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My thought is that overfishing is neither legal nor scientific, but a
'common' term. I don't know how far back one would need to look to cite the
first paper that defined overfishing. I think that it has been used in
common language for quite some time; probably since the first commercial
fisherman started to experience reduced yields. It was probably used in
everyday language before ever being used in a scientific paper. It is
important to keep in mind that overfishing is only one factor of many that
can cause reduced yields in a fishery. Extrapolating from the theory that
stocks are heavily influenced by year class strength (I think it is a fair
assumption that the fish must first recruit to fishable sizes before
overfishing can occur), and that year class strength is determined during
early life stages (Hjort 1914, Sissenwine 1984, Kendall and Duker 1998),
overfishing is probably not the primary factor controlling the health of a
fishery. However, overfishing reproductive size classes combined with heavy
predation by other organisms on younger size classes may have an influence
on the overall health of the fishery. My thought would be that pollution or
natural variation would likely have a greater influence on stocks of fish or
scallops. The most insidious form of pollution that has probably been
influencing the stocks of many great lakes fishes would be biological
pollution or invasive species near the base of the food web like Dreissena
sp., Bythotrephes sp., and Cercopagis pengoi. In any case I would say that
simply throwing out the blanket statement that just because a stock is down
overfishing must be the culprit is not a good idea. It may be part of the
answer, however the fishery should be studied first to determine the cause
of decline. It will be interesting to see what others think about this
topic.
Cheers!
Justin C Johnston
Biologist
AMEC Earth and Environmental
Professional Building III
11676 Perry Highway, suite 3101
Wexford, PA 15090
[log in to unmask]
office: (724) 940-4200x229
fax: (724) 940-4205
-----Original Message-----
From: Scientific forum on fish and fisheries
[mailto:[log in to unmask] <mailto:[log in to unmask]> ] On
Behalf Of Mike Flaherty
Sent: Thursday, May 26, 2005 9:05 AM
To: [log in to unmask]
Subject: Is overfishing a scientific or legal term?
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An article titled, "Scallops overfished for past 2 years, official says",
appeared on the front page of today's New Bedford Standard Times.
http://www.southcoasttoday.com/daily/05-05/05-26-05/a01lo102.htm
<http://www.southcoasttoday.com/daily/05-05/05-26-05/a01lo102.htm>
There was one excerpt in it which gave me pause...
===============================
"Overfishing is a legal term, not a scientific term, and is therefore not an
accurate way to evaluate the health of the scallop fishery, Dr. Kenchington
said."
===============================
As I roughly understand things, "overfishing" is defined as a point beyond
which harvest/mortality levels exceed sustainable levels in a fishery. It
is further my understanding that the thresholds for sustainability are
arrived at scientifically. If this is true, then isn't overfishing truly a
scientific term? More importantly, is it a reasonably accurate way to
evaluate the health of a fishery?
Thanks,
Mike Flaherty
Wareham, MA
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