Iranian Scientific Fisheries Journal
Year:2001 | Volume:10 | Issue:1|Papers Count:7

During one year period, 603 specimens of white cheek shark (Carcharhinus dussumieri) were examined monthly. Results indicated that, sex ratio is 1:1.13 (Male to female). Maturity occured along with increase in ovary and testis weight, increasing ova diameter, uterine width, and also increase in clasper length and its calcification. Size at first maturity of males was 670mm (Total Length). Size at 50% maturity (LM50) was 690mm in males and 680mm in females (T.L.). This shark has placental attachment and an umbilical cord. Number of emberios ranged from 1 to 5 and mainly were 2. Maximum length of male and female emberios were 380 and 385 mm (T.L.) respectively. Pubs had umbilical scars which remains for some times. Lengths ranged from 345-490 and 350-425 mm (T.L.) for males, and females respectively. Sexual reproduction continue throughout the year, with a pick of mating in spring and a distinct pregnancy period from October to April and a pick of parturition in June to July.

Aquatic insects as bioindicators and in order to determine water quality in relation to organic matters were used to evaluate the water quality of Fars Province streams and two drainages. Eighteen springs that were presumed to be undisturbed by human activities and two others, disturbed by human activities were chosen to show the effects of the pollutions. Insects fauna of each stream were sampled seasonaly in a year period by D. framed aquatic net. Each species (with index value) was used for calculating the biotic index pollutants of these water resourses. Water quality determined for 18 springs and two drainages. Based on these values, Chel Cheshmeh, Salavat, Shirin and ... streams had excelent water qualities (no organic pollution). Paeen, Tang-e-Bostanak and Kamfirooz had good water quality with possible slight organic pollution. Kavar and Barm-e-delak streams had fair water quality (significant organic pollution) and two c1rainages had poor water qualities (very significant and sever organic pollution). To compare the results, some physical and chemical parameters of water were measured.

This study was carried out to evaluate some biological reproductive aspects of Sillago sihama, a valuable gonochoristic species living in coastal areas of the Persian Gulf, from August 1997 to September 1998. Forthy fish were caught each month, and their tota11ength, standard length and total weight were measured. Fish were then disected and liver, stomach and gonads were weighted. A piece of gonad samples of different stages of maturity were taken and placed in bouins fixative. Minimum and maximum fish length were 9.8 and 23.5 centimeters respectively. Length-weigth relationship showed isometric growth in this species. Gonadosomatic index (GSI), gastrosomatic index (G I) and hepatosomatic index (HSI) were also measured. GSI was averaged 4.5 in March for females and 1.50 in April for males. Histological evidence showed that this fish has an ovary with free riped ova at the same time and spawn once a year in spring (synchronus). Sex ratio was measured (1 M: 1.2 F), (a=0.05, df=l, X2=5). Size of maturity were 11.4 and 12.6cm for males and females respectively.

Biological study on Gorganrood River was performed from November 1990 until October 1991. Fortheen sampling stations along the 200km distance from Chai Qushan to estuary. Fish distribution was not similar in all parts and was more dense in lower parts. Density of common carp, roach and white fish were more considerable particularly in spawning s-eason. Density of benthic organism was very low and blood worms (Chironomidae) and shells of dead mollusca were obtained. Frequency of phytoplankton maximum in September and minimum in January. Bacilliarophyceae, Chlorophyceae and Mynophyceae had more biomass during studying period. Zooplankton had maximum biomass in September and minimum in February and March. Among zooplankton, Protozoa and Rotatoria had maximum biomass.

Golden snapper is a species of family LUTJANIDAE which is distributed in Hormozgan waters. Biological (specially reproductive) study of each species is necessary both for the cultivation and stock assessment of that species. 613 specimens were sampled monthly from May 1996 to July 1997 in Hormozgan waters, for determining some reproductive factors such as Lm50, spawning season, fecundity and sex ratio. Spawning season was determined based on GSI from April to July with a pick in August. Lenght of fish in which half of females were matured (Lm50) was obtained at length of 44cm. Fecundity range was calculated in each month. Maximum fecundity was 2539592 in July. This fish is a total spawner species. Sex ratio was 1.23 female to 1 male. Chi square test was applied to compare female and male frequency, and did not show a significant difference (p=0.012) yearly.

This research was conducted to evaluate total petroleum hydrocarbon (TPH) in the sea water of Mazandaran and Golestan provinces situated in the southern part of the Caspian Sea, during fall 1996 to winter 1997. 330 water samples were collected from the depths of less than 5 meters and 10 meters in seven selected stations. Total petroleum hydrocarbon (TPH) was determined using IR instrument according to ASTM (1995), ROPME (1989) and Russian standard method (1992). As a result, the minimum and maximum TPH of water were 0.11-0.63 and 0.11-2.9 mg/l, in less than 5m depth and 0.078-0.627 and 0.083-0.648 mg/l, in 10 meters depth respectively. The statistical analysis indicated that there was a significant relation between stations and seasons (P<0.001), but there was not any significant difference between the less than 5m and lam depths (P<0.346). As a conclusion, this region was found to have very low oil pollution comparing to Baku region in Azarbayjan, but higher than the Mediterranean region concerning the fact that no sign of oil activities were observed in this area. Therefore, southern part of Caspian Sea has the lower pollution rate because of the low industrial sewages from coastal rivers and oil platforms.