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Descriptions of Manatee Death Categories

Manatee deaths are broken down into nine categories based on gross, histological, and microbiological findings. 


Watercraft-related mortality. Death may result from propeller wounds, impact, crushing, or any combination of the three.

Crushed/Drowned in Flood Gate or Canal Lock

Manatees killed by crushing or asphyxiation in flood gates and canal locks.

Other Human-Related

Manatee deaths caused by vandalism, poaching, entrapment in pipes and culverts, complications due to entanglement in ropes, lines, and nets, or ingestion of fishing gear or debris.


Manatees less than or equal to 150 cm (5 feet) in total length which were not determined to have died due to human-related causes.

Cold Stress

Manatees which die as a result of exposure to acute or prolonged cold weather. Animals are usually emaciated and in a general state of malnutrition. (Combined with "Other Natural" in some printouts.)

Other Natural

Manatee deaths resulting from infectious and non-infectious diseases, birth complications, natural accidents, and natural catastrophes (such as red tide blooms).

Undetermined; Too Decomposed

Manatee deaths in which the cause of death could not be determined due to an advanced stage of decomposition.

Undetermined; Other

Manatee deaths in which the carcass was in good condition (fresh or moderately decomposed), but necropsy findings were inconclusive. (Combined with "Undetermined" in some printouts.)

Verified/Not Necropsied

Manatee deaths that were reported and verified, but a complete necropsy was not performed (Combined with "Undetermined" in some printouts.) Some manatees will still receive varying levels of examination and tissue collection.