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July 04, 2020

This page last modified:
March 21, 2001

Boating Impacts to Florida Keys Seagrass Beds

by Pam Wingrove

University of Florida/Monroe County Cooperative Extension

Florida Bay Education Project

There is an old saying that goes something like, "there are two kinds of boaters, those who have run their boats aground, and those who admit to running their boats aground." While this pokes fun at a serious issue in the Florida Keys, it also points out how common it is to find yourself stranded in shallow water. Hundreds of calls come into marine law enforcement offices each year from vessel operators who need assistance in removing their boats from seagrass and sand flats. As the coastal population grows, this becomes an increasingly serious concern for resource management.

In 1997 there were 206,301 registered power boats in South Florida including Lee, Collier, Monroe, Dade, Broward, and Palm Beach counties. That figure has grown from 186,855 registrations in the same area for 1993. Monroe County alone has 23,079 registered boats. The growing number of vessels on the water means increasing pressure on marine resources. Alarming reports of ships running into coral reefs are all too familiar and upsetting. Less recognized but no less important are the seagrass beds which take a beating from repeated groundings and prop scarring. In a 1995 report by the Florida Marine Research Institute, Monroe County ranked the highest statewide in the amount of moderate to severe damage to seagrass habitat from boating impacts.

Seagrass habitats are the cradle of recreational and commercial fishing resources, often called nurseries, because many juvenile fish and invertebrates spend their early life stages there. The seagrass beds of Florida Bay are important to the florida spiny lobster, pink shrimp, stone crab and numerous other animals. In addition to providing shelter and food for animals, seagrass beds also help to stabilize the bottom through their root systems, reduce wave energy, trap sediment and improve water clarity.

Unlike the grass in our lawns, which seems to grow right in front of our eyes, seagrasses take a long time to recover when damaged or cut. The actual recovery time is different for the 7 species of seagrass found in the Florida Keys and depends on the type of growth each species has, the degree of damage, water quality conditions and sediment characteristics. Turtle grass, a common species locally, may take anywhere from 3 to 6 years to fully recover.

Seagrasses are damaged when props gouge the bottom tearing through root systems and digging up plants. A single engine vessel can leave a long trail of mud and uprooted seagrass when attempting to power through a shallow area. Vessels have been known to do acres of damage and become stranded. It happens to experienced operators and beginners alike.

The key to avoiding prop dredging and grounding is having local knowledge gained from experience on the water. Every vessel operator should carry and be able to use a detailed navigational chart of the area. These charts have marked channels and depth readings to assist the operator. Always stay within marked channels. They indicate areas known to be deep enough for your vessel to navigate. Don't operate your vessel in water less than 3 feet deep. Finally, learn to read the water. The sun's angle can make this a challenge. Remember the rhyme, "blue blue, sail on through; white white you just might; green green, nice and clean; brown brown, run aground!"

For more information contact the Florida Bay Education Project at 305-852-3592. Additional information on a variety of topics is available from the University of Florida/Monroe County Cooperative Extension Service, 5100 College Road, Stock Island or call at 292-4501; fax: 292-4415; email: or visit our web site Our services are free and available to all without regard to race, color, sex, or national origin.

The Florida Bay Education Project is an archived site. For more information go to NOAA's South Florida Ecosystem Education Project at