Scientists from the Florida Keys National Marine Sanctuary and Florida Fish and Wildlife Conservation Commission departed Thursday on a 10-day research trip to map snapper and grouper spawning sites between Key West and the Dry Tortugas.

The researchers are focusing on gaining a better understanding of historic spawning locations and fish movements in and around the sanctuary's Tortugas Ecological Reserve.

The trip is part of an ongoing study in the Tortugas that began in 2008. About 180 snappers have been tagged and their movements tracked.

"I think this is important for management purposes," said Alejandro Acosta, an FWC researcher. "We are looking at connectivity between different habitats and spawning areas. Where they go? Where they come from? This shows the importance of protecting these areas."

On the expedition, scientists are using multi-beam and split-beam sonar equipment to provide high resolution maps of the seafloor while simultaneously searching for fish -- a technique that will help determine what features spawning sites have in common. Divers plan to conduct visual surveys to validate the sonar scans, and use remotely operated vehicles to document observations at deeper depths.

Divers will also perform maintenance on 74 acoustic receivers moored in the Tortugas Ecological Reserve, Dry Tortugas National Park and the surrounding area. The network of receivers is used to detect tagged fish. The program has been instrumental in documenting the successes of both the reserve, the national park's Research Natural Area and a historic mutton-snapper spawning area called Riley's Hump.

The researchers are from the National Oceanic and Atmospheric Administration's (NOAA) Office of National Marine Sanctuaries, NOAA's National Centers for Coastal Ocean Sciences, the Florida Fish and Wildlife Conservation Commission, Florida Department of Environmental Protection and the College of Charleston.

In 2001, the sanctuary designated the 151-square-nautical-mile Tortugas Ecological Reserve as a no-fishing area to protect habitat and biodiversity. Fishing and anchoring are prohibited throughout the reserve, and boating and diving without a permit is prohibited in the reserve's southern section.

A major focus of the research is on the mutton snapper spawn. Fishing during the mutton spawn has become a controversial issue in the Keys. During full moons in May and June, droves of fishermen descend on the Keys reefs at night to target the spawning mutton snapper.

Some fishermen, both recreational and commercial, have called on state and federal governments to reduce bag limits during the spawn so the species is not depleted.

The bag limit for mutton snapper is 10 fish per person per day.

Daily photo updates from scientists on the expedition are posted on the sanctuary's Facebook page, http://www.facebook.com/floridakeysnoaa.gov.

tohara@keysnews.com