The number of fish that have reached sexual maturity from currently available source material (eggs, larvae, juveniles), irrespective of the part used by the fishery. Expressed as a percentage and as a coefficient. The biological survival rate makes it possible to compare the effectiveness of different artificial rearing methods, to make predictions about fish stocks in waters and to establish catch values.

The performance of hatcheries and nurseries in artificial fish production is measured by the fishery yield - the amount of fish that can be caught after a certain number of years from the production (larvae, juveniles).