Investigation of fishing changes and growth pattern of Huso huso (Linnaeus, 1758) in a 13-year period in fishing grounds of Golestan province

This study aimed to investigate the changes and growth pattern of Beluga sturgeon fishing in fishing regions of Golestan and biological characteristics of this species over a period of 13 years. The highest amount of Beluga sturgeon fishing was in 2008, when a total of 95 pieces of this species were caught from five fishing grounds in Golestan province, and the lowest amount was caught in 2020, when 3 pieces of this species were caught. The results showed that the highest average total length was observed in 2020 and the highest total weight was observed in 2017 and the lowest average total length and total weight was obtained in 2011.The sex ratio of male to female elephant fish in the thirteen-year period was 0.66:1, which was significantly higher than the female population (X2=19.69, p<0.05). The range of growth coefficient (b) for the population of Beluga sturgeon between 2008 to 2020 years varied from 2.56 to 3.97. The results of Pauli test for the relationship between length and weight of Beluga sturgeon species showed that the growth pattern of this species in 2008 and 2010 were negative allometric, in 1393, 1396 and 1397 positive allometric and in 2009, 2011, 2012, 2013, 2015, 2016, 2019 and 2020 were isometric. In general, in a period of 13 years, the amount of elephant fishing in the coasts of Golestan province decreased by more than 90%, so in this region, this trend for Beluga sturgeon is among the most endangered species, concluding an alarm for conservation of this valuable species in Caspian Sea..