Manatees in 2008

CAPTAIN TOM McGILL, P. E. 321-1453-1218 & 321-917-2782 capttom@cfl.rr.com Photo Courtesy of FWRI

Let's have "Stats", the manatee, once again be the spokesperson and tell us how well Florida manatees fared in 2008.

We Manatees in 2008

This past year was an interesting year for us manatees. A lot of us noticed Dr. Edmund Gerstein and his wife Laura conducting research in the Banana River near Kennedy Space Center which is our favorite sea grass dining location. That device he put on his boat really gives us advance notice and provides plenty of time for us to get out of the boat's path. We'd sure like to see all vessels with such a device.

Our 2008 total mortality was higher than last year (337 Vs 317) even though there were many fewer red tide deaths (3 Vs 52) but more perinatal (101 Vs 59). The 90 watercraft-related deaths were a little higher at 27% Vs the average of 24% over more than a quarter of a century. It sure doesn't look like those slow speed zones help protect us. The percentage is supposed to reduce not increase. Note: All data derived from FWC / FWRI Database

1. The listed 6 counties account for 54% (182 of 337) of all manatee mortality in the state. 2. Those same 6 counties account for 60% (54 of 90) of watercraft-related mortality, yet they have extensive slow speed zones. More than 1/3 of all Brevard and Lee County waters are regulated at slow or lower speed!

3. Palm Beach has 75% (6 of 8) of its mortalities due to watercraft (75% last year, too), yet it is a county that has had extensive slow speed zones operational for some time with a low total mortality. What analysis has been done in this matter? Why has Palm Beach had the worst % for watercraft-related mortality over the past three (3) decades? Ref. The Florida Manatee Conspiracy of Ignorance, pp. 151-153. Is it because a disproportionate number of us manatees are killed by large vessels rather than smaller ones there?

4. Brevard County had 34% (34 of 101) of all the Dependent Calf (perinatal) mortalities in the state (31 % last year), yet Brevard had only 22 % of the total state mortality (73 of 337)? Why is perinatal so high and at an increasing rate? Could this be a sign of the manatee reaching its carrying capacity, particularly in Brevard, or is it because a significant % of manatees no longer migrate putting the calves at higher risk.

5. Also, the perinatal mortality exceeds the watercraft-related mortality in the State of Florida as it did last year, but look at the increase from 57 to 101, almost doubling. Brevard County and Lee County have the largest number of total mortalities (73 and 45 respectively), yet Brevard has 4.9 times the Perinatal rate of Lee County (34 Vs 7).

6. Palm Beach continued to have the worst watercraft-related mortality rate at 75% (6 of 8) while Brevard continues to have a rate less than the state average (14% Vs 24%) rate. Why? One part of the answer is the much higher perinatal rate in Brevard effectively lowers the watercraft-related percentage.

Now let's look at how the 2008 mortality status compares with the past 4 years.

Note: All data derived from FWC / FWRI Database

An additional observation can be made: In 2008, total manatee mortality exceeded last year by a small amount (20) in spite of reduced red tide deaths (~ 50) counted as natural and offset by a significant increase in perinatal mortality (42).

Our manatee population continues to grow even in light of periodic red tide albeit temporarily at a lower rate. This is reflected by the slope of the total manatee mortality curve after those special events have been removed. However, this growth continues primarily because these special events are relatively small compared to our overall population birth rate.

Contrary to the nonsense put out by the FWC, our Atlantic manatee population has been growing at a good rate. When the conditions are favorable for a synoptic count we should have another record count in the east coast /Atlantic area, as we did in January 2003.

Happy New Year!

Stats 1/05/08 1.