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Where are the Manatees?

March 25, 2013

Where are the Manatees?

With 10-foot-long adults weighing some 1,000 pounds, the laid-back marine mammals aren't hard to spot in places like Florida's the aptly named Crystal River

Red devils, retired-from-service Blue Bird school buses, are better known for ripping up Panama's streets, packed to the gills with hot and sticky passengers who pay a quarter for a hell-raising public transportation ride. Héctor Guzmán's red devil gently putters through the Sixaola River in search of manatees. Packed with a dual-frequency side-scan sonar and hydrophone arrays, food and tents, the modified-for-water bus is the research vessel for the STRI marine biologist's latest project made available from locals.

With 10-foot-long adults weighing some 1,000 pounds, the laid-back marine mammals aren't hard to spot in places like Florida's the aptly named Crystal River. The murky Sixaola is another story. Héctor's team counts manatees with acoustics, both, passive (hearing them) and active (using a dual frequency sonar), and telemetry of tagged individuals. “This is a huge challenge for us,” says Héctor, who has tracked humpback whales in the Pacific and monitors corals around Panama. “This is the first time in my life I'm working underwater with something I don't see.”

Counting the manatee population on the Caribbean coast around the Panama-Costa Rica border is part of a binational project to take stock of the area's biodiversity. While large areas of the Sixaola watershed are protected, deforestation, tourism, hunting and agrochemicals threaten the area. The project, funded by the Interamerican Development Bank and the Global Environment Facility, aims to create more robust conservation schemes for the area. He was invited to participate in the project.

“The design is beautiful,” Héctor says. “The project is trying to work not only in the parks but in the whole area of influence. That includes an evaluation of sources of pollution, land use, and a component for biodiversity.”

Manatees are among the Sixaola's iconic large fauna, which includes jaguars and leatherback turtles. Anywhere between 20 and 150 manatees are said to live in the area. Héctor's work over the rest of 2013, in collaboration with his colleague from Universidad de Costa Rica Mario Rivera, will not only zero in on a more precise population estimate but also reveal their areas of preference for feeding and mating. Héctor's team will also make conservation recommendations. “The overall goal is to protect them, of course.”

OLD BONES


Manatees were certainly much more plentiful in Sixaola. Héctor believes pollution is their biggest current threat but they have long been hunted. Part of his research includes a bit of historical ecology. One family with three generations of (now-retired) manatee hunters has pointed him in the direction of manatee boneyards. Samples will contribute to the genetic analyses he will run on living animals. Unfortunately, some middens have already been overrun by development. “Even if I get just a few samples, that will be great,” he says.

Photo caption: “El BUTE”, an old Diablo Rojo modified-for-water, is the research vessel for STRI marine biologist Hécor Guzmán’s latest project.

Photo caption: The binational project to take stock of the biodiversity on the Caribbean coast around Panama-Costa Rica border is funded by the Interamerican Development Bank and the United Nations Global Environment Facility.

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