an investigation on caviar quantity status of sturgeon from fishing grounds of the southwestern caspian sea (guilan province)

the aim of this study was to investigate on obtained caviar quantity status of sturgeon at fishing grounds of the southwestern caspian sea. data of catches by means of fixed gill nets in sturgeon fish fishing grounds and beach seine were used during 5 years survey (2005-2009). a total of 1361 female sturgeon was caught including: 788 acipenser persicus, 410 a. stellatus, 60 a. guldenstaedti, 70 a. nudiventris and 33 huso huso. the total amount of obtained caviar declined from 1652 kg (in 2005) to 925.06 kg (in 2009) that this reduction was about 44%. based on pearson test, the relationship between caviar amount and time was linear and had negative and significant correlation (p= 0.015). additionally, the trend of obtained caviar amount reduced highly in the west coasts of guilan province (p= 0.016), but it was almost fixed in the east coasts of guilan province (p= 0.514). furthermore, the maximum and minimum of obtained caviar amount were 66.60% and 4.19% that belong to a. persicus and a. guldenstaedti, respectively. the maximum and minimum of relative frequency caviar (%) were 72.90 and 3.27 for high quality caviar and compressed caviar respectively that differed significantly (p