More than half a dozen shark attacks have happened in North
Carolina in the last three weeks, nearly as many as happened all of last year.
Experts say this summer is brewing up something of a
perfect storm for the attacks. But while they seem like they're everywhere,
shark populations are actually dwindling.
And the real reason there have been so many attacks likely
isn't because there are more sharks in the water — it's because there are more
people swimming in it than ever before.
Shark expert George Burgess of the International Shark
Attack File explained the trend in a recent NPR interview:
Shark populations in the US and around the world are at
perhaps all-time lows. On the other hand, the human population continues to
rise every year. We have no curbing of that.
And fundamentally [a] shark attack ... is driven by the
number of humans in the water more than the number of sharks, and when areas
such as the Carolinas become popular tourist destinations, as they have,
there's [sic] more people entering the water. You're going to end up having
more shark bites.
While a number of studies in recent decades have suggested
that shark populations around the world are all declining sharply, it's hard
for scientists to get exact numbers on them.
Nevertheless, by comparing recent population numbers with
past data, we can get a general estimate of how sharks are doing across the
globe, marine biologist and University of Miami graduate student David Shiffman
explains in a recent post on his blog.
One frequently-cited survey of data published in 2003 from
fisheries gathered between 1986 and 2000 suggests that shark populations are in
deep trouble.
The data from that survey found that hammerhead populations
were declining by an average of 89%; great whites by 79%; tiger sharks by 65%,
thresher sharks by 80%, blue sharks by 60%, and mako sharks by 70%:
(Science/"Collapse and Conservation of Shark
Populations in the Northwest Atlantic") Declines in estimated relative
abundance for coastal shark species: (A) hammerhead, (B) white, (C) tiger, and
(D) coastal shark species; and oceanic shark species: (E) thresher, (F) blue,
(G) mako, and (H) oceanic whitetip.
"We may never know exactly how many sharks are out
there, or exactly how many are killed each year. What we do know, from a
variety of different types of analysis, is that many species of sharks are
decreasing in population at alarming rates," writes Shiffman.
Why are sharks in trouble?
While vigilante shark hunters can do significant damage to
local shark populations, the real problem centers around two main activities:
Hunting sharks for their meat and fins and irresponsible fishing practices.
Each year, thousands of sharks are caught and trapped in fishing nets and
other fishing gear.
And while it might seem like good news that there are fewer
sharks around, it's actually a very big problem for the rest of us.
In many places, sharks are apex predators, meaning they
occupy the spot right at the top of the food chain. If their populations aren't
healthy and stable, it throws all of the other life in the oceans out ofbalance.
.
Plus, sharks have a bunch of characteristics that make them
especially vulnerable to exploitation http://www.seethewild.org/shark-threats/,
including the fact that they live long lives, mature late in life, and have
very few young.
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