|
|
Wave of Marine Species Extinctions Feared
By Juliet Eilperin
Washington Post Staff Writer
Wednesday, August 24, 2005; A01
BIMINI, Bahamas -- The bulldozers moved slowly at first. Picking up
speed, they pressed forward into a patch of dense mangrove trees that
buckled and splintered like twigs. As the machines moved on, the pieces
drifted out to sea.
Sitting in a small motorboat a few hundred yards offshore on a mid-July
afternoon, Samuel H. Gruber -- a University of Miami professor who has
devoted more than two decades to studying the lemon sharks that breed
here -- plunged into despondency. The mangroves being ripped up to build
a new resort provide food and protection that the sharks can't get in
the open ocean, and Gruber fears the worst.
"At the end of my career, I get to document the destruction of the
species I've been documenting for 20 years," he lamented as he watched
the bulldozers. "Wonderful."
Gruber's sentiments have become increasingly common in recent years
among a growing number of marine biologists, who find themselves
studying species in danger of disappearing. For years, many scientists
and regulators believed the oceans were so vast there was little risk of
marine species dying out. Now, some suspect the world is on the cusp of
what Ellen K. Pikitch, executive director of the Pew Institute for Ocean
Science, calls "a gathering wave of ocean extinctions." Dozens of
biologists believe the seas have reached a tipping point, with scores of
species of ocean-dwelling fish, birds and mammals edging toward
extinction. In the past 300 years, researchers have documented the
global extinction of just 21 marine species -- and 16 have occurred
since 1972.
Since the 1700s, another 112 species have died out in particular
regions, and that trend, too, has accelerated since the mid-1960s:
Nearly two dozen shark species are close to disappearing, according to
the World Conservation Union, an international coalition of government
and advocacy groups.
"It's been a slow-motion disaster," said Boris Worm, a professor at
Canada's Dalhousie University, whose 2003 study that found that 90
percent of the top predator fish have vanished from the oceans. "It's
silent and invisible. People don't imagine this. It hasn't captured our
imagination, like the rain forest."
Many activists have focused on the plight of creatures such as the
ivory-billed woodpecker and the grizzly bear, but relatively few have
taken up the cause of marine species. Ocean dwellers are harder to
track, and some produce so many offspring they can seem invulnerable.
And, in the words of Ocean Conservancy shark fisheries expert Sonja
Fordham, often "they're not very fuzzy."
Although a number of previous extinctions involved birds and marine
mammals, it is the fate of many fish that worries experts. The
large-scale industrialization of the fishing industry after World War
II, a global boom in oceanfront development and a rise in global
temperatures are all causing fish populations to plummet.
"Extinctions happen in the ocean; the fossil record shows that marine
species have disappeared since life began in the sea," said Elliott A.
Norse, who heads the Marine Conservation Biology Institute in Redmond,
Wash. "The question is, are humans a major new force causing marine
extinctions? The evidence, and projections scientists are making,
suggest that the answer is yes."
Large-scale fishing accounts for more than half of the documented fish
extinctions in recent years, Nicholas K. Dulvy, a scientist at Lowestoft
Laboratory in England, wrote in 2003. Destruction of habitats in which
fish spawn or feed is responsible for another third. Warmer ocean
temperatures are another threat, as some fish struggle to adapt to
hotter and saltier water that can attract new competitors.
But nothing has pushed marine life to the edge of extinction more than
aggressive fishing. Aided by technology -- industrial trawlers and
factory ships deploy radar and sonar to scour the seas with precision
and drag nets the size of jumbo jets along the sea floor -- ocean fish
catches tripled between 1950 and 1992.
In some cases, fishermen have intentionally exploited species until they
died out, such as the New Zealand grayling fish and the Caribbean monk
seal; other species have been accidental victims of long lines or nets
intended for other catches. Over the past two decades, accidental
bycatch alone accounted for an 89 percent decline in hammerhead sharks
in the Northeast Atlantic.
Today, sharks, along with sturgeon and sciaenids (known as croakers or
drums for the sounds they make undersea), are among the most imperiled
of the species that spend most of their lives in the ocean.
Populations of sharks, skates and rays -- creatures known as
elasmobranchs that evolved 400 million years ago and have skeletons of
cartilage, not bone -- have difficulty rebounding because they mature
slowly and produce few offspring. Shark-fin soup, an Asian delicacy that
sells for more than $100 a bowl, has spurred intensified shark hunting
in recent years.
Despite the sturgeon's fecundity, overfishing and habitat destruction
have caused that population to dive as well. Beluga sturgeon, the source
of black caviar, release 360,000 to 7 million eggs in a year, Pikitch
noted, but they have declined 90 percent in the past 20 years. Just this
month, scientists in Kazakhstan reported that they failed to find a
single wild, reproducing beluga female, leaving them with no eggs for
hatcheries.
Croakers' large swim bladders -- air-holding sacs that help them
maintain buoyancy -- account for their imminent demise. Traditional
Chinese medicine prizes the bladders, and the sound they make when
pressed against vibrating muscles can reveal croakers' location to
fishermen through sonar.
"They've been survivors on an evolutionary scale, but they've met their
match, and it is us," said Pikitch, who writes about sharks and sturgeon
in an upcoming book, "State of the Wild 2006."
Despite scientists' warnings, American and international authorities
have been slow to protect marine species. The only U.S. saltwater fish
to make the protected list is a ray, the smalltooth sawfish, which was
added in 2003.
The National Oceanic and Atmospheric Administration's Fisheries Service
is charged with protecting 61 threatened or endangered marine species.
Director Bill Hogarth said his agency focuses on protecting vulnerable
populations so they will not have to be listed.
"That's our job -- to make sure species don't wind up on the endangered
species list," he said.
But conservationists said NOAA officials are reluctant to classify fish
as endangered because doing so conflicts with the agency's mission of
promoting commercial fishing.
Michael Hirshfield, chief scientist at the advocacy group Oceana, said
he has repeatedly seen government officials provide shifting estimates
of how many threatened or endangered sea turtles can acceptably die each
year in eastern scallop fisheries.
"You never get an answer to the question how many turtles would have to
be killed before you would say, 'That's not okay,' " he said.
On Bimini, 50 miles from the Florida coast, Gruber is trying
unsuccessfully to stave off the golf resort that could bring 5,000
tourists a day. The island has just 1,600 residents but supports more
than a dozen shark species.
Based on an 11-year survey starting in the mid-1990s, Gruber documented
that between 2000 and 2001, during the heaviest dredging of the ocean
floor for the resort's construction, the survival rate for lemon sharks
fell 30 percent, and sharks in the dredging area had higher toxin
levels. He has yet to assess the impact of the mangrove destruction,
which began on a large scale this year.
The president of the Bimini Bay Resort and Casino, Rafael Reyes, said he
understands the concern but questions Gruber's statistics and the idea
that "sharks and development don't mix."
"We have a vested interest in making sure things remain as they are,"
Reyes said, adding that he is demolishing mangroves in a place that is
"basically not a sensitive area. . . . I have to make sure the
environment's pristine because my clients are fishermen."
But Gruber remains unconvinced.
"I believed when I started the ocean was so vast there was no way you
could ever kill off the sharks or anything," he said. When it comes to
being a fish, he said, "Now you can run, but you can't hide."
© 2005 The Washington Post Company
|
|