Reproductive biology of Rachycentron canadum in the Persian Gulf (Hormozgan Province waters)

We collected 478 specimens of Cobia, Rachycentron canadum, from Hormozgan province waters during October 2005 till September 2006, and studied reproductive parameters such as spawning season, sex ratio, maturity stages, fecundity and ova diameter. The maturity and spawning season were investigated through macroscopic and microscopic (ovarians histology) observation. Studying average gonadosomatic index (GSI), the percent of maturity stages and ova diameter average changes revealed that the spawning occurred from July to the beginning of September

Study of existing biological communities in Hormuzgan province waters (Persian Gulf) for installation of artificial reefs

To determine the suitable locations for installation of artificial reefs we studied Persian Gulf waters (Hormuzgan province) from December 2006 to March 2007 seasonally. The area was stratified to 10 transects and each transect was divided to three layers and used random sampling method. Habitats of fauna and flora including: Communities of corals, seaweeds, sea cucumbers and sea grasses, and sedimentation depth using SCUBA diving method were studied in each transect and layer. Sea grass communities existed in some places with below 10m depth of Bandar Mesan, Bandar Kang, Kish Island and Bandar Chirooyeh transects. Also, seaweed habitats were seen in Bandar Mesan and some areas in Bandar Lengeh and Kish Island in 10-20m depth transect. The study of coral and sea cucumber communities indicated presence of Acropora sp. habitats in Bahman jetty, Bandar Mesan and Bandar Bostaneh transects , and Porites sp. habitats in Hengam island transect, Holothuria sp. habitats in Bandar masen and Bandar Lengeh transects and Stichopus sp. habitat in Hengam Island transect. All these species were found in shallow waters bellow 10 meters depth and showed a patchy distribution. Sedimentation depth results showed a statistically significant difference between layer <10m in Bandar Salakh and the same layers in other transects, also between layer 10-20m and 20-30m in other transects. Based on the sedimentation depth and habitats studies, we recommend layer 10-20m in Bandar Lengeh area and Bandar Lengeh to Hendurabi Island area as suitable for artificial reefs installation

Study of biotic communities for artificial reef placement in Hormuzgan Province waters, the Persian Gulf

Persian Gulf waters (Hormuzgan Province) were studied from seasonally to determine the best locations for installation of artificial reefs. The area was stratified for 10 transects and each transect was divided into three stations: Station 1 for waters below 10m, station 2 for waters between 10 and 20m and station 3 for waters between 20 and 30m deep. Habitats of fauna and flora including communities of corals, seaweeds, sea cucumbers and sea grasses and sedimentation depth through scuba diving were studied in each transect and sub-transects. Sea grass communities existed in some spots within station 1 in Bandar Mesan, Bandar Lengeh, Kish Island and Bandar Chirooyeh transects, while for station 2, sea grasses were absent from Chirooyeh transect and present in Bandar Mesan, Bandar Kong and Kish Island transects. Also, seaweed habitats existed in station 1 in Bandar Mesan transect and some areas in Bandar Lengeh transect. Study of coral and sea cucumber communities indicated existence of Acropora sp. habitats in Bahman jetty, Bandar Mesan and Bandar Bostaneh transects, Porites sp. habitat in Hengam Island transect, Holothuria sp. habitats in Bandar Mesan and Bandar Lengeh transects and Stichopus sp. habitat in Hengam Island transect. All of these habitats were located in station 1 and had patchy distribution which was drawn in GIS software. Calculated sedimentation depth using degree scale in different transects demonstrated statistically significant differences between station 1 in Bandar Salakh transect and the same stations in other transects, also between station 2 and station 3 in other transects (P<0.05). The result of sedimentation depth assessment showed that station 2 in Bandar Lengeh area up to Hendurabi Island were better for artificial reefs installation compared to south of Gheshm Island with the exception of Bandar Kong and Bandar Chirooyeh transects

Propagation and rearing larvae of black lip pearl oyster Pinctada margaritifera until spat stage

The black lip pearl oyster Pinctada margaritifer is one of the three valuable species of pearl oyster for the cultured pearl industry of the world. Due to its high economical value, endangered species status in Persian Gulf, its historical and social importance, and the technical feasibility to produce pearl oysters seeds in hatchery, Persian Gulf Shellfish Research Center in northern part of Persian Gulf, Iran developed the spat production of this important species for the first time. Ten pairs of matured P. margaritifera broodstocks collected from the pearl oysters beds in Lavan Island, Persian Gulf during Jun-July 2004, were transferred to the hatchery at the Persian Gulf Shellfish Research Center. All the broodstocks were thoroughly brushed free of fouling organisms and washed with freshwater. The oysters subjected to thermal stimulation (temperature elevated from 20 °C to 30 °C). Around 70% of oysters spawned approximately after an hour. Fertilization was normal ranging between 97-98% and early larval development was viable. Six one-tone fiberglass tanks holding 1μ filtered and UV sterilized seawater with gentle aeration were used for culturing the larvae. Pure culture of three micro algae, Isochrysis aff galbana ,Chaetoceros calcitrans and Chaetoceros mulleri were used as diets. Feeding started with I. galbana and a combination of I. galbana and C. calcitrans from day 4 of rearing period. The initial larval density was 50 larvae/mL at D-Shape larval stage and reduced to 1 laravae/mL at later stages. The larvae reached to the D-Shape stage between 20-24 hours, Umbo stage on day 6-12, Eye-spot on day 17-21and Pediveliger and Plantigarad on day 22-30. Oyster Spats were settled on collectors after 32 days of rearing period. Survival rate was 70% at D-Shape stage, 60% for Umbo stage, 50% for Eye-spot and 30% for Spat. Total produced spat 123500 in two years and realized and transferred 23500 spat to sea

The study of fluctuation of large pelagic stock (yellowfin tuna, skipjack tuna, longtail tuna, Narrow-barred Spanish mackerel) in order to optimum exploitation in the Persian Gulf & Oman sea

The study of fluctuation of large pelagic stock (yellowfin tuna, skipjack tuna, longtail tuna, Narrow-barred Spanish mackerel ) in order to optimum exploitation in the Persian Gulf & Oman sea This study was carried out from 2005-07 in order to acquire some biological characteristics and population dynamic parameters for stock management and responsible fisheries. Thunnus albacares (yellowfin tuna), katsuwonus pelamis (skipjack tuna), Thunnus tonggol (longtail tuna) and scomberomorus commerson (Narrow- barred Spanish mackerel) were sampled. In total, length frequency of 9345 specimens of yellowfin tuna were analyzed. Size range was 37-172 cm. Teleost fishes were the most dominant prey species observed in this study (42%), Occurrence of Potunus Pelagicus was found to be the second (28%).Sthenoteuthis oualaniensis (22%), Natosquilla (5%) and octopus (3%) also were identified in the gut content of the yellowfin tuna. Length of maturity (50%) of yellow fin tuna was estimated 77.2 cm and spawning season was started from May. 8443 specimens of skipjack with size range of 32-90 cm were sampled. 48% of food items were teleost fishes. Squid and shrimp were also identified. Spawning season was begun from June. Growth parameters & fishing mortalities of yellow fin tuna and skipjack tuna were also estimated. Size range if longtail tuna was from 26-125cm Length infinity was estimated 132.3 cm with growth parameter of 0.35 per year. In total 10451 specimens of narrow- barred Spanish mackerel were sampled. Size range was from 20-164 cm. Teleost fishes were the most dominant prey species observed in the study (91.3%). Crustaceans (0.6%) and Indian squid (0.2%) also were identified in the specimens. Length maturity (50%) was estimated 83.6cm

Assessment of dominant species food relation in habitats of commercial shrimp in Hormuzgan Province waters (Persian Gulf)

Shrimp is one of the most important aquatic animals,that have decreased their stocks in Hormozgan province, especially the eastern province . Evalution of food interaction in shrimp habitats (Estuaries of Tyab, Yek shabeh, Laft and Khouran) was studied with Ecopaht with Ecosim software (ver. 6.5) in Hormuzgan province. After entering the input components (Biomass,P/B and Q/B), model was balanced and outputs were extracted. Results of trophic levels, was close to previous research in these areas for all species in estuaries. Maximum of ecotrophic efficiency was belonged to phytoplankton and other preys that were observed in predator stomachs. Biological future of food web estimated to be threatened based on omnivore index of planktonivore groups. Maximum food competition between the four food models was estimated in detritivores communities in Laft estuary, that may be related to the low density of mangrove in this region. Khamir estuary ecosystem could be more stable, because each impacting group had its own separate ecological niche and special predation territory. key indices in each of four food models were related to phytoplankton communities, this key role has been demonstrated much better in Yek Shovy estuary than others. Future of commercial shrimp stocks will be expected to be in better condition in Khoran estuary compared to other three ones, due to selection of separate ecological niche by predators and High biomass of detritus in this estuary