Marine Mammal Strandings
March 1, 2012

It’s not that I don’t like winter. I like the part that involves tobogganing, hot chocolate, and curling up all cozy with a good book. Wind, bitter cold, and icy roads do not thrill me. But this winter doesn’t leave me with too much to complain about, with mild temps and a few trips to the winter beach where I could actually walk without being blown half way to Spain. However, for some of the marine animals of our region, this has been a very tough fall and winter, as there have been a great many strandings of dolphins and seals washing up on local beaches.

What exactly is a stranded marine mammal?  The Marine Mammal Protection Act defines it as:

•    Any dead marine mammal on the shore or in the water.
•    A live marine mammal on the shore, unable to return to the water.
•    A live marine mammal that is on shore, and in need of medical attention.
•    A live marine mammal in the water, unable to return to its natural habitat without assistance.

In New England, strandings often involve dolphins, porpoises, whales, and seals, but can also include marine reptile sea turtles, too. Strandings occur for a great variety of reasons, any time of year—some for simple reasons and some for more complex ones. Animals who are ill, with parasites or viruses for example, or those who are young, malnourished, or weakened may be found stranded on beaches or in shallow waters. Injured animals who have been harmed in a variety of manners—including injuries from man-made debris in the ocean, boat accidents, pollutants, and encounters with other animals—may also be found stranded. Rough weather, heavy seas, and unusual tides can affect animals by blurring their sense of direction and throwing them off-course, leaving them in low water. Dolphins, porpoises, and whales can get trapped in marshes, bays, and even rivers, without an effective option to swim back to deeper waters. Often the animals will panic in their confusion, become exhausted, and injure themselves further. Sometimes, too, strandings seem to just happen accidentally. Social animals, like dolphins, travelling in groups may follow the leader and run ashore together, while others may have separated from a larger group or have lived on their own; these individuals may simply get trapped in low water.

Spotting a stranded dolphin, porpoise, or whale is obvious, as they are either in very shallow water or exposed on dry land. Seals are a bit different, as they naturally haul-out, or come on shore, for long periods in order to rest, enjoy the warmth of the sun, molt, or care for their young. But when they are injured or ill, seals will often strand on beaches to expend less energy than they do in the water. It can be difficult for the untrained eye to tell if a seal is simply hauled-out or stranded. On the other hand, unless its nesting season, sea turtles only come ashore when they are very ill. Most turtles head for warmer waters when winter approaches, but the turtles that remain behind are often compromised by the cold. Turtles that are “cold-stunted” often die in the ocean; the ones that wash on-shore are at the mercy of rescuers.

So, based on all this information, it shouldn’t surprise us to know that strandings aren’t all that uncommon. But this year we have experienced mass strandings of dolphins on Cape Cod in record numbers. Mass strandings are defined as strandings involving more than three animals. Since January, there have been over 175 recorded dolphin strandings, and of that number, more than 100 have died. Marine wildlife experts are baffled as to the reasons for the strandings but say that there haven’t been strandings of this magnitude in the Northeast in the last 20 years. The number of strandings this year is about five times greater than average.

Seals have also been adversely affected this year. Over 160 sick and dead seals have been found along the coast of New England since last September. After much analysis of tissue and blood samples, it has been discovered that the reason for this “unusual mortality event” is due to a flu virus similar to one found in birds but never before seen in seals. While this most important information won’t save all of the seals, it is an important first step for researchers looking to find causes and cures.

Many times animals that are found stranded are either dead or very ill. Trained expert rescue teams assess the live stranded animals to see if they are healthy enough to be released back into deeper waters. If not, animals are often transported to marine facilities or aquariums that can offer specialized veterinary care and rehabilitation. Ultimately, however, animals that are too sick or injured are humanely euthanized. All stranded animals assessed are tagged and have blood samples taken to be analyzed in hopes of discovering reasons for the strandings. Studying marine mammals can be a bit trickier than studying some land mammals with easier access to populations. There is much to be learned about marine mammals and sea turtles, so continuing these efforts and sharing information are vital to learning about and protecting our precious wildlife.

Three things you can do to help:

1.    Read! There is lots of information out there about seals, dolphins, porpoises, and whales. Read about what makes them tick—what they look like, where they can be found, what they like to do. Having the knowledge of what is “normal” in appearance or behavior will also allow you to question when an animal may be in distress.

2.    NEVER APPROACH A STRANDED MARINE MAMMAL—Call the New England Aquarium’s Stranding Hotline: (617) 973.5247. It is illegal to approach, touch, or feed marine mammals, as they are protected under the Marine Mammal Protection Act. Also, they are wild animals under stress that can cause serious harm. Stay away, and call the experts. They will need your help in identifying the type of animal, specifically where it is, and how it may be behaving.  Watch from a distance and ask others—especially dogs—to keep away, too.

3.    Volunteer to help a Stranding Rescue Team. When you are old enough (usually 18) you can take a training course to be “on-call” to help with local strandings. Volunteers are usually in great demand. With the large number of strandings in our area this season, fresh volunteers were always needed to step in and help. It is hard work but very rewarding!

Read more:

Christian Science Monitor

Huffington Post


Mystic Aquarium

New England Aquarium