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Fishing for ScienceTBEP Asks For Help "Sampling" Dredge Holesby Nanette Holland Fishing guides and recreational anglers from throughout the Bay Area will be "fishing for science" over the next year as part of a research project to assess the habitat value of manmade dredge holes in Tampa Bay. The project, sponsored by the Tampa Bay Estuary Program (TBEP), will analyze water quality and fisheries use for about 15-20 major dredge holes in the bay. Dredge holes are depressions - some as deep as 30 feet - in the bay bottom left over from dredging projects that routinely occurred from about the 1940s to the 1970s. Material taken from the holes was often used to build up adjacent shorelines or fill wetland areas. TBEP and its research partners want to find out if some of the dredge holes could be enhanced, either by filling them completely to encourage the growth of shallow-water seagrasses; by partially filling them to improve flushing and water quality; or by installing artificial reefs in some of the holes to provide habitat for fish, crabs and other marine creatures. Another option is simply to leave the holes alone. TBEP Senior Scientist Holly Greening said bay managers intend to leave in their existing state dredge holes that are shown to provide important winter refuges for cold-sensitive sportfish such as snook - who hunker down in the deep holes because the water is warmer there than at the surface. That's where the "fishing for science" comes in. Fishermen from local angling clubs will be recruited to "sample" the holes with conventional fishing tackle over the next 12 months, and record the numbers and species of fish they catch. Participating anglers will be asked to fish the same hole or holes on a regular basis. Holes that are shown to provide either seasonal or year-round sportfish habitat will be left alone. Holes that have little to no oxygen at the bottom, or extremely poor flushing with little utilization by fish, will be prime candidates for habitat enhancement. The dredge hole assessment study is being financed by a $150,000 wetlands grant from the U.S. Environmental Protection Agency Region 4 office in Atlanta. Another $50,000 in in-kind services are being provided by the Florida Marine Research Institute. Other partners include the U.S. Army Corps of Engineers, the Hillsborough County Environmental Protection Commission, and the Southwest Florida Water Management District. The U.S. Army Corps of Engineers is participating in the project because partial or complete filling of some dredge holes in the bay may provide an environmentally beneficial way to dispose of some of the 1 million cubic yards of sediment that must be dredged from channels and shipping berths each year to maintain navigational safety. The Corps is even allowed to spend a little more money for dredge disposal projects that benefit the environment. Capt. Dave Markett, a member of the Florida Guides Association, is among the sport fishermen serving on an advisory committee overseeing the project. He said many of the dredge holes in the bay serve as a "safety net" for fish when water temperatures plummet. "There are certain times of the year when fish populations in the holes might be 100 or more times greater than at other times," he said. "We are just concerned that our primary goal with this be not to do damage." Representatives of the guides association, the Coastal Conservation Association, and the Tampa Bay Fly Fishing Club serve on the committee and will recruit anglers to "sample" the dredge holes on a regular basis. The decision about which holes may be candidates for enhancement will depend on many factors, including: whether dissolved oxygen levels are consistently too low to support fish, whether the bottom sediments contain potentially toxic contaminants; and how important the holes are for fisheries. An initial series of trawls for small or juvenile fish by the Florida Marine Research Institute has shown that several holes support a variety of species at varying depths, from pink shrimp to bay anchovies to gobies and sea robins. The recreational angler sampling will help to determine which of the holes is important for adult sportfish such as snook, black drum, redfish or sheepshead. Holes to be studied will be selected this fall, with sampling occurring over the next year. An evaluation of the project, with recommendations on site-specific strategies for each hole examined, will follow. For more information on the dredge hole assessment project, contact Nanette Holland at (727) 893-2765 or e-mail nanette@tbep.org. Nanette Holland is public outreach coordinator for the Tampa Bay Estuary Program. |
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Nitrogen Levels on Target for Bay Restoration
In addition, goals for water clarity and algae concentrations (measured by chlorophyll-a) are tracked annually. The most recent report, completed earlier this year, shows that overall chlorophyll-a targets were met in 2000 and 2001, although algae levels increased dramatically during the record rainfalls of 1998. "We knew we'd have years like El Ni–o and we planned for them when we set these goals," said Holly Greening, senior scientist for TBEP. "What we didn't know was how long it would take for the bay to recover from the additional loadings." Water clarity - a key issue in seagrass health - returned to pre-El Ni–o levels within 12 months, although damaged seagrass meadows are rebounding more slowly, she said. |
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A key component of the Tampa Bay Estuary Program's plan for restoring Tampa Bay is reducing nitrogen inputs by 17 tons per year. Working with partners including local governments, utilities, industry and agriculture, the TBEP tracks those reductions with a sophisticated computer program that calculates the cumulative impact of actions taken by each partner. This pie chart represents total nitrogen loadings from all sources.