Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 6 - 20
Comments: The precise number of distinct occurrences (subpopulations) is unknown. MtDNA data suggest the existence of three main lineages, which could be regarded as occurrences from the broad perspective but may be too large for most practical conservation purposes.
In Florida, where manatee distribution is well known, manatees exist as four major units that in the past have been referred to as subpopulations but today are recognized as management units rather than as discrete subpopulations, due to the high level of gene flow among the four units (USFWS 2007).
USFWS (2001) identified 26 winter aggregation sites in Florida, not counting many lesser known minor aggregation sites used as temporary thermal refuges. These do not necessarily represent distinct occurrences from the perspective of population biology, but they do help identify some of the important focal areas for manatee conservation in the northern portion of the range.