Three control nets were also set in each bottom type the day
before each monitoring dive. Irrespective of bottom type, nets’ fishing area decreased to about 40% during
the first 30 days, and then gradually (rocky bottoms) or sharply (sandy bottoms). It was estimated that
during the experiment 541 and 257 individuals were caught per 100 m of net in rocky and sandy bottoms,
respectively. Catching efficiency decreased in a negative exponential manner in parallel with the nets
deterioration. The nets’ effective fishing lifetime, when catching efficiency became lower than 1%, was
10–11 months in the rocky bottom and 8 months in the sandy bottom