Wow, not often that anyone agrees with me. Thanks Wayne, stop by for a beer
next time you are in the Algarve.
About the PS comments, I won't address those in detail, but a couple stand
out. With regard to #1 and #2, our impacts are both direct and indirect. We
are of course direct predators on fish populations, but our actions can also
enhance other predation pressures or reduce prey. By removing sharks and
other predators on seals, the amount of fish taken by seals increases. By
exploiting forage fish (usually for industrial purposes) we reduce their
food. And then there is the matter of habitat...
As for #8, there is a dangerous positive feedback loop involved. As fish
become scarcer the price goes up, so there is a greater incentive to catch
the few that are left.
And #9? That's a no-brainer if there ever was one!
Thanks again Wayne, Bill Silvert
----- Original Message -----
From: "Wayne Tyson" <[email protected]>
To: <[email protected]>
Sent: Friday, July 24, 2009 9:14 PM
Subject: Re: [ECOLOG-L] Education vs Indoctrination Can sustainability be
sustained?
For what it's worth, I entirely agree with Silvert. I would only add that
there's a lot of distance between a clearly defined term and a muddy one.
A definition that addresses the principles that support Silvert's
statements surely can have enough resilience to apply to all valid and
relevant cases can't it? Can the same be said for more rigid definitions
that, for example, restrict consideration to the fate of Homo s. alone?
WT
PS: While we're fishing around this subject, are these statements true or
false?
1. There's more than one [fish] predator out there.
2. Only one of the predator groups that has much of a choice of reducing
predation pressure on [fish] populations, Homo s.
3. Both biotic and abiotic factors can affect populations.
4. If one or more nonhuman factors depress prey [fish] populations below
some modeled (and "valid") lower limit, the [fish species] resource
population can be reduced lower than that limit, even with a "reasonable"
fudge factor.
5. Human "sustainable" harvest levels could bend the reproduction curve
downward, perhaps terminally so, or below some threshold of recovery to
sustainable levels such that the modeled sustainable population might no
longer be maintained.
6. Thus the options, if any, open to "management" are limited to reducing
the "sustainable" harvest, killing off other predators, or increasing the
productive/carrying capacity of the support system/habitat conditions.
7. Since everything is connected to everything else, some management
options, such as "aquaculture," may require transferring energy from other
systems, thus affecting those systems, requiring "blinders" to such
"external" options, something on the order of accounting tricks.
8. [Fish] populations are likely to "crash" before markets for them.
9. Technology is increasingly capable of pushing [fish] resources below
sustainable levels.
----- Original Message -----
From: "William Silvert" <[email protected]>
To: <[email protected]>
Sent: Friday, July 24, 2009 3:58 AM
Subject: Re: [ECOLOG-L] Education vs Indoctrination Can sustainability be
sustained?
After following this thread for a bit I would like to comment on one of
Wayne's sentences. Sustainability is context-dependent and under
different
situations means different things. Consider just the exploitation of a
variable natural resource, such as a fish stock. Sustainable exploitation
means leaving enough fish in the sea so that we can keep fishing the
stock
forever - right? But since the stock is variable we need to know how much
variation in supply the market will support. If the fishery relies on
long-term contracts then sustainable fishing means taking the same amount
every year, while in a more opportunistic market an adaptive strategy,
constantly revising the catch quota on the basis of stock availability,
can
produce variable yields with a higher mean value. Thus the sustainable
catch
depends on market conditions and other constraints.
For me the sustainability of any strategy means that it can be carried
out
indefinitely. But the concept applies to an entire strategy, not to just
the
result from a single strategy such as MSY (Maximum Sustainable Yield). In
other words, it is a complicated socio-economic-biological concept, not
just
an ecological term.
Bill Silvert
----- Original Message -----
From: "Wayne Tyson" <[email protected]>
To: <[email protected]>
Sent: Wednesday, July 22, 2009 6:56 AM
Subject: Re: [ECOLOG-L] Education vs Indoctrination Can sustainability be
sustained? Re: [ECOLOG-L] Managing the social aspects of ecosystem
management - LfS portal update
Because sustainability is an "important matter," it seems to me
important
that the term is clear and unambiguous rather than muddy and ambiguous.
