DNR STOCKS 800 COBIA IN COLLETON RIVER

Biologists with the S.C. Department of Natural Resources stocked 800 tagged cobia in the Colleton River Nov. 4. The six-month-old fish range from 12 to 20 inches in length, and were stocked in the Colleton River because it is one of the nursery areas for fish originating in the Broad River.

Planning for this event began almost two years ago when S.C. Department of Natural Resources (DNR) biologists caught the parents of these stocked fish in the Broad River. They were taken to Charleston where they spawned, or reproduced, on May 9 of this year. These large 25- to 60-pound adults, or "brood stock" fish, were held in indoor environmentally controlled tanks where they were fed daily and conditioned to spawn in the spring during their natural spawning season.

"By releasing tagged six-month-old juveniles, we hope to document their movements after they leave South Carolina's inshore waters," said Ted Smith, a DNR senior marine scientist who oversees the cobia project. "We are very excited about our work with cobia. Not only have we demonstrated the ability to spawn newly captured as well as long term captive adults, but we are also able to produce advanced juveniles during a limited six-month outdoor growing season."

The DNR released the fish directly into the river at Trask Landing to minimize handling stress. "Additional stress would occur with netting them into a boat and netting them back out in a different location," Smith said. "Also, there should be no predators near the boat landing to fish that are the size of these cobia."

The DNR began work on raising and stocking cobia in 2001 as part of a collaborative effort with the South Carolina Sea Grant Consortium.

"There are two main areas of interest for cobia-to obtain basic life history and ecological information on the species, such as movements and growth rates, and to examine their potential for commercial aquaculture," Smith said.

Cobia are highly migratory saltwater fish that inhabit most tropical, subtropical and warm temperate waters throughout the world.

"South Carolina citizens have shown a strong interest in evaluating stock enhancement as a possible management tool," Smith said. "Although additional information is needed, being able to produce and tag fish lays the groundwork for the potential need to supplement the wild population in the future if necessary."

Interestingly, 85 percent of all cobia fishing in South Carolina occurs in Port Royal Sound in Beaufort County, making it basically a county-specific fishery. It is the only place where cobia congregate in inshore waters in large numbers in the state, and is one of only few such areas along the eastern seaboard. The Port Royal Sound system serves as a major feeding area during cobia's seasonal spawning migration. After spawning, fish tend to disperse along the entire coast.

"The DNR's success so far in spawning and growing cobia has provided a unique opportunity to learn much about this coastal species," Smith said. "Besides collecting information on environmental tolerances and diets, this year we are also testing two types of tags that should provide information on the best ways to mark, or tag, the rapidly-growing cobia for long term identification."

In 2001, the DNR tagged and released about 1,500 cobia in four locations in Port Royal Sound, with the help of the Hilton Head Island Sportfishing Club, the Beaufort Sportfishing and Dive Club and local charter boat captains. These were the first cobia ever to be stocked on the Atlantic coast. Similar to the cobia released in 2001, this year's juvenile cobia were also raised in ponds at the DNR's Waddell Mariculture Center in Bluffton.

"We had expected these fish to provide new information on movements, growth, and site fidelity of this highly valuable recreational species," said Al Stokes, manager of the DNR's Waddell Mariculture Center.

Shortly after the first release in 2001, the DNR obtained several reports of captures, with one fish migrating to Cocoa Beach, Fla., soon afterward. "The tags used then were not as durable as those being used with these released fish and therefore we are optimistic about receiving future returns," Stokes said.

DNR is encouraging the public to help report tag returns. The external orange tag has a DNR return address, and successful anglers will receive their choice of a hat or T-shirt in return for reporting the tagged cobia.

Other than angler speculation, not much is known about the population abundance of cobia either in the Gulf of Mexico or along the South Atlantic coast. Hopefully, information derived from stocking efforts such as these may help to shed light on the population of fish entering South Carolina waters.

Although the cobia fishery in the United States is primarily recreational, researchers are also considering cobia's potential as an aquaculture candidate because of their fast growth, excellent consumer appeal and success of aquaculture in other countries. "In Taiwan, cobia are grown in offshore cages, and this development stimulated interest within the aquaculture community in the United States a few years ago. Now fish are being reared in cages off Puerto Rico and in the Bahamas," Smith said. Researchers in Virginia are developing techniques to grow these fish year-round in heated greenhouses and results have shown that they can grow to seven pounds during the first year.

In spite of its high value as a seafood product, the number of cobia landings are typically low, consisting primarily of incidental captures. Cobia inhabit South Carolina waters from May to September but are absent during winter months when they move to warmer waters.

It is legal for recreational anglers (those fishing from a boat must purchase an annual South Carolina Saltwater Recreational Fishing License) to take two fish per person per day having a minimum size of 33 inches fork length. The public is reminded of Coast Watch, which was developed to better help citizens report violations of saltwater recreational and commercial fishing laws, as well as marine environmental laws. The Coast Watch hotline number (1-800-922-5431) is toll-free and available 24 hours a day.

For more information on the DNR's cobia research program, call Ted Smith at (843) 953-9839 in Charleston or e-mail smitht@mrd.dnr.state.sc.us.

- Written by Jennie R. Davis -

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