مجله علمی شیلات ایران
سال هفدهم شماره 1 (پیاپی 62، بهار 1387)

During the years 2003-2004, biological aspects of Tiger-toothed Croaker, Otolithes ruber, was investigated in Oman Sea along Sistan and Baluchistan Province. Based on the frequency of developed maturity stages (IV,V), a prolonged spawning activity extending from August to March was determined for 0. ruber. The Gonadosomatic Index (GSI) suggests two peaks which a minor one in October and a major one in March-April. Comparison of Hepatosomatic Index (HI) and Condition Factor (Kn) with the spawning peak indicated a reverse relationship. According to length at first maturity (Lm50%=40cm) data and exploitation of fish at lengths more than 40cm, the stretched optimum mesh size of nets was calculated at 100mm. Analysis of stomach food items, showed that fish group dominated the diet (80%), of which Anchovy accounted for 40% of the total frequency. We estimated the exploitation rate of the fish at E= 0.6. The length infinity (L¥), natural mortality (M), fishing mortality (F), total mortality (Z) and Growth Coefficient per year (K) were calculated at 68.6, 0.69, 1.05, 1.74 & 0.35 respectively. The relationship between length and weight of the fish in the province was also determined. The parameters a, b and r (correlation coefficient) of the relationship were 0.0085, 3.0435 and 0.98 respectively.

Marine structures, man-made or natural, have a recognized potential to attract and enhance fish propagation. The effectiveness of artificial reefs (AR) in increasing productivity depends on structural design of a reef and in particular, whether it meets the specific habitat requirements of the target species. The catch of lobsters (Panulirus homarus, Panulirus versicolor and Panulirus polyphagus) in the coastal area of south Iran, north of Oman Sea has reduced in quality and quantity over the past years. These commercial species which for many years have been the main catch of the local fishermen, have suffered a decline of more than 70% in the last decade. To combat the decline, we deployed thirty artificial reefs in three different forms, sizes and sea bottom depth, relevant to the bio-characteristics of lobsters, in the Chabahar area. We collected data on the existence of lobsters (P. homarus) among different reef structures. The results of one year data collection showed a significant difference between the lobsters nestling in different kind of reefs. Generally, the lobsters preferred square and pyramid shaped reefs (SPR). This study showed that the design of reefs based on biology of lobsters is an important factor in attracting lobsters to inhabit them.

This research was carried out over a period of 60 days in the summer and autumn of 2005 in the Caspian Sea Aquaculture Research Station (Inland Water Aquaculture Research Center).
Fingerlings of Rutilus frisii kutum weighting one gram were transferred to fiberglass 100 liter tanks each stocked with 35 fish. The fish were divided into five groups and treated with five treatments and three replicates including, fresh water, 4ppt, 6ppt, 8ppt, and 10ppt salinity by completely randomized design. We found that different salinities did not affect the mortality rate of the fish. Comparison of food conversion ratio (FCR), special growth rate (SGR) and weight gain (WG) between control and other treatments revealed a significant difference (p£0.05). We also found that the 4ppt treatment differed meaningfully with 8ppt and 10ppt treatments in terms of FCR, SGR and WG (p£0.05) and the same was true between 6ppt and 8ppt and 10ppt treatments for the FCR, SGR and WG. The results showed that the maximum and minimum weight gain were related to 10ppt treatment (mean 58.9±2.71) and control (mean 39.1±4.73) respectively. The minimum special growth rate (0.549±0.057) was referred to the control treatment and the maximum (0.772±0.028) was seen in 10ppt salinity. The minimum average FCR (3.93±0.122) was seen in 10ppt salinity and the maximum (5.6±0.601) was observed in the control treatment. According to the results, it is suggested that the optimal salinity for fingerlings with mean weight 1gr is 8ppt and 10ppt.

The genetic structure of Hilsa Shad Tenualosa ilisha in Khouzestan waters including Karoon, Arvandrood and Bahmanshir Rivers as well as Persian Gl1lfwas studied using RAPD technique. After optimizing PCR condition, nine RAPD primers were selected from which 58 polymorphic loci were obtained on 12 specimens from each geographical region (A total of 48 specimens). RAPDPLOT, RAPDDIST and PDPGENE computer software were used to analyze the RAPD data. Canonical discriminant analysis was deployed for statistical assessment of the RAPD data. Maximum and minimum genetic distances were found between samples from Arvandrood River and Persian Gulf (0.1987) and Arvandrood and Bahmanshir Rivers (0.0852), respectively. The UPGMA dendrogram showed that the samples from Karoon River and Persian Gulf form one group and samples from Arvandrood and Bahmanshir Rivers form another suggesting the hypothesis that there are Iranian and Iraqi populations of the species that chose their own specific rivers for spawning. According to this hypothesis, the specimens from Persian Gulf chose Karoon as their spawning river. Other populations migrate to Tigris and Euphrates Rivers in Iraq. The canonical discriminant analysis of the RAPD data indicates that samples from the four geographical regions are statistically different from each other and high correlation was found for within region data (P<0.01). This suggests that Tenualosa ilisha is a schooling species. According to the hypotheses and considering the distribution of specimens in phylogenetic tree, it is concluded that Bahmanshir River is a specific pathway for the Iranian population fish heading towards Karoon River for spawning. The Iraqi population of the fish uses both Bahmanshir and Arvandrood Rivers to reach Shat-Al-Arab with Arvandrood being a specific route for the population. To verify these hypotheses further studies are needed.

Encrasicholina punctifer is one of the dominant small pelagic and economically most important fishes of the Persian Gulf, especially in Qeshm Island's coastal waters. Specimens of the fish were collected monthly from the fishing area in the coastal waters of Qeshm Island by random sampling method. Investigation on biological parameters of E. punctifer continued from April 2005 to March 2006. E. puncqfer is mainly caught by double-boat purse seine in this area. Reproductive studies showed that maturity season of the fish occur in August. The sex ratio fulfill the theoretical 1:1 (P>0.05). LMSO was attained at a total length of 84 mm. The absolute fecundity was estimated at 1217±331. We showed that the species is planktonivore, its diet consisted of a board spectrum of food types, but crustaceans dominated the food with copepods and their eggs, naplius and semi digested copepods constituting 54% of the diet. The next major food groups found in the diet of the fish were Cyanophyceae 21%, Bacillariophyceae 11%, fish egg and scale 6%, Dinophyceae 4%, with Euglenahyceae, Chiorophyta, Dinoflagellates and others items consisting only 4% of the diet. Analysis of monthly variation in the stomach fullness indicated that feeding intensity fluctuated throughout the year, with the highest value in winter. Vacuity Index indicated this species was of semi-voracious appetite fishes.

Population dynamics of Ferosagittaferox (Chaetognatha) was carried out in coastal waters Of Khur-e-Mussa's Channel in Khuzestan Province, northwest Persian Gulf. Monthly samples were collected with 300 mm mesh size plankton net in oblique tow from near bottom to surface waters. In total, 7 species of Chaetognaths were identified belonging to I class (Sagittoidea), 1 order (Aphragmophora), 2 families (Sagittidae and Krohnittidae) and 4 genera (Aidanosagitta, Ferosagitta, Flaccisagitta and Krohnitta). The identified species included Aidanosagitta bedfordi, A. neglecta, Ferosagitta ferox, Flaccisagitta enflata, F. hexaptera, Krohnitta pacifica and one unknown species. Due to presence and excessive frequency of Ferosagitta ferox in all samples, we focused on its population variation as an indicator of Chaetognatha. We determined length groups for adult individuals in 4-21mm range with 1mm increments. The year round presence of juvenile and small individuals showed the continuous reproduction of F. ferox with two considerable peaks in March and July. The evaluated recruitment indicated that the species has a low growth rate and a long life cycle.

A survey on parasitic infection of Barboid fishes of Khouzestan Province in southwest Iran was conducted from spring 2002 to autumn 2004. A total of 296 specimens from five fish species were examined. The specimens were collected from five stations including Ahwaz, Golestan, Mollasani and Dez Reservoir on Karoun River and Hamidieh Reservoir and Shadegan Lagoon on Karkheh River. The fishes were transported alive to the laboratory where they measured and weighed and then killed by cutting their spinal cord. Eleven parasites were separated of which seven were identified to the species level and four to the genus level. Of the protozoans we found Ichlyophthirius multifiliis, Trichodina sp., Goussia sp., Balantidium sp. and of the myxozoans we observed Myxobolus persicus, Mkaruni, M nodulointestinalis, Miranicus, Mmesopotamia, Myxobolus sp., Myxidium rhodei, and Myxidium pfiefferi. We reported three new parasites and eleven new hosts for Iranian freshwater fishes and three new hosts for three Myzoxoans.

Nutrition experts have a large audience form the general public, so they can exert high impacts on the fish consumption attitude of the lay people. As such, we deemed an investigation of the fish consumption attitude of nutrition experts of great importance in fish extension planning and policy making. We selected 144 nutrition experts and interviewed them in September 2005. The results showed that 64% of the respondents believed advertisement on fish .consumption could have high to very high effect on the promotion of fish consumption attitude of the people. The experts believed that a significant relationship exists between success in promotion of fish consumption in the general public and people's age (P<0.05). 74% of respondents believed that market expansion and access to it would promote the consumption while and 34% noted that trust in the seller was of higher importance. 40% of respondents preferred gutted fish or fillet, fresh or frozen. Overall, fish market expansion, advertisement and promotion, health factors, quality and trust in the seller were flagged by the experts to have effects in increasing fish and fishery products consumption in Iran.

Anesthetic drugs are widely used aquaculture farms and can create consumption problems for humans, so there is a great need to safer drugs. With regard to long record of herbal drugs consumption in Iran and their benefits, we survey the possibility of using Valerian officinalis, Melissa officinalis, Papaver somniferum, and Papaver bracteatum as fish anesthetic. We provided, processed, and made consistent extractions of Valerian officinalis (2, 3 4 g/lit), Melissa officinalis (5, 10, 15 g/lit), Papaver somniferum (0.85, 1.6, 3.2 g/lit) and Papaver bracteatum (0.3, 0.6, 0.9 g/lit). We selected 60 goldfish Carassius auratus in the weight range of 7.41±0/2 g, and the length range of 8.4±0/11cm and kept them in laboratory conditions under the same oxygen and temperature. The fish were divided into four groups each containing 15 fish and further into three subgroups of five fish each. During the experiments, two herbs Parpaver somniferum and Papaver bracteaturn were eliminated from statistical analysis because of biased results. We found a significant correlation between the required time to reach level 4 of anesthesia and recovery using Melissa officinalis (P<0.01). The required time to reach the level 4 of anesthesia and recovery using 10 and 15g1/it dosages of Melissa officinalis was significantly lower than 3 and 4g/lit dosages of Valerian officinalis (P<0.05).

Population structure of Ship sturgeon, Acipenser nudiventris, from the south coast of Caspian Sea and Ural River was investigated using Microsatellite method. For this reason, 73 specimens of the sturgeon were collected from five locations in two sampling regions the first consisted of Bandar Anzali, SefidRud River, Babolsar, and Gorgan, and the second was Ural River. Four SSR markers were used in this investigation, of which 5 loci produced DNA band, with three of them being polymorph. One primer showed two loci with one of them being polymorph and another was monomorphic). Average expected and observed heterozygosity was 0.86 and 0.75 respectively. Genetic variation was assessed through analysis of molecular variance (AMOVA) that indicated almost all of the variance in data namely %94 (p£0.03) was within locations. Genetic variance among locations was 3% (P<0.02) and among regions was %3 (p£0.08). According to the results, we suggest that the sturgeon population from Ural River is different from that of the south Caspian Sea samples. This information is of utmost importance in artificial reproduction and stock rebuilding of the fish.

This study was conducted in the Shrimp Reseach Center of Bushehr in winter 2005. We treated reared White Leg Shrimp (Litopenaeus vannamei Boone 1931) with five diets containing 20%, 25% ,30%, 35% and 40% protein levels and three salinity levels 15-17ppt, 27-30ppt, and 40-45ppt. We focused on growth, survival, food conversion ratio, hemolymph osmolality, hemolymph protein and corpse protein content. We applied 15 treatments each with three replicates in 45 tanks with 300 liter capacity. Shrimps average weight was about 2 grams at the start and reared after 60 days of culture. Shrimp biomass growth in 15-17 salinity was higher than other salinities showing statistically significant difference with those grew in 40-45ppt salinity (P>0.05). No statistically significant difference was found between growth of the shrimp in 15-17ppt and in 27-30ppt water. Survival in 15-17ppt salinity was 97.03, lower than other salinities, while those in 24-30ppt and 40-45ppt salinities had the highest survival 99.33%. The highest growth was seen in diet number 5 with 40 percent protein content which showed a meaningful difference to that of other diets (P<0.05). No statistically significant differences were found between diets in terms of production costs and survival rates.

This research was conducted to construct an appropriate automatic fish sorter for sorting large amounts of trout fish in Iran. We found that for sorting trout fish in three sizes simultaneously, two conveyor belts moving horizontally and vertically are needed to create an angle relative to each other. The belts had been put on stainless steel frames and made their distance adjustable according to the fish width, and let the belts move left and right side easily. The belts rotating power derived from two 110 VAC electrical motors and gearboxes. A water system was also designed within the sorter for facilitation of fish movement and prevention of injury and stress to fish. The results showed that mortality and injury to the trout fish could be totally eliminated through application of the constructed sorter. Fishes that were extruded from the second outlet of the sorter had minimum weight error in comparison with two other outlets. The results showed that we can increase the speed and accuracy of sorting fish by adding more belts with their position fixed on the frame. We also demonstrated that the sorting machine required 5-7 times less time as compared to the manual method. The constructed sorter was also showed to have the ability of sorting fish weighing less than 10 grams which is another plus of the machine as compared to the imported ones.

We used commercial fishing data and samples in the Choebdah landing near Abadan port to estimate population dynamic parameters for Euryglossa orientalis. Sampling period was October 2004 to October 2005. After collecting the samples, they were transported to the laboratory for further biometry measurements. The minimum and maximum length was 12 and 40cm respectively. Length-weight relationship was calculated as: W=0.0004*L2.5586 40. According to the equation, growth of Euryglossa orientalis is allometric. Length frequency data were processed in FiSAT -II package. Growth coefficient was estimated at K=0.28, infinite length was 37.57cm, total mortality was Z=2.09, natural mortality was M=0.92, and fishing mortality was F=1.17. Exploitation rate was calculated at E=0.56 and since the E value was higher than 0.5, over-fishing is expected to be happening to the species.

Fish parasites from Valasht Lake and Chalus River were studied in spring 2005 and summer 2006. Fish specimens were caught by hand net and transported to local laboratory alive. We found three protozoa species, Trichodina trutta and Ichthyophthirius multifiliis on Oncorhynchus mykiss; and Chilodonella hexastica on the skin of O. mykiss and Leuciscus cephalus. We also separated metazoan parasites from the fish in the two sampling sites that included Gyrodactylus derjavini infecting skin and gill of O. mykiss, G. sp 1 infecting Alburnoides bipunctatus, G. sp2 from Barbus capito and G. sp3 from Capoeta capoeta gracilis and Tetraonchus menonteron that infested the gills of Esox lucius. Other parasites which we found were Myxobolus saidovi from the gills of C. c. gracilis, Bothriocephalus gowkongensis from intestine of Barbus capito, Raphidascaris acus from intestine of E. lucius and finally Argulus foliaceus from skin of Chalcalburnus chalco ides. This is a first time report of a new host, B. capito for Bothriocephalus gowkongensis and a new locality Chalus River for Myxobolus saidovi parasites. Furthermore, with the exception of Tetraonchus menonteron which have been reported before, the rest of the parasites of the fishes from Valasht Lake are reported for the first time.

During the decade 1991-2001, culture of Indian White Shrimp grew rapidly in Iran due to high profitability, but afterwards suffered a decreasing trend with many farms still being idle after construction. The trend occurred mainly due to (1) increase in production costs with simultaneous decrease in international shrimp market price, (2) Agro-climatic conditions that favored only one crop a year, which is not profitable, and (3) fear about spread of disease as already experienced in the case of white spot disease in Khouzestan and Bushehr provinces. Based on these facts, we aimed in our study to increase production of the shrimp per year, to reduce days of culture (DOC) in second crop through nursery system, to control food conversion ratio (FCR), and to manage shrimp production in Gwatar shrimp farming complex. Six farms were selected, and in three we applied two crops a year production system using nursery for the second crop. In other three farms one crop was harvested. Shrimps in two-crop farms were kept 52 days of the second crop in nursery and then transferred to grow out ponds. All farms harvested before DOC 128. Mean productions per hectare in the first and second crop were 1794 and 1691kg, respectively. The FCR dropped from 1.6 in the first to 1.27 in the second crop. Total production per hectare per year reached 3485kg in two-crop farms. Shrimps in one-crop farms were harvested mainly at DOC 145. The mean production per ha/year and FCR of one-crop farms reached 2089kg and 1.65 respectively. We harvested around 47114kg of shrimps in each two-crop farm which was 17 tons more than one-crop farms. The results of this study showed that production of shrimps in two crops a year system could be continued with pre-designed schedules. We presented a time table for two crops a year culture system.

The LC50 of Virkon-S which is an antimicrobial agent for the shrimp Litopenaeus vannamei juveniles with mean body weight 2.39g was determined. The study was conducted in Iran Shrimp Research Centre in Bushehr City, south Iran in 2006. The LC50 96h value of Virkon-S was 43.23 mg/lit corresponding to 43.23ppm. All of important physicochemical parameters of sea water were monitored and maintained at a constant value so that temperature was 28-33 degrees centigrade, pH was between 7.2-7.9, dissolved oxygen was £4.8 and salinity was around 37ppt. Five treatments and three replicates were run for each treatment. The software used was LC50ModelSystem version 1.0 that let the estimation of LC50 values by Spearman-Karber rule with (P£0.05).

Beluga Huso huso is commercially an important species of sturgeon fish in the Caspian Sea. We determined the sex ratio of the commercial catch of the fish along the Iran coastal waters of the Caspian Sea during the years 1990-2003. Females dominated the catch and composed between 60-80 % of the landed fish. Observations on gonads maturity showed that immature females decreased from 71% to 47% of total catch. Female fish ratio increased from west to east in the coastal waters.