[6][dubious – discuss] Vessel strikes and entanglement in fixed fishing gear, which together account for nearly half of all North Atlantic right whale mortality since 1970,[8] are their two greatest threats to recovery.

Other unique features include a large head, which makes up a quarter of its total body length, narrow tail stock in comparison to its wide fluke, and v-shaped blowhole which produces a heart-shaped blow.

[25] Right whales feed mainly on copepods and other small invertebrates such as krill, pteropods, and larval barnacles, generally by slowly skimming through patches of concentrated prey at or below the ocean surface.

Combined with the right whale's lack of speed through water, feeding habits, and coastal habitat, they were easy to catch, even for whalers equipped only with wooden boats and hand-held harpoons.

It had previously been assumed that Basque whaling in eastern Canada had been the primary cause for the depletion of the sub-population in the western North Atlantic, but later genetic studies disproved this.

[8] A 2001 forecast showed a declining population trend in the late 1990s, and indicated a high probability that North Atlantic right whales would go extinct within 200 years if the then-existing anthropogenic mortality rate was not curtailed.

[2] Additionally, it is possible that the official figures underestimate the actual ship-strike mortality rates, since whales struck in offshore areas may never be sighted due to low search effort.

[44] In 2006, the US National Oceanic and Atmospheric Administration (NOAA) established a set of recommended vessel routes to reduce ship strikes in four important eastern-US right whale habitats.

[48] It is believed that chronically entangled animals may in fact sink upon death due to loss of buoyancy from depleted blubber reserves, and therefore escape detection.

After disentangling the whale, scientists attached a satellite tracking tag, administered a dose of antibiotics to treat entanglement wounds and then another drug to reverse the sedation.

[58] In 2022, the Marine Stewardship Council revoked its certification for the commercial Gulf of Maine lobster fishery, citing risks of entanglement of North American right whales in lobster-fishing gear.

[59] A 2011 analysis of data collected in the Bay of Fundy has shown that exposure to low-frequency ship noise may be associated with chronic physiological stress in North Atlantic right whales.

Following the tragic events of September 11th, maritime activity in the Bay of Fundy, a crucial calving and nursing ground for right whales, experienced a marked reduction in both ship traffic and density.

The US Navy proposed plans to build a new undersea naval sonar training range immediately adjacent to northern right whale calving grounds in shallow waters off the Florida/Georgia border.

[64][65] Documented effects in the scientific literature include impacts on reproduction, range, prey access, interactions with human activities, and individual health condition.

Though zooplankton abundance began to rise again in 1999, right whales have such a long reproduction and migratory cycle that the population was greatly affected by the minimal food availability from the year before.

[66][73] This has meant whales are present in habitats and times of year that are not accounted for by existing regulations intended to protect them from threats such as vessel strikes and gear entanglements.

There are however two other hypotheses which claim, respectively, one super-population among the entire North Atlantic (with mixing of eastern and western migratory routes occurring at locations in relatively high latitudes such as in the Denmark Strait), and three sub-populations of eastern, western, and central Atlantic right whales (with the central stock ranging from Greenland's Cape Farewell in summer to the Azores, Bermuda, and Bahamas in winter,[79][80] although recent study indicates that the Azores had probably been a migratory corridor rather than a wintering ground).

There could be various areas along or off the west coasts where could have been frequented by whales potentially and might be re-colonized in the future such as Quoddy, Eastport,[101] Plymouth Harbor,[102] Sagamore Beach,[103] Island of Nantucket, Florida Bay, Pamlico Sound, Gulf of Mexico (as far as to Texas[104][105]), Bahamas, Long Island Sound and vicinity to New York City,[106][107] the mouth of Potomac River, Delaware and Chesapeake Bay, the mouth of Altamaha River,[108] Cape Canaveral, Sebastian Inlet and around Melbourne.

[120] Aerial and shipboard surveys are conducted annually to locate and record seasonal distribution of North Atlantic right whales along the northeast and southeast United States coast.

[121] The surveys have been used to produce seasonal maps showing the density of right whales (number of animals per square kilometer) throughout the U.S. east coast and Nova Scotia.

Phenology of catch records in the early twentieth century in Nordic countries shows that whale presences in northern waters was at peak in June.

Historical records suggest that summering grounds could have reached further north to northern coasts of Scandinavian Peninsula, and some might have turned up at the mouth of Hudson Bay.

Earlier known occurrences of right whales in the basin include the stranding of a juvenile near Taranto (southeastern Italy) in 1877 and the sighting of two (one of which was later captured) in the bay of Castiglione (Algiers) in 1888[143][144] and Portugal.

[166] Prior to this, no right whales had been killed or confirmed present off the coast of Greenland for around 200 years[167] except for the sighting of "1718", a unique animal seen only twice (off Cape Farewell in July 1987 and at the Nova Scotian Shelf in June 1989).

For southward migration, the sighting of two whales displaying courtship behaviors in the Bermuda was recorded by a team of researchers including Roger Payne in April, 1970.

[170] Since entanglement in floating gear accounted for 82% of documented right whale deaths in 2022,[171] the Canadian Wildlife Federation has been providing ropeless equipment to snow crab fishers in and around the Gulf of St Lawrence.

[172] This obligates member nations to strive towards strict protection of these animals, habitat conservation or restoration, mitigation of obstacles to migration, and control of other factors that might endanger them.

[175] The Atlantic area bounded on the west by a line running from Cape St. Vincent in southwest Portugal to Casablanca, Morocco, and on the east by the Strait of Gibraltar.

Onlookers lucky enough can spot them from shores time to time on whales' migration seasons especially for feeding (vicinity to Cape Cod such as at Race Point and Brier Island), and breeding/calving (off Georgia to Florida coasts) when whales strongly approach shores or enters rivers or estuaries such as at Outer Banks, Pamlico Sound, Indian River Inlet, Cape Lookout, Virginia Beach, Virginia, Golden Isles of Georgia, beaches on Florida (e.g. most notably at Flagler, Jacksonville, St. Augustine, Ponte Vedra, Satellite, Crescent, and Cocoa, and any others like Ormond, New Smyrna, South Melbourne, Wrightsville, Vero), Boynton, and so on.