Iranian Scientific Fisheries Journal
Year:2009 | Volume:18 | Issue:3|Papers Count:19

The effects of social interactions on survival, growth indices and competitive behavior of common carp (Cyprinus carpio) at four stocking densities (350, 400, 450 and 500 fish per hectare) were investigated. A poly-culture of Chinese carps was implemented for 7 months in 12 culture ponds each 10 hectares in size at Dikjeh area, Golestan province of Iran. Monthly biometrical characteristics such as total length, weight, and condition factor and growth rate were measured. The introduced common carp weighing on average 45g reached 705g after 7 months. With increase in common carp density up to 450 fish per hectare, growth indices including secondary weight, growth rate, SGR and fish biomass showed no significant differences (P>0.05), whereas 500 common carp individuals per hectare caused secondary weight, growth rate and SGR indices decrease significantly (P<0.05). At this density, fish biomass showed significant increase (P<0.05). Based on the results of this study, we conclude that common carp can be successfully cultured up to a density of 450 fish per hectare.

Nerds diversicolor worms were collected from the Anzali lagoon during the years 2004- 2006 using Van Veen grab sampler with a surface area of 400cm2.Water salinity, temperature and total organic matter (TOM) of sediments in !he sampling region was determined. The worms were maintained in 0.5 tons (lxlm2) tanks until they reached a weight of 200-300mg. Sexual maturity in the samples was attained at4-6oC and spawning occurred at approximately 16oC.The first gametes were observed after the temperature increased from 6 to 16oC. Sexual maturity was studied at various salinities (0.5, 5, 12, and 15 %0).Results indicated that the worm attains sexual maturity at salinity 15%0 in a shorter period as compared to other salinities. No significant differences were observed between sexual maturity attained at salinities 12 and 15%0 (P>0.05). The effect of light and photoperiod in synchronizing reproduction in male and female N diversicolor was also studied.We observed that reproduction behavior in adult worms increased for a period of one week at the end of each month after they were exposed to a prolonged photoperiod (L:D 16:8) followed by a period of dim light.Mature males crawled around outside the tubes in search of a female. In the presence of a mature female, the males released sperm directly in front of the female tube. Soon after, there was an increase in the activity of the females which showed intense ventilation movements.The female worms with their eggs already released began to carry the sperm into their tube.The ripe females nearby which had not yet laid eggs in their tubes released their gametes a few minutes after the male and began to carry sperm into their tubes. The fertilized eggs remained inside the tube protected by the female. The benthic larvae developed fast, feeding on the mucus and microbial film on the tube wall. After 10 to 14 days, larvae began to leave the tube. A few days later the females died.

A three dimensional simulation of cooling and freezing process of fish as a complex geometry is presented. The 3d geometry of the fish was produced by digitizing and the thermo-physical properties of the fish were considered as functions of temperature and water content of the fish. Heating loads and product temperatures during chilling, freezing and post cooling processes for immersion cooling, method in brine and for cold air blasting method were predicted. The influence of effective parameters such as initial temperature and fish water content are also investigated on processing time. Because of the slow freezing rate in immersion cooling technique, the results show that the initial temperature of fish highly affects freezing time. We suggest that a combination of immersion and cold air blasting methods will decrease the freezing time in comparison with immersion method when solely applied. Comparison of temperature distribution in present study shows a good agreement with other numerical and experimental results.

Fungal flora in egg, yolk sac larvae and larvae of Acipenser persicus were identified and studied. Totally, 270 specimens from Shahid Beheshti Sturgeon Rearing Center were examined. A heterogeneous solution from samples>was prepared and inoculated on culture media SDA+C and CMA+C in lines under sterile conditions. Wet mounts were prepared for the identification of Saprolegnia sp. and the inoculants were cultured on culture media GP containing gentamycin and chloramphenicol. We found Penicillium, Cladosporium, Fusarium, Yeast, Mucor sp., Aspergillus niger and Paecilomuces on egg samples in order of frequency and in water samples we observed Penicillium, Cladosporium, Fusarium, Yeast, Mucor sp., Aspergillus niger, and Paecilomyces. Fungal species identified in yolk sac larvae included Penicilliium sp., Cladosporium sp., Fusarium sp. ,Alternaria sp., Yeast and in water samples we found Penicillium, Cladosporium, Fusarium, and Yeast, while in larvae we saw Cladosporium sp., Penicilliium sp., Fusarium sp., Alternaria sp., Aspergilus fumigatus, Yeast and Mucor spp. In water samples containing larvae we were able to identify Cladosporium sp., Penicilliium sp., Fusarium sp., Yeast and Aspergilus niger. Fungal species such as Cladosporium sp., Penicillium, Fusarium, Yeast and Saprolegnia were detected in all four sampling mediums. T-test indicated no significant differences in total counts (colonies/2 plates in all samples) in eggs (15.08±3.51 colony forming unit; CFU) and in water (15.91±2.63) samples. However, t-test indicated significant differences in total counts in yolk sac larvae (5.33±1.05) and in water (11.77±2.39) samples. T-test showed no significant differences in total counts of larvae (32±12.46) and water (31.11±12.79) samples.

Bahmanshir River branches out of the Karoun River and empties into the Persian Gulf.This river is a tidal water body with characteristics under effects of such condition. Sea water moves ahead of the river by tidal forces and affects salinity, phytoplankton species composition and distribution. We conducted a year round study in five stations in the river and determined phytoplankton species composition and distribution. Bacillariophyceae had the highest frequency and Cyclotella, nitzschia and Melosira genera were very frequent.Cyanophyceae was present in estuary area. Salinity caused areas of water to be dominated by Euryhaline and Stenohaline species. Some species including Nitzschia, Cyclotella. Synedra and Melosira were seen in wide range of salinity and other frequent species such as Lauedria, Coscinodiscus, Cheatocerus and Rhizosolenia were only presented in the estuary or highly saline waters. Because of high tide, some of the marine phytoplankton species were also spotted at the mouth of Bahamanshir River.

Scombermorus commerson is one of the most important commercial fish species in the Persian Gulf and Sea of Oman. To arrange for a sustainable fishing pattern, growth parameters, mortality and exploitation rates of the, fish were estimated. Fish length data were collected from 4515 fishes, science April 2007 to March 2008 in three major artisanal fish landing sites Bandar Lengeh, Bandar Abbas arid Bandar Jask in hormouzgan province waters. The Von Bertalanffy growth parameters (L¥ K and to)were estimatedat 150.24(em), 0.66 year-1 and -0.157year, respectively.The resultsshowedthat S commerson grows very fast in the first 2 years. The results indicated that S. commerson attains its fork length 80.3cm at the end of first year. The fork length attained at the end of the second, third and fourth years were 114.1, 131.6 and 140.6cm, respectively. Growth perfonnance index (ǿ) was calculated at 4.1 which were in agreement with the findings of the other studies in the Indian Ocean. Total, natural, fishing mortality and exploitation rate were estimated at 2.11, 0.67, 1.44 year-1 and 0.64, respectively. Five cohorts were distinguished based on Bhattacharya's method.

The genetic diversity of Cobia, Rachycentron canadum populations in the Persian Gulf and Oman Sea were assessed using mietosatellite technique. We removed about 3-5g of pectoral and dorsal fin tissue from 184 samples in winter 2006 and spring 2007, and stored it in pure ethylic alcohol (96%). Polymerase chain reactions (PCR) were conducted on the target DNA using 10 paired microsatellite primers. The dendrogram was constructed and drawn using MEGA software package version 4. Based on the analysis of molecular variance, the highest Fst (0.063) was observed when comparing specimens from Dayer Port and Pozm zones. Significant differences (P<0.01) were not observed between Rst recorded for the specimens studied in the same region but were observed between Rst recorded for different regions. The dendrogram of genetic distance showed two major clusters: the Bushehr and Dayer populations were in one cluster, and the remaining four populations in the other. The second cluster was further separated into two sub-clusters: the Lengehand Bandar Abbas populations composed one cluster and the Pozm and the Beris populations were in the other cluster. The present study showed that at least three different populations of R. canadum are living in the Persian Gulf and Oman Sea. The populations include Bushehr, Bandar Abbas and Chabahar populations.

Monthly samples of common kilka (Clupeonella cultriventris caspia) were collected at night on board of kilka fishing vessel during the years 2004-2005 in Mazandran province. The decreasing kilka population in the Caspian Sea and the associated economic loss of fisheries sector were the main reasons encouraging the research. The stomach contents of common kilka and biotic and abiotic factors at the fishing areas were examined in this project. The length and weight of common kilka fluctuated between 100±7 to 113±5 mm and 7.0±1.9 to 10.3±1.0 gre, spectively. The highest feeding activity was observed in April with 280±153 individuals of prey weighing 2.9±1.6 mg per fish consisted of 7% Acartia and 93% Balanus nauplii and cipris. The zooplankton population taken in during March to September was composed of Balanus nauplii and cipris (67% to 100%) but the biomass of copepod (Acartia) was dominant from October to February.We observed that with increasing temperature in spring, Balanus reproduced and the stomach contents of kilka comprised more than 90% Balanus cipris and nauplii. In winter, Copepoda was observed more in stomach contents of kilka while Balanus decreased.

Heavy metals Zn, Cu, Pb, Cd concentration in. sediments of the Iranian waters of the Caspian Sea was measured in fall 2001.Samples were collected from transects along the Iranian coastline in five stations lying between Astara (48o52', 38o26') up to Kiyashahr (49o 53', 37o27'). Metals were extracted from sediments by digesting with hydrofluoric and hydrochloric acid. Metals concentrations were measured using the Atomic Absorption Spectrophotometer. Reliability of results was tested using Soil-7, a certificated reference material (CRM). Sediment samples were-:also collected from each station to determine grain Size.The results showed that except for Cd concentration which was measured at 4.5mg g-1 dry weight, other values were lower than the Effects Range Low (ERL) (1.2mg g-1 dry weight) based on the Sediment Quality Guidelines from NOAA, USA for Cd. Also, the highest concentration determined for Cu (19.55mg g-1 dry weight) in this study was lower than the ERL (34mg g g-1 dry weight) value determined by NOAA for Cu. The highest concentrations for Pb and Zn in the present study were 25.7mg g-1 dry weight and 54.5mg g-1 dry weight, respectively that were lower than the ERL values (pb=47mg g-1 dry weight and Zn=124mg g1 dry weight) declared by NOAA for these metals.It is evident from the present study that heavy metals concentrations in sediments in the study area were lower than Effects Range Low values for these metals. We conclude that the studied metals are not threatening to the environment at the present time.

Phytoplankton identification, density and dispersal assessment were conducted from June to October 2005 in Lar Reservoir. Samples were taken by simple plankton net (30rm mesh size) and by Ruttner from different depths (0, 5, 10, 20, 30m) and then fixed with formalin 4%. We used inverted microscope in the laboratory to study the samples.We distinguished 34 genera of phytoplanktons consisting of 7 Phyla. Number of genera for Bacillariophyta was 11, for Euglenophyta was 1, for Chlorophyta was 11, for Cyanophyta was 5, for Pyrrophyta was 3, for Cryptophyta 1 and for Chrysophyta was 2. Phylum Bacillariophyta was dominant comprising 82.83% of phytoplankton population annually.Cyclotella, Navicula and Nitzchia were the dominant genera. Phylum Chlorophyta was second in dominance and consisted of Oocystis, Pediastrum, Scenedesmus and Chlorella genera altogether sharing 12.89% of the total phytoplankton frequency. Chrysophyta with genera Dinobryon. and Malomonas had a frequency of 2.21%, Cyanophyta with Genera Anabaena, Oscillatoria and Gleocapsa comprised 1.32% of the total frequency, Pyrrophyta with genera Cyratium, and Peridinium had a frequency of 0.52%, Euglenophyta with genus Euglena had a frequency of 0.13% and Cryptophyta with genus Cryptomonas had a frequency of 0.08%.In all sampling months, the highest mean density belonged to Phylum Bacillariophyta with 10,770,666±21.571 individuals per liter of water. Also, in all seasons, the most dominant genus of the Phylum Bacillariophyta was Cyclotella. Phylum Chlorophyta came second in numbers, with a mean density of 2927000±39.573 individuals per liter of water. The dominant genera of this Phylum were Oocystis, Pediastrum, Scenedesmus and Chlorella.Non-parametric Kruskal-Wallis and Mann-Whitney analyses showed that Phytoplankton frequency in different stations and months were statistically different (P<0.05). No significant statistical difference was found between different depths (P>0.05).

Freshwater crayfish (Astacus leptodactylus Eschscholtz, 1823) is a very valuable macrobentic organism which was introduced Aras reservoir to the Shorabil Kake in the amount of 15000 specimens during the years 2002-2006. This species produce very good population in the Shorabil Lake. We investigate biological, biomass and MSY of the crayfish in the Lake during the years 2006-2007.Results showed that the mean total lengths and weight of this crayfish for both sexes were 82.5±32.4mmand 82.5±32.4g, respectively. Maximum total length and weight of the caught crayfish was 196mm and 328g respectively. The sex ratios of male: female crayfish caught with a funnel trap of 10mm mesh size (stretched mesh) were estimated at 1:2.4 that was significantly difference from 1:1 ratio (X2= 479.01; P<0.05). Mean number of ovarian and pleopodal eggs were estimated at 396.6±36.5 and 311.11±22.92 eggs with 95% confidence limits, respectively.The time of the first molting of the male stared from beginning of the May at a water temperature of around 14oC and ended in mid-June. The second molting of the male and the first molting of the female is done simultaneously and started in beginning of the October at a water temperature of around 17oC. Reproduction period of this species started from beginning of the December and lasted until the mid-June in Shorabil Lake.

Growth of gonads and spawning time in white-spotted rabbit fish, Siganus sutor, in culture conditions were surveyed. Around 800 juveniles weighing 50-80g were captured from wild and stocked at a density of a15 indlm3in concrete tanks during years 2004-2005 located in the Persian Gu1f & Oman Sea Ecology Research Center. The fishes were cultured for about 12 and 24 mounts to obtain 1 year and 2 year old specimens. Culture was continued till the year 2007. Using 574 records, the length-weight relationship was determined as W=0.0155(FL)3.0701 Results revealed that Siganus sutor has alometric growth. Monthly changes in GSI showed the lowest GSI values at stage I and V. We observed that GSI values of females and males peaked in April and May. The total fecundity of S. sutor ranged from 170,000 to 1,300,000 oocytes in specimens of 22-35cm, F.L. 215-800 g B.W. and ovary weight of 15- 117g. The average (±SE)total fecundity was 737931.03±77503.41 oocytes per female. The relative fecundity ranged from 458.47 oocytes to 2303.80 oocytes per g B.W. with an average (±SE)of 1606.31±131.89 oocytes per g B.W. Results showed the best time for S. sutoe to culture is month of May According t6 the results, one year old males are mature and produce sperm whereas females are ready to reproduce at age 2.

Over-fishing of marine resources has endangered many commercial fish species in the world. Setting up artificial reefs is now considered an important way for marine stocks and fishing enhancement. The present study was designed to monitor fish abundance and species changes around a small and newly established artificial reef system in Moloo area at Bandare-Lengeh during two years after installation in September 2005.The artificial reef includes three types, of concrete structures arranged in a seven by three grid. Each cross point was considered as a sampling station and two other stations were also selected from two sides of the system as control points. The CPUE and frequency of fishes in transect7 with a mixed structure showed significant differences with other 6 transects (P<0.01).No fish diversity differences were seen between transects (P>0.01). Although there were differences between C PUE averages of different seasons, the ANOVA test of difference significance was negative. The t-test showed no significant differences between the abundance and number of different species per trap per day and seasons. The dominant species were Epinephelus coioides, Plectorhinchus shotaf, Diagrama pictum, Siganusjavus.

The length-weight frequency and sex ratio of crayfish (Astacus leptodactylus) in Aras Reservoir, was studied seasonally from spring 2008 to winter 2009. The total mean length and weight for the crayfish were 106.43±7.94mm and 35.8±10.86g, respectively. A measured 18.99% of the caught crayfish exceeded the standard commercial size (120mm) and only 16.43% of the catch weighed higher than the standard commercial weight 50 grams. The standards have been set forth by West Azerbaijan Fishery Office. Generally, the male crayfish dominated the samples. Comparisons of growth equations confirmed that the males are heavier than females with the same size. The results showed that crayfish Astacus leptodactylus has critical condition in Aras Reservoir.

Polychaeta are the most important benthic .animal sand consist of many species with a vital role in food web. We conducted a survey froin, summer 2005 to spring 2006 to complete the ecological studies of macro benthos in rocky shotes of the intertidal zone of the Hormouz Island. Three main regions were studied in the west, south and south-eastern parts and three transects were sampled in each region to test variation in Polychaeta distribution and abundance along the entire intertidal zone. At each one of the nine transects the shore was levelled and a general qualitative description was made, which also aided in the stratification of subsequent quantitative sampling. Samples were fixed in %4 formalin and transported to lab for analysis. Results showed presence of 10 genera of Polychaeta among which Nereis was the most abundant in the intertidal rocky shores. Our study also revealed seasonal and zonal distribution of Polychaeta in rocky shores of the area. Abundance of Polychaeta was markedly higher in summer compared to winter and in the upper zone compared with the mid littoral zone. Results of Shannon and Simpson diversity indexes affirmed above conclusion.

The present study was designed to obtain the most effective dose for phtytohemagglutinin (pHA-P) and lipopolysaccharide (LPS) extracted from E. coli to optimize the lymphocyte culture method, the highest mitotic index (MI) and metaphase plates number of ship sturgeon, Acipenser nudiventris. Twenty specimens of two-year old A. nudiventris weighing on average 137g and with an average length of 32cm were used in this study. Different doses (0, 40, 60 and 80 mgmrl) of PHA-P, LPS and a combination of the most effective dose of both mitogenic factors {(40 mgmr -1) PHA-P + (80 mgmr -1) LPS} were added to the culture media and mitotic indices were calculated for each treatment.Results indicated that a dose of 40 mg mr-1 PHA-P and 80 mg mr-1 LPS produced the highest MI (6.26 and 3.02 respectively). Using higher concentrations of PHA-P and LPS resulted in decreased MI, whereas at lower doses of these mitogenic factors, mitotic arrest of cultured lymphocytes was observed. Using a combination of the most effective dose of the two mentioned mitogens {(40 mgmr -1) PHA-P + (80 mgmr -1) LPS} yielded a MI of about 3.84. A dose of 40 mg mr-1 PHA-P produced the highest MI (6.26), the highest number of lymphocytes was cultured and the largest number of metaphase plate was counted.