Small vessels, boats threaten shallow water habitats in Florida Keys - What you can do to help

March 2019

Boats crisscross the turquoise waters of the Florida Keys taking divers to the reef, anglers to the flats, lobstermen to their traps, and fun seekers to sandbars. The beautiful, unique environment of Florida Keys National Marine Sanctuary harbors an abundance of fish and wildlife, fueling the tourism-based economy and the local way of life.

Not surprisingly, boat usage in Florida Keys National Marine Sanctuary has increased exponentially. With that increase in boats comes a distinct downside: a large increase in the extent and severity of boating impacts to shallow water habitats. With caution and familiarity with this seascape, boaters can help reduce impacts to these vital habitats.

A view of a large patch of seagrass from above the water.
Florida Keys National Marine Sanctuary is home to 1.5 million acres of seagrass beds. Photo: Will Benson

The Florida Keys are unlike most boating environments. When you leave the dock, water often gets shallower, rather than deeper. Navigating these complicated waters challenges even the most seasoned mariner. Often, fishing boats strand in seagrass meadows and yachts ground on patch reefs. Waiting for higher tide may be the best option, but it's seldom the one anxious boaters employ.

More than 300 groundings are reported within Florida Keys National Marine Sanctuary each year, with nearly 80 percent of these incidents impacting seagrass habitat. Many more groundings go unreported.

Acreage of Mapped Impact
Year Light Moderate Severe Moderate + Severe Total
1995 14,560 10,430 5,060 15,490 30,050
2015 26,007 11,481 19,462 30,943 56,950

This chart shows the quantity of impact in Florida Keys National Marine Sanctuary. Severe impact means damage to more than 20 percent of an area; moderate impact indicates damage to five to 20 percent; light impact means damage to less than five percent.

Among the contributing factors to the increase in seagrass habitat destruction are more vessels in sanctuary waters. Watercraft registration in Monroe County, which encompasses all of the Florida Keys, experienced a 40-percent jump from 1993 to 2015.

The sustained health of the nearshore marine environment is vital to the tourist-based Florida Keys economy, and supports the coral reef ecosystem in many ways. Hardbottom communities and seagrass beds provide important feeding and nursery grounds for numerous commercially-important fish and protected species. Sea turtles and birds forage in seagrass beds and tidal flats.

Disturbance and direct impacts, including damage by boat propellers, groundings, turbidity, and degraded water quality, are major contributing factors to declines in these habitats, which are essential for birds, fish and other animals.

Wildlife Management Areas, established in 1997 throughout the Florida Keys to minimize disturbance to especially sensitive wildlife populations and their habitats, while allowing for public use, are proving beneficial. Aerial images illustrate a significant reduction in prop scarring due to idle speed/no wake zones within some wildlife management areas. However, problems persist outside of managed areas.

Aerial views near Tavernier Creek taken in 1996 showing much damage
Aerial views near Tavernier Creek taken in 1996 and 2014 show significant shallow water habitat recovery due to the 1997 designation of a Wildlife Management Area. Credit: Curtis Kruer
Aerial views near Tavernier Creek taken in 2014 showing a recovery

Shallow water habitats, and their protection from disturbance and destruction by boaters, are a key component of the current Florida Keys National Marine Sanctuary zoning and regulatory review and the U.S. Fish and Wildlife Service Backcountry Plan update.

When hitting the water

By planning ahead, you can help reduce impacts to sanctuary ecosystems. Before heading out on the water in the Florida Keys, consider where you are going and what areas you will traverse. Study the most up-to-date nautical charts of the area. Check the weather – storms can pop up with little warning. Visit to obtain the latest marine weather conditions, forecasts, and possible warnings or advisories.

Know the draft of your boat and how much water you need to operate safely.Use marked channels and stay in deeper water where your propellers and hull won't damage shallow water habitats and your activity won't disturb sensitive fish and wildlife on the flats. Always pay attention to signs, markers, navigational aids, and information buoys that may indicate shallow areas closed to motorized vessels and provide user information for that area.

Wear polarized sunglasses to help you "read" the water. Shallow water appears dark (brown) to the observer, while deeper water appears blue or green. Sand-covered bottoms appear white and may or may not be deep enough for your vessel to navigate. Remember:
 "Brown, brown, run aground. 
  White, white, you just might. 
  Blue, blue, sail on through.
  Green, green, nice and clean."

A large number of boats parked at a sandbar
Boaters at the sandbar at Whale Harbor in Islamorada, Florida, are often stranded when the tide goes out. Photo: Florida Fish and Wildlife Conservation Commission

Keep track of the tides. The greatest range of tides (shallowest and deepest water) occurs during a full moon and new moon. When in doubt about the depth, slow down and idle. Make sure the bow of your boat is down and the motor is trimmed or tilted up.

A sediment trail means you're churning up seagrass. Stop immediately and tilt your engine. Pole or push the boat into deeper water.

If you get into trouble, contact the Coast Guard on VHF Channel 16, and use an Emergency Position Indicating Radio Beacon (EPIRB) to send a distress signal, helping rescue crews pinpoint your location.

If you're coming to the Keys to fish or dive, consider hiring a Blue Starguide who knows the waters and the rules. The Blue Star Fishing Guide program recognizes charter boat captains who are committed to sustainable fishing and educating their customers about resource protection in Florida Keys National Marine Sanctuary. Similarly, Blue Star dive operators commit to sustainable diving practices.

man fishing from a boat
Blue Star Fishing Guides are committed to using responsible practices to preserve Florida Keys fisheries. Photo: Will Benson

In April 2019, the sanctuary will launch an online course to better educate boaters on the intricacies of Florida Keys waters and the regulations that apply.

All of us who enjoy the waters of the Florida Keys play a role in maintaining the quality of shallow water habitats that support the diverse abundance of fish and wildlife that make the Keys unique.