2012 COURSE DATES: AUGUST 4 – 17, 2012 - Sirenian International

Table 3. Simulation results: Percentage of declines detected (in bold italics) for six different sampling regimens and three different
levels of decline, assuming a perfectly consistent relationship between population index and actual abundance (1000 runs for each
simulation). Scan duration indicates whether the negative binomial distribution parameters were generated from 20 or 30-minute
scans. Number of points indicates the number of points used to create the array of manatee sightings for the simulation models
Parentheses indicates which points were used to generate the negative binomial distribution parameters. > 30% means points with
greater than 30% sighting probability. Number of two-week survey periods indicates the number of survey periods used in the
Sampling Regime
Scan Interval 20-minute scan 30-minute scan
6 8 6 6 8 8
21
(>30 %)
28
(>30 %)
28
(>30 %)
21 points
(all points)
28 points
(>30% )
28 points
(all points)
Num. of two-week survey
periods
Num. of points
(Points used to generate
negative binomial
distribution parameters.)
Results
10% 11 14 9 12 16 13
25% 51 65 33 57 71 60
50% 100 100 99 100 100 100
simulation. We ran our simulation for three potential declines in the number of manatees after 15 years: 10%, 25% and 50%.
These declines are equivalent to a 0.7%, 1.7% and 3.6% decrease in the number of manatees sighted per scan per year.
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