Iranian Scientific Fisheries Journal
Year:2004 | Volume:12 | Issue:4|Papers Count:20

Artemia urmiana cyst shells collected, purified and dried from ashore of Rashkhan and Bozorgrah in the Urmia Lake in January and February 2002.According to the results obtained by standard methods of analyses the cyst shell contains: 4.8±0.5% lipid, 32±2% protein, 10.5±1.0% moisture, 0.5±0.2% haematin and 20.6±2.0% total ash.The chemical composition of ash are: Na2O 1.98%, MgO 1.14%, S03 6.82%, CI 3.23%, K20 2.12%, CaO 4.05%, Fe2O3 1.68%, Zn 0.05%. The chitin was extracted from Artemia cyst shells by using different methods of demineralizaion, delipidization, deproteinization and decolorization. The yield of extraction from cyst shells was 28±3%. Composition of chitin was determined by FTIR, X-Ray Powder diffraction and C.H.N.O analyser.Artemia urmiana cyst shell contains approximately about 28±3% percentage chitin.

The Caspian kutum, Rutilus frisii kutum, and grass carp, Ctenopharyngodon idella are two commercially important fishes with similar external features, the first one being endemic to the Caspian Sea, and the second one is cultured in freshwater polyculture system.In this study the nutrient composition of these fishes were compared. Then with the intention of better shelf-life, their hot processed marinades were organoleptically analysed at intervals of 2, 4, 6 and 8 months, using Total Volatile Nitrogen (T.V.N) and peroxid values.The comparison of the fish composition with Duncan test showed no significant difference (p< %5) in average amount of protein, ash and energy content, but significant difference in amount of lipid, P, Ca content, iodine value, saponification value, acid value, peroxide value (at 0,1,3,5 and 7 days after oil extraction) was observed. It means that lipid content, peroxide value and acid value in kutum were higher than grass carp (0.93%, 1.5 mEq/kg and 4.33% fatty acid according to oleic acid, respectively), and Ca, P contents, iodine value and saponification value, on the other hand, were higher in grass carp (39.89 and 12.01 mg/100g , 6.20 %12 and 8.62 mgKOH/g, respectively). The organoleptic results showed that the produced marinade from grass carp (according to variance analysis) is perferable than the other one. Also, it was found that this marinade can be stored during 6 months at 10°C in good condition.

The most part of the fauna population in the Caspian Sea comprised invertebrates that is dominated by benthic organisms. Cumacea belongs to Arthropoda phylum, class of Crustacea and has an important role as food for sturgeon fishes in the Caspian Sea. This study was performed from autumn 1992 to summer 1993 in sixteen transects and each transect had four stations located at 10,20, 50 and 100 m depths.The survey revealed that the maximum mean biomass of this family was observed at 10 m depth in transect 15 with 9.62 gim2 and the minimum was observed at 20 m depth in transect 1 with 0.07 g/m2. The greatest biomass of this family was observed in spring with average biomass of 6.48 g/m2 and the lowest biomass was observed in autumn-winter with average biomass ofl.47 g/m2. The maximum and minimum mean biomass was observed at 100 m and 10 m depths respectively. The average biomass of this benthos had significant differences in different depths and seasons (P<0.05).The amount of T.O.M had high and considerable changes in different depths with a range of 3.55-10.37% for depths of 10 to 100m, respectively. Also the maximum percentage of sand in sediment was observed in 10m depth with value of 58.64% and minimum value was 34.73% in 100m depth. The mean biomass of this aquatic organism was 4.75 ± o.45 g/m2 in eastren area and 3.59±0.31 g/m2 in western area of this province. Nonparametric statitical analysis of Kruskal- Wallis showed significant diffrence between mean biomass in this two areas (P < 0.05).

Schizothorax zarndnyi is one of the most economic and endemic species, which are found in rivers and triple lagoons of Hamoon.In this study, reproduction cycle, type, season and optimum temperature of spawning period was studied from July 1998 to June 1999. The maximum GSI was 7.9-9.6 in March and April with 14-18°C mean temperatures. The minimum GSI was 0.92 in May. Variation in GSI values shows that reproduction has annual cycle which begins in May and ends in April of the next year. From October significant increase of oocyte diameter and GSI were observed in 2 different groups, while oocyte distribution observed only in one group in May. The rate of HSI had flucatuation, during resting period of ovule (from May to September) and from October simultaneously with significant increase of GSI, the HSI increased and continued to January and decreased in March and April. The condition factor, was changed during reproduction cycle and it was minimum in March (0.92). Concerning these investigation, Sch. zarndnyi is a total spawner and showing a synchronous ovary.

In this investigation acute toxicity of phenol and 1-naphthol were determined based on OECD guideline in the laboratory. Experimental fishes were Caspian kutum (Rutilus frisii kutum) and bream (Abramis brama orientalis). Static bioassays were used for acute toxicity tests during the period of 96 hours and all of important physicochemical parameters of water including pH, dissolved oxygen, hardness, temperature and conductivity were monitored continuously and maintained at a constant value. Five treatments were used and three replicates run for each treatment.The 96h LCSO values of phenol and 1-naphthol for Caspian kutum and bream were 21.5928 and 2.1544 mg/lit and 25.1880 and 2.8490 mg/lit, respectively.The Maximum Allowable Concentration (MAC) of phenol in Caspian kutum and bream were 2.1593 and 2.5188 mg/lit, respectively. The MAC value of 1-naphthol in Caspian kutum and bream were 0.2154 and 0.2849 mg/lit, respectively. It is evident from the results of the present study that Caspian kutum is more sensitive comparing to bream and the toxicity of I-naphthol is higher than phenol.

This study was conducted in order to determine the LCSO of organochlorine insecticide, Endosulfan, lethal limit, Maximum Allowable Toxicant Concentration (MATC), clinical signs and histopathological changes in vital organs due to the toxic effects of the toxin on beluga (Huso huso).The experimental investigation was done at 20°C water temperature using 35% emulsion of ndusolfan and Organisation Economic Cooperation and Development (OECD) method. For this purpose 150 specimens of this species with 3-5g body weight were used in static water quality condition during 4 days.A LCso of 0.0063, 0.0016, 0.0006 and 0.0003 ppm and also a MATC of 0.00063, 0.00016, 0.00006 and 0.00003 ppm, were determined at 24, 48, 72 and 96 hours post exposing, respectively. The affected fish showed irregular swimming, whirlling, convulsion and bottom sitting behaviours as well as pale colour and respiratory disorders resulted in a short time death specially in high concenteration of endosulfan. Histopathologically, hyperaemia, swelling and separating basement membrane of gill lamellae were evident in fishes exposed to high concenteration (≥1ppm) of endosulfan. Also congestion, and necrosis of kidney, blood congestion, hepatocytes degeneration and to some extent, necrosis were observed in the liver of affected fishes. According to the lethal limit and LCso results (< %0.1), this insecticide should be considered as a very high toxic (VHT) chemical substance for beluga fingerlings causing a rapid and accumulative mortality in this species.

In the present research which was done during the period of July 1997 to June 1998, histological studies on maturation stages of 40 yellowfin tuna specimen (Thunnus albacares) were conducted.It was concluded that the ovaries of this fish had the following characteristics; Germination disk were not persent. There were no difference among anterior, posterior and middle parts of maturity stage of ovaries. All observed ovaries were asynchronous. The ovaries had five maturity stages which were as follow:a) Immature      b) maturing       c) Rippening      d) Ripe             e) SpentAvarage dimension of oocyte in different stage are as follow: Immature (<20µ); maturing (>40µ); Rippening (<60µ) and Ripe (<120µ).

One of the pathogenic agents for live creatures are fungi. They have wide distribution and spores of them is everywhere, however, fungi as well as other organisms, are the pathogenic agents in shrimps. The best example for the diseases caused by fungi in adult and juvenile shrimps are Black gill disease and larval mycosis. In this study 578 specimen of Green tiger shrimp of Bushehr province area (Helleh site) were investigated. Totally 719 fungal colonies were isolated and identified from shrimp surface, gill, haemolymph, hepatopancreas and water of pools. The results of fungal identification were: 526 mould colonies, 179 yeast colonies, 12 strile mycelia and 2 unknown colonies. Aspergillus spp. (9.45%), Fusarium spp. (7.78%); Cladosporium spp. (6.35%), Aspergillus niger (6.11%), Rhodotorula rubra (5.98%), Aspergillus flavus (5.98%), Penicillium spp. (5.84%), Alternaria alternata (5.28%), Candida albicans (5.28%) and Candida spp. (5.14%) were dominant genera and species among the identified fungi in order of frequency, and 37.60% were other fungi species. None of the isolated Cladosporium spp. matched with pathogenic criteria. Two isolated (4.65%) of A. flavus are proved to be able to produce Aflatoxin.

Influence of microelements; Zinc (as ZnCI2), Nickel (NiCI2.H20), Cobalt (CoCI2) Manganese (MnCI2.2H20), Iron (FeCl2) and Copper [copper chloride CuCI2, copper sulphate CuSO2.5H20, copper acetate (CH3COO)2Cu.2H20 and copper nitrate Cu(NO3)2,3H20 on the level of total alkaline protease activity (trypsin with enzymatical code (E. C) 3.4.21.4, chimotrypsine E.C. 3.4.21.1 and different peptidases) in intestinal mucosa, acidic protease activity (pepsin E. C.3.4.23.1) in the stomach mucosa and alkaline phosphatase activity (E.C.3.1.3.1) in the pyloric caecaes in juvenile beluga (Huso huso) were measured.This study was done in vitro condition with five replicants of 1 and 1×10-4 mg/l of ions Zn2+, Ni2+, Co2+, Mn2+, Fe2+ and Cu2+. 217 specimens of juvenile beluga with an average weight of 25±7 g, necropsied and necessary organs were removed and freezed as soon as possible. The frozen organs were thawed and the experiments were followed. The results showed that, in most of treatments, the level of enzyme activities were less than control. The level of total alkaline protease activity under influence of copper nitrate with a dose of 1mg/l in the intestinal mucosa and the level of acidic protease activity, under influence of zinc with a dose of 1×10-10 mg/l in the stomach mucosa, were significantly more than control (P < 0.05). Also, the level of alkaline phosphatase activity, under influence of copper nitrate with a dose of 1×10-10 mg/l in pyloric caecaes, was significantly more than control (P < 0.05).

The pearl oyster (Pinctada fucata) is considered as a valuable resources in the Persian Gulf. The aim of this research was to investigate the impact of petroleum hydrocarbons on density as well as destruction of this oyster. For this purpos, the Lavan region (Dardur, Hedabad, Chalil), Nakhilou and Hendurabi were chosen as the present habitat of the pearl oyster and Bostaneh, Moghooyeh, Molou and Geshe as the former habitat.The statistical analysis showed that the amount of petroleum hydrocarbons in sediments and soft tissues of oysters of Lavan stations is significantly different and Lavan region due to being close to oil terminals is more polluted. Meanwhile in winter petroleum hydrocarbons was found more than summer. Regarding to the density of oyters, it can be concluded that in present habitats with the increase of petroleum hydrocarbons in the body of oysters and sediments, the density of oyster was decreased.

This study has been conducted for determination of optimum time and duration of thermal shock on tetraploidy induction in Rainbow trout. This study was carried out by induction of 28°C thermal shock in different times after fertilization (49.5, 54.0, 58.5, 63.0, 67.5, 72.0, 76.5 and 81,0°C/hour and different duration (8, 10 and 12 min).Nuclear erythrocytes, cellular area and volume measurement were determined among blood smears of fingerling and statistic analysis showed that, induction of tetraploidy was conducted between 0-75% on various treatment, but highest tetraploidy yield (8.4%) was achieved by thermal shock on 28°C within 12 minutes, 74 degree-hour after fertilization.Moreover, tetra ploidy diagnostic was also approved by determination of nucleolus number in fishes. In this respect tetraploid and diploid fishes have 3-4 and 1-2 nucleolus, respectively.

Since a little information is available in relation with feeding of Lutjanus johni, this study was conducted to determine its food diversity. 613 specimens were studied from May 1996 to July 1997 and their dietary regim was defined. In this study, capacity vacuous index (CV) and food preference (Fp) calculated for this fish. The study of stomachs showed that stomach of 44 fish were full, 27 semifull and 524 were empty. CV was obtained 88.4 and Fp for crustacean (55.6), fishes (44.3) and molusca (1.4).In particularly study, Fp calculated for crab (54.0), squilla (23.2), shrimp (20.2) and lobster (2.5). Ultimately, in this survey was found that this fish possibly is fast feeder and crustacean to be omposed their main food. Among crustacean, crab is main food.

In order to identify the fishes of Qanats in Birjand area located in north-east of Iran, a series of sampling were carried out during 2001-2002, with covering 44 Qanats. The samples were collected by net and after fixation in 10% formaline, they were transferred to laboratory for further precise identification.At the end, there were found only 2 species of Capoeta fusca and Garra rossica belong to Cyprinidae family. Also, some samples were sent to Canada for attesting the identifications.It was found that the Capoeta fusca is an endemic species and geographically is only found in eastern part of Iran.

The changes of Russian sturgeon stocks in the southern Caspian Sea was studied by measuring and considering different population parameters such as fish length, weight and age and also fluctuation of catch and catch per unit effort.Amount of catch and biomass showed an descending trend during last 3 decades. In 1971-72 catch and CPUE of Russian sturgeon had been 837 tons and 602 kg/boat/day and was decreased up to 57 tons and 0.34 kg/boat/day in 1999. The abundance of young fishes was decrease during last decade and older fishes have been dominated at present. Because of a sharp decrease of sea ranching of Russian sturgeon fingerlings and consequently decrease of young fish abundance, therefore it is predicted that amount of catch will be considerably declined in the future.

In order to determine the species composition and abundance of fishes in Amirkelayeh International wetland a series of seasonal survey were carried out in 2001-2002. The samples were collected by different methods of gillnet, beach seine, castnet, electroshocker and dipnet. After catching the fishes, they were transfered to the laboratory for further species indentification.A total of 1639 specimens were collected that belong to 7 orders, 9 families, 15 species and subspecies. The identification orders were: Cypriniformes, Salmoniformes, Syngnathiformes, Cyprinodontoformes, Siluriformes, Perciformes and Gasterosteiformes.Among different orders, the order of Cypriniformes and Gasterosteiformes and among different families, the Cyprinidae and Cobitidae and among different species, Perca jluviatilis and Scardinius erythrophthalmus had the most and the least abundance, respectively. The stock of Tinca tina and Esox lucius were so high. It should be noticed that three species of Cyprinus carpio, Scardinius erythrophthalmus and Cobitis taenia were found for the first time in this wetland.