The most obvious danger a turtle faces from recreational boaters are impacts with boat propellers. Numerous studies have documented turtles with propellor damaged shells, including Northern Map Turtles and Eastern Spiny Softshells – both species at risk.
The magnitude of the threat of strikes are very difficult to document. When a turtle is killed by a propellor, its carcass will likely sink to the bottom and/or be eaten by scavengers – not as visible as a turtle on the side of a road. This makes getting at the number of turtles actually killed by boats extremely difficult. In 2009, scientists at the University of Ottawa predicted, using current injury rates, that if only one female turtle is killed by a boat every three years, the population of Map Turtles at the St. Lawrence Islands National Park will become extinct within 500 years.
So what can you do?
SLOW DOWN, especially in relatively shallow areas, and areas where many turtles may congregate – such as nesting beaches. In Quebec, volunteers have already created econautical charts showing sensitive areas for the threatened Spiny Softshell, suggesting particular spots where only low-impact boating, such as canoeing and kayaking, should take place.
While it would be particularly difficult to stop all boat-turtle collisions, it is not difficult at all to be more conscious to the risk. Stick to marked boat channels, go slowly in shallow areas, watch for turtles along shorelines and in the water – in areas where there are many turtles, consider switching off your propellor altogether. We are only recently recognizing the impacts of boating on turtle populations, continued research and monitoring of affected populations are necessary for scientists and conservationists to determine the best methods for reducing boat mortality.
Until then – slow down and be turtle aware!