This issues seems muddled with different opinions and varying statistics.  I think what is difficult to assess is the bigger picture and real issue in my mind which is not just about the number of these these fish in the wild but the effect that a large decrease or extinction would have on the bigger ecosystem.  Ecosystems are often based on interdependence and interconnection.  So in the food chain, perhaps these fish have a job to eat and consume certain plants and animals to who's population will now not be controlled, which then has other effects. Perhaps these fish are the main food source for animals higher up on the food chain so now they will starve and their population will drop as a direct result which then has other effects on animals and plants that may connected to those animals.  So looking at counts of only the species being harvested is missing the bigger picture.  Perhaps with logical big picture thinking the actual effects on the ecosystem can be calculated better.