Record Deaths, Mysterious Mortality — Ongoing Threats Make Manatee Recovery Tenuous

Op Ed by Katie Tripp, Ph.D.
Director of Science & Conservation, Save the Manatee Club

Opinion Editorial:
For Immediate Release: May 9, 2013

David Schrichte manatee photo.
Watercraft, water control structures, marine debris, red tide, climate change, seagrass loss, and cold stress deaths are other natural or manmade factors affecting manatees’ continued existence. Above, a living manatee bears scars of a watercraft collision.

In 2012, the U.S. Fish and Wildlife Service (FWS) announced plans to stakeholders, to move forward with a manatee “reclassification” to threatened under the federal Endangered Species Act (ESA). However, with unprecedented manatee mortalities in 2013 (829 through December 31st, many due to red tide in Southwest Florida and others dying mysteriously in Brevard County), FWS announced that downlisting plans were on hold. The ESA dictates that FWS base any reclassification decision on 5 factors. If the answer to any of the questions posed by the 5-factor test is “yes,” then FWS cannot downlist or delist. Our review of the 5 factors comes up with several “yes” answers that tell us downlisting is premature.

1. “Is there a present or threatened destruction, modification, or curtailment of species’ habitat or range?”

  • Yes.
    • 50% of Florida’s manatees depend on artificial sources of water that could fail or disappear. Loss of even one site could result in catastrophic mortality.
    • More than 17% of manatees use springs habitat. Spring flows are threatened by over-pumping of the aquifer for consumptive use and degraded water quality.
    • We are witnessing the legacy of nutrient pollution in the Indian River Lagoon system, where a natural event has likely been exacerbated by nutrients from years’ worth of runoff churned up to feed algal blooms that wiped out seagrass.
    • Waterfront development continues, facilitating more boat traffic that directly threatens manatees and secondarily impacts to the species’ habitat.

2. “Is species subject to overutilization for commercial, recreational, scientific, or educational purposes?”

  • No.

3. “Is disease or predation a factor?”

  • Not currently.
    • Manatees have not suffered from widespread disease in the past, but their winter congregations do leave them susceptible to widespread disease transmission.

4. “Are there inadequate regulatory mechanisms in place outside the ESA?”

  • Yes.
    • The ESA and federal Marine Mammal Protection Act are important safeguards. Florida does have some state-level protection for manatees including the Manatee Sanctuary Act. However, manatees are impacted by many of the environmental decisions made in our state, and Tallahassee’s strong anti-environmental sentiment in recent years has eroded growth management, weakened state environmental and regulatory agencies, and stood in the way of meaningful protections for our waters, including springs.

5. “Are other natural or manmade factors affecting its continued existence?”

  • Yes.
    • Watercraft, water control structures, marine debris, red tide, climate change, seagrass loss, and cold stress deaths all fall under this category. Climate change stands to cause massive negative changes to the manatee’s world, from increased storm events, wide temperature swings (think cold stress), possible shifts in food availability, and even reduced spring flows.

Some people (including perhaps FWS) argue that we now have more manatees than we used to, so it’s time for a status change. However, none of the ESA’s 5 factors simply consider a population snapshot. Decisions under the ESA are to be made in full consideration of what the future holds for a species. For Florida’s manatees, unfortunately, both the immediate and long-term scenarios indicate ongoing perils that make recovery tenuous.


Dr. Katie Tripp has been Save the Manatee Club’s Director of Science and Conservation since May of 2008. She received her Ph.D. in Veterinary Medical Sciences from the University of Florida, where she conducted research on manatee physiology.