The effect of some environmental parameters on recruitment of golden grey mullet in the Caspian Sea during 1991-2018

This study was conducted to determine the effects of some environmental parameters (sea surface temperature SST, sea level SL and Volga river water volume VRWV) on biomass of golden grey mullet Chelon aurata in Iranian coastlines of the Caspian Sea. In the study, the catch and population parameters of golden grey mullet during the years 1991-2017 used as input data. In these years, the catch of golden grey mullet ranged from 1425 to 6600 mt. The total biomass increased from 10870 mt in 1991-92 to 20950 mt in 2000-01 and then declined to less than 8800 mt in 2017-18. Also, the biomass of 2 years (as recruitment R) increased from 1757 mt 1991-92 to 2617 mt in 2001-02, then declined to 387 mt in 2016-17. There is a significant negative relationship between R-SST (p<0.017), and a positive relationship between R-VRWN (p<0.024) and R-SL (p<0.002). By using stepwise regression, among three environmental parameters, only SL had significant effects on R biomass (R2 = 0.339). It seems that the SL has the main role in the biomass of golden grey mullet in the Caspian Sea. Therefore, an ecosystem-based approach to Management is required to sustainably exploit of golden grey mullet stocks in the Caspian Sea.