Biology of the penaeid shrimp populations exploited by Estuarine Set Bagnet

Results of analysis of part of the data collected during October, 1989 to December, 1990 are given on the biology and catch assessment studies on the Estuarine Set Bagnet (ESBN) from six sampling stations covering the entire coast line of Bangladesh. Length frequency analysis of seven most commonly occurring penaeid shrimp species have been done with complete ELEFAN software package. The result of exploitation patterns indicate that all penaeids except P. stylifera are being over exploited on their way back to the Sea from the nursery ground. This appeared to be the instances of serious growth over fishing. These species are exploited at a size much lower than the length at first maturity, which strongly suggests a complete withdrawal of the bagnet fishery from the coast of Bangladesh.

Reproductive biology of Catla catla in the Udawalawe reservoir, Sri Lanka

The reproductive biology of Catla catla (Hamilton-Buchanan) in the Udawalawe reservoir was studied from June 2007 to December 2008. Samples of eggs from Indian major carp C. catla were collected from fish landed in the reservoir and analysed in the laboratory to assess the reproductive characteristics. C. catla. Cirrhinus mrigala, exotic Cichlids and Labeo rohita accounted for 62.2%, 21.0%, 12% and 1.0% respectively of the total landings in the Udawalawe reservoir during the study period. Gonads of C. catla were collected in the field and examined in the laboratory to determine the stage of maturity and fecundity. Data on fish length and gonad weight were collected to estimate the gonado-somatic indices (OSI). Landed catches were also examined in the field to determine the sex ratio of C. catla in the catch and was found to be 1:5.6 male to female. Results of fecundity estimates revealed that C. catla females in the Udawalwe reservoir were fully mature in June and October of the year. From the monthly variation of OSI, two recruitment pulses per year were evident. The length of the body at first maturity in female C. catla in the Udawalwe reservoir was estimated to be 74.2 cm.

Examining the possibilty of multiplication and breeding of (Schizothorav [sic] zarudnyi) in order to restoration of regional aquatics reservations of Hamoon Lake and taking its advantag [sic] for aquaculture

Schizothorax zarudnvi, is an endemic fish of east country waters. (Triple lagoons of Hamoon and relevant water resources) that in the world it is reported in this resource specially. This fish named Hamoon mahi is one of the most economically valuable species in this region. Because of the recent years droughts, Hamoon logoon has been drive since 2000. Also, semi-wells (a semi natural resource) were affected drastically by recent drought years and their volume reduced to nearly one third of their real volume and resulted in changing at growth and reproduction physiology process in Schizothorax zanidnyi, brood stocks. Beginning of this project was done from October 2003. It's field studies begun (brood catching) since November 2001 by two methods including entangling gairs and at semi wells of Sistan that (Beach seine) had maximum rate of preparing qualified brood stocks. Broods transferred to Cyprinidea reproduction work shop of Zahak and after taking primary measures they stored in to the edaphic pools. Increasing the success safety factor (coefficient) for artificial reproduction of Sthizothorax zarudnyi , identifying the appropriate tune for Hormonal acceptance (physiological preparation of broods) is needed , so this important work was done regularly by histological studies and GSI measurements since November. Highest GSI rates of females (%80.51) and highest IV stage abundance of sexual maturity (%l 00) were observed an march. On the base of this date, Hormone therapy was done on broods on march. The used hormones are as follows Hypophysis. extraction, GnRHa and Anti Dopamin at the dozes of 3-6 ml, 20-30kg and 10-15 ml per kg body weight respectively and 2-3 times from 11-12-80 they were injected. Injected broods kept in to two circumstances, flow-through (rounded pool) and stagnant systems. In stagnant system 14 and 19 individuals of female and male (Schizothorax zauiulnri) broods, respectively injected in 11th, 15111, 19th, and 24th of march 1380. Non of the injected broods in 11 and 15 and 19th march (in stagnant Condition) answered to Hormone therapy. After final injection broods had general less activity and a few of them died. Mean temperature of brood pond waters (daily) which were injected. Fluctuated between 10-25-13. 63°c but injected broods on 24th march had different characteristics. They had pale color and had few fecundity. In this stage of injection they hadn't any successful vulation. After injection, Mean daily water temperature was 15, 88-17, 54°c. In Flowing system, 13-16 individual of males and females respectively were injected on 15th, 19th, 22th and 23th march. None of injected producers on 15th and 19th march with mean daily water temperature of 10, 25-12°c were prepared for spawning but injected producers on 22nd an 23th march with mean daily water temperature of 13.5-1 rc responded about 75-100 percent. (Schizothorax zarudnyi) brood stocks were prepared for spawning after 353-428 hours/day from final injection. Diameter of obtained eggs (before fertilization) was between 1.9-2.3 min and of fertilized eggs was 3.8mm. Fertilized eggs of (Schizothorax zarudnyi) were hatched after 6-7 days with mean water temperature of 17.08°c. Mean length of on one day larvae was 9.47 mm. Larvae was 9.47 mm. Larvae adsorbed the whole yolk sac after , 5-6 days at 17- 1°c and were prepared for releasing in to edaphic pools. Because of the lack of necessary and complementary facilities in the region , they had to release them in to veniros and growing them for 8 days. At the end of 18th day , 35000 larvae (at first) released into an edaphic pond with a volume of 150m2. After growing them for one moth , mean length and weight of new hatched larvae was 29.41 mm and 1.12►r , respectively. With respect to results of this investigation , artificial reproduction of (Schizothorax zarudnyi) Can be possible at 14-17°C and flowing water with Hormonal treatment. It -s breeding has increased development than other cultural specious in the region. Due to high economical value of this specious in Sistan and ti-s specialization east waters of Iran and having high resistance and proper growth There is a need of it's development and reproduction and culture in fish culture fanns (edaphic ponds• two-purpose pools) at the region and country.

Fishery biology of Indian mackerel in Sri Lankan coastal waters

The objective of the project was to determine the reproductive biology of Indian Mackerel (Rastrelliger kanagurta) using Gonado-Somatic Index (GSI); length at first maturity; spawning season; morphological characteristics; and stomach contents.

Survey of reproductive physiology on Epinephelus coioides in Khozestan province, Persian Gulf

Epinephelus coioides (family serranidae) is protogynous. This species is one of the most important fishes in food chain of marine proteins of persian Gulf. Therefore knowing about the reproductive biology and physiology of this species is an important role on aquaculture procedures. Monthly samples of Epinephelus coioides were obtained in khozestan Bahrekan province from 2001 to 2002 for annual variation of base line of reproductive hormone. The hormones such as: 17-B estradiol, Testosteron, Progesterone, Gonadotropin I ,II GTHI, II) and cortisol have assayed and also different stages of gonads from the histological point of view were studied by light and electron microscope. Aditional to morphometric and fecundity measurements, the important factors such as : Gonadosomatic index (GSI) Hepatosomotic index (HSI) and Condition factor (KF) were also studied. Environmental factors such as temperature, salinity, photoperiod and pH were analyzed for the determination of effective factors responsible for the changes of reproductive cycles. The flactmation of estroid hormones and gonadotropines show a significant variation in different stages of maturation, e.g 17-B estradiol's concentration in the third stages, GTH II in fourth stages of sexual maturation or final oocyte maturation, plasma Testosteron in post ovulation and Progesterone during maturation indicates the highest levels of above mentioned hormones. The total calcium concentration was high in all year. calcium concentration was correlated with GTH II synthesis and increases with GTH II in June. 17-B estradiol concentration was also correlated with GSI. The high concentration of cortisol throughout the year was an index of stress and development of ovary maturational processes. This species was protogynous synchronous hermaphrodites , and belongs to annual spawning species, being monandric. The sexual transition was found to occure in individuals of 51.2- 105 cm in length. GSI and HSI level confirms the time of spawning period is in April- June. Electrone microscopic studies of gonad tissues showed some changes in mitochondria and endoplasmic reticulum in the post ovulation, maturation and post spawning periods. During the monthly sampling the biochemistry of tissues variations indicated decrease in protein and lipid content, but an increase in water content of spawning fishes which was correlated to the maturation of Epinephelus coioides . sex ratio indicative of higher frequences of females to males during monthly sampling periods. The females were smaller than males in sizes, therefore the females lived in 8-15m depth, but males were living in upper limits of depth. The results indicated that the temperature was the most effective parameter in reproductive cycle of Epinephelus coioides and the mean 24°c was a convenient temperature for spawning. Photoperiod was the second effective. factor on the reproductive cycle for this species. It seemed that the increase in the photoperiod between January to May caused a development of the oocyte. Regarding to the results of this research, it seems that the period of spawning in Epinephelus coioides is in May- June and the aquaculture procedure of Epinephelus coioides could be performed in the above mentioned periods.