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January 20, 2006

How Many Manatees Are There?

by Captain Tom McGill, P.E.

The Federal Fish and Wildlife Service (FWS), the Florida Fish and Wildlife Conservation Commission (FWC), and the many conservationist organizations like Save the Manatee Club ($MC) all have a position that the manatee population is endangered and there is no way to tell how many manatees there are. That’s hogwash!

The FWS in conjunction with the FWC published a document titled, Florida Manatee Recovery Plan, 3^rd Revision in October 2001. In that document they state, “The focus of recovery is not on how many manatees exist, but instead the focus is on implementing, monitoring and addressing the effectiveness of conservation measures to reduce or remove threats which will lead to a healthy and self-sustaining population.” That statement, which is on page 41 of the “Recovery Plan,” speaks volumes. The number of manatees is of no consequence to them!

When the conditions are right: a wide cold spell across Florida for at least for several days, light winds, and good visibility, synoptic surveys are conducted to count the observable manatees at congregating locations such as power plant warm water outlets. Not withstanding this process, the agencies say that such data is not reliable to determine manatee population due to “inherent bias errors,” and that too is nonsense! Such counts at least indicate a minimum observed population.

The word, “population,” is used hundreds of times in the “Recovery Plan” document, but there are no metrics, plots, tables, or any other graphic display which show manatee population growth, but there are lots of references and exhibits to manatee mortality-particularly those caused by watercraft. It’s clear the agencies don’t want to talk about how many manatees exist, rather just those that die. That’s like taking a human census and only reporting how many people have been buried in the cemeteries and emphasizing those that were hit by cars.

There is excellent correlation between manatee population growth and the increase in manatee mortality. Reference: “The Florida Manatee Conspiracy of Ignorance,” page 135-136. The attached figure shows the manatee population growth history using high synoptic counts (when conditions were favorable). The plot indicates the estimated current observable manatee population is approximately 4,300, and if one adjusts for those that are not observed by using a conservative 90% factor (assumed) than the total manatee population would be about 4,800. The next synoptic survey (if this year) conducted under the needed favorable conditions could yield a count of 4,300 manatees. Does that sound like a species that is endangered?

The manatee has flourished over the past 30 years in Florida with an average growth rate of > 5.5 %, and it should immediately be down listed from the endangered species list. It clearly is not endangered by any reasonable definition of that term.

Captain Tom McGill, P.E.
254 Sykes Point Lane
Merritt Island, Florida 32953-3067
Tel: 321-453-1218
Fax: 321-453-3897
Cell: 321-917-2782
capttom@cfl.rr.com