We crowd to see them, touch them, even as we destroy the very ecosystem that manatees need to survive. For those who don't know this phrase, miners carried canaries in cages down into the mines where they worked to warn them if the air filled with deadly gases. If your canary keeled over, it was time to dash from the mine to fresh air. Coastal and riverine wetlands that surround the waters where manatees roam launder the runoffs from overdeveloped land. Once wetlands are filled to make room for new houses, they no longer do the laundry.
Pollutants build in the waterways.
Some over-fertilize aquatic plants. The nutrient-laden plant overgrowth suddenly interferes with boat propellers and fishing, although manatees love it. Herbicides are brought in to kill the aquatic plants that feed manatees and entangle boat propellers. Another irony is loving manatees to death. Remaining wild is a requirement for survival of an endangered species.