Length Weight Relationships of Rutilus caspicus during 2016-2018 in the Southeast Caspian Sea - Golestan province

One of the most important data in the stock assessment models is knowing the coefficients of Length weight relationships of a species. In this study, the results of the length weight relationships of the Caspian roach in the years 2016 to 2018 were evaluated to investigate the trend of changes in coefficients a and b based on nonlinear regression. The total length of the study population in this study was from 12/31 to 30.02 cm and the total weight was between 28 and 346 g. The maximum length and weight were recorded in 2016, 27.26 cm and 262 g, in 2017, 22.28 cm and 178 g, and in 2018, 30.02 cm and 346 g. Relationship between population length and weight in 2016, W= 0.054TL3.26 (r2 = 0.94), in 2017, W= 0.0032TL3.47 (r2 = 0.96) and in 2018, W=0.0090TL3.09 (r2=0.74) was obtained. The results showed that the growth pattern in 1995 is allometric negative and in 1996 and 1997 is allometric positive for this species in the study area. The condition factor was 0.53±0.05 in 2016, 0.35±03 0.03 in 2017 and 0.94±0.04 in 2018.