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The base of the VPA (Virtual population Analysis) is sampling. This is true for any species not just bass. Take a look at the sotck assessment for weakfish (sequetog) and you'll see that the biomass is estimate at an alltime low. Look a little further and you'll see that they don't know what is killing all the fish, they just know that something is. The similar model for bass would take all mortality into account. To put it simply this years estimated biomass is the sum of last year's biomass minus all mortality plus all recruitment. They don't need to know what the source of the mortality is to estimate the biomass. Once the estimate the total mortality then they can subtract the known mortality factors and then try to estimate what is causing the unknown sources of mortality. But that has nothing to do with setting the quotas. If they set the quota too high this year it will automagically be compensated in the next year.
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