North Florida Ecological Services Office
Southeast Region

West Indian Manatee (Trichechus manatus) ESA Five-Year Review Frequently Asked Questions

Updated: April 9, 2007

Q1: What is a five-year review?

A1: A five-year review is an Endangered Species Act (ESA) mandated process which is conducted to ensure the listing classification of a species as either threatened or endangered is still accurate. The five-year review is not a rulemaking in and of itself; it provides an analysis and a staff "recommendation" rather than a "determination" and as such is not a decision document.

Q2: What species were considered for this review?

A2: The animal listed under the ESA is the West Indian manatee which includes two subspecies, the Florida manatee ( Trichechus manatus latirostris ) and the Antillean manatee ( Trichechus manatus manatus ) .

Q3: What is the result of the review?

A3: After extensive data review and analysis, the Service concluded the West Indian manatee species' status better fits the ESA definition of threatened and as such has recommended reclassification. Currently the species is classified as endangered under the ESA. The five-year review analyses considered the status of both subspecies in coming to the recommendation on the West Indian manatee. The best available science shows the overall population of the Florida Manatee has increased and the Antillean manatee levels are stable, and neither subspecies is currently in danger of becoming extinct within all or a significant portion of their range.

Q4: What will happen as a result of this five-year review?

A4: As a result of the review, biologists are recommending that the West Indian manatee should be reclassified to threatened status. In addition, Service biologists and managers outlined additional recommendations in Section IV of the review, entitled Recommendations for Future Actions. These recommendations identify what is needed to further address knowledge gaps and threats for each subspecies. The recommendations are tied directly to the specific ESA listing factors or compliance issues identified in the review: for a detailed look at all the recommendations see Section IV of the five-year review. Thus, we will review all of the specific recommendations and information provided in the five-year review to identify priority recovery actions.

Q5: What opportunities did the public have to participate in this review?

A5: There were two comment periods open to incorporate public input. We originally announced the review as applying to only the Florida subspecies, but later reopened the comment period and included the species as listed – West Indian manatee – which then brought the Antillean subspecies in to the five-year review process.

Q6: What information was considered in the review?

A6: For this review, we reviewed new information and data in the following categories:

  • species biology , including but not limited to, population trends, distribution, abundance, demographics, and genetics;
  • conservation measures that have been implemented that benefit the species;
  • threat status and trends ; and
  • other new information, data, or corrections , including but not limited to, taxonomic or nomenclatural changes, identification of erroneous information contained in the Listing, and improved analytical methods.

Q7: How does the Service determine whether a species is endangered or threatened?


Section 4(a)(1) of the ESA establishes that we determine whether a species is endangered or threatened based on one or more of the five following factors:

  • Over utilization for commercial, recreational, scientific, or educational purposes;
  • Disease or predation;
  • The inadequacy of existing regulatory mechanisms; or
  • Other natural or man-made factors affecting its continued existence.

Section 4(a)(1) of the ESA also requires that our determination be made on the basis of the best scientific and commercial data available.

Q8: In what context was this information reviewed and analyzed?

A8: The best scientific and commercially available data and information was reviewed within the context of the ESA's five listing factors and the most recent recovery plans for each subspecies. Service biologists and managers looked at the status and trend of manatee populations, the ESA listing factors that categorize threats, and recovery plan actions or tasks. In all, over 150 individual sources of literature and data were reviewed during this process. Our review also included an assessment of the value of protection efforts in place by our partners in manatee conservation, such as the Commonwealth of Puerto Rico and the State of Florida . In the case of the Florida manatee, we also relied upon the results of a threats analysis conducted using the Core Biological Model (CBM) developed by U. S. Geological Survey (USGS) scientists. (For information on threats analysis results using the CBM, please see the open file report entitled A Quantitative Threats Analysis for the Florida Manatee ( Trichechus manatus latirostris ) which is available online at

Q9: How was the CBM used in the Service's analysis?

A9: Under contract with the Service, the CBM was applied to determine the particular significance of certain threats . This quantitative analysis calculated probabilities associated with three possible levels of quasi-extinction (100, 250, and 500 adult manatees); three time frames (50, 100, and 150 years); and, six different threats (collisions with boats, hypothermia as a result of loss of warm water sources, drowning or crushing in water control structures, poisoning from red tide [brevetoxicosis], drowning due to entanglement, and the combination of collisions with boats and loss of warm water).

The modeling analysis yielded a matrix of probabilities of future Florida manatee population viability for use by Service managers. Under current levels of threats, which include loss of warm water sites, probabilities that manatees would go quasi-extinct on either coast of Florida ranged widely depending on the level of quasi-extinction chosen and the projected future time frame for analysis. For example, the model predicts that over a 50 year time span, the probability of falling below 100 animals on either coast is less than 1%. The model also predicts that over a 150 year time span, the probability of falling below 500 animals on either coast is nearly 60%.

Service biologists and managers reviewed this modeling information in the course of conducting the five year status review, and focused on a 100 year time span and 250 adult manatees as a quasi-extinction threshold. We believe this threshold is conservative and that 100 years is a reasonable length of time for measuring the risk to extinction given the life span of manatees.

Q10: What does “quasi-extinction threshold” mean?

A10: For this review, a quasi-extinction threshold is defined as a level at which the number of adult manatees may be insufficient to assure persistence of the species. In the case of the Florida manatee, the CBM analyses were conducted to look at the probabilities of going below threshold benchmarks of 100, 250 and 500 adult animals.

Q11: Does this mean that the Service's management goal is 250 adult manatees on the Atlantic and Gulf coasts?

A11: No. We would consider a population of 250 adult manatees to be functionally extinct. This is why we consider our conclusion to be “conservative”, that is, erring on the side of the species. Management goals for the species will be developed in the next revision to the recovery plan.

Q12: How do you reconcile your recommendation to reclassify the manatee with the high Florida manatee mortality of 2006?

A12: Use of single data points, such as 2006 Florida manatee mortality numbers, would not provide sufficient information upon which to base management decisions. We analyzed demographic data over a 18-year timeframe to assess the status of the population. The data used spanned the period from 1986 through 2004, and included the high mortality numbers of the late 1990's. Therefore we are confident that our use of the information provided by the CBM reflects a realistic assessment of the population as a whole.. Future analyses using the CBM will incorporate new information as it is compiled and made available.

Q13: Is the Federal review process the same as that used by the State of Florida or the Commonwealth of Puerto Rico ?

A13: No, while we may have looked at similar or even identical literature and data, the context within which that information is assessed and analyzed is significantly different. While we have made a recommendation to reclassify the West Indian manatee to threatened, similar to the state of Florida 's decision, the criteria that the state uses to evaluate conservation status is different than the federal process. Also, unlike Florida 's current formal rulemaking process, our five-year review is not a decision document or formal rulemaking proposal. These are two distinctly different and separate processes.

In the case of Antillean manatee, the Commonwealth of Puerto Rico has not conducted an independent status review for that subspecies.

Q14: When will you formally propose reclassification of the West Indian manatee?

A14: This five year status review is a significant body of work that will inform any future rulemaking. In the immediate future we will be evaluating our workload and balancing our funding priorities. The Service has many five-year reviews in varying stages of completion, and the results of those reviews may also impact our priorities. With limited resources, we may not be able to pursue all recommendations immediately. For example, a recommendation to reclassify a species from threatened to endangered or to remove a species from the list of threatened and endangered species would likely take priority over reclassification from endangered to threatened.

We will also be evaluating the specific recommendations in the manatee five-year review regarding the highest priority recovery actions that need to be pursued to ensure the manatee continues to move towards full recovery.

Q15: Given the limited amount of information available for the Antillean manatee, could the Service choose to not reclassify that subspecies?

A15: The West Indian manatee is the listed species and is inclusive of both the Florida and Antillean subspecies. The Service would have to go through a rulemaking process in order to split the two subspecies into individually listed species and reclassify one but not the other. Based on the data and information analyzed during the review, such a process is not currently justified. Further genetics research is recommended.

Q16: If the Service reclassifies the manatee's status from endangered to threatened, will such a change reduce the level of protection for the species?

A16: No. All Federal manatee conservation and protection measures, including refuges, speed restrictions and sanctuaries, remain in force. Addressing the threats associated with watercraft and habitat loss will continue to be a significant focus for the Service. This may include proposals for additional protection measures in some areas.

Q17: What is the biological basis for the recommendation to reclassify the West Indian manatee?

A17: The best science and commercial information available shows the population of the Florida manatee has increased and the Antillean manatee levels are at least stable, and neither subspecies is in danger of becoming extinct within all or a significant portion of their range.

However, threats of potential habitat loss and watercraft collisions and our concerns regarding the adequacy of regulatory mechanisms associated with those threats lead us to believe the West Indian manatee should be classified as threatened.

Q18: Your review identifies challenges with the current Florida manatee recovery plan, do you intend to address those challenges?

A18: Yes. Some of these challenges were identified during earlier federal rulemaking efforts and we choose to table changes to the recovery plan until we had completed this comprehensive review. This gave our biologists and conservation managers the opportunity to see a tremendous amount of cutting edge science, information and data all come together to give them the tools and capabilities to address these challenges – both now and into the future.

Q19: Does this mean you have all the information you need to make the recommended changes in the Florida Manatee Recovery Plan?

A19: No. There are still areas of research which need to either continue or be expended upon. This is particularly true in the southwest part of Florida where we have uncertainty in the population trend data, especially in the most southern areas of that region. However, we believe the science and tools may now be in place to enable us to develop reasonable, scientifically sound, and measurable recovery criteria.

Q20: Is the recovery plan for the Antillean manatee up-to-date?

A20: No, the recovery plan for the Antillean manatee was developed 21 years ago. We are recommending to update the recovery plan and to develop measurable recovery criteria.

Q21: Were you able to identify with any reasonable level of certainty which threats were the greatest to the manatee's long-term survival?

A21: Yes, after running various scenarios through the CBM we were able to clearly see which threats posed the greatest risks to the Florida subspecies. The top two were the potential loss of warm water habitat and collisions with boats.

Q22: What about red tide? Doesn't that pose a significant threat to the Florida manatee?

A22: Yes. This was identified as the third greatest threat to the Florida manatee, but it is localized primarily to the southwest part of the State. However, when combined with the top two threats, potential loss of warm water habitat and watercraft-related mortalities, it worsens the effects of the other two threats in that part of the State.

Q23: Did your five-year review consider the effects that harassment, such as that shown on recent videos, has on Florida manatees?

A23: Yes. However, there are no data at this time to indicate that harassment is limiting the recovery of the Florida manatee. Harassment is illegal and joint Federal and State efforts are ongoing to minimize harassment at warm-water refuges. The efforts include the designation of sanctuaries at warm-water sites, stepped up law enforcement patrols in these areas, and use of the Service's refuge permitting authorities to minimize harassment. Outreach and education programs are also in place to minimize harassment in key areas. Violations are addressed through law enforcement actions.

Q24: Did your review and analysis consider the effectiveness of recent Federal and State manatee protection measures, such as speed zones?

A24: No. Our analysis included ten (10) years worth of demographic data, all of which was collected prior to the most recent Federal and State conservation and protection measures being implemented. Many of these actions are so new that insufficient data was available. Thus, we were unable to quantitatively assess the effects of these measures on manatee populations. Eventually, we anticipate having sufficient data to factor these directly into our analyses. This is an unfortunate but realistic aspect of data gathering; there is frequently a lag time between when raw data is collected in sufficient quantities and quality to be converted into useable or meaningful data.

It is important to note that while the effect of these new protection measures was not factored into our analyses, the data used did capture the high mortality of the late 1990's. Therefore we feel confident that our use of the information provided by the CBM is very conservative (e.g. protective of the species) as it based on data from what was a less than optimistic period of time for manatee survival projections. As new information and data are acquired, processed and made available, future analyses using the CBM will capture this information.

Q25: Will the public be given an opportunity to provide comments on the Five-Year Review?

A25: No, The five-year review is an internal agency staff analysis which makes a classification recommendation. As such, it is not a decision document nor is it a proposal for change. Therefore, the Service is not soliciting formal public comments on its review or recommendation. See Q5 for details on public comment opportunities during the review process.

Q26: Will the public be given an opportunity to participate in any proposed status change?

A26: Yes. A proposed change in status requires a separate formal rulemaking process, including ample opportunity for public review and comment. No change in classification would occur until the completion of that process; so the manatee would remain listed as endangered until we are able to complete the formal rulemaking process.

Q27: What does all this mean for conservation stakeholders and organizations?

A27: This is an opportunity for all of our manatee partners to celebrate a conservation success milestone. We are proud of the contributions our partners and stakeholders have made over the past years towards the conservation, protection, and recovery of the West Indian manatee. Our recommendation to reclassify this species to threatened is, in part, a recognition of the success those efforts have had in bringing this animal back to a level that it is not currently in danger of extinction.

We are excited about the manatee's future, but also know there is still a lot of work to be done. Federal, State and local wildlife agencies, researchers, conservation interests, resources users and the power and marine industries still have key roles to play in continuing our forward momentum toward recovery of this species.

Q28: When would the Service be able to remove the manatee from the Endangered Species List?

A28: The five-year review identifies threats of potential habitat loss and watercraft collisions and our concerns regarding the adequacy of regulatory mechanisms associated with those threats as the primary reasons the species should be listed as threatened. Our specific recommendations include several actions that are needed in order to address these threats and concerns. We will not propose removal of the West Indian manatee from the ESA federal list of threatened and endangered species until we are confident that the future of the species is secure.

Q29: How can I stay current or find out more information on the Florida manatee and your conservation efforts?

A29: The most current Florida manatee information is available online at . The most current information on the Antillean manatee is available from the Boquerón Field Office located at P.O. Box 491 , Boquerón, PR 00622.

2007 ESA Five-Year Status Review

2007 Final 5-year Status Review News Release

2007 5-Year Status Review Field Supervisor Editorial

Manatee Information

Bookmark and Share

Last updated: May 21, 2015