Frequent Questions: 2018 Bottlenose Dolphin Unusual Mortality Event
Since July 2018, elevated bottlenose dolphin mortalities have occurred and been associated with the red tide bloom along the southwest coast of Florida including Collier, Lee, Charlotte, Sarasota, Manatee, Hillsborough, and Pinellas counties. This event has been declared an unusual mortality event (UME).
Southwest Florida has been experiencing an ongoing severe red tide bloom since November 2017. The dinoflagellate (Karenia brevis) that forms red tides is commonly found at low levels in Gulf waters, but it can have devastating impacts when the cells multiply to form a harmful algal bloom. Other species, such as fish, sea turtles, and manatees, are confirmed to be dying as a result of this ongoing harmful algal bloom.
What is an unusual mortality event?
An unusual mortality event, or UME for short, is defined under the Marine Mammal Protection Act as a stranding event that is unexpected, involves a significant die-off of any marine mammal population, and demands immediate response. There are seven criteria that make a mortality event "unusual." If the national Working Group on Marine Mammal Unusual Mortality Events, a group of marine mammal health experts, determines that an event meets one or more of the criteria, then it forwards a recommendation to NOAA’s Assistant Administrator for Fisheries to declare a UME.
What additional resources are now available to pursue the investigation since an unusual mortality event has been declared?
An unusual mortality event declaration provides additional expertise from the working group (an international and multidisciplinary team of scientists) and additional stranding response partners, as well as access to additional funding through the National Unusual Mortality Event Contingency Fund. In addition, a detailed investigative plan will be developed that may include more targeted necropsies; further testing of samples for biotoxins, bacterial or viral agents; and diagnostic pathology services. Finally, through the UME process all finding and interpretations undergo national and international scientific review.
What criteria have been met for this UME in Southwest Florida?
In this case, the Working Group concluded that three of the seven criteria for determining an unusual mortality event have been met. These include the following criteria:
- A marked increase in the magnitude or a marked change in the nature of morbidity, mortality, or strandings when compared with prior records.
- A temporal change in morbidity, mortality, or strandings is occurring.
- Affected animals exhibit similar or unusual pathologic findings, behavior patterns, clinical signs, or general physical condition.
Will you be collecting additional biological and environmental information?
Stranding network partners will continue to collect and analyze samples as needed to evaluate the situation. The working group will decide whether additional information is needed.
What are the findings in the stranded dolphins?
Full or partial necropsy examinations were conducted on several dolphins with preliminary results showing the stranded dolphins were positive for the red tide toxin (brevetoxin). This indicates the event is related to the red tide bloom. Many carcasses have been decomposed, limiting diagnostic sampling. However, feces, stomach contents, and other samples were collected for red tide toxin (brevetoxin) testing.
What is a red tide? What are red tide toxins and how do they impact dolphins?
A red tide, or harmful algal bloom, is a higher-than-normal concentration of a microscopic alga (plantlike organism). In Florida and the Gulf of Mexico, the species that causes most red tides is Karenia brevis. Karenia brevis produces brevetoxins that can affect the central nervous system of fish and other vertebrates, such as dolphins, manatees, birds, and sea turtles, causing these animals to become ill and die. Wave action can break open Karenia brevis cells and release toxins in the air, leading to respiratory irritation. Dolphins, manatees, and turtles can be exposed to the toxins by consuming prey fish or sea grass contaminated with the toxin or by breathing in the toxin released from the algal cells. Additional information about red tide in Florida, including NOAA and the state of Florida's role can be found on the NOAA Ocean Service and Florida Fish and Wildlife Conservation Commission pages.
Is this die-off being caused by the red tide event?
Our stranding network partners have conducted full or partial necropsy examinations on numerous dolphins and discovered several were positive for the red tide toxin (brevetoxin). This indicates the event is related to the red tide bloom. The Investigative Team will continue to conduct sampling and testing, and we will update results as we learn more. It may take weeks or months to return results. There was a 2005–2006 multi-species UME that ranged along the Southwest Florida coast and involved approximately 190 dolphins caused by exposure to red tide toxins, so an event like this has occurred before.
Are there any risks to pets?
Pets should always be kept away from marine mammals, particularly diseased or dead marine animals.
Where can I find more information about the red tide bloom in Southwest Florida?
There are several resources available for more information on the red tide bloom:
- NOAA's Red Tide Condition Report and Bulletins
- Red Tide in Florida and Texas
- State of Florida Department of Environmental Protection
- Florida Fish and Wildlife Conservation Commission
- Florida Department of Health
- Florida Sea Grant, Understanding Florida's Red Tide
What is the current dolphin population along the Southwest Florida coast?
Eight stocks of bottlenose dolphins co-occur in the UME area along the Southwest Florida Coast, one coastal stock and seven bay, sound, and estuary stocks.
The Gulf of Mexico Eastern Coastal Stock primarily occurs from the Big Bend area of Florida south to Key West, Florida, with a best estimated abundance of 12,388 from a 2015 Stock Assessment Report.
The seven Bay Sound Estuary Stocks along the Southwest Florida coast primarily include St. Joseph Bay in the north to Estero Bay in the south. Not all Bay Sound Estuary Stocks in the region have best abundance estimates but the Sarasota Bay and Charlotte Harbor Stocks have estimates of 158 and 826 individuals.
What is the Unusual Mortality Event Contingency Fund?
MMPA section 405 (16 USC 1421d) establishes the Marine Mammal Unusual Mortality Event Fund, describing its purposes and how the public can donate to the fund. According to the MMPA, the fund “shall be available only for use by the Secretary of Commerce, in consultation with the Secretary of the Interior:
- To compensate persons for special costs incurred in acting in accordance with the contingency plan issued under section 1421c(b) of this title or under the direction of an Onsite Coordinator for an unusual mortality event.
- For reimbursing any stranding network participant for costs incurred in preparing and transporting tissues collected with respect to an unusual mortality event for the Tissue Bank.
- For care and maintenance of marine mammal seized under section 1374(c)(2)(D) of this title.”
The National Contingency Plan for Response to Unusual Marine Mammal Mortality Events outlines the types of expenses that are reimbursable under the fund and the process for requesting reimbursement.
How can deposits be made into the Unusual Mortality Event Contingency Fund?
The following can be deposited into the fund:
- Amounts appropriated to the fund.
- Other amounts appropriated to the Secretary for use with respects to UMEs.
- Amounts received by the United States in the form of gifts, devises, and bequests under subsection (d) of section 405(d) of the MMPA.