Types of Dolphins in Massachusetts

1. What are the most common dolphins in Massachusetts?

The three species you are most likely to see are the bottlenose dolphin (Tursiops truncatus), Atlantic white-sided dolphin (Lagenorhynchus acutus), and short-beaked common dolphin (Delphinus delphis). Bottlenose dolphins are the most familiar, often seen near shore. Atlantic white-sided dolphins are more pelagic, with a distinctive yellow patch on their sides. Common dolphins have a striking hourglass pattern. Check ourdolphin species overviewfor more details.

2. How can you tell bottlenose dolphins from Atlantic white-sided dolphins?

Bottlenose dolphins have a useful body, short snout, and curved dorsal fin. Atlantic white-sided dolphins are slimmer, with a longer snout, a white belly, and a yellow patch behind the dorsal fin. The best field mark is the flank coloration: white-sides have a clear white stripe below the yellow patch. Bottlenose dolphins are uniformly gray. For a deeper comparison, visit ourMassachusetts dolphin identification guide.

3. Where and when are each type most likely to be seen?

Bottlenose dolphins are found year-round in coastal waters, especially around Cape Cod and Nantucket. Atlantic white-sided dolphins occur from May to October on the outer continental shelf, often near Stellwagen Bank. Common dolphins prefer deeper waters but can be seen on offshore trips from June to September. Start with aMassachusetts wildlife overviewto plan your trip.

4. What other dolphin species might be encountered?

Less common but possible sightings include Risso's dolphin (Grampus griseus), striped dolphin (Stenella coeruleoalba), and white-beaked dolphin (Lagenorhynchus albirostris). Risso's have a blunt head and heavy scarring. Striped dolphins have a thin dark stripe from eye to anus. White-beaked dolphins have a short white beak and pale saddle. These are more frequent on deeper, longer whale watch excursions.

See ourstate animal guidefor the next step.

5. How do you identify dolphins from a distance?

Look at fin shape, body size, and color patterns. Bottlenose have a tall, curved fin. Atlantic white-sided have a smaller, sickle-shaped fin. Common dolphins show a distinct hourglass pattern when they surface. Pay attention to bow riding behavior: all three species will approach boats. A pair of binoculars helps. For more tips, see ourwildlife viewing gearlist.

6. What is the best time of year for dolphin watching in Massachusetts?

Peak season runs from June through September when water temperatures are warmest and prey is abundant. Many whale watch companies operate daily trips. Early morning or late afternoon often yield calmer seas and more active dolphins. TheMassachusetts seasonal guidecan help you pick the right month.