Is japanese chub mackerel still overfished?
Is japanese chub mackerel still overfished? A problem on the current stock assessment in Japanese fisheries
I think that the generic model used to calculate the MSY and ABC of each fish species stock is somewhat unrealistic. At least in the case of chub mackerel on Pacific waters, the result looks very odd and it will drastically different if decadal change of oceanic environment (regime shift) is incorporated, or if we exclude the data before 1990 when the recruitment was very weak. we must obtain that there seems to be no problem with the current catch.
Since the MSY concept has changed to take into account process errors and regime shifts, the criticism to classic MSY theory based on stationary environmental condition without decadal change or yearly change in the oceanic condition, is not appropriate (criticism to the straw man), but process errors are taken into account, but interspecific relationships and regime shifts are not incorporated into generic methods in the current stock assessment in Japanese fisheries.
This is the reason why the Kobe plot of the chub mackerel in Pacific waters (right figure on P2) still looks very odd. From around 2008, it is understood that the stock increased steadily despite being it is consistently been overfishing. The historically largest stock in 1970s was also less than the MSY stock level.
The assessors may consider that, in the case of the chub mackerel stock, since around 2008, RPS has been consistently abnormally high (the resources that should be reduced on average) have continued to increase, and decreased for the first time in 2017. They did not use the concept of regime shift.
After all, I doubt the stock assessment by Japanese Fisheries Research Agency that the chub mackerel was still been overfishing.
Calculation without looking at the faces of fishermen is not "resource management that is rooted only in science". Regarding the assessment of resources and the new ABC (Allowable Biological Catch) rules, the Fisheries Agency respects the independence of research institutions (Fisheries Research Agency =FRA). Since it is an administrative matter regarding the TAC for each fish species and the development of measures for stock assessment, On the other hand, the resource assessment will be led by the FRA, and the Fisheries Agency will not be involved. Recently FRA stock assessors whose office was close to fisheries markets moved to central building (Yokohama). They will have much fewer chances to hear or see the fishing markets and voices of fishers.
However, even if the resource evaluation is calculated by getting data from the site, it may or may not match the site feeling. I think that resource evaluation will be often odd from the result of this arrangement.
I think that the generic model used to calculate the MSY and ABC of each fish species stock is somewhat unrealistic. At least in the case of chub mackerel on Pacific waters, the result looks very odd and it will drastically different if decadal change of oceanic environment (regime shift) is incorporated, or if we exclude the data before 1990 when the recruitment was very weak. we must obtain that there seems to be no problem with the current catch.
Since the MSY concept has changed to take into account process errors and regime shifts, the criticism to classic MSY theory based on stationary environmental condition without decadal change or yearly change in the oceanic condition, is not appropriate (criticism to the straw man), but process errors are taken into account, but interspecific relationships and regime shifts are not incorporated into generic methods in the current stock assessment in Japanese fisheries.
This is the reason why the Kobe plot of the chub mackerel in Pacific waters (right figure on P2) still looks very odd. From around 2008, it is understood that the stock increased steadily despite being it is consistently been overfishing. The historically largest stock in 1970s was also less than the MSY stock level.
The assessors may consider that, in the case of the chub mackerel stock, since around 2008, RPS has been consistently abnormally high (the resources that should be reduced on average) have continued to increase, and decreased for the first time in 2017. They did not use the concept of regime shift.
After all, I doubt the stock assessment by Japanese Fisheries Research Agency that the chub mackerel was still been overfishing.
Calculation without looking at the faces of fishermen is not "resource management that is rooted only in science". Regarding the assessment of resources and the new ABC (Allowable Biological Catch) rules, the Fisheries Agency respects the independence of research institutions (Fisheries Research Agency =FRA). Since it is an administrative matter regarding the TAC for each fish species and the development of measures for stock assessment, On the other hand, the resource assessment will be led by the FRA, and the Fisheries Agency will not be involved. Recently FRA stock assessors whose office was close to fisheries markets moved to central building (Yokohama). They will have much fewer chances to hear or see the fishing markets and voices of fishers.
However, even if the resource evaluation is calculated by getting data from the site, it may or may not match the site feeling. I think that resource evaluation will be often odd from the result of this arrangement.
posted by Hiroyuki Matsuda @ 11:04 AM
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