Florida Manatees Can Survive for at Least Another Century

In great news for manatees, researchers predict that the gentle 'sea cows' will endure for at least another 100 years as long as threats continue to be managed.

It’s a strange world we live in when we celebrate the idea that a species might actually survive through the next century. It’s all become so fragile that small victories can feel like big wins – but regardless, a new study predicting that Florida’s iconic manatees can survive another 100 years is cause for cheer.

“Today the Florida manatees' numbers are high. Adult manatees' longevity is good, and the state has available habitat to support a population that is continuing to grow," said US Geological Survey (USGS) research ecologist Michael C. Runge, lead author of the report. "Still, new threats could emerge, or existing threats could interact in unexpected ways," Runge said. "Managers need to remain vigilant to keep manatee populations viable over the long haul."

Tracy Colson/USFWS Endangered Species/CC BY 2.0

A subspecies of the West Indian manatee, the Florida manatee has the gloomy distinction of being one of the first animals to be listed as endangered when the federal Endangered Species Act went into effect in 1973. At the time, only 1,000 of them were left. But after 40 years of manatee-protecting measures like boat speed limits and habitat protection, there are now more than 6,600 of them.

The manatee experts involved in the study predict that the population will double over the next 50 years and then plateau, with very little chance of the numbers dipping to below 500, as long as conservation efforts are maintained.

The main threats they face will continue to be collisions with watercraft and the loss of warm-water habitats where they are protected from cold water in the winter. Red tides could also become a serious threat if they increase in intensity and frequency.

"If the rate of mortality from watercraft collisions were to double, the population's resilience would be compromised," says Runge. If that were allowed to happen, the chance that the population would drop to under 500, the crucial number, would be around 4 percent. "We looked at all the other pressures people have mentioned, and we did not find any combination of threats that raised the risk of a decline to fewer than 500 animals on either coast above nine percent."

David Hinkel/USFWS Endangered Species/CC BY 2.0

Of interest is that the populations will likely “shift around the state” thanks to regional environmental changes. According to a summary of the report:

For example, some southeast Florida power plants are expected to shut down over the next 40-50 years, and if they do, manatees will lose the warm water refuges created in the plants' discharge canals. Manatees in southwest Florida are likely to be increasingly affected by red tide and may also lose some warm water refuges. So southeast and southwest Florida may see their manatee populations decline.
Those losses will be balanced by increased manatee numbers in northeast and northwest Florida, where warm natural springs are capable of hosting more manatees.

"Manatee populations will continue to face threats," Runge says. "But if these threats continue to be managed effectively, manatees will be an integral and iconic part of Florida's coastal ecosystems through the coming century."