Charakterystyka biologiczna narybku łososi i troci rzek zachodniopomorskich

The basic form of restocking Polish marine areas are smolts. However, some salmon smolts and trout smolts come from stocking of Polish rivers and their inflows by summer and autumn fry. It was interesting to check the sizes obtained by those fish in the first and second season of growth under natural conditions. The study was carried out in three rivers’ basins of the West Pomerania – Rega (fish from 8 tributaries), Parsęta (from 3 tributaries) and Ina (from 2 tributaries), which were stocked by salmon and trout. We caught totally 407 salmon and 411 trout aged 0+ and 158 salmon and 273 sea trout aged 1+. Salmon aged 0+ had an average length from 7.46 to 12.12 cm, average weight 11 g and had condition factor KF 1.1. There were more trout in the same rivers and they were larger than salmon, although they developed from the hatching fry. At the age of 0+ trout measured (average) from 8.13 to 12.14 cm, weighed 14 g and had condition factor KF 1.06. Studies have shown that trout fry grow faster in our stream than salmon fry in similar age.