West Indian manatees and their relatives suffer chronic injury and mortality from motorboat propeller strikes. Slow swimming speed, surface-breathing behaviour, and warm-water aggregations make them acutely vulnerable to vessel traffic in coastal waterways.
Propeller wounds cause deep, painful lacerations that take months to heal and may result in chronic pain, impaired diving ability, and secondary infection. Manatees with severe spinal injuries survive but with permanent disability affecting mobility and foraging efficiency. Boat strikes also cause blunt trauma injuries not visible externally but causing internal haemorrhage and organ damage. Effective welfare protection requires rigorously enforced no-wake and idle-speed zones, mandatory boat propeller guards in high-use areas, and acoustic warning devices that alert manatees to approaching vessels.