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Daniel E. Duplisea - et al.
"...many things can affect a population and therefore when
there is a decline in standing stock of an exploited population it could
be
both because of the current fishing level or other factors. This concept
is
usually called "productivity regime" nowadays and it is generally
accepted
that they occur and can alter change the stock biomass and its
productivity. Fishery allowable yield may be based on assessing the
stock in
one productivity regime (i.e. a carrying capacity of K1 and growth rate
r1)
giving a maximum sustainable yield Y1."
Yes Sir! Presuming anything like a constant or even continuous MSY woupd
be sheer denial of what is known. The 'concept' of MSY was built around
a long-term Equilibrium Process that simply does not exist in Nature.
You have correctly identified the situation with respect to defining
'overfishing' within the naturally occuring 'Productivity Regime'
changes.
Recognizing the dozen or so major production fisheries in the world
cycle continuously in response to such processes, as pointed out for
several decades (even centuries) now by various folks, it is really time
for 'management theory' to be adjusted to these same patterns and invoke
better monitoring of population 'status' via careful measurement of
growth/age parameters, fat content, and egg production be applied as the
basis for fisheries management decisions.
The webpage Linked below starts off with the description of the recent
70 plus years, and some basic understanding of what we have observed.
<http://sharpgary.org/21stCenturyFish.html>
Then, of course, where the data sets allow, the continuous Cyclical
rises and falls of many regional ecosystem components are linked to
basic regime Changes, as per the California Current example from Gerrold
Norton and Jan Mason's analysis efforts:
<http://sharpgary.org/Nort_Mas_%2304.jpeg>
The basic image should IMHO be tattooed onto the forehead of every
person involved in fisheries resource management - as a reminder every
morning that 'equilibrium theories', 'Means' and 'Constants' are
inappropriate to understanding what to expect from any living
Ecosystems.
And, no, it should not be a surprise to anyone with a small sheet of
paper and the landings data for such dynamic forage species as
Chesapeake Bay's menhaden that their coming and going is also 'in tune
with' the records of those species within the last Warm Bloom epoch,
that had started its mass decent in and around 1991 -
Colleagues from JJ Magnuson's lab and John Miller et al., who looked
into menhaden recruitment successes vs not so good periods had already
linked the survival and transport from the northern spawning areas and
wind-driven transport into the mouths of the various juvenile grow-out
refuges back in the late 1980s... Pretending that a fishery that does
not target the smaller stages is the problem is really missing the
point.
Meanwhile, as the NE Atlantic coast of Canada and USA are experiencing a
grand cooling process, that started from Labrador in the late 1980s, and
has recently reached well into and beyond Cape Hatteras - one should not
be pointing fingers, but learning what to do, as the next two or so
decades of Ecosystem Regime proceeds,.
There are hints about that in both webpages' imagery.
It is time to rethink the entire approach, including the role of all
those recent immigrees to the various Bay Ecosystems. The Milford
Connecticutt NMFS lab spent decades documenting the consequences of
simlar human effluent issues around Long Island - and the consequences
were simply malformation of chromosomes in early life history stages of
aquatic species - zero survival nearshore, and a near linear improvement
the farther away from human effluents the samples were collected.
Overfishing?
Only if you still believe everyone is made of stone - and that we don't
leave 'footprints'.
Ignorance and Denial are usually linked, as well.
Meanwhile, life goes on - and those toities keep on flushing.
Cheers,
--
Gary D. Sharp
Center for Climate/Ocean Resources Study
PO Box 2223, Monterey, CA 93940
<http://sharpgary.org>
831-449-9212
[log in to unmask]
"The improver of natural knowledge absolutely refuses
to acknowledge authority, as such. For him, scepticism
is the highest of duties; blind faith the one unpardonable sin."
Thomas H. Huxley
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