Stock enhancement and estimation of growth rate of green tiger prawn (Penaeus semisulcatus) and Banana shrimp (Fenneropenaeus merguiensis) released in the Persian Gulf

Present study was conducted in the Persian Gulf (Iranian waters) from 2009 to 2012. The main objective of the research was economical evalution of the stock enhancement of banana prawn (Fenneropenaeus merguiensis) and green tiger shrimp (Penaeus semisulcatus) in the studied area. Also tagging effects on the growth and mortality of tagged shrimp were studied. In banana prawn, broodstock shrimps were hatched in June. In July 2010 and 2011some of the juvenile of this species were marked by red fluorescent liquid injection and released were made at night in the estuaries of Tiab, Kolahi and Koolgan in the Hormozgan province. 84000 juveniles of banana prawn in 2010 and about 50000 in 2011 were released in this area. In Bushehr province waters, adults shrimp were reared and when juveniles reached to optimum size, some of them were tagged by red and blue coloures and were released in the coastal waters of Bandargah and Delvar. Tagging and releasing program of green tiger prawn was performed in 2010 and 2012. A total number of 8000 prawn in 2010 and about 30000 juveniles prawn in 2010 were released. Activities for recaptured shrimps were informed by posters describing the tagging program that were distributed to local peoples, as well as local magazines, and a tagging program awareness film was broadcast on national television three times prior to the shrimp fishing season and during catch season. To encourage people to report recaptures a reward of two handered thousent riales was paid for the return of each marked shrimp accompanied by information. Economical evaluation of banana prawn was performed based on releasing and recaptured program in 2011. As it mentioned in this year 50000 of juvenile shrimp were tagged and released. At the same time 4700000 of unmarked shrimp were released in this area. In the shrimp season 11 (./022%) of tagged shrimp were recaptured. Movements of tagged shrimp were northwesterly to released area. Weight average of tagged prawns was 1.2 gram. Mean weight of the recaptured prawns was 22.06±4.9 gram. Body weight Growth of the recaptured prawns was between 16-26 grams with the growth speed of 0.88-1.41 per week. The number of recaptured prawn to the released prawn was 0.022 percent. Based on the released prawns (4700000) to the recaptured percent (./022%), about 103400 of released shrimp with mean weight of 2.5 tones were observed in the Hormozgan shrimp catch. The average price of shrimp in the studied year in the local market was 85000 Rials per kilogram. These results showed that the ratio of profit is 210 milion riales. In the taggiing program of green tiger prawn in the Bushehr waters only one recaptured shrimp was observed in the catch season (2012). Total weigth and total length of this prawn was 99 gram and 22 centimeter respectively .given the small percentage of the recaptured, economical analyses was not performed on this species. The effects of tagging on the growth and mortality of green tiger prawn were studied. The present study was carried out in the shrimp research station in Bandargah and Abzistan shrimp Hatchery Company in Delvar during 2010 and 2012. The accuracy of the study was more rialable in 2012. In this year growth and mortality of juveniles that was marked by red and blue coloures, were studied in both area Bandargah and Delvar. In Bandargah, three tanks of 300 l each with 30 specimens were used for untagged shrimp as a control group, and tagged with injected liquid fluorescent during 98 days. Length and weigh of 10 specimens were measured evenly in different times. ANOVA results (α = 0.1 and α = 0.5) showed no significant differences between length growth of tagged shrimp and control group. The mortality of two groups was evaluated by numbering of remained shrimps and the average of survival was 52 percent in the tagged and 44.5 percent in tagged shrimps. In the Delvar station, Abzistan Company, the specimens were kept in the 9 tanks each 300 l that included of 30 untagged shrimps, 30 blue tagged shrimps and 30 red florescent tagged shrimp. The growth and mortality of this station were evaluated during 110 days. The growth rate of the specimens were measured and recorded evenly. The results of ANOVA (α = 0.1 and α = 0.5) showed no difference significantly in the weight growth of tagged and control groups. The mortality rates among the control group, red tagged and blue tagged were 63 percent, 59 percent and 40 percent. The mortality of the groups was differences in the two stations and it seems the management and environmental conditions were more affected on the mortalities. The results of the study show that the ratio of profit to the coast is 0.46 that is covering half of the coasts, so that the expenditures are two times more than profit. This result is the minimum of economical value of stock enhacement of shrimp. The results of study showed that the injected tags into the body tissue of shrimp has no affected on the growth rate and mortality. Iranian Fisheries Science Research Institute Published