Coastal residents have reported seeing an increase in the numbers of dolphins stranded on the beaches over the last year. A few survive; the majority are not so fortunate. Although this is not the first incidence of dolphins in trouble, concern is growing among professional marine wildlife managers about what is happening and why.
More than 740 animals from New Jersey to Florida were stranded during an Unusual Mortality Event (UME) for bottlenose dolphins in 1987-88. Under the Marine Mammal Protection Act, the Marine Mammal Health and Stranding Response Program was created to investigate. A marine virus specifically targeting these particular (cetacean) mammals reduced the population fifty percent.
Monitoring from New York to Florida between 2007 and 2012, the count of bottlenose dolphin strandings reached 295. Unexpectedly, from July 2013 through June 2014, the strandings increased to 1370 animals; Virginia, North Carolina and Florida saw the highest numbers. Another UME was declared.
Investigators do not yet know which population stocks are affected the most or have the greatest risk, but they estimate 39,206 bottlenose dolphins may be affected. “Bottlenose dolphins are about one half of the total number of strandings here (North Carolina),” said Central Coast Marine Mammal Stranding Network Coordinator, Vicky Thayer, PhD., a marine biologist with North Carolina Division of Marine Fisheries.
Stranded animals included all ages and genders and a few live mammals. They showed lesions on the skin, joints, mouth and lungs, again infected with cetacean morbillivirus. That virus particular to dolphins, porpoises and whales affects their lungs, brains and immune systems, enabling other health problems to appear. Little is known about the virus, but other morbillivirus strains produce measles in humans and distemper in canines. No vaccine or medication has yet proved successful against the strain targeting cetaceans.
The response team is mobilized quickly after a stranding. “I’m on call 24/7,” said Thayer. “The most challenging things in responding to strandings in this area are the geography, the barrier islands, and sometimes not being able to bring animals back to the lab.” Getting to one stranding location in mid-July, took three hours by boat. Unfortunately, there are probably more strandings not reported.
“We sample everything if the carcass is fresh. If it isn’t very fresh, we take fewer samples, but every sample we take costs money to analyze…we have to send them out,” said Thayer.
“With strandings, you have to be careful because, the reporting has gotten better.” In the past, reporting was by radio, or after coming back to the dock. Now smart phones send immediate photos with GPS locations. Thayer wants to avoid jumping to conclusions without comprehensive forensics.
“For most of the strandings that occur other times, we don’t know the reason. Sometimes, we find the smoking gun, sometimes its natural mortality, sometimes it’s a stingray sting, sometimes it could be propeller cuts. And just because they have propeller cuts or shark bites, doesn’t mean that’s what killed them; they could have been sick before that. So we have to be careful,” said Thayer. “The pattern of strandings, of when and where they occurred, is very similar to the last one. The last one, 1987/88 would be over by now. I’m hoping that this one is ending now.”
“As I understand it, there are some bottlenose dolphins alive now that were alive in 1987-88, so they are immune to the virus. I think some species exist with it, and it doesn’t affect them as badly; but others, it just knocks them out.” Apparently, the virus spreads by contact, for example, mother to pup through the eyes, mouth, or wounds. Contributing factors might include environmental toxins and pathogens and migratory stressors.
Necropsies determine the cause and manner of death, health and disease status. The organs are examined; samples of tissue, blubber, and teeth are taken. “For a lot of species that wash up, most of what is known about them comes from stranded animals little known out there – their biology, physiology and anatomy,”Thayer said.
The animal is genetically identified for its population stock and migration range, and a dorsal fin photo may identify the animal from a database set up by Thayer and her husband Keith Rittmaster, North Carolina Maritime Museum Curator of Natural Science.
Living animals are monitored to see whether or not they will return to open waters. In normal times, animals go to facilities for help. With the potential spread of deadly virus, facilities are not accepting dolphins, so humane euthanasia is done. Thayer indicated, “In other locations and particularly during mass strandings, under certain conditions some animals are tagged and released at a location different from the stranding site, after they are tested for certain health parameters.”
The John Prescott Grant provides some funding; stranding networks must compete for money each year. Therefore, each network is volunteer-staffed and other agencies help as needed. Thayer drives a Division of Marine Fisheries truck, has an office at Center for Marine Sciences and Technology from NCSU, gets help from Marine Patrol and the Park Service, and has a half-time assistant. Volunteers provide transportation, help with necropsies, bring food to the crew, or donate money. Thayer would like extra supplies, safety vests for the crew and T-shirts to identify volunteers.
Regarding UMEs Thayer stressed “These animals are ecosystem sentinels; they represent the health of our ecosystem, sort of the canaries in the coal mines. If they are dying in large numbers, it could be indicative of general ecosystem [ill] health. It’s something that we should pay attention to and I hope we continue to get funding to respond to these strandings.”
An UME Contingency Fund allows the public to donate money for supporting research, the special costs involving tissue collections, lab work, and care of living marine
mammals. http://www.nmfs.noaa.gov/pr/health/mmume/fund.htm or 301-427-8402.
To report injured or dead marine animals, call 877-WHALE HELP (1-877-942-5343), or use the free Dolphin & Whale 911 app, http://1.usa.gov/1b1kqfv. As a precaution, stay back 100 feet, keep animals away, and do not swim in surrounding waters, especially with open wounds.
Keep up with dolphin findings and those affected weekly, http://www.nmfs.noaa.gov/pr/health/mmume/midatldolphins2013.html.
Maryland Department of Natural Resources (dead animals only)
Cooperative Oxford Laboratory
Oxford, MD, 800-628-9944
National Aquarium in Baltimore, Marine Animal Rescue Program
(live animals only)
Baltimore, MD, 410-373-0083
Smithsonian Institute, National Museum of Natural History
Washington, DC, 202-633-1260
Virginia Aquarium & Marine Science Center
Virginia Beach, VA, 757-385-7576
To report a stranded marine mammal in Carteret, Pamlico, Craven, or Beaufort counties – or Hammocks Beach State Park in Onslow county (dead or alive) call: 252-241-5119
To report a marine mammal stranding south of Hammocks Beach, please call: 910 962-7266
To report a stranding north of Ocracoke, call: 252-455-9654
South Carolina Stranding Hotline
Georgia Marine Mammal Stranding Hotline
Florida Marine Mammal Stranding Hotline
Alabama Marine Mammal Stranding Hotline
Mississippi Marine Mammal Stranding Hotline
Institute for Marine Mammal Studies, Gulfport, MS
Louisiana Marine Mammal Stranding Hotline
Marine Mammal Stranding hotline at 888-404-FWCC (3922)
Helen Aitken is a veteran science educator, writer and photographer from eastern N.C. who loves classic wooden boats, “backyard” boat makers, and contributes regularly to All At Sea Southeast. Visit her website at www.helenaitken.com.