Hematological Features of Codfishes (Gadidae) from the Northwest Pacific

Hematological parameters of the peripheral blood of the walleye pollock Gadus chalcogrammus Pallas, 1814, saffron cod Eleginus gracilis Tilesius, 1810, and Pacific cod Gadus macrocephalus Tilesius, 1810 from the Sea of Okhotsk were studied. An analysis of the leukogram of the studied species revealed a large portion of segmented neutrophils and myelocytes in walleye pollock, which indicates a significant potential of the cellular factor of its innate immunity and a greater activity of corticosteroid hormones. The most active erythropoiesis observed in G. chalcogrammus is probably related to substantial vertical migrations, specific for the species, associated with sharp pressure variations and the necessity to provide the body with oxygen. The high level of leukopoiesis revealed in saffron cod is assumed to be caused by ecological adaptations of the species to inhabit both fresh and sea water.