Vancouver Sun, 6 Feb. 1998:
Fish researchers issue dire warning
by MARK HUME
Global fish stocks overharvested: Looking at 50 years of data, a research team says
many kinds of fish may very well be depleted within 25 years.
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THREAT CITED: UBC researchers Daniel Pauly (left) and Johanne Dalsgaard have released a
new study suggesting that overfishing around the world is endangering the survival of many
species. Mark Van Manen, Vancouver Sun
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Fish stocks are being wiped out on a global scale by over-harvesting, according to an
exhaustive study led by a scientist at the University of B.C. Using nearly 50 years of
data collected by the United Nations, the research team catalogues how in one ocean after
another industrial fishing has first caught the big, valuable stocks, then worked its way
down the food web, catching more and more of the smaller species.
At the current rate of exploitation, many stocks will be eliminated within 25 years, warns
professor Daniel Pauly of the UBC fisheries centre. "You can end up with the sea full
of jelly fish," said Pauly. "It is happening." "The big fish,
the bill fish, the groupers, they are already going. It is happening now."
The collapse of cod stocks on the East Coast and the shocking decline of salmon in both
the Pacific and Atlantic led many to worry that industrial fishing had reached
unsustainable levels. The study by Pauly validates such fears using a mountain of data on
more than 500 distinct species, caught in 180 countries.
All commercial fish show a widespread decline in what's called the trophic level -- a term
that ranks fish according to their place in the food web. Fish such as snapper and cod are
at a high trophic level because they eat other fish. The fish they feed on are at a lower
trophic level, and lower still are the krill and copepods that support the ecosystem.
By studying trophic levels, Pauly was able to reveal how fisheries are moving down
the web and affecting entire ecosystems. In both ocean and inland fisheries, when catches
of valuable, long-lived fish such as salmon and tuna decline, fishermen switch to
shorter-lived, smaller, plankton-feeding species. At first, they catch the new stocks in
huge amounts. But soon those stocks also begin to decline. Pauly calls this "fishing
down the food web" and warns it will have dire consequences because it upsets the
balance of nature.
Pauly said the collapse of East Coast cod stocks provides a classical case study of what's
happening around the world. After the cod were fished down, fishing pressure increased on
shrimp. "Cod feed on shrimp," said Pauly. "If you remove the shrimp, how
will the cod ever recover?" Pauly didn't want to comment on the collapse of salmon
stocks on the West Coast, because he said the picture here is confused by habitat loss and
climatic factors. But he did note that "fishing down the food web" is happening
in B.C., where a krill fishery has begun.
Pauly said the conclusion of the study -- that present exploitation patterns are
unsustainable -- shouldn't come as a surprise to anyone. But the definitive nature of the
data is shocking, he said, because it makes it clear that fisheries will collapse on a
global scale if things don't change. "If we keep going like this we will have a sea
full of little horrible things that nobody wants to eat. The big things will be
gone," he said.
Pauly is the main author of the report, Fishing Down Marine Food Webs, which he did with
four colleagues: Villy Christensen, Rainer Froese and Francisco Torres Jr., from the
International Centre for Living Aquatic Resources Management in the hilippines, and
Johanne Dalsgaard, also from UBC.
The study, released today, was funded by the National Science and Engineering Research
Council of Canada, the Danish International Development Agency and the European
Commission.