PHYSIOLOGICAL STATE OF ONE-YEAR-OLD AND TWO-YEAR-OLD PIKEPERCH (SANDER LUCIOPERCA) AFTER WINTERING IN CAGES AND PONDS

Abstract

Studies of the physiological state of one-year-old and two-year-old pikeperch after wintering in fish farming cages and ponds have shown significant differences in mass-size, chemical, hematological and histophysiological parameters of fish. For pikeperch of both ages, significant differences were observed in the form of higher values of the liver index in farmed fish (1.63% vs. 1.33% in one-year-olds and 2.79% vs. 1.16% in two-year-olds), abdominal fat index (0.96% vs. 0.39% in one-year-olds and 7.88% vs. 0.44% in two-year-olds), vitamin C (76.5% vs. 18.9% in one-year-olds and 69.9% vs. 12.3% in two-year-olds), in the shift of the balance of the fatty acid status of body lipids towards the accumulation of MUFAs – monounsaturated fatty acids (39.61% vs. 27.47% of the total fatty acids in one-year-olds and 54.34% vs. 39.90% of the total fatty acids in two-year-olds), a decrease in the proportion of physiologically active acids of the n-3 series (21.60% vs. 22.53% of the total fatty acids in one-year-olds and 12.19% vs. 17.70% of the total fatty acids in two-year-olds), and a significant decrease in hemoglobin (65.2 g /l vs. 76.5 g /l) and MCH – the average content of hemoglobin in the erythrocyte (28.4 vs. 33.9 pictograms, pg) in one-year-olds and a tendency to decrease these indicators in two-year-olds (68.7 g /l vs. 73.5 g /l hemoglobin and 31.7 pg vs. 35.6 pg, respectively). More pronounced differences in the studied parameters are characteristic of older pikeperch from fish farms, relative to fish from ponds. Two-year-old pikeperch reared in cages of a fish farm are characterized by significantly greater length (21.10 vs. 18.78 cm) and body weight (89.50 vs. 68.97 g), high content of body lipids (8.75 vs. 2.05%), dry matter (30.8 vs. 23.4%) and BEV – nitrogen-free extractives (4.11 versus 1.55%). Two-year-old pikeperch reared in cages of a fish farm are characterized by significantly greater length (21.10 cm vs. 18.78 cm) and body weight (89.50 g vs. 68.97 g), high content of body lipids (8.75% vs. 2.05%), dry matter (30.8% vs. 23.4%) and NFE - nitrogen-free extractives (4.11% versus 1.55%). In addition, two–year-olds (females) in industrial conditions had more developed gonads with a similar gonadosomatic index with pikeperch from ponds (0.20 and 0.23, respectively) - active formation of a reserve fund of germ cells and the presence of oocytes of various size groups were observed in the ovaries of farmed fish. Certain distinctions in pikeperch of different ages after wintering in fish farming cages and ponds are related to different conditions of keeping and feeding fish.