Investigation of length-weight relationship of fish caught in recreational fishing in Golestan, Mazandaran and Guilan province

Extensive lack of data and information gaps for recreational fishing necessitate knowledge of the species caught to establish aquatic reserve management. Therefore, in the present study in 2021, by collecting lenght and weight information of major recreational fishes in the main recreational fishing area was done with hooks. The results showed that between the length and weight of common carp in Golestan, Mazandaran and Golestan provinces, the equations were 0.444004x4004 and 0.4652/168x2/4652 with a correlation of 90%, 95% and 94%, respectively. Between the length and weight of grass carp in Golestan, Mazandaran and Golestan provinces, the equations 0.2398x2 / 2398 and 0.6333x2 / 1313 and 30.3x1 / 7769, respectively, with a correlation rate of 96%, 94% and 90% were established and between the length-weight of yellow fish in Golestan, Mazandaran and Golestan provinces were equations of 0.494x3 / 113, 1101x1 / 4615 and 982x1 / 1381, respectively, with a correlation of 89%, 90% and 97%. The results showed allometric growth of all three species in all studied provinces. The allometric growth rate of common and yellow carp was positive in Golestan province and negative in Guilan and Mazandaran provinces. Allometric growth rate of herbivorous carp was negative in all studied provinces .