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Hatchery Pins Hopes on Tiny Redfish
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Tampa Bay redfish nurseries are getting a hefty boost as part of an ambitious marine stock enhancement effort funded by saltwater fishing license revenues. Since 2000, about 2.3 million redfish fingerlings have been released in the Alafia and Little Manatee rivers, where 85 percent of the bay's juvenile reds reside. Another 2.7 million redfish are likely to be released over the next two years, as researchers zero in on the ideal size-at-release and fine-tune techniques for maximizing survival. The goal of Project Tampa Bay is to increase angler redfish catches by 25 percent without displacing wild fish. But the bigger bonus, officials say, may be the research behind the project, which is likely to shape the future of stock enhancement in Florida. "We finally got the political support to do the kind of applied research we've wanted to do for 15 years," says Bill Halstead, director of the Stock Enhancement Research Facility at Port Manatee, which opened in 1988. "No other stock enhancement project of this magnitude is being done anywhere else in the world." The state-run facility is operated by Florida Marine Research Institute (FRMI). Mote Marine Laboratory is under contract to help assess the stocking effort, while continuing research on culturing snook at its hatchery on City Island in Sarasota.
Located on 54 acres at Port Manatee, Florida's only state-run saltwater fish hatchery has released four million fingerling redfish since opening in 1988 in experimental efforts to enhance depleted sport fisheries. Funded by saltwater fishing license revenues, the hatchery is operated by the Florida Marine Research Institute. Fishing for answers While the technology exists to rear large quantities of redfish, little is known about the cost benefits of releasing game fish into estuaries, despite more than a decade of stocking efforts in Florida. Project Tampa Bay is designed to answer some of those questions. Hatchery offspring are tracked from the day of release. Researchers recapture juveniles using nets and hook-and-line as they grow, assessing survival, growth, health, migration and habitat use. Scientists extract DNA from dorsal fin clips to identify hatchery-reared fish. Larger hatchery fish are outfitted with microscopic cheek implants that can easily be detected with magnetic wands. FMRI also interviews anglers coming off the water - conducting about 15,000 surveys on Tampa Bay per year, and collecting fin clips and heads - for information on catches and locations. By comparing these "clipboard surveys" with independent monitoring of hatchery-reared fish and their wild counterparts, officials believe they have a reasonable mechanism to assess success. It wasn't always so. "When we first started, the science of stock enhancement was just evolving and the focus was on releasing as many fish as we could," says Halstead. "The real measure of success, of course, is how many survive and demonstrating a positive cost-benefit to the fishery." The hatchery uses only wild brooders, which are replenished regularly, to preserve the diversity and hardiness of the offspring. Protocols also guard against accidentally introducing diseases into the wild. A USDA-certified vet checks each group of fish scheduled for release; the rare sick crop that can't be cured is destroyed. Researchers are testing the hypothesis that hatchery fish, like their wild counterparts, select very specific habitats within the Alafia River, and that conditions for their survival are optimal in late fall and early winter when wild reds enter these nursery areas. Project Tampa Bay is expected to take six to eight years to complete. The first four years will determine optimum fish size and conditions at release, then officials will scale up to test stocking's true potential using the smallest fish that produce the biggest bang for the buck. Fisheries monitoring will continue until all fish have reached legal catch size. Advocates abound. "It's not the end-all solution," says Blair Wickstrom, publisher of Florida Sportsman magazine, "but it's an ideal way to fill in the gaps and assist recovery of the resource." So far, the state has spent more than $24 million on marine stock enhancement and research, including construction of the hatchery. Sportfishing pumps billions of dollars into Florida's economy, making stock enhancement politically popular. Skeptics say a strong bias toward stock enhancement relegates other viable options to the backseat. "It's a matter of balance," says wetland scientist and long-time bay activist Robin Lewis. "If we're going to take a limited amount of money and use it to manage fisheries, we need to fairly examine all our options. We've put millions of dollars into stock enhancement in Florida, with very little to show for it, but there's still no coordinated examination of habitat restoration as a fisheries management tool." Lewis also questions the science behind the stocking. Without control areas, he argues, it's impossible to credit stock enhancement with fisheries increases when water quality improvements and habitat restoration in Tampa Bay may be responsible. "For every advocate of stock enhancement there is an equally vocal detractor - and rightly so," says Dr. Ken Leber, director of the Center for Fisheries Enhancement at Mote Marine Laboratory and world renowned expert on stock enhancement. "The research hasn't been done to develop it and truly evaluate its potential as an additional fisheries management tool." But that hasn't dimmed Leber's enthusiasm for Project Tampa Bay, which he says is unparalleled. "It's the first time anywhere in America - outside work with salmon - that there's been a focused and extremely responsible scientific approach to answering the question." If catches increase, says Leber, we should see evidence in two places: in the ratio of hatchery to wild fish in nursery areas coupled with an overall increase in bay landings. "There's no better way to do it without quadrupling the amount of money being spent and adding controls in two different bay systems and comparing them with another two areas," adds Leber, who heads up smaller studies on snook in Sarasota Bay that include control samples. Successful stock enhancement has been demonstrated most recently in Japan, where 20 percent of the flounder ending up in fish markets were determined to be hatchery-raised. Worldwide, an estimated one to four fish eaten are raised on fish farms, although the U.S. lags behind other countries where fish is a dietary staple. Marine stock enhancement comes of age While fish farming dates back thousands of years, marine stock enhancement is relatively new. Until recently, there wasn't a perceived need: the prevailing view was that the oceans held a limitless supply of fish, plus the technology wasn't available to effectively assess stocking efforts. Interest grew in the 1970s when researchers in Chesapeake Bay demonstrated that striped bass could be cultured in a hatchery and successfully released. But it was Texas that became the model, opening a saltwater fish hatchery near Corpus Christi in 1982. Researchers there and in St. Petersburg at FMRI conducted early photo-thermal experiments, designed to trick redfish into spawning. The Tampa Bay hatchery opened in 1988 with initial plans to raise snook, but the elusive game fish proved as tricky to rear as it is to catch. Hatchery managers managed to raise just 41 snook in their first two years of operation. While survival rates eventually inched up, the snook program lost favor and officials turned to redfish, which are easier to produce in large number. "People will continue coming out of the woodwork pushing for stock enhancement, and we need to make sure we're funding things that work."Lessons of Biscayne Bay Biscayne Bay on Florida's east coast became the state's first testing ground, but a nine-year-long project ending in 1999 yielded more frustration than fish. Florida poured more than 1.7 million redfish into the highly impacted estuary, but there was limited tracking of the tiny wards, which quickly vanished. In a dire effort to locate the hatchery fish, officials turned to Mote researcher Carole Neidig. Using acoustic tags, Neidig learned that most hatchery-released fish were heading into the southern portion of the bay where mangroves and small creeks provided safe haven. Much of Biscayne Bay, they learned, lacked sufficient habitat to support juvenile reds. That prompted a switch from releasing inch-longs to eight- to 10-inch redfish that became the project's silver lining. The roughly 200,000 larger redfish released are credited with creating a small fishery in Biscayne Bay, although most acknowledge that earlier releases probably did little more than chum the water for bigger fish. Biscayne Bay also paved the way for Project Tampa Bay. Researchers and anglers alike wanted answers. Getting them would require a better testing ground. Tampa Bay's existing redfish population, available habitat and proximity to the state run hatchery, made it an obvious choice. Betting on the future Florida's closely watched experiment won't yield answers for a few more years, and even then may not quell the debate. For Mote's Leber, marine stock enhancement is not a question of why, but why not? "People will continue coming out of the woodwork pushing for stock enhancement," he says, and "we need to be sure we're funding things that work. If the agencies don't attack it, we'll never have anything but tiny studies with no meaningful scale." Mote recently purchased 200 acres near I-75 in Sarasota to build a huge aquaculture park to raise sturgeon. Halstead views marine stock enhancement as an additional fisheries management tool, designed to supplement rather than replace habitat restoration and regulation. "When a fishery becomes depleted for whatever reason - red tide, winter freeze or chemical spill - hatcheries have the potential to re-build the population faster than Mother Nature." |
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