Iranian Scientific Fisheries Journal
Year:2000 | Volume:9 | Issue:2|Papers Count:7

In this study 401 specimens of Gattan (Barbus xanthopterus) caught by drifting and set gillnets, cast nets and forks were studied. Samples were collected monthly (October 1996 to September 1997) from Hamidieh Dam to Hour-AI-Azim Lagoon. Morphometric and meristic parameters and biological characteristics were studied in the laboratory. The Highest frequency of Gattan in the river was in March and in Hour-AI-Azim was in December. The length range of the fish in the river was broader than in the hour, and fishes with lengths more than 700mm were only observed in the river. Sharp decrease in GSI in May and occurence of spawning in May and June showed that reproduction of this species occurs in spring (in a two month period) and is relativery short. Minimum and maximum ova diameter were 0.01 mm and 2.25mm in stages II and IV of gonad maturity respectively. An increasing trend in ova diameter up to April and decreasing in June showed one time spawning of this species. Surface water temperature in the spawning season was between 25.5OC and 28.65OC and turbidity was in its lowest level in this period. Sex maturation in males occurred in length of 151-200mm (one year old), and in females in 501-550mm (3 years old). Average sex ratio (male to female) was 1:1.31 which is not significantly different from 1:1 (95% confidence limit).

In order to study the quantity and quality evaluation of benthic invertebrates in shrimp ponds belonging to Persian Prawn Co., in Tiab area (Hormozgan province), sampling of sediments were carried out every other 14 days, from August 18 to October 27, 1998, during the priod of shrimp culture. Sediments were sampled from three different point of 9 ponds by grab (Van Veen 0.02 m2) for identification macrofauna, miofauna, grain size and mesurment of total organic mater. Macrofauna benthics were few and were found only in three ponds. Three groups of miofauna including: Nematoda, Naplius and copepoda were distinguished. Their abundance was increased during main shrimp culturing period and was decreased at the end of it. Silt was the main part of soil in most ponds.

This study was carried out on Iranian coastal waters of Khouzestan province during 1995-98. Ichthyoplankton sampling was performed in order to determine its abundance, distribution and diversity. Monthly sampling was carried out from 12 fixed stations in Mahshar- Abadan creeks and 4 stations in west coasts of Khouzestan province waters, by a paired 500 micron Bongo net in oblique hauls from the bottom to the surface. Larvae of 21 families were identified in coastal waters. 16 families of fish larvae were also found in creeks. Most frequent larval families in the creeks were found to be Gobiidae (86%), Engraulidae (9.13%), Clupeidae (2.5%), and in west coasts, they were Gobiidae (49%), Engraulidae (14.5%) and Scianidae (7.8%). Other families were found to have a lower frequency and occured only in limited samples. There were distinct differences in fish families occured in two studied areas, although no significant differences were found in diversity of fish families there. The highest frequency of the larvae among most of the families was in March-August period. In the west coastal area, more than 50% of the total identified larvae occured in May, while in creeks, it was in April and June. Presence of larvae from different families showed significant differences. Grouping based on diversity and distribution by one way ANOV A showed the presence of two major spawning seasons in spring and autumn, plus two minor ones in summer and winter. Most of identified specimens were exclusive to neretic and intertidal zones, which live in soft clay substrate.

A strain of parthenogenetic artemia was distinguished in Shoor and Incheh lakes in Golestan province, situated south east of the Caspian Sea. Its maximum frequency was measured 942.5 and 2426.7 individuals per cubic meters during May in Shoor and Incheh lakes respectively. Gyrosigma, Nitzschia, Chroococcus and Oscillatoria were the most aboundant genera of phytoplankton. cl- and SO--4 had highest concentrations among anions.

The goal of study was to recognize species and distribution of peryphytons in the Anzali lagoon. Peryphytons are ecologically placed as a ring in biological chain between planktons and benthosis. They play an important filtering role in aquatic ecosystem. Fish fry of sturgeons, kutum (Rutilus frisii kutum), and many other species feed on them. The study was carried out at eleven station, in different places of Anzali Lagoon from June to January in 1996. 176 plant and 17 animal species were recognized. Plant species were consisted of 4 phylum; Chrysophyta (69 species), Chlorophyta (52 species), Cyanophyta (48 species) and Rhodophyta (7 species). Animal species of 8 phylum, Annelida (3 species), Arthropoda (4 species), Briozoa (3 species), Coelenterata (1 species), Mollusca (2 species), Protozoa (2 species), Kamptozoa (1 species) and Nematoda (1 species) were also recongnized. Replacement of animal and plant species was observed in all stations except station 4 (the nearest place to the sea) where animal species were dominant. Study on marine factors showed that Dreissena polymorpha was more dominant and had a high biomass. To continuation of montly sampling, making dynamic data bank and formation of periphyton collonies, we can get more precies and more comprehensive informations on dispersion, combination and growth speed of this group of creatures in Anzali lagoon.

In this study, sampling from three main fishing areas in Oman Sea was carried out from September 1995 to August 1996. Biometry and dissection were done for 273 fish. The length for samllest and largest fish was measured 30 and over 128 centimeters respectively. Observation of stomach contents showed that maximum and minimum contents were 49.6 and 2.3 percent, belonging to fishes and octopus respectively. Cattle-fish and squid were second and thrid food preferences. With the exception of fish with length between 110 and 130 centimeters which only feed on mollusks, others mainly feed on fish. Year-round presence of gonads at maturations stages of 4 and 5 in both sexes, indicate long spawning period mainly from Agust to March. The lowest and highest rate of fatness were 0.72 and 1.9 in males and 0.68 and 1.2 in females respectively. Relationship between length and weight in both sexes indicate that dolphin fish has isometric growth in coastal water of Oman Sea. Long natural spawning period of this fish in coastal waters of the Oman Sea indicates that it is a suitable fish for artificial propagation.