Unlike most Mysticete species, Grey Whales are primarily bottom feeders and are thus restricted to shallow continental shelf waters for feeding. They are largely coastal although they do feed at greater distances from shore on the shallow flats of the Bering and Chukchi seas.

Grey Whales feed primarily on swarming mysids, tube-dwelling amphipods, and polychaete tube worms in the northern parts of their range, but are also known to take red crabs, baitfish, and other food (crab larvae, mobile amphipods, herring eggs and larvae, cephalopods, and megalops) opportunistically or off the main feeding grounds.

Most groups are small, often with no more than three individuals, but Grey Whales do sometimes migrate in pods of up to 16, and larger aggregations are common on the feeding and breeding grounds.

The Grey Whale was once found in the North Atlantic. Sub-fossil remains, the most recent dated at around 1675, have been found on the eastern seaboard of North America from Florida to New Jersey, and on the coasts of the English Channel and the North and Baltic seas (Mead and Mitchell 1984). Sub-fossil remains from Gibraltar and the Mediterranean Sea dating to Roman times have also been reported, demonstrating that the historical range of Grey Whales previously extended into the entrance of the Mediterranean Sea (Rodrigues et al. 2018). There are historical accounts of living Grey Whales from Iceland in the early 1600s and possibly off New England in the early 1700s (Rice 1998).

More recently, three extraordinary sightings occurred in the Atlantic Ocean and in the Mediterranean, well outside their usual current extant range. First, a single Grey Whale was sighted off Israel in the Mediterranean Sea on 8 May 2010 and seen again 22 days later off Spain (Scheinin et al. 2011). No match was found with existing photo-identification catalogues and no sample is available for analysis. If these whales originated from the more abundant eastern North Pacific subpopulation, they could have travelled around 22,000–23,500 km (Scheinin et al. 2011).

In 2021, an unaccompanied 8 m calf was first sighted near Rabat, Morocco in early March, and was subsequently sighted several times within the Mediterranean Sea, first in Algeria, then Italy, France and last sighted in late May around the Spanish Balearic Islands in very poor body condition (ACCOBAMS 2021). No match was found with existing photo-identification catalogues. Samples were collected and genetic analyses are currently ongoing.

In the South Atlantic, in May–July 2013, a single male Grey Whale was seen off the coast of Namibia, the first sighting of the species in the Southern Hemisphere. Photo-identification showed that this animal did not match the 2010 individual from the Mediterranean Sea and genomics showed that the animal originated from the North Pacific Ocean, possibly from the endangered western North Pacific subpopulation (Hoelzel et al. 2021), thought to include only approximately 200 individuals (Reeves et al. 2005). This migration could amount from 18,000 to 27,000 km depending on its putative route.

Grey Whales are now only found in the North Pacific and adjacent waters of the Arctic Ocean (Swartz 2018). The eastern Pacific subpopulation makes extremely long annual migrations, ~15,000–25,000 km roundtrip, which might explain their capacity for extraordinary movements into the Atlantic Ocean in the last decades.

The Grey Whale is regionally extinct in Pan European waters, so there are no specific conservation measures for this species in the region. Vagrants are protected from deliberate disturbance, capture or killing under the EU Habitat Directive as all other cetacean species within EU27 waters. They are also protected by the ACCOBAMS agreement in the Mediterranean and Black Sea and the adjacent Atlantic area.

Grey Whales have been protected from commercial whaling by the International Whaling Commission since its establishment in 1946. Limited aboriginal subsistence whaling is permitted by the IWC for the eastern Grey Whale by native people of Chukotka (Russian Federation) and Washington State. Catch limits have been set since the 1970s on the basis of advice from its Scientific Committee and are currently set at ~140 whales/year.