I. RECOMMENDATION
The FWC should defer final action until the March 2003 Commission meeting in order to address major issues regarding the validity of assumptions and analysis of results from the computer model.
Our major concerns can be seen by running the computer model with double, triple, and quadruple the current manatee population. We believe that the computer model will continue to classify manatees as “threatened” even with these population increases because the assumptions in the model make the populations decline.
A COMPUTER MODEL AND A PROCESS WHICH NEVER CHANGES THE OUTCOME AND CLASSIFICATION, NO MATTER HOW LARGE THE POPULATION BECOMES, IS SIMPLY NOT A VALID DECISION MAKING TOOL.
II. COMMENTS
- AN OVERWHELMING MAJORITY OF THE COMPUTER SIMULATIONS CREATED FOR FUTURE POPULATION PROJECTIONS DEVIATE FROM THE REALITY AND KNOWN FACTS ON MANATEE POPULATIONS FROM THE LAST 45 YEARS.
Some scenarios are justified to test worse case situations but not an overwhelming majority of the scenarios. The most obvious deviation is the assumption that “survivorship” will immediately decline by either 0.05 percent or 0.10 percent. This immediate decline is modeled into 10 of 16 (62.5 Percent) of the computer simulations. The report states that, “It is plausible to assume” such decline because average annual watercraft mortalities have risen by 10.3 percent per year over the last decade. Even if that percentage is correct, and we believe it is not, the information source quoted (Deutsh, et al) states that the number of deaths due to watercraft rose at 10.3 percent per year from 1976-2001 (except for one year – 1991-1992). How can it be “plausible to assume” that a stated percent annual increase in watercraft mortality will cause an immediate decline in survivorship when that percentage has been a constant since 1976 and there has been a substantial increase, not decrease, in manatee populations over that same time period. A majority of the computer simulations should be based upon past history and known facts not “plausible assumptions.”
- THE FWC EVALUATION HAS INCORPORATED A “RISK FACTOR” INTO THE ANALYSIS WHICH DOES NOT APPEAR ANYWHERE IN THE FWC RULE CRITERIA OR IN THE IUCN CRITERIA OR STANDARDS.
The 5 percent, 10 percent and 20 percent risk factors used in conjunction with selected computer simulation scenarios establishes major biases in interpreting the outcome of the simulation and the final evaluation. Given the fact that extremely negative scenarios are purposefully modeled into the computer simulations there is no way possible for future population reductions in a predetermined number of simulations to ever be less than 10 percent. The current variables in the simulations combined with the inserted “risk factors” insure that the population can never achieve “species of special concern” or “recovered” status. For example, in the case of species of special concern, even if 89 percent of a set of simulations does not meet the criteria, it would still qualify as meeting the criteria for “species of special concern.” The imposed risk factor in conjunction with the evaluation system used by FWC staff allows a criteria to be achieved even when 89 percent of the simulations do not meet the criteria. Such a system is simply not valid or reasonable.
- NEGATIVE VARIABLES ARE DOUBLE COUNTED IN THE SIMULATIONS
As a responsible fish and wildlife agency, the FWC should be cautious and err on the side of conservation. However, many of the variables modeled into the computer simulations amount to double counting of survival factors, which produces a more negative outcome for future population projections. For example, the computer simulations incorporate catastrophic events such as red tides and extremely cold winters. However, such events have been occurring naturally and, as such, are already reflected in the calculated adult and juvenile survival rates which are modeled into the simulations. Adding such events again in the computer simulations amounts to double counting and produces a biased and more negative outcome for future population projections. The bias is further compounded by the fact that catastrophes are modeled into (15 of 16) 93 percent of the computer scenarios.
- THE DEFINITION OF AND THE METHODOLOGY FOR CALCULATING “AREA OF OCCUPANCY” HAS BEEN COMPLETELY MISINTERPRETED.
After examining the IUCN’s definitions and examples for calculating “extent of occurrence” and “area of occupancy,” it is not possible to conclude that an animal with an “ extent of occurrence” of “7,500 square miles in
Florida
alone” has only a “14.5 square mile area of occupancy.” The report’s rationale is based on a contracted winter range theory developed by staff.
Florida
Law – Chapter 370.12(2)(j) F.S. allows state agencies to adopt manatee speed zones:
“Only where manatee sightings are frequent and it can be generally assumed that they inhabit these areas on a regular or continuous basis.”
If 14.5 square miles is truly a correct representation of the “area of occupancy” for manatees in the wintertime, then under what authority has the state adopted hundreds of square miles of manatee speed\protection zones during the winter season? The statutory criteria and justification for those zones require the data to indicate that manatees are “frequent” and “inhabit those areas on a regular or continuous basis.” The 14.5 square miles is a major misinterpretation and miscalculation of the “area of occupancy” criteria.
- FWC ASSESSMENT DIFFERS SUBSTANTIALLY FROM IUCN ASSESSMENT
In 1996, the IUCN’s “Sirenia Specialist Group” assessed the status of
Florida
manatees and placed them in the VU – Vulnerable category. (The criteria for the IUCN’s Vulnerable is virtually identical to the FWC’s Species of Special Concern category.) Since 1996, substantial additional population and adult survival information has been developed including the all time record population count in 2001. This newer data, which shows that manatee populations have not declined and have in fact expanded over the last 45 years, was not available to the IUCN’s assessment group in 1996.
How did the FWC evaluation, using essentially the same criteria as the IUCN but with more positive updated information on manatee populations, determine that manatees should be placed in a more imperiled category than the IUCN did in 1996?
III. CONCLUSION
The intent of the FWC’s Imperiled Species rule is to identify species whose survival is at risk, develop management plans to protect them, and as populations improve move them to less imperiled categories. The ultimate success is when the species population has rebounded to such a level that they no longer need to be on the imperiled species list. However, using a computer model and assumptions which do not allow the species classification to be upgraded as populations expand undermines the intent of the program.
Through our analysis of the data, we believe that if the computer model was “ground truthed” to fit the reality of increasing populations over the last 45 years and more supportable assumptions were made regarding future impacts, the final analysis will most likely show that manatees should be listed as a “species of special concern.”
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