The effect of changes in conical lift net mesh size on catch composition of Caspian Sea Sprat in Amirabad port

In the past, Anchovy fish was the most caught species between Caspian Sea Sprats, but in recent years due to collapse in Sprats stocks, Clupeonella cultriventris has been the most dominant species. According to change in catch of dominant species, it seems necessary to review the related fisheries equipment. Therefore, a study was conducted to investigate the effect of mesh size on length frequency of catch fish in the Amirabad fishing port in the months of July and August 2017. In this regard, fishing plan was done with three mesh size of 5.5, 7 and 8.5 in three nights. Weight and length of 3000 specimens were measured in more than 10 fishing efforts. The results showed that more than 99 percent of the fish caught was Clupeonella cultriventris. The lowest average length was belong to C. cultriventris and observed in mesh size of 5.5 mm. The length comparison of the caught fish between mesh size of 7 and 8.5 mm and 7 and 5.5 mm showed a significant difference but there is not any significant differences between mesh size of 5.5 and 8.5 mm. It seems that caught from different populations to be the main cause of the results.