Subject: warfare and fisheries

From: [email-masked] (Ian Rowe)
Date: 8 Jun 1996 02:44:16 +0800

Since some nations are dependent on fish as their main source of protein,
rather than upon animals, they would therefore be vulnerable in wartime to
attack from this quarter. Even a feint attack on a nation's food-chain can
create hysteria. How vulnerable are oceanic fisheries to deliberate poisoning?
In particular, what are the mechanics for exterminating/contaminating a
fishery? In a recent incident in southern Australia pilchards were accidently
fed contaminated fish. The resultant disaster was quite surprising - adult
pilchards began dying and the epidemic spread across a 3000 mile front between
Perth and Sydney. The explanation for this spreading was that adult pilchards
cannibalize their own kind so that they themselves are infected in turn. Do
most fish (that humans eat) exhibit such poor species-survival characteristics?
If so, would not a nation dependent on such fisheries be vulnerable from this
quarter in wartime?

Ian Rowe
[email-masked]

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From: [email-masked](Steven Atran)
Date: 9 Jun 1996 16:39:41 GMT

>attack from this quarter. 
 
During World War II, it was dangerous for U.S. fishing vessels to travel
offshore because of patrolling German U-boats.  However, fish as a source
of food was a national priority.  Consequently, fishing regulations on
inshore waters were eased and inshore fisheries became heavily exploited. 
Here in Florida, mullet landings reached their all-time highs during World
War II.  Although this provided a needed source of protein during the war,
the fishing regulations were not reinstated after the war.  This resulted
in a long-term cyclic decline in mullet stocks that was not stopped until
the 1990', and only in the last few years have mullet stocks begun to
recover. 
 
>How vulnerable are oceanic fisheries to deliberate poisoning? 
 
In open oceans, I would think that currents and the sheer volume of water,
and the ability of fish to detect and swim away from contaminated water,
would make it  impracticable to attempt this type of attack.  Closed or
semi-closed bodies of water are a different story, however.  For example,
consider the consequences of accidental mercury poisoning off Japan. 
Fisheries that occur in enclosed areas, or fish stocks that are dependent
upon limited habitat for spawning and nursery areas, might also be
susceptible to such attack. 
 
>fishery? 
 
That's a simple answer.  Overfishing and habitat degradation.  We've gotten
pretty good at depleting fish stocks.  It's restoring them that we're still
trying to get a handle on. 
 
>The explanation for this spreading was that adult pilchards 
 
Contrary to being a poor survival characteristic, it is a benefit.  It's
called compensatory mortality.  As the population increases in abundance,
survival rate from larval to adult decreases, often due to increased
cannibalism by the adults.   At high stock levels, this prevents the stock
>from  exceeding carrying capacity of the ecosystem, and balances mortality
against reproductive rates to establish an equilibrium.  At depleted stock
levels, it results in increased survival to allow stocks to recover.  In
your example of contaminated fish dying, it would be individuals who are
resistant to the contamination who who be most likely to survive, thus
building a natural resitance as well as recovering the stock. 
 
>If so, would not a nation dependent on such fisheries be vulnerable from
this 
 
I think that it would take a very expensive and concerted effort to even
begin to approach deliberately the level of stress and destruction that we
inadvertantly subject stocks to every day through overfishing, pollution
and habitat degradation.  A nation trying to cut off it's enemy's supply of
seafood would probably be better advised to do so by attacking the fishing
fleet rather than the fishery resource, as the Germans did in World War II.

Steven Atran 
Population Dynamics Statistician 
Gulf of Mexico Fishery Management Council