Black Sea Bass: Aquaculture Opportunities

Charter boat captain Carl Snow and University of North Carolina at Wilmington researchers have made a discovery: When it comes to black sea bass, you may be able to have your fish and eat it, too.

As appetites for seafood have grown, so have concerns for depleted fish stocks. Currently, black sea bass is listed on the N.C. Division of Marine Fisheries Web site as a “species of concern” south of Hatteras and, north of Hatteras, as “overfished.”

Many see aquaculture, or fish farming, as an alternative that can relieve commercial pressure from wild species, but little work has been done with farm-raising black sea bass in North Carolina. Until now.

A project at UNC-W studying black sea bass aquaculture started a few years ago when a fishing captain’s observations and a scientist’s expertise joined forces through an innovative grant opportunity. The Fishery Resource Grant (FRG) program is funded by the N.C. General Assembly and administered through North Carolina Sea Grant. It blends science with practical fishing experience to find ways to improve and protect the state’s fisheries.

For more than 40 years, Snow has been involved in fishing endeavors — from operating the charter fishing boat, the Fish Witch II, to running, along with wife Missy, a seafood market and packinghouse. He has aquaculture experience in shedding blue crabs and specializes, in the winter and spring, in fishing commercially for black sea bass.

Snow’s catches of the fish have gotten smaller in recent years, he says. “But different fishermen would argue about that. They say fish come in cycles. If that’s so, the last few years have been a down cycle. I don’t think there are as many fish out there,” he says.

Despite the apparent vulnerability of black sea bass populations as a whole, Snow notes a particular resilience in the individual fish. He says they thrive in the holding tank of his boat during trips from the fishing site to the docks — trips that can take more than two hours.

“Of all the bottom-feeding fish, sea bass are definitely the hardiest,” he says.

That’s what got him thinking of using sea bass for aquaculture. And while he was thinking about it, North Carolina Sea Grant fisheries specialist Jim Bahen called to tell Snow about the FRG program.

That timely call became the catalyst for the project. The conversion to scientific study began as Sea Grant paired Snow with Wade Watanabe, a research professor focusing on marine aquaculture at the UNC-W Center for Marine Science.

A Scientist’s Perspective

Watanabe’s experience with marine and freshwater aquaculture of finfish has taken him all over the world. For Snow’s idea for an FRG project, Watanabe was in the right place at the right time.

A native Hawaiian, Watanabe knows a thing or three about seafood, as well as sea science. He says the firm, white flesh of black sea bass is amenable to a variety of culinary treatments, including — but not limited to — Asian cooking techniques. It is especially good as sushi, says Watanabe, who admits to a fondness for the uncooked delicacy.

For Watanabe the scientist, the fish’s culinary merits are superceded by traits such as tolerance for different temperatures and salinity concentrations.

“They display some very good attributes for aquaculture,” he explains. And that can have implications for the species in the wild.

The business of aquaculture tends to spawn, so to speak, hatchery technologies that can supply fingerlings to be grown out in fish farms, Watanabe says. And this is where he sees a “transition between commercial fishing and aquaculture.”

“The fingerlings also could be used to replenish natural stocks,” he says. “It’s another potential application of hatchery technology.”

This use of fingerlings produced in hatcheries has precedent with other marine finfish species. Hatchery-raised red drum have been released to the wild in Texas and South Carolina, Watanabe says.

Future studies may show the impacts of such releases on wild stock.

The sea bass research represents a progression from commercial fishing to aquaculture. In the first FRG project, small but legal-sized black sea bass trapped by Snow demonstrated successful growth rates when given practical, commercially available feed. A second study showed the fish are tolerant of relatively high stocking densities.

Now, a new FRG project is focusing on spawning, using some of the original wild-caught stock.

Applying Science

“I think the best thing I’ve enjoyed about this project is that everything I’ve said (about black sea bass) has been proven right,” says Snow.

One thing that impresses Snow is how many additional people it takes to increase the scientific validity of an FRG project like his — North Carolina Sea Grant staff, academic researchers like Watanabe to design and oversee the experiments, and students who do much of the lab work.

Kim Copeland was a graduate student in marine biology when she started working on the project at the beginning, in 1999. Watanabe says her work has been “crucial” to the project’s success.

Now a research associate, Copeland has witnessed the growth of the project and of the black sea bass — from weighing and measuring the fish to compiling and analyzing the data. She went out a couple of times with Snow to see how black sea bass trapping was done, and hauled the fresh catch back to the university’s Wrightsville Beach lab.

From what she’s seen, she agrees with Snow that these are some resilient creatures.

Most fish species brought in to the lab require “feed-training,” she says, and must be introduced to artificial feed gradually.

Some, like the flounder used for broodstock, won’t take pellets at all. They eat only fish called silversides that have been frozen, then thawed. The labor and processing involved in meeting the exacting requirements of such picky eaters hikes up aquaculture costs.

But the bass took to the commercial feed readily — a rare event “anytime you’re taking fish from the wild and putting them in an artificial environment,” Copeland says.

And, attesting to their hardiness, Copeland explains that the mortality rate from the acclimated fish during the feeding study was zero. Even given some mortalities early on from transporting and holding, she says the statistics are impressive.

A potential drawback for black sea bass aquaculture, says Watanabe, is the relatively slow growth rates in wild populations of this species, which can grow to seven pounds and 24 inches long. In the study, Watanabe says growth rates proved to be much faster than in the wild.

So far, so good. But in order to be feasible for farm-rearing, the fish must tolerate stocking in tanks at numbers that will mean profit to the aquaculturist.

Using results from the feeding study, the second FRG looked at how adaptable the black sea bass were to different stocking densities. The CMS facility uses recirculating tanks — a “closed” system in which water quality is managed using biological and mechanical filtration with ultraviolet water sterilization. Heat pumps control water temperature.

The black sea bass did well with more fish per tank. Another study funded by the U.S. Department of Agriculture is looking at stocking densities high enough for profitable aquaculture.

But to say the fish tolerated more crowded conditions isn’t to say they were unaffected.

“Ours had higher body fat content, but enhanced value as a sushi product where higher fat content seems to be preferred,” Watanabe says.

Fat content is a characteristic that may be controllable in aquaculture by manipulating feed and the amount of exercise the fish get in the tanks, he explains.

The Proof is in the Eating

No one needs to tell Captain Snow that black sea bass is delicious.

“You can’t beat a sea bass. It’s a great eating fish,” he attests. Even though Snow and his wife can get all the fresh fish they want year-round, Snow says they like sea bass so much they freeze it — just so they can have it in the summer, too.

In December 2001, the fish from the study were submitted for a taste test at Elijah’s Restaurant in Wilmington’s waterfront area. It was a grand debut for the subject of an experiment, with a tasting panel that included UNC-W Chancellor Jim Leutze and local media.

The fish samples were served four ways — fried, blackened, stuffed with lobster and as sushi.

The sushi was the preferred dish at the tasting, says Kevin Yates, a UNC-W graduate student in marine science who worked on marketing for the project. However, some tasters declined the sushi, which may have skewed the results, Yates explains. Sushi afficionados were likely the ones who rated that dish so high.

All in all, the black sea bass was well received. On a scale of one to five, most dishes scored higher than four, says Yates.

Since the taste test, the black sea bass from the project have continued to get rave reviews.

Yates took some of the fish to the Fulton Fish Market in New York, which he describes as a “huge open-air wholesale market” and one of the largest seafood markets in the world. The fish were cut open right there, he says, and passed around as sushi. “They look at thousands of pounds of fish per day and really liked it,” he says.

“That’s when I came to the realization that we really had something here to target the sushi market with,” says Yates, explaining that means higher profits for the supplier.

In Maryland, the test-marketed bass brought $5 a pound, whole and on ice, even at weights less than the 2.5 “jumbo” size, according to Copeland. Commercially, jumbos normally bring $4 to $5 per pound at the most, she says.

For “live-hauled” fish, Yates says the black sea bass can bring much more at large, metropolitan markets.

Prices fluctuate considerably, based on market demand. The best way for the aquaculturist to gauge selling price is to find the current wholesale rates for wild-caught species, says North Carolina Sea Grant Director Ronald G. Hodson, a nationally recognized expert in marine finfish aquaculture.

The sea bass have received accolades close to home as well as in New York and Maryland.

“We have test-marketed the fish to a local market in Wilmington, and they’re always calling and asking if we have more fish,” Copeland says.

Out of the Lab, Into the World

Given the results from the projects so far, Snow says he plans to pursue black sea bass aquaculture.

He explains that his setup will differ from the university’s system that filters and recirculates water.

“I happen to be very fortunate, because I live on the water,” he says. He plans to pump in sea water for his operation.

Buying tanks, pumps and filters for a recirculating system would be more expensive, Snow says. “But that’s just a one-time thing,” he adds. “I feel like, if someone was serious about trying to do it for a living, it would be profitable.”

Watanabe explains that, as the business of finfish aquaculture develops, it tends to progress from a system that relies on wild-caught fish to a method in which wild stock is spared. Ultimately, through the hatchery technology that arises to supply fingerlings to the aquaculturist, wild stocks can also be replenished.

“With support from the FRG program,” Watanabe says, “we tested out Captain Snow’s idea of taking small, wild-caught black sea bass and growing them to a larger premium market size before sale. If Captain Snow were to practice this concept, he would actually be growing fish that are produced in the wild, a practice known as “on-growing.” In closed-cycle aquaculture, the farmer no longer relies on the capture of wild fish to stock his tanks, but rather on fingerlings produced in a hatchery.”

Meanwhile, the sea bass research goes on.

Some of the fish grown out in the study were used as broodstock and induced to spawn using hormones and regimes regulating exposure to light and temperature.

Copeland says the current study is going well. Fish produced in the lab two to three years ago will, she hopes, reach sexual maturity soon. If they successfully spawn, she says, “it will close the life cycle” for the fish raised in captivity. Watanabe and Copeland say that this is the first time, to their knowledge, that this has been accomplished for this species.

The feat will bring the research full circle, helping to establish the feasibility of commercial aquaculture of black sea bass along with its implications for replenishing a species.

This article was published in the Early Summer 2003 issue of Coastwatch.

For contact information and reprint requests, visit ncseagrant.ncsu.edu/coastwatch/contact/.