Iranian Scientific Fisheries Journal
Year:2003 | Volume:12 | Issue:2|Papers Count:10

With attention to different human activities around Anzali lagoon and entrance different pollutants containing heavy metals into this aquatic ecosystem and alterante absorption and accumulation of heavy metals in shell and muscle of Astacus leptodactylus which is native species of Anzali lagoon and having food and economic importance. Sampling of water and sediments from 18 stations and also shell and muscle of Astacus leptodactylus from 5 stations have been conducted. After biometric evaluation of Astacus leptodactylus, the chemical analysis of the samples were done by using international standard methods and then their heavy metals content was determined by Atomic Absorption Spectrophotometer (A.A.S). Result of the analysis stated that: There wasn't significant difference between weight and size of Astacus leptodactylus with their absorption and accumulation of heavy metals; but there was a significant difference and correlation coefficient between heavy metals content in water and sediments, and also in sediments with shell and muscle of Astacus leptodactylus in Anzali lagoon.

Since 1992, white spot syndrom disease reported from China, has overshadow all other viral diseases. The WSSD was also reported from all countries in Asia and America. In July 2002, the high mortality in cultured shrimps of Penaeus indicus occurred in Khouzestan province, south of Iran. The clinical signs of affected shrimps were characterized by distinct white spots in the carapace with size of 0.5-2 mm. Moribund shrimp usually showed reddish coloration of the body, lethargic and reduced feed intake or stopped feeding, the stomach was empty and shrimp stayed at the side of pond edge. The high mortality rates occurred within a week after the emergence of gross signs. The moribund shrimp collected and fixed in Davidson fixative, then processed routinely. The section from all tissues except hepatopancreas showed intranunclear Cowdry type-A inclusion body.According to the clinical signs, histopathological fingings and high mortality, the disease occurred in Abadan area (Khouzestan province) identified as white spot syndrome disease (WSSD).

A comprehensive hydrobiological and hydrological investigation conducted in Maco Reservoir dam during 1997-1998.The result showed that the maximum density of Phytoplankton belongs to the Phylum of Chrysophyta with species of Cyclotella menenghiniana, Synedra ulna and Diatoma vulgare. This Phylum observed mostly in summer and showed the most; frequency (%76) population during year. After Chrysophyta there was Chlorophyta phylum with species Scenedesmus bijuga and S. bijugatus with %19 frequency during year. Also, there were other phytoplankton phyla, namely: Cyanophyta with Oscillatoria limosa, Euglenophyta with Euglena sp. and Pyrrophyta with Ceratium hirdinella that had a few percent of population in the year. The highest density of Zooplankton belongs to the phylum of Rotatoria with species of Synchaeta oblonga, Polyarthera vulgaris and P. dolichoptera. This Phylum was observed mostly during autumn and had %74 frequency during year. The second phylum belongs to Arthropoda, that was included two orders consist of: Copepoda (%16 population) with speices of Cyclops vicinus and C.viridis and their naupli, order Cladocera (%7 population) with speice of Daphnia longespina. They were recognized as the most important zooplankton in Maco reservoir dam. The planktonic studies and observations show that there is a well enough potential of food for feeding of fishes inhabited in this dam.

Sampling in 5 stations was carried out from July 1999 to June 2000. Water temprature, pH and EC were measured on site. Maximum water temprature was observed in July and August, and maximum level of dissolved oxygen occured in November and February. Range of pH was between 7.2 to 9.4, in acceptable range for aquatics. The results showed that Shadegan marsh is a hard and brackish water body. Dissolved oxygen level was more than 5 ppm in most of the cases, and is optimum for fish growth and reproduction. Amount of BOD5 was 3-10 ppm. COD levels showed an increase in Autumn. With respect to N.NO3 and N.NO2, the water could be considered as unpolluted water. According to the statistical analysis of data, Mansoreh and Ataysh stations showed the same water quality. Study in various years showed that water quality in Shadegan Marsh has been diminished, probably due to decreasing run off and increasing pollution in Shadegan Marsh.

The study of morphology and biological charactristics of A. boyeri in the southern Caspian Sea was investigated during 2000-2001. The fish samples were collected by beach seine (mesh size = 6 mm) monthly and then fixed in formalin 5%. The biometric and morphometric results are as follow:Total length = 73.82 ± 17.73, mean weigth = 3.15± 2.02, number of lateral line scale= 48± 3, number of branched rays of first dorsal fin 8; number of branched rays of second dorsal fin = 12; number of branched rays of anal fin = 13; number of branched rays of ventral fin = 5, number of vertebra = 47 and gill rakers = 34. Also, the results of other measurments (in mm) were: head length = 23 , head depth = 14, inter orbital width = 5, post-orbital length = 7, maximum body depth= 14, minimum body depth = 5, peduncle length = 19, first dorsal fin length= 7, pectoral fin length = 14, pelvic fin length = 11, pelvic-anal fin distance= 34, pectoral-pelvic fin distance= 43, post-dorsal distance= 20 and predorsal distance= 43mm. The comparance between males and females showed that from point of 2 meristic and one morphometric parameters, they showed significant difference. The study on population structure of Atherina boyeri indicated the range of 1 to 3 years old with average of 1.7 year. The total length and body weight equation was caclulated W=0.00000615 T.L3.02. The sex ratio of this species was estimated as M:F=0.47:0.53.

Fish sauce is a popular fermented product used in south Asian countries which is made from different species of small fishes. In this research it was attempted to produce fish sauce from kilka fishes of the Caspian Sea. The kilka sauce was made from three different preparations of kilka, such as whole kilka, cooked whole kilka and dressed kilka. Each of these preparations was fermented in four different ways, such as traditional, enzymatic, microbial and mixture of enzyme and microorganisms. The results of this study showed that times of fermentation for traditional, enzymatic, microbial and mixture of enzyme and microbe method were 6, 1,3 and 1 months, respectively. The least and the most rate of fermentation were recognized for dressed kilka and cooked whole kilka, respectively. Microbial, biochemical and organoleptic properties of kilka fish sauce were investigated. The total bacterial count was 2.1 to 6.15 log cfu/ml, total volatile nitrogen (TVN) in samples was 250 mg/100g and protein content of kilka sauce was between 10-13 percent. The score of the taste panel for flavour, odour and colour was between 3 to 5, which means this product can be acceptable to the consumer.

During the period of 1979-1980 in Abkenar and Hendkhaleh in Anzali lagoon, 67 I genus of phytoplanktons belong to 5 phylum were identified. The results showed that there is two peaks of phytoplankton blooms during a year (summer and, autumn) in which Cyanobacteria (blue-green algae) were the most abundant groups. 5 species of them were identified in which one species was recognized toxic. This toxicity was confirmed through bioassay studies on mouse.Also, This toxin was hepatotoxin belongs to microcystins. Microcystins are cyclic peptides and contain seven aminoacids.

A series of studies were conducted to evaluate the possibility to culture Penaeus indicus in coastal area of Gorgan bay concerning the proper climate potential of Behshahr zone during summer till autumn 2000.Thirty two water samples were collected from four shrimp ponds for further laboratory studies to measure some physicochemical parameters such as: temperature, pH, salinity, transparency, nitrogen, phosphorus, D.O. according to the Russian Standard (1988).As a result, the range of water temperature, pH, salinity and trasparency were 24.5-29.0°C, 8.02-8.18, 31.5-43.5 ppt and 21-50cm, respectively and the fluctuation concentration of D.O, NH4+, NO2-, PO4-3 were 3.8-9.5 ml/l, 0.0022-0.015, 0.0021-0.1210 and 0.0145-0.3710 mg/l, respectively.As a conclusion, this shrimp species can be easily adopted with different climate, so this region is suitable for shrimp culture as view point of temprature and salinity. For demonstration of this issue, 1he semi-intensive shrimp culture has been successful. Also the toxic material such as ammunia and nitrite did not show any restriction for shrimp culture.

Shamrood river is one of the important river located in the north of Iran. In order to identify the benthic invertebrates of the river, a series of sampling were carried out during one year. The samples were collected by surber sampler (40×40 cm).In this study, the identified invertebrates were: Ephemeroptera 8 genus with the most biodiversity; Plecoptera 2 genus; Coleoptera 4 genus (larvae and pupa); Trichoptera 5 genus (larvae and pupa); Diptera 6 genus in forms of larvae and pupa with the most abundance; and also Hydracarina, Oligochaeta and Turbelaria. The frequency of different species of benthoses were the same in headwater stations and there were more genera diversity.On the other hand, in downwater stations (with lower slope substrate), the ferquency of some families and genera such as Chironomidae and Hydropschae increased but the genera diversity decreased. Based on biological index of benthic invertebrates and mean annual ferquency (26.1); the total production potential and mean total biomass were estimated 348 kg/ha and 4.15 g/m2, respectively.

In October 2000, a fish with body weight of 7500g and total lenght of 970mm was caught by a beach seine near Bandar Anzali coastal waters in the southern Caspian Sea, then in March 2001, a similar fish with 4800g weight and 800mm total lenght was caught by another beach seine in this area for the second time. Study on morphological characteristic (morphometric, meristic and anatomic) indicated that these specimens have 41 and 42 scales on lateral line, 7 branched rays in dorsal fin and 8 in anal fin. There are 17 and 19 rakers on first gill arch, respectively. These 2 samples have sub-terminal mouth, black colour, cycloid scales with a few thick, ones sharp snout, some starry plates on upper head and pharyngeal teeth in one series with unserrated, smooth and grinding surface (4-5 and 5-5, respectively). Also, ventral fins inserted vertically after dorsal fin origin. In according to ichthyoloy resources, these specimens were distinguished a commercial cyprinid species, Black carp (Mylopharyngodon piceus). Review of present literature on Caspian Sea basin and whole Iranian waters indicate that there is no previous report on presence of this fish in natural ecosystems of Iran.