Hematological analyses of some fish species in the Gulf of Riga

Abstract

The objective of this work was to detect and compare blood parameters of European flounder (Platichthys flesus), herring (Clupea harertgus membras), eelpout (Zoarces viviparous) and perch (Perca fluviatilis) at the Eastern and Western coast of the Gulf of Riga. The number of erythrocytes in herring of the Gulf of Riga ranges from 1.45 to 2.57 × 1012/L. At the same time no statistically significant difference in red blood cells (RBC) count between herring of both coasts was detected. The most common white blood cells in GoR herring blood smear were lymphocytes ranging from 73 to 94%. The number of lymphoblasts was very small (0–4%), indicating that herring of the GoR is not exposed to chronic stress. The number of erythrocytes in flounder ranged from 0.8 to 2.65 × 1012/L, but hemoglobin—from 4.7 to 16.5 g/dL. RBC count and hemoglobin level in European flounder did not differ between coasts however hematocrit was significantly higher at the Eastern coast. White blood cell count in flounder near the Western and Eastern coast was almost equal. Blood indices in eelpouts were slightly higher at the Eastern cost. Slightly higher number of red blood cells and significantly higher hemoglobin level has been observed in perch feeding near the Eastern coast, indicating physiological disturbances of fish. Although hematological analysis pointed at slightly worse living conditions of fish at the Eastern coast, in general hematological picture did not give evidence of fish welfare decline in the Gulf of Riga.