The Choice of Nutritional Objects by Predatory Fishes According to the Changes in their Species Composition in 1994-1998. The Analysis of Research

1,071 pike, pike-perch, large perch and burbot individuals were caught and their intestinal tracts were investigated on the basis of special methods in order to determine their seasonal food spectra, feeding intensity, daily, monthly and yearly rations during the period of 1994-1998. The highest yearly rations were determined for perch and pike (251 and 250% of their total body weight, respectively). They mostly fed on short-lived, commercially unprofitable fish species, such as ruff, three-spined stickleback, smelt, juveniles of roach and perch, etc. We also established that the pike, burbot, pike-perch and perch populations consumed for food the following amounts of the abovementioned fish species in 1998: 97.9 t, 55.4 t, 262 t and 527.9 t, respectively. The complex analysis of the nutrition and nutritional interrelations of the four main predatory fish species of the Curonian Lagoon (pike, burbot, pike-perch and perch) was carried out.