the relationship between gonadal and blood serum biochemical parameters in bloodstocks of the caspian lamprey, caspiomyzon wagneri kessler 1870

environmental pollutions and deterioration of spawning grounds have threatened the caspian lamprey. these problems have led to the need for special protection of the species in many localities, nevertheless, there is surprisingly few information about the physiology of caspian lamprey. thus, the present study aimed to evaluate the correlations between blood serum biochemical parameters and gonadal parameters in the caspian lamprey to investigate its physiology during its final migration. there was a positive correlation between magnesium (r = 0.88, p < 0.01), calcium (r = 0.72, p < 0.05), and phosphorus (r = 0.77, p < 0.05) concentration with gsi in the females but an inverse correlation was observed between magnesium (r = -0.73, p < 0.05) with gsi in males. also, there was a significant correlation between total protein (r = 0.885, p < 0.05), cholesterol (r = 0.77, p < 0.05), and glucose (r = 0.77, p < 0.05) in serum blood with gsi of females. the observed correlations may be attributed to the exceptional characteristics of c. wagneri which does not feed during migration and uses reserved protein and fat of the muscles.