179 Healthy Common Dolphins Have Stranded in Cape Cod
Since January 12; 108 Have Died and Cause Still Unknown
© 2012 by Linda Moulton Howe
“179 stranded common dolphins in four weeks is unprecedented.”
– Trevor Spradlin, NOAA Marine Mammal Biologist
International Fund for Animal Welfare (IFAW) rescue teams tried
to save as many common dolphins as possible that persisted
stranding, re-stranding and dying between Barnstable and Wellfleet
in Cape Cod between January 12 and February 14, 2012.
Light blue area between Wellfleet and Barnstable on Cape Cod, Massachusetts,
is where 179 common dolphins stranded, re-stranded and died between
January 12 and February 14, 2012, unprecedented in Cape history.
February 24, 2012 Silver Spring, Maryland – The common dolphin is the name given to two species, and possibly a third, of dolphins making up the genus Delphinus. Those species are the short-beaked common dolphin, Delphinus delphis; the long-beaked common dolphin, Delphinus capensis. Some studies suggest a third species, the Arabian common dolphin , D. tropicalis, that has an extremely long and thin beak and is found in the Red Sea and Indian Ocean.
Common dolphin adults range between 1.9 to 2.5 meters (6.2 to 8.2 ft), long
and can weigh between 80 and 235 kilograms (180 and 520 lb). The color pattern
on the body is unusual. The back is dark and the belly is white, while on each side is
an hourglass pattern colored light beige-grey, yellow or gold in front and lighter grey
in back.They have long, thin rostrums, or beaks, with up to 50–60 small,
sharp, interlocking teeth on the side of each jaw. Fatty deposits in the jaw
and head are used for common dolphin echolocation navigation.
The color pattern on common dolphin bodies is unusual. The back is dark and the belly is white, while on each side is an hourglass pattern of light beige, yellow or gold in front and light grey in back. Common dolphins like deep, warmer waters between 40 degrees North and 50 degrees south. They have been recorded making dives up to 200 meters, about 700 feet deep. Common dolphins live in large social groups of hundreds or even thousands of dolphins.
Common dolphins are the species most frequently represented in the art of ancient Rome and Greece. Many ancient Greek coins feature a man or boy riding on the back of a dolphin.
Fresco of common dolphins around 1600 B.C. Bronze Age,
from Knossos on the Greek Island of Crete.
Common dolphins were abundant in the western Mediterranean Sea until the 1960s, but then their population began to seriously decline, perhaps from toxins, industrial pollution, fishing nets, climate change and other human assaults on the marine environment. In the United States, common dolphins are a protected species.
Dolphins are capable of making a broad range of sounds using nasal air sacs located just below the blowhole. Dolphins also communicate with whistle-like sounds produced by vibrating connective tissue, similar to how human vocal cords function. Dolphins and some whales also navigate and find food by making burst-pulses, a clicking sound, that travels quickly through the water. The sound is bounced back from objects in front
of the dolphin into the dolphin’s head and lower jaw that process the returns similar to human radar or sonar. Dolphin echolocation clicks are some of the loudest sounds made by marine animals.
In 2011 researchers in the United States and Great Britain used a CymaScope instrument that produces visible patterns from sound. The conclusion was that dolphin communication consists of receiving and transmitting sound pictures like the pattern of signals below.
Spectogram of dolphin clicks, whistles and whines produced
on May 29, 2010, in CymaScope research.
2012 Four-Week-Long Stranding Event
Is Still A Puzzle
Beginning on January 12, 2012, 179 common dolphins stranded and re-stranded and 108 of those died – the largest Cape Cod stranding event on record. The reasons for the persistent common dolphin strandings are still unclear. Rescue teams from the International Fund for Animal Welfare, also known as IFAW, in Yarmouth Port, Massachusetts, tried to save as many common dolphins as possible as they persisted stranding, re-stranding and dying between Barnstable and Wellfleet in Cape Cod Bay from January 12 to February 14, 2012.
IFAW contacted the United States Navy about possible underwater sound interference from military projects off Cape Cod, but the Navy said it was not conducting any exercises or other projects that might have interfered with the common dolphin echolocation in January to February 2012.
One marine biologist at the National Oceanic and Atmospheric Administration’s (NOAA) National Marine Fisheries Service is Trevor Spradlin. He has studied dolphins and marine mammals for twenty-three years. After undergraduate work in marine biology at Boston University in 1991, Trevor began working for the Woods Hole Oceanographic Institution in Cape Cod. His focus was marine mammal behavior and bio-accoustics lab research. Then in 1994, he took a position at NOAA in the Marine Mammal Health and Stranding Response Program in Silver Spring, Maryland. I talked with him last week after eleven common dolphins stranded in Cape Cod on February 14, bringing the total number in the four weeks from January 12 to February 14, 2012, to 179 strandings and re-strandings and 108 deaths. Trevor told me, “This is an unprecedented number in such a short time.”
Interview:
Trevor R. Spradlin, M. S., Marine Mammal Biologist, NOAA National Marine Fisheries Service, Marine Mammal Health and Stranding Response Program, Silver Spring, Maryland: “This is a very perplexing event. We don’t know why it’s been persisting for the past four weeks. What is different about this event is the longevity of it and certainly the numbers. We are perplexed by the large volume of animals we are seeing, but common dolphins we do know live in very large groups. And when they are off in deep water, they can form huge groups of hundreds of animals. We don’t know very much about the social dynamics of common dolphins, but we’re slowly learning.
One of the important things that IFAW (International Fund for Animal Welfare) has been able to accomplish is to tag animals that IFAW has been able to release back into the deep water. And so they have been able to track the movements of these surviving animals. Some of these animals that IFAW has released – they’ve already been tracked off the coast of Maine. So the common dolphins are moving large distances in very short amounts of time.
IFAW rescue team carries one of eleven common dolphins stranded on a mud flat
during low tide in Wellfleet, Massachusetts, on February 14, 2012. Image © 2012 by AP.
IS IT FAIR TO SAY THAT THIS IS AN UNPRECEDENTED STRANDING EVENT IN THE HISTORY OF COMMON DOLPHIN STRANDINGS?
Definitely! Our colleagues have not seen something at this scale before. These animals seem to be healthy because there is no sign of disease. These animals do not appear to be sick. It’s very strange for sure. Some have re-stranded again, so we’re looking at that.
Stranded common dolphins in Cape Cod marked with green tracking numbers
by the IFAW rescue teams and floated on red mats that will be used to
transport the stranded dolphins to deeper ocean waters. Image by M. Booth/IFAW.
Stranded common dolphin mother and calf were being transported by rescue teams
from IFAW and the New England Aquarium, Boston, to release back into deeper waters
near Cape Cod Bay on January 14, 2012. Image © 2012 by Julia Cumes AP.
RE-STRANDING MEANS THAT THESE ARE DOLPHINS THAT HAVE COME INTO CAPE COD, THEY HAVE BEEN ALIVE, PEOPLE HAVE TRIED TO GET THEM BACK OUT INTO DEEP OCEAN, BUT BECAUSE IFAW HAS TAGGED SOME OF THE DOLPHINS, THEY KNOW IT’S THE SAME DOLPHIN THAT ENDS UP BACK IN CAPE COD?
Exactly!
AND THAT GOES TO THE QUESTION: WHAT WOULD BE DISORIENTING THE COMMON DOLPHIN THAT NORMALLY SPENDS ITS LIFE OUT 20 TO 30 MILES OFF SHORE IN DEEP WATERS – WHAT COULD MAKE IT CHANGE TWICE, COMING INTO THE CAPE COD HOOK?
That’s a great question. We don’t know the answer to that yet. Those animals that re-strand are already compromised by the initial stranding event. So some of them still might be in shock. They might still not have recovered from that initial stranding. So why the animals are re-stranding could be multiple reasons. It could be any myriad of factors. They could be chasing prey and their prey might be coming inland and they might be just following their prey. So we are going to be looking at the movement patterns of their prey species and see if we can see a pattern there. They could also be responding to different shifts in water temperature or currents. We’re looking at that as well.
The folks on the ground are trying to get to these animals as fast as possible just because of the treacherous nature of the habitat there. These animals are being found in remote parts of the Cape. Sometimes these animals have been stranded for quite awhile before the rescue team has been able to find them. So if the teams are able to get to the animals immediately before they strand, the dolphins have a higher probability of survival. If the animals have been on the ground and out of water for an extended period of time, their prognosis for survival is less. But they try to make sure that they release as many animals as possible. Some of these re-stranders are most likely animals that were compromised more than the healthier ones.
DOES RE-STRANDING HAPPEN OFTEN?
If the animals are showing signs of disease or illness, then re-strandings would not be unexpected. But if animals are not showing any signs of disease or have not been exposed to pollution or have not been exposed to sounds that disorient them – then we would not expect them to necessarily re-strand unless they have experienced some kind of initial trauma from the first stranding event.
BUT TODAY AS WE ARE TALKING ON FEBRUARY 17, 2012, THERE IS NOTHING IN THE NECROPSIES DONE SO FAR ON SOME OF THE DEAD AND STRANDED COMMON DOLPHINS IN CAPE COD AS A SPECIFIC CAUSE OF THE STRANDINGS AND THE DEATHS?
That is correct. These dolphins, when the team is able to handle them, they appear healthy.
IFAW rescue team watching over a stranded dolphin that appears healthy.
Photo by Kerry Branon, IFAW.
The live animals, if they are able to get them on the ocean side of the Cape and put them back into deep water, they seem to be thriving and they seem to be able to survive. The animals that have died have shown no indication of being ill when they die. It’s most likely a result of shock to being out of the water.
What is happening is that these animals are stranding on the bay side of Cape Cod. They are experiencing very extreme shifts in the tides. They find themselves high and dry and particularly for dolphins, they need to be in water. When they are on land, unfortunately they succumb to gravity. Their bodies are not designed to withhold their weight, so they need to be in water to have that kind of buoyancy. So when they are on land, it is very detrimental for them. That’s why it is always important to try to get to the stranded live animals as fast as possible so we can try to get them back in the deeper water and have them float and hopefully stabilize.
This particular species, common dolphin, is a pelagic (deep ocean but not bottom dwellers) deep water species. They are not used to being in shallow waters at all. One of the predominant theories here is that they are unable to navigate successfully in these very treacherous shallow areas around the inside of the Cape.
COULD YOU EXPLAIN HOW DOLPHINS MIGHT USE MAGNETIC FIELDS FOR THEIR ORIENTATION AND WHAT MAGNETIC ANOMALIES CAN DO TO THEM AND HOW?
Well, the science is still very much ongoing with respect to that. I’m not aware of any definitive work that has been done. It’s mostly just theories about the influence of geomagnetic forces on their ability to navigate.
Echolocation
Dolphins and some whales make burst-pulses, a clicking sound, that travels
quickly through the water. The sound is bounced back from objects in front
of
the dolphin into the dolphin’s head and lower jaw where the information is processed
for navigation and finding food, similar to human radar or sonar.
Illustration with permission © by Bioexpedition.com.
What we do know is that dolphins use a lot of acoustics to find their way through the environment. Particularly, common dolphins use echolocation – biological sonar – in which the dolphins use sound to bounce off objects and to bounce off the sea floor. And that’s one of the primary ways we think the dolphins are able to navigate.
IS IT POSSIBLE THAT THE U. S. NAVY COULD BE CONDUCTING SOME KIND OF UNDERWATER EXERCISES THAT THEY ARE NOT ADMITTING THAT COULD INTERFERE WITH SONAR ECHO LOCATION OF THE COMMON DOLPHINS?
Well, we don’t think so because we have been coordinating with the Navy and asking them to provide us information and they have told us they have not been doing anything out there. If they were, we would expect to see other species – not just common dolphins responding to that. We don’t see any evidence of noise or acoustic trauma on these animals. They seem to be healthy. They don’t seem to be showing any signs of trauma. So, it’s really perplexing about what is going on here?
SO WHAT MIGHT INTERFERE WITH THEIR ECHOLOCATION AND CAUSE DISORIENTATION AND HAVE THEM END UP IN THE CAPE COD HOOK?
We don’t really know. We will be looking at whether there have been any sounds going on, but we don’t have any evidence to suggest there are any human-caused sounds – not shipping noise or military noise that has been causing this. But because we are not seeing any immediate signs of illness, disease, pollution, toxicity – we are seeing no over-arching health issues with these animals. It’s a real mystery why this is happening.”
IFAW Necropsy Results As of February 23, 2012
IFAW completed nine dolphin necropsies in which time of death was known and several other necropsy results are pending. So far the necropsy results do not “suggest any one cause for this stranding event. One animal showed gross signs of liver disease. Many otherwise healthy animals showed only signs of stress related to the stranding event itself. Furthermore, there is no gross evidence suggesting that acoustic trauma is a cause for this stranding event.” Searching for viruses and other pathogens can cost a lot of money – in the thousands of dollars – so IFAW is seeking more funding.
Another Marine Mammal Mystery – Washington State
Three days before the large stranding of the eleven common dolphins in Cape Cod Bay on Valentine’s Day, on Saturday, February 11, the 3-year-old body of a female orca killer whale washed up north of Long Beach, Washington. The orca are toothed whales in the oceanic dolphin family and are an endangered species. So the loss of this female, known to Cascadia Research scientists as L112 from the L Pod, is serious. “To lose a 3-year-old is very sad, but especially when it’s a female and especially from L-Pod – this is pretty devastating in a community of marine animals that is so small in numbers,” said Susan Berta of the Orca Network. The monitored L-Pod has had only a few female births in recent years and the population continues to decline. The total number of monitored orca pods known as K, L and J are only 88 now.
Orca female L112 was found washed up north of Long Beach, Washington, on Saturday,
February 11, 2012, with unexplained physical trauma. Image by Cascadia Research.
Scientists from Portland State University, Seaside Aquarium, Cascade Research, Seattle Seal Sitters and the Washington State Department of Fish and Wildlife thought the young female orca died three days before. So some of the physical damage might have occurred after death. Necropsy results are not yet known about cause of death.
Dolphins and Whales Should Have Rights
As Non-Human “Persons”
This week at the annual American Association for the Advancement of Science (AAAS) annual meeting in Vancouver, B. C., Canada, Professor Lori Marino, Ph.D., in the Neuroscience and Behavioral Biology Department at Atlanta’s Emory University, presented a “Declaration of Rights for Cetaceans: Whales and Dolphins.” Prof. Marino said based on her own research that “Science has shown us that cetaceans have most, if not all, the characteristics that humans have, including intelligence, self-awareness, autonomy and social complexity. Their basic needs are very much like humans – to be able to stay alive, to not be confined, to make choices and travel, and perhaps foremost to engage in social interaction.”
It was Prof. Marino who proved in a 2001 study that dolphins are capable of recognizing themselves in a mirror and their brain power is only second to humans on this planet. Dolphins use tools to catch fish, understand words, speak in different dialects in different locations, feed their sick pod mates and grieve in sadness when calves die.
Prof. Marino told the AAAS scientists, “If these cetacean animals are self-aware, have specific cultures, stay with the same pod their whole life, and are incredibly intelligent and social, then no tank will ever be able to give them the kind of life they have in the ocean.” Prof. Marino and her colleague Annelise Sorg, President of the Coalition for No Whales in Captivity, want to prevent whales and dolphins from being captured for aquariums or caught for food and plan to take their Declaration of Rights for Cetaceans to the United Nations.
More Information:
• 05/27/2011 — Unprecedented Die-Off of Leopard Sharks in Redwood City, Calif. Bay Area
• 05/26/2011 — Part 1: Gulf Fishermen Finding Sick Fish, Few Crabs and Shrimp
• 03/30/2011 — Corexit and Crude Oil Still in Gulf A Year After BP Disaster; Marine Life Dead and Some People Sick
• 02/23/2011 — Part 1: BP Oil and Corexit Dispersant Still In Gulf of Mexico.
• 01/31/2011 — 2010 – 2011 Extreme Weather
• 01/28/2011 — New Year 2011 – Bird, Fish, Penguin, Crab Deaths and More Corkscrew-Sliced Seals on North Norfolk, England Coast
• 01/06/2011 — Updated: New Year Deaths of Birds, Fish and Crabs Around the World
• 11/30/2010 — Part 2: Naples, Florida Fire Chief Watched Lights of Unknown Origin
• 06/23/2010 — Snakes Are Declining Around the World, But Why?
• 02/25/2010 — Lionfish Invaders Are Eating Up Other Marine Life in Florida Keys, Bahamas and Bermuda
• 11/20/2009 — Red List of Earth Life Facing Extinction Keeps Growing
• 10/06/2009 — Cosmic Rays Reaching Earth At Highest Level in 50 Years
• 03/06/2009 — Unexplained Stranding of 200 Pilot Whales and Dolphins
• 03/06/2009 — Unexplained Stranding of 200 Pilot Whales and Dolphins
• 02/05/2008 — Federal Court Rejects Bush Navy Sonar Exemption
• 02/20/2006 — Mysterious Deaths of Whales in Mexico
• 06/25/2005 — “Junk DNA” That’s Not Junk
• 05/20/2005 — May 2005 Crop Formation Update in Six Countries
• 08/03/2004 — Crop Formations: Fifteen in Southern England Since July 20, 2004.
• 08/01/2003 — Field Notes About English Animal Mutilations
• 09/02/2002 — Blue Lights and Helicopters in Wiltshire’s East Field
• 09/10/2000 — Arctic Ice Melt Threatens Polar Bears
• 06/08/1999 — Increased Gray Whale Deaths in Spring 1999
• 05/04/1999 — Mysterious Deaths of Harbor Porpoises on East Coast
Websites:
International Fund for Animal Welfare (IFAW): http://www.ifaw.org/us/
NOAA Mass Stranding Event in Cape Cod, Mass.:
http://www.nmfs.noaa.gov/pr/health/capecod_mass_stranding_factsheet2012.pdf
NOAA Fisheries: Protected Resources: http://www.nmfs.noaa.gov/pr/
Declaration of Rights for Cetaceans: Whales and Dolphins:
http://cetaceanconservation.com.au/cetaceanrights/
No Whales in Captivity: http://www.vcn.bc.ca/cmeps/
Common Dolphin Wikipedia: http://en.wikipedia.org/wiki/Common_Dolphin
Common Dolphins, Delphinus delphis: http://marinebio.org/species.asp?id=32
Dolphins Wikipedia: http://en.wikipedia.org/wiki/Dolphin
Echolocation: http://www.dolphin-institute.org/resource_guide/dolphin_perception.htm
U. S. Navy Marine Mammal Program: http://en.wikipedia.org/wiki/U.S._Navy_Marine_Mammal_Program
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