New England Basking Shark and Ocean Sunfish Projects

New England Basking Shark and Ocean Sunfish Project Logo

The New England Basking Shark Project (NEBShark) and the New England Ocean Sunfish Project (NEOSunfish) are community-sighting networks for two coastal pelagic fish commonly sighted in the waters off New England.

NEBShark and NEOSunfish are working towards the collection of sighting data and photographic images to create a comprehensive database that can be used to learn more about the biology and ecology of these gentle giants. This database will help scientists better understand the population size, distribution, and movements of basking sharks and ocean sunfish in the waters of the Gulf of Maine. Sighting data is being provided by private individuals as well as government and non-government organizations. Much of the sighting information is provided by interested members of the general public through our community-sighting network.

Trained public volunteers report sightings of basking sharks and ocean sunfish that they observe from a boat or from a local beach. All sighting information is shared with other institutions to support research and conservation activities.

To learn more about NEBShark and NEOSunfish, click HERE.

NEBShark (New England Basking Shark Project)

Basking SharkThe basking shark, Cetorhinus maximus, is one of the largest fish in the world, second only in size to the whale shark. Individuals can reach lengths of 38 feet and weighs up to 8,500 pounds. Basking sharks feed on zooplankton, tiny organisms that drift with the ocean currents. The basking shark is listed as vulnerable under the International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species. Although it is not listed as threatened or endangered internationally, the basking shark it is considered endangered locally in Northeast Atlantic waters due to vulnerability to habitat destruction, entanglements in fishing gear, and vessel strikes.

The large, triangular first dorsal fin is often what alerts boaters and beach goers to the presence of a basking shark at the water’s surface.

The animal appears to be moving slowly and basking in the sunlight, giving this animal the common name “basking shark.” In reality, these sharks are typically hard at work filter feeding or traveling near the surface.

Basking sharks are one of the largest filter feeders that strain zooplankton from the water. Moving slowly with mouth wide agape, a basking shark acts like a giant plankton net allowing plankton-rich water to enter the mouth. As the water moves over the gills, bristle-like structures called gill rakers trap the zooplankton, effectively removing the food from seawater. The water then exits that body though a series of gill slits located on both sides of the head. Basking sharks prefer to feed on copepods, tiny shrimp-like crustaceans the size of a grain of rice, which is abundant throughout the Gulf of Maine waters.

Photo Identification Techniques

Basking sharks can be identified as individuals using distinctive patterns and scars, particularly on the fins. These features can be photographed to create a visual catalog of previously sighted or known individuals. These types of photo-ID techniques allow scientist and biologists to track individual basking sharks over time in an effort to learn more about their movements and degree of residency offshore.Basking Shark

And don’t forget to take photographs if possible.

CheckFirst dorsal fin: both sides
CheckCaudal fin - tail fin
CheckAny distinctive body markings: scars, cuts, pigmentations pattern, etc.

To learn more about NEBShark or to report a basking shark sighting, click HERE.

NEOSunfish (New England Ocean Sunfish Project)

SunfishIn our New England waters, the most commonly encountered ocean sunfish is the Mola mola. Photo courtesy of NECWA. also called the common mola. These large bony fish can be sighted in Cape Cod Bay and Massachusetts Bay in the summer months of July and August. Common molas are often observed lying on their sides at the water’s surface. They seem to be sunning themselves and this behavior has given them the common name of “sunfish”. Molas have been observed in both temperate and tropical waters. Yet their exact distribution and overall movements is not well understood.

Common Names: ocean sunfish, round tailed or common mola

The unusual swimming behavior of the common mola often alerts us to the presence of this animal at the water’s surface. As the fish lies on its side, the dorsal fin flops up and down causing a disturbance at the water's surface. This sculling motion can be used to help distinguish the common mola from the basking shark. The basking shark also has a large dorsal fin, but the fin is typically observed erect as it moves slowly along the water’s surface. Another view of a Mola mola. Photo courtesy of NECWA.Mola mola

The common mola has an unusual body shape as well as unique external features. The body is somewhat flat and rounded giving this fish the appearance of being “all head” and very little tail. This circular, thin body shape is the basis for the Family name, Molidae, which is derived from the Latin word for “millstone”. The skin is silver in coloration and has a slight sheen overall. Although not obvious from a distance, the skin is covered with copious amounts of mucus. The skin is also very thick and has a gritty texture when touched. The animal’s mouth is quite diminished in size and very rounded in appearance. The mouth is formed by the fusion of the animal’s 4 teeth and is used to capture gelatinous organisms, like jellyfish, ctenophores and Portuguese man-o-war. But don’t let this animal’s strange shape and unusual features fool you. Common molas are the heaviest bony fish in the world, reaching lengths of 6 to 10 feet and weights of 2 to 4 tons. However, little is known about their feeding habits and reproduction. Females have been reported to carry the most eggs of any vertebrate. These eggs are minute in size and when they hatch, produce a larvae that is quite comical in appearance. The larvae of the common mola have numerous spines projecting from many directions. As the larvae grow, their spines and the majority of their caudal while the tail fin slowly disappears. Finally, we begin to see a fish that more closely resembles the larger adults.

MolaMany people often refer to the common mola as the “ocean sunfish”. However, there are two other species of sunfish in the family Molidae including the sharp-tailed mola Masturus lanceolatus and the slender mola Ranzania laevis. Although neither species is commonly observed offshore, the sharp-tailed mola have been sighted on a number of occasions in the water’s off New England.

Sharp-tailed molas have have a similar appearance to that of the common mola. However, one obvious difference is that sharp-tailed molas have a projection on the tail fin, also called the caudal fin. This projection provides the basis for their common name. When you sight a mola offshore, it is best to photograph the caudal fin in order to verify which species of mola you have observed. The terminology used to distinguish between the three different species can be a bit confusing. In actuality, the words “ocean sunfish” can be applied to all three species of mola. Therefore, it is best to refer to the more commonly sighted Mola mola as the common mola, not the ocean sunfish. Ocean sunfish are not fished commercially in the waters of the United States. However, molas are eaten throughout Asia with Taiwan and Japan being the largest markets.

NECWA intern inspecting dead ocean sunfish that stranded on Cape Cod

Each year, a small number of common molas strand, typically dead, on New England beaches. Some animals have visible propellor scars indicating that they have been hit by boats. Others show signs of having been entangled in fishing gear. Other individuals were healthy animals that stranded in shallow tidal areas as the tide went out. A large number of strandings occur each fall and early winter, when ocean sunfish move into shallow tidal areas like harbors and bays. As the tide goes out, these sunfish will become trapped in shallow areas and strand. Later in the winter, any ocean sunfish still in our New England waters will become cold-stunned, a hypothermic response to prolonged cold water temperatures. NECWA staff and interns respond to both live and dead strandings so please call us at 508-566-0009 if you see an animal on the beach.

To learn more about NEOSunfish or to report an ocean sunfish sighting, click HERE.

NECWA staff helping to rescue a stranded, live ocean sunfish