Manatee Death Chart Cause of death Number of Deaths Percentage of total Watercraft 95 31.1% Flood Gate/Lock 05 1.6% Other Human 09 03% Prenatal 53 17+.4% Cold Stress 17 5.6% Natural 59 19.3% Undetermined 65 21.3% Unrecovered 02 0.7% The watercraft category held the most deaths By: Alex and Samuel