Gauging the Impact of Marine Reserves
Scripps Grad Students Traveling Through Caribbean
to Learn What Conditions Allow Fish and Reefs to Thrive
Ioana Patringenaru | November 27, 2006
Gustavo Paredes taking a fish census.
Photo / Tim Taylor
A graduate student at UCSD’s Scripps Institution
of Oceanography dove off the Yucatan Peninsula a few
weeks ago in an unprotected area not far from Cancun.
He hardly saw a fish. On some parts of the reef, corals
were sick or missing altogether missing. Then he dove
in protected waters off the island of Cozumel. A completely
different landscape awaited him. Large schools of
snappers were swimming around a healthy reef. He saw
plenty of large groupers too.
This contrast can be found all around the Caribbean,
said Gustavo Paredes, a graduate student at the Center
for Marine Biodiversity and Conservation at Scripps.
Without protection, the ocean’s ecosystems are
struggling, while in well-managed, large reserves
entire marine communities are thriving.
Paredes and fellow graduate student Marah Newman
spent more than two years collecting and analyzing
data about corals and fish from all over the Caribbean.
They visited Jamaica, Mexico, Belize and Florida.
They stayed at each site anywhere from two to six
weeks and dove two to three times a day. Parades counted
fish, taking down their size and type. Newman counted
and measured corals and invertebrates.
Researchers are usually working on specific reefs or species, Paredes said. He and Newman wanted to look at the whole picture. “These are important questions and they need to be addressed on a large scale,” Newman said. Setting up reserves and protecting fish is important, Paredes said. It provides badly needed income for countries that rely on tourism as their main industry. Also, healthy reefs might do a better job at protecting coasts from water surges caused by hurricanes.
|Newman and Paredes during a dive.
Photo / Tim Taylor
Newman, Paredes and their advisors recently published some of their findings in Ecology Letters. In a nutshell, they found that large reserves that prohibit all fishing and are set up over a long period of time allow fish to recover and thrive.
Follow these rules and you get Cozumel, a spot well
known for spectacular diving conditions and bountiful
fish. Without them, you get Akumal, a small community
on the mainland just a few miles away. In Akumal,
snappers were about 10 inches long. In Cozumel, some
measured two feet. Newman said she didn’t know
some of the fish she saw there could be that big.
The bad news is that during their two-year trek through
the Caribbean, Newman and Paredes saw a lot of places
that were just as desolate as Akumal. A trip to the
Dry Tortugas National Park near the Florida Keys was
particularly depressing, Newman said. The islands
are protected and really remote, so the two grad students
hoped they’d see a healthier ecosystem. Then
they got into the water. “It was incredibly
disappointing,” is how Newman put it, adding
she became really concerned. If the United States
with all its resources couldn’t protect its
marine ecosystems, what could poorer developing countries
do, she wondered. She also wondered why that ecosystem
failed to thrive even though it was protected. “That’s
when I took a step back and thought, man, this is
really complicated,” she said.
|Paredes during a dive off Florida Keys.
Photo / Tim Taylor
But there’s good news too. Paredes and Newman’s data show that inside large, no-take, well-established reserves, fish are coming back in great numbers. That’s the first step toward getting corals to come back, too, Newman said.
Fish eat algae, which compete with corals and try to take over reefs. The catch here is that marine reserves need to be at least about 39 square miles and set up for at least a decade. In small reserves, it’s too easy for fish to leave and be caught by fishermen right away, Paredes said.
The two grad students now hope their work will actually have an impact on the ground. They’re writing reports for local authorities in the areas they visited. The idea is to praise reserves that do a good job and make some suggestions for those that don’t, said Newman. In places like Akumal, the need for action is urgent, Paredes said.
“I don’t know what’s going to happen there, if they don’t protect it right now,” he said.