January 6, 2006

Study: Boaters Damaging Seagrass in Florida

MIAMI -- Negligent and inexperienced boaters are damaging fragile seagrass in the shallow Florida Bay, destroying habitat crucial to the state's fishing industry, a conservation advocacy group said Thursday.

The bay comprises about a third of Everglades National Park, and the seagrass beds that feed pink shrimp, redfish and other marine life cover about 800 square miles, an area about twice the size of Los Angeles, at the bay's bottom.

Advocates say a matrix of scars crisscrossing those beds are visible through the bay's clear waters in aerial photographs.

Boaters misreading their maps, running aground or taking shortcuts outside marked channels are cutting those wide swaths across seagrass beds, according to a study by the National Parks Conservation Association, an independent organization that advocates for the National Park Service.

Boat propellers leave deep trenches across the bay as they tear up the seagrass blades and churn sediment at the bottom, said Jason Bennis, the conservation association's marine policy manager.

"If the furrow is deep enough, and the plants are torn up and the roots are exposed and the sediment covers it, it can take decade or more to recover," Bennis said.

The habitat damage could potentially also cut into the state's annual fishing revenues, Bennis said.

Redfish, spotted sea trout, bonefish and black drum - fish sought by recreational anglers - feed in the bay's seagrass beds, and more than 90 percent of the pink shrimp caught by commercial fisherman in Florida develop in the seagrass beds in the western Florida Bay, park officials said.

According to the South Atlantic Fisheries Management Council, commercial fishing in Florida generates an estimated $1.2 billion annually, while statewide recreational fishing expenditures total $8.3 billion each year.

Seagrass is vulnerable to changes in salinity and rising sea surface temperatures, but propeller scarring has caused most of the visible damage, said David Szymanski, Florida Bay program coordinator for the National Park Service.

In 1995, using aerial photographs, the park service determined that 30,000 acres of 1.5 million acres of seagrass beds in all of Monroe County had been damaged by boats. About 10,000 acres of those seagrass beds were located in the Florida Bay, Szymanski said.

Boat traffic has increased since then, with the number of boating violations in the bay doubling since 1995, but how much of the bay's seagrass beds are currently damaged is difficult to determine because staff and funding for aerial studies of the bay have not been available, park officials said.

More seagrass damage is done by freshwater dumped into the bay than propeller scarring, but boaters could benefit from better buoys marking shallow waters, said David Ray, executive vice president of Marine Industries Association of Florida Inc.

"We need to educate boaters in waters that are shallow to watch for the signs," Ray said. "There are very few navigational aids in areas like that."

The National Parks Conservation Association recommends that boaters be required to complete a boater safety course for the Florida Bay, and posting more signs and buoys warning boaters about hard-to-navigate channels.

Some parts of the bay shrink in depth to less than 2 feet throughout the year. A park service brochure for boaters to safely navigate the bay recommends watching for wading birds, changes in water color and debris in their trail.