Seal holding a fish in its mouth


Marine Mammals in the Gulf of Maine


Julien Delarue

Cruisers exploring the Gulf of Main have unique opportunities to observe seabirds and marine mammals in their natural environments. Below are a few suggestions to make your on-board wildlife viewing more rewarding and enjoyable.


The main tools necessary for watching birds and marine mammals are probably already aboard your boat. The same binoculars you use to spot the running lights on ships at night work well for watching seabirds while underway. Stabilized binoculars are best for both purposes in a chop, but as the waves increase the point arrives when the naked eye works just as well for fast moving seabirds, whales and dolphins. Ashore or at anchor you may wish for non-stabilized binoculars with better light gathering such as the birders favorite 8x42s.

A camera, stand-alone or as part of a phone or tablet, is usually part of every boat’s gear. A picture not only preserves the memory but helps to identify what you are seeing. Even a poor picture can be a great help when you consult an identification source. Pictures of some species of whales such North Atlantic right whales can be reported to research institutions and contribute to their conservation.

Many wildlife ID guides are available, now more sophisticated and easier to use than ever. Michael H. Tove’s excellent Guide to the Offshore Wildlife of the Northern Atlantic covers birds, and cetaceans (whales and dolphins), seals and turtles. It is out of print but still can be obtained online. [Editor's note: We've linked this book to Amazon, but it's also available elsewhere, and of course first check your local bookstore!] The Marine Animal Response Society’s website covers marine mammals and other large pelagic animals, such as sharks, sunfish and sea turtles that are frequently encountered off the Canadian Maritime provinces, most of which are also present in the Gulf of Maine. Another good website for ID tips and information on marine mammals and large pelagic animals is Whale SENSE.

Many birders and whale watchers now use phone apps for ID which have a number of advantages. (See Dorothy Wadlow's recommendations for bird-watching apps in her article about birdwatching on the coast of Maine.) For reporting whale sightings, Whale Alert (for iOS or Android) helps avoid ship strikes by actively tracking whale locations. See & ID Dolphins & Whales (for iOS only, it seems), a free app from NOAA, can be useful "to identify and learn about dolphins, whales, seals and manatees while also learning how [to] protect marine mammals by responsibly watching them in the wild."

Marine mammals most likely to be encountered in the Gulf of Maine

The following are some of the marine mammals you might want to look for during your Gulf of Maine cruising. The ID tips focus on what you would see from a boat. All photos are by Julien Delarue, Christian Ramp, or David Gaspard.



Fin Whales (55-75ft) are longer than many of our boats and tend to be associated with steep bathymetric features, such as the edges of basins or the edge of the continental shelf. Their lower jaws are asymmetrically colored, being white on the right side, and dark as the rest of their body on the left. They have a smooth dark back with the dorsal fin ¾ of the way from nose to tail. The blow is tall and columnar. They arch their backs when deep diving and flukes are rarely seen. They are usually seen alone or in pairs but can form groups of up 15-20 individuals. Less common inshore than other species, they may be most reliably sighted close to Stellwagen Bank and next to Grand Manan Island.

Humpback Whales (38-48ft), found in nearshore and offshore waters, have a hump just forward of the rounded dorsal fin and lumps on the snout. As they prepare to dive, they generally lift their tail out of the water, revealing white and black patterns on the ventral side of the flukes which are individually distinctive. This species is also known for its acrobatic aerial displays, including breaches (jumps out of the water) and slapping of the water surface with their long, white pectoral fins or their tails. As fin whales, the most reliable place to see them close to shore are inside Stellwagen Bank National Marine Sanctuary and next to Grand Manan Island.

Humpback tail breaching
Humpback fluke

Minke Whales (20-40ft) are the smallest of the common whales in the Gulf of Maine and the most frequently found near shore. They are easy to overlook because they have a low surfacing profile, do not show flukes on dives, have a generally invisible blow and are almost invariably found alone. The head and back are dark and smooth. Look for the white patch on the pectoral fins, very visible underwater and allowing you to keep track of the animal between surfacings.

North Atlantic Right Whales are best known to the public due to their highly endangered status. Only approximately 350 individuals remain in the North Atlantic. Their tendency to frequent coastal waters where human activities are concentrated puts them at risk of collisions with vessels and entanglements in fishing gear, their two primary causes of mortality. Although the Gulf of Maine and Bay of Fundy used to be important summer feeding grounds, these areas are now seldom used in summer since these whales shifted their foraging grounds to the southern Gulf of St Lawrence. As a result, they are less likely to be seen during the typical cruising months but cannot be ruled out completely, especially around Grand Manan Island. Every observation is valuable and boaters are encouraged to report their sightings to the New England Aquarium. North Atlantic right whales can be recognized by their V-shaped blow, lack of dorsal fin, dark bodies and the callosities on the top of their head.

Right whale fluke


Atlantic White-sided Dolphins are one of the few dolphin species commonly seen in the Gulf of Maine in summer months. They are active swimmers and often investigate boats but do not bow ride as often as other species. They have a relatively short snout. A diagnostic white area beneath the dorsal fin and a tan patch towards the tail are sometimes visible when they surface to breathe. They are generally found in groups and can engage in acrobatic jumps.

Short-beaked common dolphins are one of the most abundant dolphins in the Gulf of Maine. They are rare close to shore but can be seen on the banks and along the edges of basins doting the Gulf of Maine. They become surface active at the end of the day as they start foraging, moving fast in groups and leaping clear out of the water. They will invariably come check out your boat and bow-ride.

Harbor porpoises are the smallest cetaceans in the North Atlantic, reaching a maximum length of 1.5 m. They are common nearshore, including in bays and harbors where they forage on small fish. They are hard to spot in sea state higher than Beaufort 2 due to their small size, inconspicuous surfacing behavior and lack of visible blow. A short triangular dorsal fin on top of the light grey back is often all one will see of this relatively shy species.


Besides cetaceans, several species of pinnipeds can be regularly observed close to shore. Although harp and hooded seals can occasionally be observed on beaches lining the Gulf of Maine, they are known as ice seals and typically live in Arctic and subarctic waters. Their presence in the Gulf of Maine is therefore generally restricted to winter months.

Grey seals are about 7 feet long. Males can weight up to 800 pounds, while females weigh around 500 pounds. Grey seals are well-known for their distinctive horse-shaped head. As their name suggests, they tend to be silver in coloring with darker spots of gray or black. Males are generally darker than females. Grey Seals haul out in large groups on rocky or sandy beaches during the mating, pupping and molting seasons, which take place in winter and spring and are typically in areas removed from human influence. But they can be regularly observed along the coast of Maine in summer as they forage on fish and other prey. 

Harbor Seals can reach 6 feet long and weigh about 220 pounds. Their fur coloration ranges from light to dark grey to tan and usually includes spots or dark speckles. Harbor Seals can be found commonly in coastal areas, hauled out on beaches, reefs and other rocky outcrops. Their heads are smaller and snout shorter than those of grey seals.


Sunfish are not mammals but might be mistaken for one. These large fish are odd looking creatures, all head and no tail. They propel themselves by moving their dorsal and ventral fins laterally so the dorsal fin flaps from side to side at the surface unlike the rigid fins of cetaceans. Sunfish are most likely to be encountered on calm days when they come to the surface to bask in the sun. Sunfish (and basking shark) sightings can be reported to the New England Basking Shark & Ocean Sunfish Project.

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