Quote:
|
Originally Posted by dales529
A Pattern of underestimation of abundance and overestimation of SSB but NOT reliable.
|
I'll touch on just this one item you posted for the moment.
In the past, the "retrospective analysis" of data from the Summer Flounder fishery found a "bias" in the estimation of mortality and biomass for the terminal year.
They habitually OVERestimated biomass and UNDERestimated mortality.
In other words, whatever the mortality rate and biomass levels were estimated in, for example, 2005 (the terminal year) when they went back later (say in 2006 or 2007) and looked at the fishery in "retrospect" they discovered that the level of mortality in 2005 was higher than they thought at that time and the size of the biomass was smaller than they thought at that time.
So, in "retrospect" the data had a tendency do underestimate mortality and overestimate biomass.
How does this make a difference for the "cause" you ask? Well, to drive home the importance of getting involved, as a direct result of the most recent stock assessment for Fluke, and a direct result of the changes that were made from the cooperative efforts of the fisheries scientists and independent scientists like Dr. Maunder, you now have a change in that retrospective analysis in Summer Flounder.
Here is a direct quote from the meeting minutes of the August MAFMC meeting while setting the quota for 2010 for Summer Flounder. This is a quote from Dr. John Boreman, Chairman of the SSC:
Quote:
|
Originally Posted by Dr. Boreman
Comment on the retrospective patterns. I remember sitting in this Council a few years ago -- and again, this was a hard lesson to learn -- was the value of taking into account retrospective patterns. But if you look at the most recent years under the new modeling regime for summer flounder, those patterns have basically diminished to be a little bit more than maybe -- maybe not -- maybe more than noise around the estimate, the current year estimate. So, some -- now we have some years where the pattern shows it was biased a little high, next year it's biased a little low, but much diminished from the earlier years when we had a high retrospective pattern always biased in one direction; that is, overestimating spawning stock biomass and underestimating fishing mortality. That doesn't seem to be the case any more.
|
So not only did the efforts of SSFFF and others have a positive effect on the biomass estimates and resulting quota for Summer Flounder, but the overall science for the fishery has improved.
