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| Thinking out-of-the-box |
Vancouver - The indiscriminate slaughter of
vast numbers of turtles, sharks, albatrosses and other endangered marine
animals that get unintentionally caught by fishermen as by-catch, could
be prevented by a radical proposal of mobile marine reserves, according
to scientists.
Protected areas of the ocean where
commercial fishing was banned would work far better if they were not
static conservation areas, as they were at present, but were moveable
reserves that took into account the mobile nature of sea life, they
said.
The proposed conservation zones
would not impose fishing restrictions in one place, but would shift
location according to where threatened species were expected to be
found. The idea has resulted from a revolution in satellite and tagging
technology that has allowed scientists routinely to monitor the seasonal
movements of marine creatures, which would have been impossible a
decade ago.
Scientists said existing marine
protection areas, where fishing was controlled to enable wildlife to
recover, frequently failed to do their job because the endangered
animals simply migrated to unprotected regions where they got caught
accidentally.
This is believed to be the main
reason that populations of loggerhead and leatherback turtles, both
critically endangered, have slumped dramatically in recent years as
commercial fishing with nets and extremely long fishing lines has become
more intense.
Leatherback turtles have suffered
particularly badly in the Pacific Ocean. Sharks and albatrosses have
also declined significantly as a result of being caught accidentally by
fishermen.
Creating
mobile protection areas monitored by satellite would enable some of the
world’s most endangered species to recover, as well as allow fishermen
to ply their trade in other parts of the ocean where by-catch was less
likely, said Larry Crowder, a professor of marine biology at Stanford
University in California, in the US.
“Small, stationary reserves do
little to protect highly mobile animals, like most fish, like the
turtles and sharks and seabirds.
“You might say that the only way
to achieve conservation of these kinds of organisms is to protect them
everywhere in the ocean,” he said.
“But we don’t need to close the
entire ocean; we only need to close the place where they are
concentrated,” he told the American Association for the Advancement of
Science in Vancouver, Canada.
Satellite tagging and other ways
of monitoring the movements of marine creatures have shown that sea life
tends to congregate near oceanographic features such as upwellings,
where rising currents bring minerals to the sea surface, and convergence
zones, where ocean currents collide.
“Those are where everything in the
ocean goes to feed, and the fishermen understand that,” Crowder said.
These features tend to move, taking sea life with them.
“Satellite
technology, tagging and acoustic technology allow us to look into the
ocean and figure out who is going where,” he added.
“The time is ripe for the idea of
mobile marine protection areas and a good candidate to consider is the
North Pacific convergence zone. We know it moves seasonally. In the
summer, it’s about 1 000 miles (about 1 600km) north of Hawaii and in
the winter, it is further south.”
Several species are
threatened. The number of leatherback turtles in the Pacific has
declined by 90 percent in 20 years with by-catch a main cause. The
loggerhead turtle has been hit particularly hard by shrimp trawling.
Albatrosses can become caught on fishing lines and drown. The northern
royal albatross is an endangered species.
An estimated 50 million
sharks are caught unintentionally every year. The angel shark,
vulnerable to by-catch, is now one of the five most endangered shark
species. – The Independent
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