Had an interesting look at the PS wild chum data. Plugged each river into the Ricker curve to get MSY. Couple interesting things emerged.
First, as ocean conditions improved so did the runs and MSY goal. But, goals remained where they had been set in the 70s. This, of course, allowed for even more short term gain from harvest. Then, when ocean conditions changed, the MSY goal declined. This was the case when looking at all the data, starting in the 60s.
Now, managers look at short, recent data sets. As Salma says, models poor conditions you get results that say MSY is small.
Years ago, I believed in fixed goals. A fixed target was, or should be, easier to hit and we all knew that there was one point of optimum production. I now believe that a FIXED harvest rate, set appropriately low, is best for optimum management and harvest. Have seen both modeled situations and real-world where the fixed rate gave more catch than fixed goal.
Again, as Salma says, the discussions need to be expanded over all the impacts. With the insatiable growth in human population playing a key role.