Meaning of AVAILABILITY in English
The proportion of a stock which is susceptible to fishing. Fish become "available" to fisheries through migration and /or change of behavior (from pelagic to demersal). It an available section of a stock is sufficiently isolated from the rest of the stock, it could be considered a management unit and be managed as such.
Fishery English glossary. Английский глоссарий рыболовства . 2012