maximum working fecundity was seen in treatment 2 for Barbus sharpeyi (33000±1450) and Barbus grypus and (13000.37±4651.57). Functional fecundity were calculated for Barbus sharpeyi in all treatments which was significantly different between treatment 2 and other treatments for the two species. After this stage, the working fecundity was decreased in treatments. We conclude that treatment 2 is the best for selection of broodstocks in the two fish species.

Reproduction period, spawning peak and sexual maturity in anchovy kilka were investigated during the year 2006 for sustainable yield assessment in Iranian waters of the Caspian Sea. The mean fork length, total weight and age were 118±5.9mm, 11±1.7g and 4.6±1.2 year, respectively. Mean (±SD) absolute fecundity was 12625±5533 ovules. More than 50 percent of the fish specimens matured when their length exceeded 92.5mm. The results showed that reproduction of anchovy kilka occurred in autumn, and spawning occurred throughout the year and especially in winter. The length and age ranges were found to be shortened compared to the past years with many older fish and less younger ones (< 2 years) in the catch which sharply decreased recruitment. This phenomenon is thought to be due to overfishing synchronized with invasion of M. leidyi pushing kilka to spawn in winter, which all cause collapse of anchovy kilka stocks in the Caspian Sea. We postulate that anchovy kilka has adopted the strategy of spawning year round to mitigate the negative effects of overfishing and invasion of M. leidyi.

Fishing companies play significant role in value-added generation in Bushehr province. According to the current conditions and based on natural potentials, fisheries are the main sector in economic development of the Bushehr province. The purpose of this paper is to identify, analyze and rank factors affecting productivity of Bushehr fishing companies using group analytical hierarchy process (GAHP) technique. We applied two standard questionnaires which were filled with 100 fishermen and 18 fishery experts. The first group of questionnaires was used to assess the two main factors: Internal and external and five subfactors including: Governmental, structural, natural, soft and hard ware aspects. The second group was used to rank the same indentified factors in the first group of questionnaires. Results indicated that fishery headquarter of the governmental sub-factor, economic changes of the structural sub-factor, management approaches of the software sub-factor and the catch tonnage and its composition of the hardware sub-factor are the main parameters affecting productivity. Suggestions were made to improve productivity of the fishing companies in Bushehr province.

The in-vitro effects of biochemical factors on trypsin activity from intestine and pyloric caeca of common kilka (Clupeonella cultriventris caspia) was evaluated. Trypsin is known to cause belly bursting in common kilka. The assessments showed that in a range of 4-70°C, trypsin from pyloric caeca and intestine of common kilka had the maximum activity and the satiability at 60 and 55°C, respectively. The pH assessments indicated that maximum activity and stability for trypsin were at 8. 5 at pH range of 4-11. The effects of metal ions on trypsin activity revealed that CaCl2, MgCl2 and MnCl2 increased trypsin activity while CuCl2، ZnCl2 and Al2 (SO4) 3 decreased its activity. The effect of inhibitors on trypsin activity also showed that SBTI and TLCK (specific inhibitors for trypsin) significantly inhibited trypsin activity. This study suggests that belly bursting in common kilka can be prevented by trypsin inactivation through application of low temperature (4°C), acidic pH, metals of CuCl2, ZnCl2 and Al2 (SO4) 3 and inhibitors of SBTI and TLCK.

We assessed the possibility of western white shrimp culture using underground brackish water in Bushehr province, Iran. In July 2008, white shrimp post larvae were stocked in 4 fiberglass tanks, each with a capacity of 3.8m2. Two tanks were filled with brackish water 35ppt in salinity and two others with underground brackish water 4ppt in salinity. Tanks were situated outdoor and aerated nonstop using a central aerator. The stocking density was 58ind/m2 and the culture period was 90 days. Shrimps were fed with commercial diet by two trays, 80 cm in diameter in each tank. Water exchange was carried out two times a week. During the culture period, the weights of 40 ind. of shrimps were measured every 15 days. At the end of culture period, mean weight of 21.34g and 18.22g, survival of 92.25% and 97.75%, mean production of 1.11 and 1.03kg/m2 and food conversion ratio of 1.20 and 1.28 were recorded for 34ppt and 5ppt salinities, respectively. Statistical analyses showed no significant difference between treatments.

The effects of diets containing enriched Artemia with highly unsaturated fatty acids and different amounts of vitamin C on the growth factors and survival rate of Litopenaeus vannamei larvae was studied. We used four different groups (three treatments and one control) with 3 replicate for each treatment during 15 days. All post larvae were randomly selected and fed with four diets containing normal Artemia (control treatment), Artemia enriched with cod liver oil (treatment 1), Artemia enriched with cod liver oil and 10 percent of vitamin C (treatment 2) and Artemia enriched with cod liver oil and 20 percent of vitamin C (treatment 3). Farming of shrimp larvae from PL1 to PL15 was completed in 300 liters tanks each containing around 150 liters of water. At the end of the experiment, the growth factors and survival rate of stage PL15 in treatments 1, 2 and 3 improved in comparison with control treatment. The survival rate at PL15 in treatments 2 and 3 showed a significant difference from control due to the synergistic properties of unsaturated fatty acid and vitamin C. No significant difference was found for survival rate between treatment 1 and the control treatment in PL15 stage. Also, no significant difference was seen for growth rate between treatments 2 and 3 in PL15. The highest growth factors and survival rate among different treatments in stage PL15 was observed in treatment 3 (diets containing Artemia enriched with cod liver oil and 20 percent vitamin C) and the lowest was associated with control treatment, diets containing un-enriched Artemia.

Effects of Goldstrip sardine (Sardinella gibossa) and poultry by-product protein hydrolysate on amino acid composition, growth and alevines survival of rainbow trout (Oncorhynchus mykiss) were investigated. Two hydrolyzed protein sources were incorporated into six diets for start-feeding rainbow trout (Oncorhynchus mykiss) alevines, in 3 different replacing levels (10%, 25% and 50%) of fish meal. Goldstrip sardine protein hydrolysate (SPH) and poultry by-product protein hydrolysate (PPH) were used, respectively. To compare the results, we used the same diet without protein hydrolysate. The diet with 25% SPH and 10% PPH offered the best results in terms of growth, survival, protein efficiency ratio, protein productive value and condition factor. Alevines fed with 25% SPH and 10% PPH showed more balanced amino acid composition in their body. By enhancing the protein hydrolysate in the diet, free amino acid composition in the diet and fish body was enhanced. The protein hydrolysate enhancement showed negative correlation with growth factors. Also, non essential amino acid composition of the body composition showed positive correlation with the lipid/protein percentage of the alevines. We conclude that an optimum level of protein hydrolysate can improve growth and performance of the rainbow trout alevines. However, excess protein hydrolysate can cause imbalanced amino acid composition in fish body and reduces the growth and survival factors. Based on this study, the optimum replacement of fish meal by SPH and PPH in rainbow trout alevines’s diet is 25% and 10%, respectively.

The main objective of this study was to determine the interactive effects of dietary selenium and fat on fatty acid compositions of rainbow trout tissues. We formulated six experimental diets by addition of two fat levels (15 and 30%) and three selenium levels (0.1, 0.15 and 0.2mg/kg) to a basal diet, according to a 3x2 factorial design. Juvenile rainbow trout with initial weights of 6.99g were assigned to 18 tanks with 300L capacity each containing 25 fish, with three replicates for each diet. The result showed that unsaturated fatty acid and tissue oxidation rate increased with an increase in fat content of the diets. Addition of dietary selenium increased enzyme of Glutathione (GSH-Px) activity and at high-fat diet (30% fat), selenium addition improved polyunsaturated fatty acid compositions by depression of oxidation rate. However, inclusion of high dose of selenium (0.2mg/kg) had a negative impact on the Arachidonic and Eicosapentaenoic acids. In conclusion, dietary selenium supplementation can preserve fatty acid quality by controlling fatty acid oxidation at high-fat diet. The results obtained from the current study suggest that rainbow trout at high-fat diet requires 0.15mg/kg selenium to reduce oxidation level.

This study was carried out during October 2008 to July 2009 in Bushehr coastal areas at 6 stations to examine biomass variations in red algae. Algal samples were collected by hand from intertidal zone, during low tide. Quadrates 50 ×50cm each were marked randomly in the study area, and all algal samples were collected within the quadrate area. Total biomass was found to be 2598.91g.m belonging to 15 Rhodophyta species. The maximum biomass was 1114.32g. m (43%) observed at the Nirougah station. Summer showed maximum biomass 1076.36g. m (41%) compared to other seasons. Results of this study showed Rhodophyta species are dispersed more in mid littoral and sub-tidal areas. Also, the maximum biomass was observed in the sub-tidal zone. The highest biomass of the species belonged to Grascilaria canaliculata.

Thunnus tonggol is one of the most important large pelagic fish species in Hormuzgan province waters. Nominal catch of T. tonggol in 2010 was 32405 tones comprising 65% of total catch of large pelagic fishes. For sustainable exploitation of the resources of this fish, we need to identify its fishing pattern, maximum constant yield and recruitment pattern. Hence, length and weight data were collected randomly from 6 major artisanal fish-landing sites Hassineh, Kong, Bandar Abbas, Salakh, Sirik and Jask in Hormuzgan province, starting in April 2010 over one year. Growth parameters L∞ and K were estimated at 112.23cm 0.3 and (1/year), respectively. Hence, the natural mortality was calculated at 0.43 (1/year) and the maximum constant yield was computed at 11880 tones. Length-weight power relationship, W= aFLb, was W= 3×10-05FL2.82 that showed T. tonggol have isometric growth. Fishing pattern indicated that almost 85% of the catch was under the size at first maturity. Maximum recruitment pattern was in November with average fork length being 27cm. For optimum exploitation of T. tonggol stocks, we suggest two approaches including fishing ban in the maximum recruitment time and gear (Drift gillnet) modification.

Population parameters of Whipfin silver-biddy (Gerres filamentosus) and Longtail silverbiddy (Gerres longirostris) were studied from January to December 2006 in three creeks (Markazi, Khalasi and Gabrik) of Hara protected area in Jask, Oman Sea. All fishes were sampled by boat trawl and beach seine. Growth parameters were determined using the monthly length–frequency parameters. The Mean total length was calculated at 6.2 and 5.4cm for Whipfin silver-biddy and Longtail silver-biddy. The values of L∞ and K for Whipfin silver-biddy were 16.8cm and 0.99 yr-1 and for Longtail silver-biddy, these were 15cm and 0.77 yr-1, respectively. The value of to was calculated at -0.12 year for both species. The longevity was estimated to be 3 years for Whipfin silver-biddy and 3.8 years for Longtail silver-biddy. The length-weight relationship were determined as W= 0.0088 L3.21 and W= 0.0087L 3.18 for Whipfin silver-biddy and Longtail silver-biddy, respectively. Results showed the fish were in their juvenile stage which emphasized the supporting roles of creeks for Gerridae as nursery ground.

This study was carried out in Turkmen fishing station to examine suitable mesh size of gill nets for Persian sturgeon, Acipenser persicus, to decrease possibility of catching immature specimens and increase catch likelihood for larger fish. The Holt model was used to determine suitable length for catch and selection of mature Persian sturgeon females. Following preliminary studies some 920 experimental gill nets (mesh size 170mm) similar to those generally used by Iranian Fisheries except for mesh size (150mm) were set up in the Caspian Sea. During the experimental period, 128 and 110 sturgeons were caught in control and experimental nets, respectively. Out of those caught in control nets, 63 specimens were Persian sturgeon (49.2%), 57 were Stellate sturgeon, Acipenser stellatus (44.5%) while in the experimental nets, 95 specimens (86.4%) were Persian sturgeon and 7 specimens (6.4%) were Stellate sturgeon. Regarding maturity status of fishes, 42 Persian sturgeon caught in control nets were mature females while this figure was 83 (87.4%) in experimental nets. Mean fork length of the Persian sturgeon was 152.9±13.8cm and 162.4±13.6cm in control and experimental nets, respectively. The mean caviar yield of the Persian sturgeon in control nets was 6.4±1.7 kg and in experimental nets was 7.4±1.9kg. One way ANOVA and Tukey’s test showed significant differences between factors like age, mean caviar yield and fork length of the Persian sturgeon caught in control and experimental nets. The results showed increasing mesh size of gill nets to 170mm for the Persian sturgeon may help achieving objectives of stock managements including decrease in catch of immature fish and increase in catch of mature and larger sturgeons which can secure optimum and sustainable stock yield.

A month after movement of 1800 pieces of L. vannamei (average weight of 16g) from culture ponds in Heleh region to concrete ponds of Bandargah hatchery (Bushehr province) some shrimps showed symptoms such as decrease in growth rate, loss of appetite, dark pigmentation of cuticle and presence of black foci on it, redness of uropods and white, irregular and circular spots on the eye with 2-5mm diameters. For detection of etiological agent samples were taken for PCR, bacteriological and histo-pathological tests. Nested PCR test using IQ2000 kits for detection of major shrimp viral pathogens (IHHNV, WSSV, YHV and TSV) were conducted and all results were negative. In histo-pathological tests, lesions in eyes were liquefactive necrosis of cone cells and cone crystals with infiltration of hemocyte and formation of micro abscess in the diapteric region of eye. In bacteriological tests, a gram negative pleomorphic bacterium of the genus Aeromonas was isolated. However, it seems that this bacterium is the secondary agent and for detection of the primary agent more research is needed.