- Associated Press - Saturday, March 29, 2014

CHARLESTON, S.C. (AP) - Ask most any ocean fisherman and he will tell you he has a favorite offshore fishing spot.

Now researchers from the College of Charleston using state-of-the art mapping equipment are providing insight into what makes such spots off the South Carolina coast so attractive to fish like snapper and grouper and, in turn, to the fishermen who catch them.

Their mapping work in recent months has ramifications for everything from developing wind energy to finding the best places to pump sand to rebuild beaches and creating sanctuaries to prevent overfishing.

Geology and marine biology students from the college spent the better part of a week earlier this month using high-tech sonar equipment mapping areas of the mid-continental shelf about 25 miles off the coast. They later invited a group of reporters on their research ship to see what they had done.

The areas they mapped were around prehistoric ocean floor meanders first discovered by researchers from the college about decade ago. The meanders are areas on the bottom about 70 feet down. They were carved by channels of streams and creeks that fed the ocean about 12,000 years ago when sea level was lower and the shoreline farther to the east.

The channels exposed so-called hard ground - underlying limestone that invertebrate organisms can hold onto and populate. That creates habitat for small fish and, in turn, larger fish and so fishing grounds for humans.

“They are not everywhere on the continental shelf but they are very concentrated in the areas where the fishermen go,” said Leslie Sautter, an associate professor in the college’s Department of Geology and Environmental Geosciencies.

Last year Sautter, along with Scott Harris, also an associate professor in the department, and several other researchers published a paper on their findings in the journal Geomorphology. Sautter said researchers worked with the South Carolina Department of Natural Resources in selecting areas to map.

“Finding these areas and mapping them for potential use in fishery management is very important,” she said. She added the maps will also be important in positioning offshore wind turbines to make sure they don’t affect fisheries habitat.

On a computer screen, the meanders on a map of the ocean floor look like a river might appear on a land map.

Wes Rivers, a junior geology major at the college, works on a fishing boat out of Charleston over the summer. He said he knew where some of the best fishing spots were. He suspected it had something to do with the bottom in those areas but now has a greater understanding.

“This is a unique opportunity,” said Rivers, who wants a career that has to do with ocean mapping. “I love what we do because you get a chance to explore something no one has seen before.”

Although there are maps of the nation’s offshore waters, only a small area, probably less than 3 percent, has been mapped with the latest technology, Harris said.

“Some of the maps were created in the 1870s with a lead line. Some were created in the 1960s with a single (sonar) ping,” he said.

The multibeam sonar used by the students and researchers uses multiple sound signals to map a swath of the sea floor. Single beam sonar can only capture a single point below a ship. The new surveys were also made with equipment that accounts for water salinity and temperature that can influence sonar readings.

Harris said such maps can help in projects to rebuild eroded beaches showing if pipes coming from offshore sand pumping sites are disturbing fisheries or crossing areas on the ocean floor that could cause the pipes to break.

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