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Collapse of all
wild fisheries predicted in next 45 years
If over-fishing and
other trends harming fish stocks around the world continue on their
current path, we'll be saying sayonara to the seafood we love best
in coming decades
All species of
wild seafood that are currently fished are projected to collapse by
the year
2050, according to a new four year study by an international team of
ecologists and economists. Collapse is defined as 90 percent
depletion.
The scientists
warn that the loss of biodiversity is 'profoundly' reducing the
ocean's ability to produce seafood, resist diseases, filter
pollutants, and rebound from stresses such as over-fishing and
climate change.
"Whether we
looked at tide pools or studies over the entire world's ocean, we
saw the same picture emerging," says lead author Boris Worm of
Dalhousie University. "In losing species we lose the
productivity and stability of entire ecosystems. I was shocked and
disturbed by how consistent these trends are - beyond anything we
suspected."
The study
published in the November 3 issue of the journal 'Science' was based
at the National Center of Ecological Analysis and Synthesis, NCEAS,
funded by the National Science Foundation, the University of
California and UC Santa Barbara.
It contains some
good news - the data show that ocean ecosystems still hold great
ability to rebound. But the scientists found that every species lost
causes a faster unraveling of the overall ecosystem.
Conversely, every
species recovered add to overall productivity and stability of the
ecosystem and its ability to withstand stresses. "Every species
matters," the scientists say.
"Unless we
fundamentally change the way we manage all the oceans species
together, as working ecosystems, then this century is the last
century of wild seafood," says co-author Steve Palumbi of
Stanford University.
The analysis is
the first to examine all existing data on ocean species and
ecosystems, synthesising historical, experimental, fisheries, and
observational datasets to understand the importance of biodiversity
at the global scale.
The results reveal
that progressive biodiversity loss not only impairs the ability of
oceans to feed a growing human population, but also sabotages the
stability of marine environments and their ability to recover from
stresses.
"The data
show us it's not too late," says Worm. "We can turn this
around. But less than one percent of the global ocean is effectively
protected right now."
"We won't see
complete recovery in one year, but in many cases species come back
more quickly than people anticipated - in three to five to 10 years.
And where this has been done we see immediate economic
benefits," Worm said.
The scientists on
the NCEAS study say a pressing question for management is whether
losses can be reversed. If species have not been pushed too far
down, recovery can be fast - but there is also a point of no return
as seen with species like northern Atlantic cod.
In 1992, the cod
population nearly reached a point of commercial extinction in waters
off eastern Canada and New found land, and a fishing moratorium was
imposed. This moratorium has removed the main source of employment
and income for thousands of fishermen from hundreds of small fishing
communities.
"This isn't
predicted to happen, this is happening now," says co-author
Nicola Beaumont an ecological economist with the Plymouth Marine
Laboratory. "If biodiversity continues to decline, the marine
environment will not be able to sustain our way of life, indeed it
may not be able to sustain our lives at all."
Collapses are
hastened by the decline in overall health of the ecosystem. Fish
rely on the clean water, prey populations and diverse habitats that
are linked to higher diversity systems.
The study suggests
that these relationships point to the need for managers to consider
all species together rather than continuing with single species
management.
"This
analysis provides the best documentation I have ever seen regarding
biodiversity's value," adds Peter Kareiva, a former Brown
University professor and US government fisheries manager who now
leads science efforts at The Nature Conservancy.
"There is no
way the world will protect biodiversity without this type of
compelling data demonstrating the economic value of
biodiversity," Kareiva said.
Wild fisheries
support the economies of many countries. The impacts of species loss
go beyond declines in seafood. Human health risks emerge as depleted
coastal ecosystems become vulnerable to invasive species, disease
outbreaks and noxious algal blooms. Many of the economic activities
along our coasts rely on diverse systems and the healthy waters they
supply.
"The ocean is
a great recycler," explains Palumbi, "It takes sewage and
recycles it into nutrients, it scrubs toxins out of the water, and
it produces food and turns carbon dioxide into food and
oxygen."
But in order to
provide these services, the ocean needs all its working parts, the
millions of plant and animal species that inhabit the sea. The study
drew immediate criticism from the Australian government, which
'categorically rejects' claim made by northern hemisphere scientists
led by Canada's Dalhousie
University that
Australia's fisheries are set to collapse.
"The reality
is Australia is a world leader in fisheries and oceans
management," Australian Fisheries Minister Senator Eric Abetz
said recently.
"While we
obviously welcome any serious scientific contribution, instead of
trying to tar us all with the same brush, these scientists should
instead be singling Australia out as an example to the world of how
to ensure fisheries sustainability," said Abetz.
"Frankly, we
get a bit annoyed at northern hemisphere scientists, whose fisheries
management often leaves a lot to be desired, making sensationalist
predictions about the state of Australian fisheries from half a
world away," he said. Australia has a comprehensive plan to
ensure the sustainability of Commonwealth fish stocks for
generations to come, said Abetz, emphasising that of the world's
area of marine protected areas, some one third is in Australian
waters.
The strength of
the NCEAS study is the consistent agreement of theory, experiments
and observations across widely different scales and ecosystems, the
participating scientists say.
The study analysed
32 controlled experiments, observational studies from 48 marine
protected areas, and global catch data from the UN's Food and
Agriculture Organization's database of all fish and invertebrates
worldwide from 1950 to 2003.
The scientists
also looked at a 1,000 year time series for 12 coastal regions,
drawing on data from archives, fishery records, sediment cores and
archeological data. "We see an accelerating decline in coastal
species over the last 1,000 years, resulting in the loss of
biological filter capacity, nursery habitats, and healthy
fisheries," says co-author Heike Lotze of Dalhousie University
who led the historical analysis of Chesapeake Bay, San Francisco
Bay, the Bay of Fundy, and the North Sea, among other bodies of
water.
Examination of
protected areas worldwide show that restoration of biodiversity
increased productivity four-fold in terms of catch per unit effort
and made ecosystems 21 percent less susceptible to environmental and
human caused fluctuations on average.
The buffering
impact of species diversity also generates long term insurance
values that must be incorporated into future economic valuation and
management decisions.
"Although
there are short-term economic costs associated with preservation of
marine biodiversity, over the long term biodiversity conservation
and economic development are complementary goals," says
coauthor Ed Barbier, an economist from the University of Wyoming.
The authors
conclude that restoring marine biodiversity through an ecosystem
based management approach - integrated fisheries management,
pollution control, maintenance of essential habitats and creation of
marine reserves - is essential to avoid serious threats to global
food security, coastal water quality and ecosystem stability.
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