SECTION 4: Management Measures

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4.14. BOAT OPERATION

Management Measure for Boat Operation:

Manage boating activities where necessary to decrease turbidity and physical

destruction of shallow water habitat.

Management Measure Description

No wake zones, motorized craft restrictions, and

sign and buoy placement are widely used practices for protecting shallow-water habitats.

Important aquatic vegetation should be protected

from damage due to boat and personal watercraft

propellers because of its ecological importance

and value in preventing shoreline erosion. This

management measure presents effective, easily

implemented practices for protecting aquatic

vegetation and shorelines.

Boat traffic (including personal watercraft)

through shallow-water areas and in nearshore

areas at wake-producing speeds can resuspend

bottom sediment, uproot submerged aquatic

vegetation, erode shorelines, and harm some

animals, including manatees. Resuspended

sediment and erosion along shorelines increases

turbidity in the water column. Turbid waters can’t

support submerged aquatic vegetation to the same

depths as clear waters because sunlight can’t

penetrate to as great a depth. With photosynthesis

limited to the upper foot or so of water, less

dissolved oxygen is produced.

Fish that locate prey primarily by sight have a

harder time finding prey in turbid waters. Plant

leaves can become coated with fine sediment, and

bottom-dwelling organisms are continually covered by resettling sediment.

Resuspended sediment can also contain harmful

chemicals that were discharged at the marina or

elsewhere in the watershed and had been trapped

in the sediment. Once in the water column, these

chemicals are more likely to be ingested by fish

and shellfish and to work their way up the food

chain, possibly to someone’s dinner table.

Uprooted submerged aquatic vegetation can no

longer provide habitat for fish and shellfish or food

for waterfowl. Instead of recycling nutrients

released from matter decomposing in the

waterbody, the vegetation adds more nutrients as

it decomposes. It also cannot reduce wave energy

at shorelines, so the shorelines become more

exposed to the erosive forces of storm waves and

the boat wakes that contributed to their initial loss.

Replacing submerged aquatic vegetation once it

has been uprooted or eliminated from an area is

difficult, and the science of replacing it once it is

lost is not well developed.

Many manatee mortalities are human-related,

occurring from collisions with watercraft, and

restrictions on boating activity in shallow water

habitats favored by the animals could reduce the

number of animals injured by propellers. West

Indian manatees (Trichechus manatus) are found

in shallow, slow-moving rivers, estuaries, saltwater

bays, canals, and coastal areas. They are a

migratory species, and in the United States they

are concentrated in Florida in the winter but can be

found in summer months as far west as Alabama

and as far north as Virginia and the Carolinas.

There are about 2,600 West Indian manatees left in

the United States.

Manatees are protected under federal law by the

Marine Mammal Protection Act of 1972 and the

Endangered Species Act of 1973, which make it

illegal to harass, hunt, capture, or kill any marine

mammal. They are also protected by the Florida

Manatee Sanctuary Act of 1978, which states:
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National Management Measures Guidance

 “It is unlawful for any person, at any time,

intentionally or negligently, to annoy, molest,

harass, or disturb any manatee.” Anyone convicted of violating Florida’s state law faces a

possible maximum fine of $1,000 and/or imprisonment for up to 60 days. Conviction on the federal

level is punishable by a fine of up to $50,000 and/

or 1 year in prison.

The manatee is mentioned to illustrate the harm

that can be done to aquatic life by boats. Species

other than manatees, such as seals or dolphins,

might be more likely to be affected by boat

operation in other regions of the country. The

state natural resources agency can be contacted

for state- or region-specific information.

Applicability

This management measure is applicable to state

natural resource managers. Marina managers and

boaters can become involved in efforts to protect

sensitive aquatic habitats.

Best Management Practices

♦ Restrict boater traffic in shallow-water

areas.

Where shallow areas that normally have submerged aquatic vegetation are found instead to

have trenches (usually 10 to 24 inches wide)

without vegetation running through them, boat

propellers or personal watercraft are probably the

reason. Seagrass beds usually grow in patches;

the center of the patch is protected from erosive

currents by vegetation at the edge of the patch.

Trenches cut by boat propellers act like roads cut

through a forest, exposing the center of the patch

to currents and making the entire patch less

stable. The sediment in the trench is also newly

exposed to currents, making it difficult for new

vegetation to establish itself. Further loss of

submerged aquatic vegetation and sediment next

to the trenches is likely after the initial loss.

Guidelines for Responsible Personal Watercraft Operation

Personal watercraft, include jet skis and waterbikes, are propelled by waterjet drives, have shallow

draft designs, and are able to achieve planing speeds (65 mph and higher). Approximately onethird of all new boat sales in recent years have been personal watercraft. They are defined as

Class A inboard boats by the U.S. Coast Guard and are required to follow most boating regulations. The personal watercraft industry encourages users of personal watercraft to adopt the

following simple guidelines to preserve natural resources:

• Ride in main channels to avoid stirring bottom sediments; limit riding in shallow water.

• In coastal areas, be aware of low tide when seagrass beds, other delicate vegetation, and

bottom organisms are more exposed.

• Operate away from shore as much as possible to avoid disturbing wildlife with wakes and

noise and to avoid interfering with their feeding, nesting, and resting.

• Ride at controlled speeds in waters where sea otters, sea lions, manatees, whales, and sea

turtles live and swim, so you can avoid hitting and injuring them.

• Avoid mangrove communities, kelp forests, seagrass beds, and coral reefs, since these are

delicate ecosystems that are easily damaged.

• Avoid high speeds near the shore to minimize or eliminate your contribution to shoreline

erosion.

• Wash your personal watercraft off after use and before trailering it to other waters to avoid

spreading exotic, nonnative species to uninfected waters.

(PWIA, 1999)
SECTION 4: Management Measures

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To protect seagrass beds and bottom habitats,

shallow-water areas can be established as “off

limits” to boat traffic of any type, including

personal watercraft. Signs or buoys in the water

around the edges of these areas can help the

public comply with shallow habitat protection

efforts. Distribution of flyers with maps that show

shallow areas and indicate permanent landmarks,

so boaters can easily determine whether they are

near shallow areas, is another effective tool.

Boaters usually try to protect these habitats once

they understand their ecological importance and

are aware of their presence. Shallow-water

habitat destruction is due more to a lack of

knowledge than to negligence.

♦ Establish and enforce no wake zones to

decrease turbidity, shore erosion, and

damage in marinas.

No wake zones are more effective than speed

limits in shallow surface waters for reducing

turbidity and erosion caused by boat passage. Hull

shape strongly influences wake formation,

allowing some boats to go fast with little wake

while other boats throw a large wake at slow,

nonplaning speeds. In shallow areas, larger waves

from the wakes of “speed-limited” watercraft are

more likely to resuspend bottom sediments and

create turbid waters.

Although the prime responsibility for creating,

enforcing, and posting signs for no wake zones

rests with government, marinas can (and many

do!) post NO WAKE signs within their marina

waters.

BMP Summary Table 14 summarizes the BMPs

for Boat Operation mentioned in this guidance.