Boat strikes are a growing threat to manatees in Belize

The Antillean manatee (Trichechus manatus) is a currently endangered subspecies of the West Indian manatee, living in the waters off Belize and facing a variety of threats, such as habitat degradation and loss, poaching, pollution, and entanglement in fishing gear. 

Now, a team of researchers led by the University of California, Santa Cruz has found that, with the growth of tourism over the past three decades and subsequent increase in boat traffic, the local manatee population – consisting at the moment of about 1,000 specimens – is also facing a growing threat from boat strikes.

How the study was conducted 

To quantify the impacts of increasing boat traffic on the manatee population, the researchers used 25 years of data on manatee strandings (injured or dead animals), six aerial surveys of the manatee population, and two decades of boat registration data.

The investigation revealed that, with increasingly more boats in the water, the number of manatee strandings has risen from one to four per year in the 1990s and early 2000s to 10 to 17 per year by the late 2100s. Strandings were more frequent in regions with high boat traffic, mangrove habitats, and high human population density.

“We knew that boat strikes were happening, but this study provides strong quantitative evidence of boat strikes as an increasing source of mortality for manatees in Belize, and it shows the areas where the risk is greatest,” said co-author Marm Kilpatrick, a professor of Ecology and Evolutionary Biology at UC Santa Cruz. “These findings provide a basis for conservation measures that can be implemented to reduce the risk.”

Conservation efforts are needed

According to the researchers, conservation efforts should focus on decreasing the number of boats and their allowed speeds within areas of high manatee use, creating more protected areas with strict restrictions on boat traffic, including regions designated for non-motorized boating or restricted access, and implementing speed restrictions in shallow seagrass habitats.

“This work has been shared with policymakers in Belize and will contribute directly to conservation planning, including protecting key areas for manatees such as the Belize River Mouth and the Placencia Lagoon,” concluded lead author Celeshia Guy Galves, a scientist at the Clearwater Marine Aquarium Research Institute in Belize, who conducted this research as a graduate student in the Coastal Science and Policy Program at UC Santa Cruz. The study is published in the journal Endangered Species Research.

More about boat strikes

Boat strikes refer to the collision of boats with marine life, such as whales, dolphins, manatees, turtles, and various types of fish. These incidents can result in injury or death to the marine animals and can damage boats as well.

Boat strikes are a significant conservation issue, especially for endangered or threatened species. They are a particularly significant problem in areas with heavy boat traffic, such as Florida’s waterways where the manatee population is at risk, or busy shipping lanes where large whales might be present. They can be a significant source of mortality for some species.

There are a variety of methods being used to try to reduce the incidence of boat strikes. These include:

Education

Boat operators are often not aware of the presence of marine animals in their vicinity or the potential harm they can cause. Educational campaigns can help to raise awareness and change behavior.

Regulation

Speed limits in certain areas, especially those known to be inhabited by vulnerable species, can reduce the risk of boat strikes. Regulations may also limit the times or seasons when boats can operate in certain areas.

Technology

There are technologies being developed to help boats detect the presence of marine life, such as sonar systems. Other innovations aim to make the animals more aware of approaching boats.

Design

Changes to boat design, such as propeller guards or hull shapes that are less likely to harm animals, can also reduce the risk.

Despite these efforts, boat strikes remain a significant conservation concern. As human activities in the marine environment continue to increase, it’s likely that the issue of boat strikes will continue to receive attention from researchers, conservationists, and policymakers.

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By Andrei Ionescu, Earth.com Staff Writer

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