Performance of a Square Mesh Panel in Capturing Immature Indian Halibut in Shrimp Trawlers in the Persian Gulf

The performance of a square mesh panel (90 mm stretched mesh size) on reducing the catch of immature Psettodes erumei Bloch and Schneider, 1801 smaller than Lm50% value was tested in a small-scale shrimp-trawl fishery along Hormuzgan coasts in the The Persian Gulf. During shrimp season, 25 trawl hauls were carried out and a total of 371 P.erumei was caught in the codend and cover net. Length ranges of Indian halibut caught in the codend and cover net were 8-35.2 cm and 9-25 cm and their mean lengths were 24.58±5.8 cm and 15.29±3.5 cm, respectively. Two sample Kolmogorov-Smirnov tests detected significant difference in the size-frequency distribution of P.erumei between codend and codend plus cover net (Dks= 2.464 P< 0.001). The results of two-sample t-tests detected a significant difference (P<0.001) in the mean length of P.erumei caught in the codend and cover net. The escape rate, based on number was 28.8%. The length of 50% retention (L50) was 17.2 cm and differed greatly from the Lm50% (37.3 cm). The square mesh panel efficiency was not so acceptable. An increase in mesh size of codend or mesh size of square mesh panel during shrimp fishing season will be required to delay capture until fish is reached Lm50% and Lm value. It is more likely that samples of immature Indian halibut were influenced by the spatial and temporal distribution of the species as well as mesh size of panel, weak swimming capability of P.erumei and body form of species.