Iranian Scientific Fisheries Journal
Year:2006 | Volume:15 | Issue:2|Papers Count:20

Skin of 20 normal, mature and same size fish (27.27±3.33cm) were subjected to microscopic assessment in different regions including lip, pectoral fin, head, back, side (on lateral line).and abdomen. The skin sections were prepared using routine paraffin embedding and stained by H&E and PAS. The alarm cells distribution were counted in 100μ length of epidermis. Microscopic results showed that voluminous cells existed in the middle to deeper layers of non-keratinization stratified squamous epidermis in all regions except for lip. These cells contained large and euchromatic nucleus in the center of cytoplasm. The cytoplasm has negative reaction to PAS staining. Histo-metrical results showed that shape and number of these cells vary in different regions of skin, with the differences being significant in all regions except for the back, abdomen and pectoral fin skin (P<0.05). Based on the distribution of alarm cells, we could divide the epidermis into four regions: 1- The skin of lip region carrying no alarm cells.2- The skin of head region with 14.814±0.304 alarm cells in 100µ length of epidermis. 3- The skin of dorsal and ventral regions and pectoral fin containing 27.628±1.167, 228±1.54 and 29.629±0.314 alarm cells in 100µ length of epidermis respectively.4- The skin of lateral region with 47.4971±0.512 alarm cells in 100µ length of epidermis.

Digestive parasites of commercial fish species in the Boojagh wetland were studied in 2002. The fish species included Esox lucius, Cyprinus carpio, Blicca bjoerkna, Tinca tinea, Carassius auratus, Rutilus frisii kutum, Rutilus rutilus and Seardinius erythrophtalmus. Species C. auratus, R. frisii kutum and B. bjoerkna were found free of digestive parasites.The other five species were carrying one of the three digestive parasites Raphidasearis aeus, Caryophyllaeus fimbericeps and Asymphylodora tincae. R.acus parasite was isolated from E. lueius and E. erythrophtalmus infecting the species with a mean intensity of 11±11.15 and 1.8±0.83,a prevalence of 15.4% and 20.2% and a mean abundance of 1.69 and 0.38 respectively. C. carpio and R. rutilus were only infected with C. fimbericeps parasite with a mean intensity of 30.30±46.33 and 5±0, a prevalence of 46.5% and 2.78%, and a mean abundance of 15.48 and 0.14 respectively.The parasite A. tincae was observed only in T.tinca infesting the fish with a mean intensity of 20±0, a prevalence of 25% and mean abundance of 5. Infection of Esox lucius with the parasite A. tincae had been reported from other sites, but this is the first record of Scardinius erythrophtalmus being infected with the parasite. This is also the case for infection of C. carpio with the parasite Caryophyllaeus fimbericeps which was reported before, but found infesting R. rutilus in the Boojagh wetland for the first time.

Increase in water pH in recirculation fish culture systems turns ammonium into ammonia which can kill fish even in low concentrations. The purpose of this study was to apply ion exchange and air stripping methods to remove ammonium in effluents of recirculation fish culture systems. Ion exchange method was done using Graded Zeolite Clinoptilolite from Semnan Province to remove ammonium and air stripping was applied to zap ammonium from Zeoilte. Regeneration tests were conducted in which known weights of ammonium saturated Clinoptilolite were contacted with 1 normal concentration of CINa solution. Different concentrations of ammonium were selected and the effects of temperature and pH in releasing ammonia were also investigated.Results show that the cation exchange capacities in continuous systems were 7.61 to 11.22 (in breakthrough point) and 16.31 to 19.5mg ammonium per gram of ion exchanger as total capacity. The results of regeneration experiments by NaCI (1 normal) solution proved the efficiency of chemical regeneration of zeolite column to be as high as 94.9% to 99.1%. The efficiency of regeneration by air stripping was determined to be 92% in 16 hours. The efficiency of acid absorption of released ammonia in stripping process was determined as 55% where the surplus was rejected to the atmosphere. It is concluded that the method may be regarded as a completing process for water treatment in closed fish tanks.

The effects of chromosome manipulation on the digestive enzyme activity in the rainbow trout were studied. The enzymes included Pepsin, Trypsin, Chymotrypsin, a-Amylase, Lipase and Alkaline Phosphatase which were assessed in diploid and triploid female of rainbow trout. Pepsin activity in the stomach of the assessed fish showed no significant difference between the diploid and triploid fish (P>0.05). The measurement of Trypsin and Chymotrypsin activity in the intestine and pyloric caeca revealed no significant difference in the treated and untreated fish (P>0.05). The activity of α-Amylase, Lipase and Alkaline Phosphatase showed no significant difference in the intestine and pyloric caeca of the diploid and triploid fish (P>0.05).The results indicated that chromosome manipulation in rainbow trout had no effects on digestive enzyme activity.

Shrimp hatcheries around the world continue to be heavily dependent of wild broodstock. One of the factors that could damage this industry is fungal infestation. Hence, we studied the fungal flora infesting shrimp larvae in hatcheries of Khouzestan Province, south Iran. The study covered two reproduction periods 2001-2002 and totally 140 specimens were collected from 2 hatcheries under Thailand and Philippine management systems. Samples were obtained in completely sterile condition from water, live food and different stages of shrimp larvae P. indicus. The samples were cultured on SDA, PYGA, PYGSA and similar media. We diagnosed ten fungal species including Cladosporium sp, Pencillium, Trichothesium sp., Aspergilus sp. A. niger, Rhizopus, Mucor and Fusarium, the last being the most abundant fungus. We found that the contaminating fungal species were all opportunistic.

A series of chemical and instrumental analyses was employed using final buoy samples in a Reversed Engineering Method to develop the formulation for production of Ethylene Vinyl Acetate (EVA) buoys. To accomplish the goal, FTIR, DSC, and TGA and chemical analyses such as Furnace Test were conducted on the samples. The formulation was found to be composed of Co-Polymer Ethylene Acetate PHR 84, LOPE 16 PHR, ADCA 6 PHR, Zinc Oxide 3 PHR, Kaolin Clay 3 PHR, Dicumil Peroxide 1.7 PHR, and Stearic Acid 2 PHR.  

In 2001, we studied 2600 sturgeon fingerlings including: 2242 Acipenser persicus, 150 Acipenser stellatus, 150 Acipenser nudiventris and 58 Huso huso from Shahid Beheshti and Yousefpour hatcheries for parasitic infection. We found three parasites including Diplostomum spathaceum, Trichodina sp. and Gyrodactylus sp infesting the fish. The prevalence and average intensity of Diplostomum spathaceum was 5.49% and 1.66 for Acipenser persicus, 0.66% and 1 for Acipenser stellatus and, 22.41% and 5.38, for Huso huso fingerlings respectively. No Diplostomum infection was observed in Acipenser nudiventris. The prevalence and average infection intensity of Trichodina sp. was 45.05% and 76.14 for Acipenser persicus, 44% and 51.36 for Acipenser stellatus, 36% and 63.51 for Acipenser nudiventris, and 32.76% and 34.73 for Huso huso fingerlings, respectively. Totally, the prevalence of Gyrodactylus sp. was 0.46% in the two hatcheries. The prevalence of infection with Gyrodactylus sp. was 0.36% in Acipenser persicus and 2.66% in Acipenser stellatus.

Twelve P. merguiensis specimens were collected from fishing grounds of Sirik area in the north of strait of Hormoz. The sampling was carried out from April to November 2003 and the brood-stocks with a mean weight 36.3 grams were transported to Kolahi hatchery center. The samples were kept in two separate 6 ton fiber glass tanks, filled with sea water with a salinity of 32ppt and temperature of 30 degrees centigrade. After spawning, the total collected nauplii from the first and the second tanks were 41800 and 960000, respectively. The survival rate from nauplii stage to PL15 tage was 31% and 21.2%, for the two tanks respectively. We fed the larva up to N6 stage with Chaetoceros and from mysis to post larvae stages with Artemia. We conclude that Hormozgan province is a suitable area for collection of Banana shrimp brood-stocks and that propagation of the species can be successfully carried out.

Shafarud river is lied in south-west Caspian Sea and it is important for spawning of anadromous fishes, feeding and spawning of estuary fishes and special fish population. Studied fishes have been sampled in 7 stations from river mouth to upstream from Fall 2001 until summer 2002 and electroschoker, cast net and beach seine were used to catch them and main purposes of this study were: determining fish diversity, abundance and their spatial and temporal distribution and present role of the river in restocking migratory and estuary fish species. The study on 1912 specimens showed 21 species and subspecies fish belong to 8 families. Cyprinidae family with 10 species and abundance 62.87 % of total populations was dominant in all stations and seasons. Among the identified species, Neogobius kessleri, Capoeta capoeta gracilis, Albumoides bipunctatus and Barbus lacerta cyri that are native and river resident had the most dispersion and the fish with 25/58 , 20/61 , 19/87 and 8/37 percent of total sampeled fish, had respectively the most abundance in the river. There were 11 species of freshwater resident species, 6 species of marine or estuary fishes and 4 species of migratory or anadromous fishes in Shafarud River and in the river were identified 5 species of alein fishes, too. In general, the study showed the river have good potential in restocking of migratory fishes and its stuary is suitable for feed and growth of marine species fingerling.  

Overfishing, destruction of spawning grounds together with intensive artificial reproduction and release of Rutilus frisii kutum fingerlings have caused remarkable fluctuations in the stocks of the fish in the Caspian Sea over the past decades. The mean catch size of the fish during periods 1937-1947, 1967-1977 and 1987-1997 were 3110, 990 and 8505 tons respectively. Also the minimum catch was recorded as 121 tons in 1964 and the maximum catch was recorded as 11175 tons in 1994. The catch per unit effort (CPUE) of the species shows high variations such that it has been 17 kg/ton in 1971,216 kg/ton in 1989 and 112 kg/ton in 1999. The decline in CPUE in 1999 was due to increased fishing efforts of 3.8 orders of magnitude (in comparison to the year 1989) as a result of fishing cooperatives increasing in number during that period.The calculated stock biomass of the fish was 1300 tons in 1971 fluctuating between 18489 to 25400 tons in the period 1990-2000. The mean biomass of the fish in the recent past 10 years was 22750 tons which shows 17-fold increase in comparison to the year 1971. The accomplished catch in the recent 10 years has been 35 to 46 % of the annual stock. The exploitation rate being more than MSY and decreased mean weight of the released fingerlings plus lowered return rate might have caused the decrease in the stock size of the fish during 1998-1999.

To determine the acute toxicity and bioaccumulation of mercuric chloride in Rutilus frisii kutum, specimens of the fish were exposed to various concentrations of the chemical in water. We carried out ten treatments with three replicates and one control for each of the chemicals using the static O.E.C.D. method in 55 liter tanks each containing 14 fingerlings. During the experiments, the average pH was recorded as 7.8, total hardness was measured to be 255 mg/l, average water temperature was 27±1 degrees centigrade and dissolved oxygen was 7.2 mg/l. Mean LC50 values of Hgcl2 for juvenile R. frisii kutum with mean weight 1±0.2 grams were 0.102 and 0.086 mg Hg/l at 24h and 96h, respectively.The bioaccumulation values during 24h in muscle tissue, kidney and gill were 1.55, 16.1 and 22.7 mg Hg/l respectively. The values during 96h exposure were 2.8, 16.8 and 26.65 mg Hg/l in tissue, kidney and gill respectively. The bioconcentration values for muscle tissue, kidney and gill during the first 24h were 14.75, 153.39 and 216.11 after 96h were 33.8, 198.1 and 313.5 times that of the environment. These results show the bioaccumulation to be the highest in gill followed by kidney and muscle tissue. The study suggested direct relationship between mercury concentration in and its bioaccumulation in the fish organs tissue.

The age structure of John's Snapper (Lutjanus johni) in Hormozgan waters, south Iran was studied. We conducted monthly sampling starting in May 1996 and ending in July 1997. Totally, 613 fish specimens were collected, of which 567 and 308 specimens were aged based on whole and sectioned otoliths respectively. The snappers were found to be aged from 1 to 17 years old. Results showed that each year only one pair of opaque and translucent zones was formed. Age determination based on the two methods was significantly different especially in the fish aged 1 to 6 years (P<0.05).Age-length relationship of the species based on sectioned otolith reading and total fish length using the least squares method was obtained as Lt = 89 (l-e-0165(t+1.476. Also, the length-weight relationship for the fish was determined as W= (4x10-5) x L2.8214.

Fifty common kilka (Clupeonella cultriventris) specimens from Guilan Province and fifty others from Mazandaran Province, South Caspian Sea were collected to study genetic variation in the fish using Restricted Fragment Length Polymorphism (RFLP) of the mtDNA. DNA was extracted from fin tissue by phenol-chloroform method. The PCR products were digested using 13 restriction endo-nuclease enzymes. Five out of thirteen restriction enzymes were polymorphic resulting in nine different haplotypes. The haplotype divergence ranged from 0.0073 to 0.0369. The mean value of haplotype and nucleotide diversity among populations was 0.7339±0.0006 and 0.0098±0.0, respectively. The nucleotide divergence among populations was 0.01%. Statistically significant differences in haplotype frequencies among all samples were observed (P<0.01). Therefore, we conclude the populations are different genetically.

Fishing vessels equipped with bottom trawls cause high amount of by-catch and discards. We investigated the catch composition and by-catch percentage in October -November 2002 during shrimp fishing season in Hormuzgan Province waters. The studied area was located in Dar-Soorkh area, east of Hormuz Island and Toola area. Sampling was done using wooden fishing dhows. During shrimp season, 36 hauls with a total catch of 6050kg were treated. The catch composed of 88 species belonging to 50 families of which 67 species were bony fish from 38 families, 9 species were cartilaginous fish from 6 families, and 3 species were mollusks from three families and also 9 species of crustacean were found belonging to 3 families. The percentages of different groups of by-catch and target catch (shrimp) were 49.4% small discards, 18.7% large discards, 4.7% commercial species and 27.2% shrimp. The ratio of total by-catch to shrimp was estimated to be about 2.7 times that of the shrimp.

This study was carried out to identify the different species of Pleuronectiformes order in the Khuzestan province waters (persian Gulf) from March 2003 to June 2005. A Total of 671 specimens were collected by bottom trawl or from 7 main landings. The sampling period was seasonal. 36 main morphometric and meristic characteristics were measured. The results showed that 6 families of Soleidae, Cynoglossidae, Paralichtidae, Bothidae, Psettodidae and Citharidae are found in the studied area consist of 25 species of: Brachirus orentalis, Solea elongata, Monochirus lutenus, Parachirus marmoratus (family Soleidae); Cynoglossus arel, C. bilineatus, C. Puncticeps, C. durbanensis, C. lachneri (family Cynoglossidae); Pseudorombus annulatus, P. elevatus, P. arsius, P. malayanus, P. navaleusis, Paralichthodes algoensis, Poecilopstei javanicus (family Paralichtidae); Arnoglossus aspilos, A. arabicus, Engyprosopon grandisquama, Laeopes guentheri, L. natalensis, L. pectoralis, Psettina bre.virictis (family Bothidae); Psettodes erumei (family Psettodidae) and Citharoides macrolepis (family Citharidae).  

Infection with Ligula intestinalis was found to be the main cause of fish mortality in Satarkhan Dam of East Azerbaijan Province. Zooplanktons, fish, water and water birds were sampled and studied for infestation with the parasite. We randomly sampled 100 copepods, fixed them in Chloridric Acid 0.01% for 3-4 minute until tissue became soft and colored by Logol. After washing the sample with distilled water, the parasites were separated and identified perevalance of infection was sixteen (1% male and 15% female Cyclops).

To study Infection of Three-Spined Stickleback, Gasterosteus aculeatus (L.), we sampled 530 specimens of the fish during November 2000 till October 2001 in Gomishan Lagoon, southeast of Caspian Sea. The fish were collected using beach seines with 3mm mesh size. The specimens were transferred to lab fresh or fixed in 10% formalin and examined by standard methods. Numbers of parasites for each male or female were recorded and intensity, frequency and prevalence of the parasite for each month and sex were calculated. Maximum infection occurred in late winter and early spring and the maximum number of parasites was 82, obtained from a female fish in early spring.