Frequent Questions: Unusual Morality Event, 2011-2012 Texas Bottlenose Dolphins

Why are you closing the Unusual Mortality Event?

The conditions under which the UME was declared are no longer occurring. Scientists are no longer documenting a marked increase in strandings. The team of scientists who investigated this UME determined the cause of the UME as being due to biotoxin exposure from several harmful algal blooms off the coast of Texas, primarily brevetoxin and okadaic acid.

How widespread was this Unusual Mortality Event?

Increased mortalities of bottlenose dolphins were observed along the Texas coastline.  The highest number of strandings occurred in the following counties: Aransas, Brazoria, Calhoun, Galveston and Kleberg.

What are the dates for this UME?  How many bottlenose dolphins are included in this UME?

The UME is defined as occurring from November 1, 2011 to March 31, 2012, and during this time 126 bottlenose dolphins were documented.  Peak strandings occurred between November 1, 2011 and February 29, 2012 with 79% (99/126) of the bottlenose dolphins stranding during this time.

What do scientists believe is the most likely cause of this UME?

After analyzing various differentials relative to available data, scientists say the most likely cause of this UME was biotoxin exposure from several harmful algal blooms off the coast of Texas, primarily brevetoxin and okadaic acid. 

What unusual ocean conditions occurred in 2011-2012?

From November 2011 through February 2012 these strandings coincided with a red tide bloom (Karenia brevis, brevetoxin) nearshore and in the bays and estuaries of northern Texas (Brazoria, Galveston counties) and southern Texas (Calhoun, Kleberg and Aransas counties). In 2011-2012 due to the lack of rain and a mild winter, the red tide bloom continued much longer and was present in Texas regions through January. In the beginning of February, a Dinophysis sp. (okadaic acid) bloom occurred in northern Texas (Brazoria County) and in southern Texas (Aransas County) simultaneously.  The Dinophysis bloom was no longer detected by the end of the month. Additionally, there were concurrent fish, sea bird, sea turtle and coyote die-offs all linked to brevetoxin and other biotoxins during the same time-period along the Texas coast.

What did scientists test for? What did they find?

Although many carcasses were too decomposed to allow for necropsies, the samples scientists were able to gather were examined for biotoxin exposure and infectious diseases. Over 85% (17/20) of the dolphins testing positive were positive for brevetoxin at background or high levels, and 50% (16/32) of all dolphins tested had background levels present for at least one biotoxin.  Lastly, dolphins had low levels of Brucella ceti infection (28%) that were similar to baseline levels for Gulf of Mexico dolphin populations from previous studies.

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 the toxin released from the algal cells.  Additional information about red tide, can be found at: https://oceanservice.noaa.gov/news/redtide-florida/.

What types of marine mammals did this UME effect?

This event involved bottlenose dolphins (Tursiops truncatus), which is one of the most common marine mammal species found in the coastal waters of the Gulf of Mexico.

What is next now that the Unusual Mortality Event has been closed?

Scientists plan to continue post-UME monitoring the bottlenose dolphins in Texas for the next several years. Expected steps include:

• Continue monitoring of stranding demographics and pathologic findings in stranded dolphins across Texas especially monitoring for future algal bloom and biotoxin impacts.

Where can I find additional information on bottlenose dolphins and other Unusual Mortality Events?

You can find more information on our bottlenose dolphin and UME webpages.

What should people do if they encounter a dead dolphin floating or stranded on the beach?

Please immediately contact your local stranding network or local authorities to report a live or dead stranded dolphin:

• For the Southeast Region, call 877-WHALE HELP (877-942-5343).
• Do not touch the dolphin.
• Don’t allow pets to approach the dolphin.
• Observe the animal from a safe distance of 100 yards (safe for you and the animal).

What should people do if they witness harassment or any marine mammal violation in the water or on the beach?

To report violations please contact NOAA’s Office of Law Enforcement at (800)853-1964.

What is the UME 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.

Learn more about the UME Contingency Fund.

How can deposits be made into the UME Contingency Fund?

The following can be deposited into the fund:

• Amounts appropriated to the fund.
• Other amounts appropriated to the Secretary for use with respect 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.

The public may use Pay.gov to donate to the UME Contingency Fund for this or other UMEs and help cover costs incurred by the Marine Mammal Stranding Network.