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

Reproduction and feeding biology of Sind Sardinella (Sardinella sindensis) from coastal waters of Qeshm Island, Persian Gulf

Sardinella sindensis is one of the dominant small pelagic fishes of Persian Gulf, especially in Qeshm Island's coastal waters. Investigation on some of the biological parameters of Sind Sardinella was carried out from April 2005 to March 2006. Sind Sardinella is economically the most important small pelagic fish species mainly caught by double boat purse seine in this area. Reproductive studies showed that peak maturity season occurred in May. The female to male ratio was calculated at 1:1.08 and chi-square analysis showed the difference in ratio was not statistically significant (P>0.05). LM sub(50) is attained at a total length of 112 mm. The average absolute and relative fecundity were estimated to be 23396 ( plus or minus 5337) and 739 ( plus or minus 117), respectively. This fish is planktonivore, and we found the diet of the species consisted of a broad spectrum of food types, but Crustaceans were dominant, comprising 44% of the food. The other major food groups and their share w....

POPULATION DYNAMICS OF SIND SARDINE, SARDINELLA SINDENSIS, IN COASTAL WATERS OF QESHM ISLAND

Sardinella sindensis is economically the most important small pelagic fish species in the coastal area of Qeshm Island. Population dynamics of Sind sardinella from Qeshm Island coastal waters, during April 2005 to March 2006 were studied. The asymptotic length (Lx) and growth coefficient (K) were estimated at 178mm and 1.11yr-1, respectively. The minimum and maximum T.L was recorded at 42 and 172mm respectively. The value of to was calculated at -0.17, and Tmax was estimated at 2.7 year. The Yon Bertalanffy growth equation was obtained at L (t)=178 (1-exp(-1.1 1(t-(-0.17))) for this species. Total mortality (Z) rate was estimated to be 3.48yr-1 (r2=0.88) on length-converted catch curve method. The rates of natural mortality (M) based on Pauly's empirical equation, fishing mortality (F) and exploitation ratio were estimated at 1.13y-1, 2.35yr-1 and 0.67, respectively. Four cohorts were distinguished annually based on Bhattacharya's method with mean length of 56,89, 107 and 141mm. Maximum recruitment was in September at 18.62 percent. The length-weight relationship was determined as W=0.000005 L3.1399

REPRODUCTION AND FEEDING OF BUCCANEER ANCHOVY (ENCRASICHOLINA PUNCTIFER) FROM COASTAL WATERS OF QESHM ISLAND, THE PERSIAN GULF

Encrasicholina punctifer is one of the dominant small pelagic and economically most important fishes of the Persian Gulf, especially in Qeshm Island's coastal waters. Specimens of the fish were collected monthly from the fishing area in the coastal waters of Qeshm Island by random sampling method. Investigation on biological parameters of E. punctifer continued from April 2005 to March 2006. E. puncqfer is mainly caught by double-boat purse seine in this area. Reproductive studies showed that maturity season of the fish occur in August. The sex ratio fulfill the theoretical 1:1 (P>0.05). LMSO was attained at a total length of 84 mm. The absolute fecundity was estimated at 1217±331. We showed that the species is planktonivore, its diet consisted of a board spectrum of food types, but crustaceans dominated the food with copepods and their eggs, naplius and semi digested copepods constituting 54% of the diet. The next major food groups found in the diet of the fish were Cyanophyceae 21%, Bacillariophyceae 11%, fish egg and scale 6%, Dinophyceae 4%, with Euglenahyceae, Chiorophyta, Dinoflagellates and others items consisting only 4% of the diet. Analysis of monthly variation in the stomach fullness indicated that feeding intensity fluctuated throughout the year, with the highest value in winter. Vacuity Index indicated this species was of semi-voracious appetite fishes