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Marine Mammal Strandings

Single strandings, strandings of only one animal, can occur for a number of reasons. Dolphins, whales, porpoises, and seals may strand alone when the animal becomes lost or disoriented or is suffering from an illness, infection or injury. Newly weaned animals sometimes have a hard time thriving on their own and may strand as a result of their own inexperience. Older animals may also die of natural causes. Unfortunately, our actions as humans can often affect marine mammals. Some animals strand and/or die as a result of Human Interaction. The detrimental interactions include entanglement if fishing gear and marine debris, being struck by ships, being shot, and even being harassed by well-meaning beachgoers.

The phenomenon of mass strandings affects only cetaceans (dolphins and whales, infrequently porpises). Mass strandings occur when two or more of these animals strand (excluding a mom/calf pair) within the same general geographic region and within the same tidal cycle. There are usually multiple factors that play a role in causing these events. The one constant thread among all mass strandings is that like humans, the species of whales and dolphins involved are highly social animals that depend upon the safety and resources of the group in order to survive. This group mentality that is so helpful to these animals at sea can unfortunately cause otherwise healthy animals to strand en masse when they are near shore. When one animal enters shallow water or strands, the entire group may follo.

Other factors that may contribute to a mass stranding include predator evasion, complex topography, tidal fluxes, extreme weather, geomagnetic anomalies, and sonar or other acoustic disturbances. Mass strandings of whales and dolphins have occurred on Cape Cod for hundreds of years, thus it is unlikely that the events in this region are the result of modern human activities.

In most stranding cases, the cause of stranding is unknown, but some identified causes include:

  • disease
  • parasite infestation
  • harmful algal blooms
  • injuries due to ship strikes
  • fishery entanglements
  • pollution exposure
  • trauma
  • starvation

In addition, strandings often occur after unusual weather or oceanographic events.

Social structure:
The species of cetaceans (dolphins and whales) that typically mass strand are often pelagic (offshore) animals that form tight social groups. Unfortunately, the very social bond that serves them so well at sea may be the cause of their downfall as they come close to shore. These animals stick together at all times, so if one animal becomes sick, injured or disoriented, the entire group may strand instead of just the one affected dolphin or whale.

Scientists and researchers believe that threats by predators such as sharks and orcas may cause marine mammals to swim closer to shore where they are at increased risk of stranding.

Complex topography:
Animals come near shore at different times of the year and may become disoriented and trapped by complex inlets and the hook-like shape of areas such as Cape Cod, Massachusetts. Wellfleet Bay is an additional hook of land within Cape Cod Bay, and this added level of topographic complexity is likely the reason that 60% of all mass strandings in this area have taken place in Wellfleet. Researchers have also found similarities in the substrates of areas around the world with a high propensity for mass strandings: these locations tend to have gently sloping sandy or muddy flats that may inhibit the animals’ ability to navigate.

Extreme tidal fluxes:
Mass strandings often coincide with full and new moon tidal cycles. The extreme high and low tides during full moons allow animals to swim farther inshore than normal, leaving them high and dry when the tide turns. The tides in Wellfleet Harbor can fluctuate up to 12 vertical feet (high tide to low tide) during a full moon cycle.

Extreme weather:
High winds and stormy seas can cause a storm surge, allowing animals to go farther inshore than usual, making them more likely to become stuck when the tide recedes. It is also thought that these conditions may increase the likelihood that animals become disoriented in complex coastal areas.

Sonar and other acoustic disturbances:
Since many dolphins and whales rely on sound for navigation, underwater acoustic disturbances from oil exploration, military sonar or other sources may cause disorientation that could result in a stranding.

Examples Of Strandings Around The World

16 November 2011 New Zealand Department of Conservation
New Zealand conservation officials have euthanized the last surviving pilot whales from a pod of 65 that stranded on a remote South Island beach.

Department of Conservation Golden Bay Area Manager John Mason said 16 whales had died since yesterday morning and DOC staff had taken the difficult decision this morning to euthanize the remaining 18 whales to end their suffering.

'We had wanted to give the whales a chance to refloat and hopefully find their way out to sea in the high tides yesterday and overnight. But they re-stranded each time and more whales died.

'The whales seem to have come in a little further inshore in each re-stranding. The tides are reducing so it became very unlikely the remaining whales would get out to sea and that they would survive.

"Rather than prolong the whales' suffering we decided to take the humane course of euthanizing the remaining 18 whales this morning.'

The stranded pilot whales were reported to DOC staff on Monday evening by a Farewell Spit tour guide. DOC rangers who went to the area found 20 dead whales and one whale in a poor condition was euthanized. The next morning the rangers found another 44 whales stranded nearby, 2 - 3 kilometers from shore, 34 of which were alive and 10 dead.

A rescue of the whales was too dangerous to undertake given the distance of the whales from shore in a remote location where tides come in rapidly over the shallow tidal flats. It would be arduous and unsafe for people to walk the 2 - 3 kilometers back to shore after refloating the whales in chest-deep water.

DOC rangers remained at the Spit yesterday and overnight to monitor the whales. They found another 10 whales had died late yesterday afternoon when the high tide receded. A further six whales were found dead when rangers checked again at first light this morning.

Whales die in stranding

 Australia November 13, 2011-16 sperm whales died  yesterday, leaving another four of the ocean giants struggling for survival overnight.

The deaths occurred after 20 whales became stranded at Ocean Beach, near Strahan, on the West Coast, late in the morning.

Only four survived despite the rescue efforts of West Coast Parks and Wildlife Service personnel.

Late last night, another eight sperm whales were being monitored in nearby Macquarie Harbour. Four of them were stranded on sandbars.

Marine experts consider Ocean Beach and Macquarie Harbour to be among Australia's main hot spots for whale strandings.

PWS West Coast parks and reserves manager Chris Arthur said it was not known why so many strandings occurred at the locations.

"We don't know why, but there are several locations in the world where whale strandings occur frequently and Ocean Beach is one of them," Mr Arthur told the Sunday Tasmanian.

Mon 11 Nov 2010 Whale deaths in Donegal: pod stranded on Rutland beach

SCIENTISTS HAVE taken skin and tissue samples from some of the 33 long-finned pilot whales which died after a mass stranding off Donegal.

The carcasses of the 33 mammals were discovered early on Saturday on the back strand of Rutland Island between Burtonport and Arranmore island.


NOAA steps up probe of 146 New England seal deaths

November 5 , 2011 NOAA At least 146 dead seals have been documented from September 1, 2011 to November 3, 2011, most of which were harbor seals (120), including 19 females, 28 males, and 99 animals of unknown sex. The majority of cases have involved young of the year and many have similar skin lesions (ulcerative dermatitis). Unlike historical young of the year harbor seal mortalities, which are often attributed to malnutrition, many of these animals are in good body condition. The highest number of strandings occurred during the week of September 25 (42 harbor seals). The 146 seals generally were less than a year old and had healthy appearances. They were found in Maine, New Hampshire and northern Massachusetts.

Stranding records for the northeast region over the preceding four years show an average of 31 harbor seal strandings for the month of September and 24 harbor seal strandings for the month of October. Thus, the 2011 strandings that involved 61 seals in September and 46 seals from October 1-21 are above the expected average.

30 whales stranded on Tasmanian South Bruny Island beach

March 17, 2011-A POD of about 30 pilot whales has stranded on Tasmania's South Bruny Island.

The whales are believed to be pilot whales and became stranded late this afternoon.

Department of Parks and Wildlife spokeswoman Liz Wren said about 12 of the whales were still alive and Parks and Wildlife are on the beach trying to help the stranded mammals.

28 whales die in New Zealand stranding

Feb 15, 2010 WELLINGTON New Zealand Twenty-eight pilot whales have died after they became stranded on a remote beach in the far south of New Zealand, conservation officials told local media .

The whales came ashore at West Ruggedy Beach in the northeast of Stewart Island, Department of Conservation (DOC) manager Mark Townsend told the Southland Times.

The whales were found by a hiker on Sunday morning. The DOC staff arrived about an hour later but were unable to save any of them.

The conservation officials found nine whales already dead and there was no alternative to killing the remaining 19.

Unprecedented mass whale stranding

New Zealand Sep 22, 2010 -Department of Conservation staff are calling a mass pilot whale stranding at Spirits Bay in Northland "unprecedented".

Seventy-four whales are stranded across two kilometres on the remote beach north of Kaitaia.

So far nine have been successfully refloated. There are up to 50 whales just off-shore.


Whales die after stranding on Senegal coast At least 38 died after dozens showed up on shore

DAKAR, Senegal — The bodies of at least 38 whales have washed up on a Dakar beach and wildlife officials say as many as 100 swam up close to the shore.

Villagers living nearby said the whales were spotted late Tuesday night, veering closer and closer to the coast as the tide came in. By Wednesday morning many were beached.

United States Marine Mammal Unusual Mortality Events

UME No. Year Declared UME Name Species Body of Water/ Location Cause
71 2021 Atlantic Florida Manatee Manatee Atlantic Ocean, Florida Undetermined
70 2019 Alaska Ice Seal Bearded, ringed, and spotted seal Bering and Chukchi Seas Undetermined
68 2019 West Coast Gray Whale Gray Whale Pacific Undetermined
65 2018 Atlantic Minke Whale Minke whale Atlantic Ocean Suspect Human Interaction (Entanglement)/Infectious Disease
64 2017 North Atlantic Right Whale North Atlantic right whale

Atlantic Ocean, Canada, and U.S.

Human Interaction (Vessel Strike/Rope Entanglement)
63 2017 Atlantic Humpback Whale Humpback whale

Atlantic Ocean

Suspect Human Interaction (Vessel Strike)

Nonactive UME's-Closure Pending


Year Declared

UME Name


Body of Water/Location


67 2018 Northeast Pinniped Harbor and gray seal Atlantic Infectious Disease

Closed UMEs

UME No. Year Declared UME Name Species Body of Water/ Location Number of Animals Date Range Cause
69 2019 Northern Gulf of Mexico Bottlenose Dolphin Bottlenose dolphin Northern Gulf of Mexico, Florida Panhandle, Alabama, Mississippi, Louisiana 337 February 1, 2019, to November 30, 2019 Ecological Factors
66 2018 Southwest Florida Bottlenose Dolphin Bottlenose dolphin Gulf of Mexico 183 July 1, 2018-June 30, 2019 Biotoxin
62 2015 Guadalupe Fur Seal and Northern Fur Seal Guadalupe fur seal and northern fur seal Pacific Ocean, California, Oregon, and Washington 715 Guadalupe fur seals; 170 northern fur seals January 1, 2015, to September 2, 2021 Ecological factors
61 2015 Alaska and British
Columbia Large
and humpback
Pacific Ocean,
Gulf of Alaska,
United States;
52 April 23, 2015, to
April 16, 2016
60 2013 Mid-Atlantic
Bottlenose Dolphin
Bottlenose dolphin Atlantic Ocean, New York to Florida ~1,650 July 1, 2013, to March
1, 2015
Infectious disease
59 2013 Florida Indian River Lagoon Bottlenose Dolphin Bottlenose dolphin Atlantic Ocean, Indian River Lagoon, Florida 79 January 9, 2013, to December 31, 2013 Ecological factors
58 2013 Florida East Coast Manatee Manatee Indian River Lagoon, Florida-East Coast 111 January 1 to December 26, 2013 Infectious disease secondary to ecological factors (e.g. change in forage)
57 2013 California Sea Lion California sea lion Pacific Ocean, California 8,122 January 1, 2013, to September 30, 2016 Ecological Factors
56 2012 Texas Bottlenose Dolphin Bottlenose dolphin Gulf of Mexico, Texas 126 November 1, 2011, to March 31, 2012 Biotoxin
55 2011 Alaska Pinniped Bearded, ribbon, ringed, spotted seal, and walrus Bering and Chukchi Seas, Alaska ~657 May 1, 2011, to December 31, 2016 Undetermined
54 2011 Northeast Pinniped Gray and harbor seal Atlantic Ocean, Maine, New Hampshire, Massachusetts 784 June 1, 2011, to November 15, 2012 Infectious Disease
53 2011 South Carolina Bottlenose Dolphin Bottlenose dolphin Atlantic Ocean, South Carolina 37 February 27, 2011, to May 30, 2011 Undetermined
52 2011 Florida Manatee Manatee Atlantic Ocean, Gulf of Mexico, Florida 143 December 16, 2010, to February 13, 2011 Ecological Factors
51 2010 Florida St. Johns River Bottlenose Dolphin Bottlenose dolphin St. Johns River, Florida 23 May 24, 2010, to November 7, 2010 Undetermined
50 2010 Northern Gulf of Mexico Cetacean Bottlenose dolphin, Atlantic spotted dolphin, spinner dolphin, melon-headed whale, sperm whale, pygmy sperm whale, dwarf sperm whale, pantropical spotted dolphin, Gulf of Mexico Bryde’s whale, minke whale, short-finned pilot whale, Risso’s dolphin, Blainville’s beaked whale, Clymene dolphin, rough-toothed dolphin Northern Gulf of Mexico, Florida Panhandle, Alabama, Mississippi, Louisiana 1,141 March 2010 to July 2014 Human Interaction
49 2010 Florida Manatee Manatee Atlantic Ocean, Gulf of Mexico, Florida ~529 January 11, 2010, to April 9, 2010 Ecological Factors
48 2009 Virginia Bottlenose Dolphin Bottlenose dolphin Atlantic Ocean, Virginia 40 April 21, 2009, to June 30, 2009 Undetermined
47 2008 California Harbor Porpoise Harbor porpoise Pacific Ocean, California 170 May 1, 2008, to December 31, 2009 Ecological Factors
46 2008 Indian River Lagoon Bottlenose Dolphin Bottlenose dolphin Atlantic Ocean, Indian River Lagoon, Florida 48 May 2, 2008, to September 4, 2008 Undetermined
45 2008 Mid-Atlantic Small Cetacean Short-beaked common dolphinAtlantic white-sided dolphin Atlantic Ocean, New Jersey to North Carolina 35

January 1, 2008,


April 26, 2008

44 2008 Texas Bottlenose Dolphin Bottlenose dolphin Gulf of Mexico, Texas 113 February 1, 2008, to March 31, 2008 Undetermined
43 2007 Northwest Guadalupe Fur Seal Guadalupe fur seal Pacific Ocean, Oregon, Washington 29 June 20, 2007, to March 31, 2008 Undetermined
42 2007 California Blue Whale Blue whale Pacific Ocean, California 6 September 8, 2007, to November 29, 2007 Human Interaction
41 2007 Southwest Florida Manatee Manatee Gulf of Mexico, Southwest Florida 54 March 7, 2007, to April 28, 2007 Biotoxin
40 2007 California Cetacean Short-beaked common dolphin, harbor porpoiseminke whale, sperm whale Pacific Ocean, California 91 February 10, 2007, to September 30, 2007 Undetermined
39 2007 Texas to Louisiana Bottlenose Dolphin Bottlenose dolphin

Gulf of Mexico, Texas, and Louisiana

65 February 27. 2007 to July 26, 2007 Undetermined
38 2006 Everglade Manatee Manatee

Gulf of Mexico, Everglades, Florida

24 November 9, 2006, to December 31, 2006 Biotoxin
37 2006 Northwest Harbor Porpoise Harbor porpoise Pacific Ocean, Pacific Northwest 114 January 11, 2006, to December 20, 2007 Undetermined
36 2006 Northeast Pinniped Gray, harbor, harp, and hooded seal Atlantic Ocean, Maine to Virginia ~800 April 20, 2006, to October 31, 2007 Infectious Disease
35 2005-2006 Northeast Large Whale Humpback whale Atlantic Ocean, Maine to Virginia 48 January 1, 2006, to December 31, 2007 Undetermined
34 2006 Alaska Sea Otter Sea otter Pacific Ocean, Alaska ~491 January 1, 2004, to October 1, 2012 Undetermined
33 2005-2006 Florida Panhandle Bottlenose Dolphin Bottlenose dolphin Gulf of Mexico Panhandle, Florida ~93 September 19, 2005, to April 30, 2006 Biotoxin
32 2005 Northeast Large Whale Minke, humpback, and fin, and sperm whale Atlantic Ocean, Canada to Maryland 34 July 1, 2005, to November 7, 2005 Undetermined
31 2005 North Carolina Harbor Porpoise Harbor porpoise Atlantic Ocean, North Carolina 43 February 12, 2005, to May 8, 2005 Undetermined
30 2005 West Florida Multi-Species Bottlenose dolphin, manatee Gulf of Mexico, Florida ~190 dolphins; ~92 manatees; ~38 manatees

July 1, 2005, and Nov 30,  2006;

March 4, 2005, to December 31, 2005; July 17, 2006, to December 31, 2006

29 2004 Virginia Small Cetacean Bottlenose dolphin, harbor porpoiseAtlantic white-sided dolphin, short-beaked common dolphin, Risso’s dolphin, short- and long-finned pilot whale, minke whale Atlantic Ocean, Virginia ~52 May 1, 2004, to July 12, 2004 Undetermined
28 2004 Mid-Atlantic Small Cetacean Bottlenose dolphin, short-beaked common dolphin, Risso's dolphin, pygmy sperm whaleshort-finned pilot whale, dwarf sperm whale, minke whale,  Atlantic white-sided dolphin, Atlantic spotted dolphin, pantropical spotted dolphin, Clymene dolphin, Sowerby’s beaked whale, Gervais’ beaked whale, fin whale Atlantic Ocean, New Jersey, Maryland, North Carolina, South Carolina, Georgia ~37 July 1, 2004, to December 31, 2004 Undetermined
27 2004 Florida Panhandle Bottlenose Dolphin Bottlenose dolphin Gulf of Mexico, Panhandle, Florida 107

March 10, 2004, to April 13, 2004

26 2003-2004 Northeast Minke Whale and Harbor Seal Minke whaleharbor seal Atlantic Ocean, Maine ~22 minke whales; ~42 harbor seals May 1, 2003, to  November 30, 2003 Undetermined
25 2003 Florida Manatee Manatee Gulf of Mexico, Florida ~96 March 2 to September 3, 2003 Biotoxin
24 2003 Gulf of Maine Large Whale Humpback whalefin whale, minke whale, long-finned pilot whale Atlantic Ocean, Gulf of Maine, Canada to Massachusetts 21 June 17, 2003, to September 1, 2003 Undetermined
23 2003 California Sea Otter Sea otter Pacific Ocean, California ~69 January 1, 2003, to October 1, 2003 Ecological Factors
22 2002 Florida Manatee Manatee Gulf of Mexico, Florida 34 March 10, 2002, to April 8, 2002 Biotoxin
21 2002 California Multi-Species California sea lion, short-beaked common dolphin, sea otter Pacific Ocean, California ~500 January 1, 2002, to December 31, 2002 Biotoxin
20 2001 Hawaiian Monk Seal Hawaiian monk seal Pacific Ocean, Northwest Hawaiian Islands ~11 March 24, 2001, to February 5, 2002 Ecological Factors
19 2001 Florida Indian River Lagoon Bottlenose Dolphin Bottlenose dolphin Atlantic Ocean, Indian River Lagoon, Florida ~30 May 1, 2001, to October 31, 2001 Undetermined
18 2000 Harbor Seal Harbor seal Pacific Ocean, California ~26 Not Available Infectious Disease
17 2000 California Sea Lion California sea lion Pacific Ocean, California 184 June 23, 2000, to December 1, 2000 Biotoxin
16 1999-2001 Pacific Gray Whale Gray whale Pacific Ocean, California, Oregon, Washington ~651 January 1, 1999, to December 31, 2000 Undetermined
15 1999-2000 Bottlenose Dolphin Bottlenose dolphin Gulf of Mexico, Panhandle, Florida 115 August 5, 1999, to May 20, 2000 Biotoxin
14 1998 California Sea Lion California sea lion Pacific Ocean, California 70 May 15, 1998, to June 19, 1998 Biotoxin
13 1997 Harbor Seal Harbor seal Pacific Ocean, California ~90 Not Available Infectious Disease
12 1996 Bottlenose Dolphin Bottlenose dolphin Gulf of Mexico, Mississippi ~30 Not Available Undetermined
11 1996 Florida Manatee Manatee Gulf of Mexico, Florida 149 March 5, 1996, to April 27, 1996 Biotoxin
10 1996 Right Whale North Atlantic right whale Atlantic Ocean, Georgia, Florida ~6 Not Available Human Interaction
9 1994 Texas Bottlenose Dolphin Bottlenose dolphin Gulf of Mexico, Texas ~72 (57) December 1, 1993, to April 30, 1994 Infectious Disease
8 1994 California Common Dolphin Short-beaked common dolphin Pacific Ocean, California ~53 Not Available Undetermined
7 1993 Pinniped California and Steller sea lion, harbor seal Pacific Ocean, Washington ~53 Not Available Human Interaction
6 1992-1993 California Sea Lion California sea lion Pacific Ocean, California ~1000 January 1, 1992, to December 31, 1992 Ecological Factors
5 1992 Texas Bottlenose Dolphin Bottlenose dolphin Gulf of Mexico, Texas 220 January 1, 1992, to May 31, 1992 Undetermined
4 1992 Northeast Pinniped Gray and harbor seal Atlantic Ocean, Maine to Massachusetts ~24 September 1, 1991, to April 30, 1992 Undetermined (suspect Infectious Disease)
1991 Bottlenose Dolphin Bottlenose dolphin Gulf of Mexico, Sarasota, Florida 30 Not Available Undetermined
2 1991 California Sea Lion California sea lion Pacific Ocean, California ~160 September 1, 1991, to December 31, 1991 Infectious Disease
1 1991 Northeast Pinniped Harbor seal Atlantic Ocean, New Jersey ~34 Not Available Undetermined



October 2011-Under the Marine Mammal Protection Act of 1972 (as amended), an Unusual Mortality Event (UME) has been declared for cetaceans (whales and dolphins) in the northern Gulf of Mexico (Texas/Louisiana border through Franklin County, FL) from February 2010 through the present.

Note: These numbers are preliminary and may be subject to change. As of November 13, 2011, the UME involves 594 Cetacean "strandings" in the Northern Gulf of Mexico (5% stranded alive and 95% stranded dead). Of these:

All stranded cetaceans (dolphins and whales) from Franklin County, FL to the Texas/ Louisiana border.
NOTE: Historical data from 2002-2009 excludes 2 previous UMEs in the panhandle of Florida (March-April, 2004 and Sept. 2005-April 2006). Historical data from 2008 through present are unvalidated and numbers may be subject to change as more information becomes available. Data include any strandings reported on or before November 13, 2011 and include 6 cases that were incidental scientific data collection takes and 1 take incidental to trawl relocation for a dredging project. Data from 2010 and 2011 are considered preliminary and may be subject to change as more information becomes available.

2008 Texas Bottlenose Dolphin (Tursiops truncatus) Unusual Mortality Event

An increased number of bottlenose dolphins (Tursiops truncatus) stranded along the Texas coastline in February and March of 2008. The February strandings were spread out along the entire Texas coast, although Brazoria, Galveston and Nueces counties saw the most increase. On March 3rd, 21 dolphins washed ashore in Galveston and Jefferson counties in late stages of decomposition. Most animals showed evidence of severe scavenging from shark bites with only a partial carcass present. The dolphin strandings continued to occur in high numbers throughout March 2008.

The high numbers of strandings in March were limited to Matagorda, Brazoria, Galveston, and Jefferson counties with very few strandings (5 total) occurring along other areas of the Texas coastline. The total number of strandings recovered by the Texas Marine Mammal Stranding Network (TMMSN) in March was 78. In April, bottlenose dolphin strandings have decreased significantly with the total of 119 from February 1.

2008 Mid-Atlantic Small Cetacean Unusual Mortality Event 

An increasing number of small cetaceans have stranded along the Mid-Atlantic. An elevated number of common dolphin, Delphinus delphis (27), and Atlantic white-sided dolphin, Lagenorhynchus acutus (5), mortalities occurred from New Jersey to North Carolina from January 1 to April 15, 2008. The 24 of the 32 strandings were in February and March, with 17 occurring in Virginia. Several animals have stranded on the Outer Banks, NC where access is difficult or limited. Approximately one-third of the animals have stranded alive and most of the remaining animals have been fresh dead to moderately decomposed.

Washington Post  Friday, April 28, 2006-Washington -- Federal marine specialists have concluded that Navy sonar was the most likely cause of the unusual stranding of melon-headed whales in a Hawaiian bay in 2004.

melon-headed whale

Image Credit:FAO Fisheries Global Information System

The appearance of as many as 200 of the normally deep-diving whales in Hanalei Bay in Kauai occurred while a major American-Japanese sonar training exercise was taking place at the nearby Pacific Missile Range Facility.

The report is the latest in a series of scientific reviews linking traditional mid-frequency naval sonar to whale strandings. The sonar has been used for decades, but it was only recently the apparent connection to strandings was established.

While the National Oceanic and Atmospheric Administration scientists said they could not definitely state that sonar caused the strandings, they said extensive study led them to the conclusion that there was no other likely cause.

The Navy says it was virtually impossible for its sonar to have led to the Hanalei Bay stranding.

The Navy is planning another major sonar testing maneuver in the same area in July and -- for the first time -- NOAA has formally asked the Navy to use expanded measures to protect whales from the possible effects of its sonar.

The active sonar used by navies around the world sends out loud pings of sound that appear to frighten and disorient whales, especially deep-diving species like melon-headed whales. 

Dolphins stranded on day of sub mission 


Tue, Mar. 08, 2005 A nuclear-powered submarine used two different types of active sonar to navigate over several days as it trained off the Florida Keys last week, including the day of a massive dolphin stranding in Marathon, the U.S. Navy said late Monday.

At the time, the submarine was approximately 39 nautical miles southwest of Marathon, where about 80 rough-toothed dolphins -- nearly 30 of which have since died -- beached suddenly late Wednesday.

The submarine, the Connecticut-based USS Philadelphia, was in the Keys for about 10 days, the Navy said.

USS Philadelphia (SSN 690)

A Navy spokeswoman said it was premature to speculate on the cause of the strandings and whether the incident had anything to do with sonar use. Necropsies and tests are underway on the dead animals by fisheries biologists from the National Oceanic and Atmospheric Administration. That process could take months to complete.

''The cause is not known and I cannot speculate, but every effort will be taken between federal agencies to determine what might have caused the stranding,'' said Lt. Cmdr. Jensin Sommer, spokeswoman for Naval Submarine Forces, based in Virginia.

Some scientific reports say there is evidence that marine mammals may have a particular sensitivity to active sonar. The technology allows subs and ships to spot targets and other vessels by emitting sound waves that bounce off objects, revealing distance and location.

Marine mammals rely on sound for just about everything, from feeding to finding a mate to communicating, which different animals do at different frequencies.

Dolphin and whale strandings, however, are not unusual in Florida and can stem from a variety of circumstances, from a sick dolphin leading a pod onto shore to harmful algae blooms.


After it surfaced last Monday, the Philadelphia used mid-frequency active sonar on its bow in reduced visibility to ''provide for the submarine's ability to avoid potential contact with other vessels at sea'' for a period of 21 minutes, Sommer said.

On three other days, Feb. 27, March 1 and March 2 -- the day the normally deep-water dolphins mysteriously beached on offshore flats -- the sub used high-frequency active sonar mounted on its sail while it was submerged to help it ''avoid other ships'' before it came to the surface, Sommer said. She did not know how long the high-frequency sonar was used, but said it was ''short duration'' and of low intensity.

High-frequency sonar is considered to have a shorter range than medium frequency or low frequency. Factors like water temperature and salinity can also affect how far the sound travels.

After a whale stranding in 2000 in the Bahamas, the Navy acknowledged in a report the existence of some marine mammal sensitivity to sonars, but has also argued at times that the extent of any cause-and-effect is scientifically vague.

The Natural Resources Defense Council, an environmental group, successfully sued the military in 2002 to limit use of new, low-frequency sonar believed by some to be particularly damaging because of its ability to travel extremely long distances. Some types of sonar can be extremely loud -- as much as 235 decibels at close quarters, equivalent to the noise made by a Saturn V rocket on takeoff -- according to the council.

''It's too early to draw a conclusion, but the Navy's use of active sonar near the stranding site heightens our concern that sonar played a role in harming these animals. We already know that exposure to high-intensity sonar can kill marine mammals. A full transparent investigation is needed to get to the bottom of it,'' said Joel Reynolds, director of the council's Marine Mammal Protection Project.


Within the past two months, at least 35 whales of three species stranded off the Outer Banks of North Carolina. The stranding coincided with Navy sonar exercises in the area, though a final cause of death for the animals hasn't been determined.

In recent years, military sonar use has also been alleged as a factor in the strandings of porpoises off the coast of Washington state, and of melon-headed whales off the coast of Hawaii, while other potentially sonar-related strandings have occurred in Greece and the Canary Islands.

The International Whaling Commission last year issued a report supporting a link between active sonar use and whale deaths.

Some researchers believe that sonars may disorient or scare marine mammals, causing them to surface too quickly and creating the equivalent of what divers know as the bends -- when nitrogen is formed in tissue by sudden decompression, leading to hemorrhaging.


In South Florida, biologists are hoping that necropsies of the dolphins who died after the stranding may shed some light on what prompted the incident. One key clue may be the condition of the animals' acoustic tissue, a potential indicator of sonar damage.

''As with every marine mammal stranding, we are conducting a thorough investigation,'' said Laura Engleby, a biologist for NOAA Fisheries, which coordinated a massive response to the stranding last week and is now spearheading efforts to determine its cause.

``It's way too early for us to know what caused this, and our scientists are collecting as much data as possible.''

Eleven dead animals were examined and their tissue sampled over the weekend, with more scheduled for necropsy later this week.

At least 20 of the dolphins managed to make it out to sea within a day of the incident.

But at least 28 in poor condition or pain were subsequently euthanized or perished on their own.

Researchers and volunteers are still trying to nurse back to health 26 rough-toothed dolphins that survived after being moved to several South Florida dolphin rehab centers.


Report: Sonar likely affected Puget Sound orcas

Thursday, March 17, 2005 SEATTLE, Washington (AP) -- Sonar pulsing from a Navy guided-missile destroyer during training exercises near the San Juan Islands two years ago was likely loud enough to send killer whales fleeing, according to a government agency report.

The National Marine Fisheries Service (NMFS) report backed up local experts who said sonar from the USS Shoup caused a group of orcas to behave abnormally, apparently trying to avoid the sound.


It contradicts the Navy's previous findings that orcas in Puget Sound's J Pod seemed unaffected by the sonar coming from the Shoup on May 5, 2003.

The 10-page report, dated January 21 but not released publicly until March 10, said the Shoup's sonar was not loud enough to cause the whales any temporary or permanent hearing damage.


Image Credit:FAO Fisheries Global Information System

Cmdr. Karen Sellers, the Navy's spokeswoman for the Northwest, acknowledged the Shoup's sonar signals were the "dominant noise event" experienced by the orcas that day. She said the Navy maintains the "biological significance" was minimal, The (Bremerton) Sun newspaper reported Wednesday.

Ken Balcomb of the Center for Whale Research in Friday Harbor said whether the whales suffered hearing loss is beside the point.

"They are trying to get away, and they are stranding and dying. It is irrelevant whether they had hearing loss if they are dead," Balcomb said.

Marine mammal researchers have also expressed concern about 15 harbor porpoises found dead in northern Puget Sound in the spring of 2003. Sellers said the Navy stands by its conclusions those deaths were not related to sonar.

The NMFS report said scientists found no signs the porpoises' ears suffered any acoustical trauma, although decomposition hindered researchers' analysis.

Puget Sound's orca population has been proposed for listing under the federal Endangered Species Act.

NATO blamed for dead whales

Ted Harrison
Saturday September 28, 2002

 The Guardian

The Canary Islands authorities have asked Nato to halt a naval exercise in the area, fearing it may be responsible for the death of 17 whales washed up on the coast of Fuerteventura and Lanzarote this week.

The heads of six Cuvier's beaked whales have been taken to the veterinary department of Las Palmas University for examination, in particular to discover if their inner ears were damaged by pressure from sonar devices.

Cuvier's beaked whale

Image credit: Garth Mix, GMIX Designs

The exercise Neo Tapon 2002, organised by the Spanish navy and involving about 30 Nato ships and submarines, is being held in the Atlantic between the Canaries and Gibraltar.

They include the US frigate De Wert, which specialises in anti-submarine warfare.


Two months ago a new sonar system, Surtass LFA, was authorized for US naval use, despite fierce lobbying by conservationists who claimed that sonar had been responsible for the mass death of whales in the Mediterranean and off the Bahamas.

The US government gave the navy a five-year exemption from the Marine Mammal Protection Act after tests led to the conclusion that the system was unlikely to injure marine mammals.

One of the independent marine biologists conducting the tests, Dr Kurt Fristrup, said: "If the stranding is tightly correlated in time and space to the Nato exercise, this will be another clear indication of an environmental issue that must be studied."

A Greenpeace spokesman in the Canaries said the link was clear, but a Nato spokesman said that by the time the whales were found dead the ships involved were 500 miles to the north-east.

The Surtass LFA system can transmit signals as powerful as 215 decibels and the US navy says its use is vital in helping to detect super-quiet submarines. Some scientists believe that a whale's eardrums can explode at 180 decibels.

Beaked whales which were studied after the Bahamas incident in March 2000, when eight died, were found to be bleeding from the ears, and there was evidence of damage consistent with an intense pressure injury.

Whales Die in Beaching Incident in The Bahamas

March 22,2000-Fourteen whales beached and eight of them died soon after the U.S. Navy conducted anti-submarine exercises off the northern Bahamas.

Children trying to help a beached whale


Navy Cmdr. Greg Smith said the tests took place from about 1 p.m. to 5 p.m. March 15 off Abaco Island — part of a series of exercises testing ``sonar buoys'' that were to continue through March 22.

Navy P3 Orion Aircraft


Marine biologist Ken Balcomb of the Earthwatch environmental group said beachings began that same day, and within two days at least 14 whales had grounded themselves on Abaco, Grand Bahama to the north, and Eleuthera to the south. Eight died, prompting investigations by Bahamian and U.S. scientists and authorities.


``A whale beaching in the Bahamas is a once-in-a-decade occurrence,'' said Balcomb, an American who has been studying whales around Abaco island for nine years.

``We will be making recommendations to the Bahamian government that these sort of exercises be terminated,'' he said. ``The fact that it coincides with the military exercises cannot be just coincidental.''

But the Navy spokesman said there was no evidence linking the two events. ``My understanding of the actual locations would put the island between the operations where the `sonobuoys' were located and where the whales eventually beached themselves,'' said Smith.

Balcomb said the mammals included several deep-water beaked whales, goose beaked whales measuring 16-19 feet, dense beaked whales measuring 10-13 feet, baleen whales measuring up to 27 feet and some small minke whales.

Smith said the exercise was testing for upgrades of what the Navy calls the Directional Command Activated Sonobuoy System.

The exercise involved a Navy P-3 aircraft dropping two buoys north of Abaco, one as close as 35 miles to the island, the other 70 to 75 miles from the island. One buoy emitted a sonar signal which was received by the other, and a submarine was moving between the two buoys.

Marine scientists have been expressing growing concern in recent years about the possible effects of man-made noises on marine mammals who rely on their hearing perhaps more than their sight.

The mass stranding occurred less than a week after two other whales washed ashore in a different part of the Bahamas during a period of "live fire" naval exercises in that region.

A Navy spokesman in Virginia said yesterday that the Navy had followed all standard procedures to protect wildlife in the area and had concluded there was no connection between the exercises and the strandings.


U.S. Navy Tests On Whales

HONOLULU 3/4/98 - The U.S. Navy began aiming piercing blasts of underwater sound at humpback whales Wednesday, testing a new sonar submarine detection system that environmentalists say could harm the endangered marine mammals.

The tests, designed to see how the whales react when bombarded by deafening noise, were cleared to begin after a federal judge in Honolulu Tuesday refused a request by environmental groups to stop them.

humpback whale


"A week from today we're going to go back to ask for an injunction," said Paul Achitoff, the Earthjustice Legal Defense Fund lawyer who filed the failed request for a restraining order.

Sonar simulation


"We will go back to this same judge and try to persuade her that she misunderstood the situation."

The Low Frequency Active (LFA) sonar tests, being run for the Navy's Space and Naval Warfare Systems Command, will use huge transmitters towed behind ships to pump sound into waters just a few miles from the new Hawaiian Islands Humpback Whale National Marine Sanctuary.

The tests are part of a project to develop a new long-range sonar system to detect "quiet" submarines by flooding the oceans with soundwaves.

Environmental groups, including Greenpeace and the Animal Welfare Institute, have described the noise as "a thousand times louder than a 747 jet engine" and say it could harm the whales in their favorite breeding habitat.

"They really have no idea how this is going to effect the whales, let alone other marine life," Achitoff said. "It is really a question of looking for a pain threshold."

Navy scientists acknowledge that LFA will use sounds of up to 215 decibels to see how loud a sound must be before it causes a "behavioral change" in the whales.

But they say the test will not harm the humpbacks, and will help the Navy avoid disturbing marine life in future by obtaining data on what exactly the whales can and cannot tolerate.

Similar tests have already been conducted on whale populations off the California coast without any noticeable adverse effect, navy scientists say.


LONDON, March 4 1998 - NATO tests of an underwater sonar system could have caused a mass stranding of whales off the coast of Greece, scientists said today.
Twelve Cuvier beaked whales, a deep diving breed that is rarely stranded, washed up on the west coast of Greece in May 1996 just days after the North Atlantic Treaty Organisation tested a Low Frequency Active Sonar (LFAS) system used to detect diesel and nuclear submarines.
Alexandros Frantzis, and colleagues at the University of Athens, think the two events are more than just a coincidence.
"We know that LFAS was used in the Kyparissiakos Gulf. We also know that no other LFAS or mass strandings have occurred in the Greek Ionian (Mediterranean) Sea since 1981," he said in a letter to the scientific journal Nature.
"Taking the past 16.5 year period into account, the probability of a mass stranding occurring for other reasons during the period of the LFAS tests is less than 0.07 per cent."
The LFAS generates very loud, low-frequency sound which enables long detection ranges. Although its effect on whales has not been studied thoroughly, many specialists think that at high levels it could physically damage the whales and affect their behavior.
Mass strandings of the creatures are extremely rare. Since 1963 there have been only seven cases worldwide of four or more whales and three of them occurred near the Canary Islands during similar military maneuvres.
The latest stranding was also odd because the animals were not stranded together, but over a 40 kilometre area. Deep diving whales also seem especially affected by low-frequency sounds, even at low levels.
Frantzis said that more information is needed to solve the mystery, but unfortunately most of the data about the use of LFAS are a military secret.


Press Release


Press Release


The Director of NATO’s SACLANT Undersea Research Centre (SACLANTCEN) announced the public release of the findings of two panels, which convened in June 1998, relating to protection of the marine environment. A Bioacoustic Panel was formed to make assessments and provide advice and recommendations on an incident of whale strandings in Kyparissiakos Gulf (Greece) in May 1996. A second panel met to evaluate SACLANTCEN environmental policy and mitigation procedures and suggest improvements.

Information was received in the fall of 1997 that a stranding of Cuvier’s Beaked Whales occurred (in May 1996) in the same general time and area in which NATO sonar research was being conducted. Based on that awareness, NATO scientists began to reexamine the acoustic data collected during that time. The issue received public attention in March 1998, when correspondence on this matter was published in the journal Nature.

The NATO Supreme Allied Commander, Atlantic established guidelines for two panels to investigate the stranding incident and to review NATO procedures for protection of the marine environment. It was requested that the NATO Nations nominate national experts in various disciplines to sit on the two panels. The two panels were tasked to write reports to be reviewed for public release.

The Bioacoustics panel met in mid-June 1998 to investigate circumstances surrounding the stranding of Cuvier's Beaked whales (Ziphius cavirostris) on the Greek Coast in Kyparissiakos Gulf in May of 1996. The NATO Research Vessel Alliance had been conducting sonar testing in Kyparissiakos Gulf at the time of the strandings. The following summary of findings regarding possible causes and panel recommendations are quoted from the panel report. Bioacoustics Panel Summary of Findings

Acoustic and behavioural

An acoustic link can neither be clearly established nor eliminated as a direct or indirect cause for the May 1996 strandings.

Behavioural responses to acoustic transmission must be taken into consideration as a possible cause for strandings: therefore, acoustic characteristics that induce behavioural changes or physical damage to marine animals should be determined.

The effects of sound on marine mammals vary according to species; therefore, additional research is needed to determine hearing characteristics and behaviour of the entire range of marine species.

Biological and Chemical Agents

Because of the lack of a comprehensive necropsy and complete tissue analyses, the possibility of a pathological cause for the strandings cannot be eliminated.

Environmental Factors

Based on reasonably comprehensive data, no physical environmental factor was found to be a causative agent for the strandings.

Biacoustics Panel Recommendations

With regard to high intensity acoustic sources, there was a strong recommendation from the panel that appropriate environmental assessment procedures be implemented as soon as possible with a view to recommending suitable mitigation and monitoring protocols.

The panel also noted the lack of adequate anatomical data on the stranded animals, particularly auditory and other tissue analyses, was a serious obstacle. It is acknowledged that an exceptional effort was made by the Hellenic Cetacean Research and Conservation Society, considering the resources available; however the panel recommended that proper specimen collection be supported to ensure complete necropsy in the future.

The Environmental Policy and Mitigation Procedures Panel met in June 1998 at the SACLANT Undersea Research Centre in La Spezia, Italy, to review and provide expert opinion on a draft policy by the Centre for protection of the marine environment. The panel reviewed procedures for the use of active sonar and methods of monitoring and mitigating procedures used during active sonar trials. The panel consisted of sonar, marine mammal and environmental policy experts nominated by NATO nations. Based on available knowledge and the results of the Bioacoustics panel, the Policy Panel gave valuable guidance to SACLANTCEN on the further development of its policy to conduct sonar research. The results of this review have resulted in the production of SACLANTCEN Human Diver and Marine Mammal Environmental Policy and SACLANTCEN Human Diver and Marine Mammal Risk Mitigation Rules.

This policy and summary of the panel proceedings may be found at the SACLANT Undersea Research Centre's web site on the World Wide Web, at  http://www.saclantc.nato.int/whales/, published in Adobe Acrobat format. For further information on the SACLANT Undersea Research Centre, see . For further information on the Supreme Allied Commander, Atlantic, see . Further inquiries should be directed to the Public Information Office at the Headquarters of the Supreme Allied Commander, Atlantic, in Norfolk, Virginia, USA .