Posted on 16-5-2003
Great
Fish Going the Way of the Dinosaurs
HALIFAX, Nova Scotia, Canada, May 14, 2003 (ENS) - Ninety percent
of all
large fish in the world's oceans are gone, and just 10 percent
remain after
commercial fishing vessels have taken their toll over the past
50 years,
according to a long term study conducted by Canadian and German
scientists
and released today. The scientists say there is an urgent need
to attempt
fisheries restoration on a global scale.
"From giant blue marlin to mighty bluefin tuna, and from tropical
groupers
to Antarctic cod, industrial fishing has scoured the global
ocean. There is
no blue frontier left," says lead author Ransom Myers, a fisheries
biologist based at Dalhousie University in Canada. "This isn't
about just
about one species," he says. "The sustainability of fisheries
is being
severely compromised worldwide." "The impact we have had on
ocean
ecosystems has been vastly underestimated," says coauthor Boris
Worm of
Dalhousie University and the University of Kiel in Germany.
"These are the
megafauna, the big predators of the sea, and the species we
most value.
Their depletion not only threatens the future of these fish
and the fishers
that depend on them, it could also bring about a complete reorganization
of
ocean ecosystems, with unknown global consequences."
Their 10 year long study based on data sets representing all
major
fisheries in the world, shows that industrial fisheries take
only 10 to 15
years to reduce any new fish community they encounter to one
tenth of what
it was before. The research will be published as the cover story
in
tomorrow's issue of the international journal "Nature." "Since
1950, with
the onset of industrialized fisheries, we have rapidly reduced
the resource
base to less than 10 percent - not just in some areas, not just
for some
stocks, but for entire communities of these large fish species
from the
tropics to the poles," said Myers.
The authors constructed trajectories of biomass and composition
of large
predatory fish communities from four continental shelves and
nine oceanic
systems, from the beginning of exploitation to the present.
For shelf
ecosystems they used data from standardized research trawl surveys
to track
the decline in the populations of large fishes.
To measure the decline in open ocean ecosystems, the researchers
used
Japanese longlining data. Pelagic longlines are the most widespread
fishing
gear, and the Japanese fleet is the most widespread longline
operation,
covering all oceans except the circumpolar seas. Longlines catch
a wide
range of species in a consistent way over vast areas, but today
the hooks
are coming up empty more often than not. "Whereas longlines
used to catch
10 fish per 100 hooks, now they are lucky to catch one," says
Myers. "The
longlining data tell a story we have not heard before, says
Daniel Pauly, a
fisheries scientist from the University of British Columbia.
"It shows how
Japanese longlining has expanded globally. It is like a hole
burning
through paper. As the hole expands, the edge is where the fisheries
concentrate until there is nowhere left to go."
Pauly says that because longlining technology has improved,
the authors'
estimates are "conservative," and "the declines are even greater
than they
are saying." "We have forgotten what we used to have," says
Jeremy Jackson
of the Scripps Institution of Oceanography. "We had oceans full
of heroic
fish - literally sea monsters. People used to harpoon three
meter (10 foot)
long swordfish in rowboats. Hemingway's "Old Man and the Sea"
was for
real," he said, referring to Ernest Hemingway's novel. "Where
detailed data
are available we see that the average size of these top predators
is only
one fifth to one half of what is used to be. The few blue marlin
today
reach one fifth of the weight they once had. In many cases,
the fish caught
today are under such intense fishing pressure, they never even
have the
chance to reproduce," says Myers. “The findings of the Nature
study should
be a wake-up call to fishery managers and regulators all over
the world,"
said Dr. Michael Hirshfield, chief scientist of Oceana, an ocean
conservation organization based in Washington, DC. "Without
immediate
action," Hirshfield said, "fishery managers will not have anything
left to
manage - and fishermen will have nothing left to catch. For
years, the
conservation community and responsible fishermen have argued
that the ocean
is not limitless, and have called for actions to prevent overfishing,
reduce wasted catch, and limit the use of destructive fishing
gear."
This year, Oceana started two campaigns to stop harmful fishing
practices.
The Stop DirtyFishing campaign is working to eliminate the approximate
44
billion pounds of fish – an amount equal to 25 percent of the
world catch –
that are wasted in the course of commercial fishing.
The Stop Bottom Trawling campaign is working to prohibit the
use of bottom
trawling fishing gear, a method of fishing that Hirshfield calls
"the
world’s damaging," because it causes "unselective and systematic
destruction of the ocean."
Myers and Worm sent their findings to many of the top fisheries
scientists
in the world for review. They found acceptance of the overall
pattern of
rapid depletion of fish populations, but when it came to the
current status
of individual species, especially tuna, says Myers, some fisheries
managers
"find it very hard to accept."
Myers has dealt with this type of denial when he was a fisheries
biologist
with the Canadian Department of Fisheries and Oceans in Newfoundland
during
the 1980s. He fought to save the Atlantic cod, which were declared
and
endangered species by the Canadian government last week.
"No one understood how fast the decline happened at the end
- it was only a
couple of years," says Myers. "The quotas had been too high.
They refused
to slow down because they had seen lots of little fish coming
in - a good
year class. The little fish were caught and discarded and there
was no
future."
"This is extremely troubling news for anyone who cares about
the health of
the oceans," said Dr. Randy Kochevar, science communications
manager at the
Monterey Bay Aquarium and a principal investigator with the
Tagging of
Pacific Pelagics (TOPP) research project. TOPP is a collaboration
among
scientists from around the world to understand the migration
patterns of
large open ocean animals in the North Pacific Ocean. "The magnitude
of the
threat is startling," Kochevar said. "Even if the authors' numbers
are off
by as much as 50 percent, this is a big, big problem. The trends
they've
identified have profound consequences for the future of ocean
life." At the
World Summit on Sustainable Development in Johannesburg last
summer, 192
nations called on the global community to restore world fisheries
stocks to
levels that can provide maximum sustainable yield by 2015. Myers
and Worm
say their results provide the "missing baseline" needed to restore
fisheries and marine ecosystems to healthy levels.
The fishing nations must reduce quotas, reduce overall fishing
effort, cut
subsidies, reduce bycatch, and create networks of marine reserves,
the
scientists say.
Worldwide, 27 million tons of fish, mammals, turtles, birds
and other
marine life is discarded dead or dying into the sea each year
as fishing
"bycatch," according to the Pew Oceans Commission, based in
Washington, DC.
"A minimum reduction of 50 percent of fishing mortality may
be necessary to
avoid further declines of particularly sensitive species," Myers
says. "If
stocks were restored to higher abundance, we could get just
as much fish
out of the ocean by putting in only 1/3 to 1/10 of the effort.
It would be
difficult for fishermen initially - but they will see the gains
in the long
run," he said.
"We are in massive denial and continue to bicker over the last
shrinking
numbers of survivors, employing satellites and sensors to catch
the last
fish left," warns Myers.
"We have to understand how close to extinction some of these
populations
really are. And we must act now, before they have reached the
point of no
return. I want there to be hammerhead sharks and bluefin tuna
around when
my five year old son grows up. If present fishing levels persist,
these
great fish will go the way of the dinosaurs."
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