Gray whale

The gray whale (Eschrichtius robustus), also known as the grey whale, is a migratory baleen whale that undertakes annual journeys between its feeding and breeding grounds. This species typically attains a length of 14.9–15.2 meters (49–50 feet) and a weight ranging from 41 to 45 tonnes (45 to 50 short tons; 40 to 44 long tons), with a lifespan generally between 55 and 70 years; however, one female was estimated to have lived 75–80 years. As of 2024, a female first observed in 1977, estimated to be 53–55 years old, represents one of the longest-living gray whales currently known. Its common name derives from the distinctive gray patches and white mottling present on its dark skin. Historically, these whales were referred to as "devil fish" due to their aggressive defensive behavior when hunted. The gray whale is the sole extant species within the genus Eschrichtius and the only living genus in the family Eschrichtiidae, although some contemporary research reclassifies it as a member of the family Balaenopteridae. This mammal evolved from filter-feeding whales that emerged during the Neogene period.

The gray whale (Eschrichtius robustus), also known as the grey whale, is a baleen whale that migrates between feeding and breeding grounds yearly. It reaches a length of 14.9–15.2 m (49–50 ft), a weight of up to 41 to 45 tonnes (45 to 50 short tons; 40 to 44 long tons) and lives between 55 and 70 years, although one female was estimated to be 75–80 years of age. One of the longest-living Gray whales currently is a female, first sighted in 1977, and estimated to be 53–55 years old as of 2024. The common name of the whale comes from the gray patches and white mottling on its dark skin. Gray whales were once called devil fish because of their fighting behavior when hunted. The gray whale is the sole living species in the genus Eschrichtius. It is the sole living genus in the family Eschrichtiidae, however some recent studies classify it as a member of the family Balaenopteridae. This mammal is descended from filter-feeding whales that appeared during the Neogene.

Gray whales are currently found in two primary populations: a Northeast Pacific (North American) population and an endangered Northwest Pacific (Asian) population. North Atlantic populations were extirpated, likely due to whaling, from the European coast between the 12th and 14th centuries, and from the American and African Atlantic coasts around the late 17th to early 18th centuries. Nevertheless, rare sightings of gray whales have been reported in the North Atlantic, Mediterranean, and even off South Atlantic coasts during the 2010s and 2020s.

Taxonomy

The gray whale is conventionally categorized as the only extant species within its genus, Eschrichtius, and family, Eschrichtiidae. However, an extinct species, the Akishima whale (E. akishimaensis), was identified and assigned to the genus in 2017. While some recent studies position gray whales outside the rorqual clade, they are considered the closest relatives to rorquals. Conversely, other contemporary DNA analyses indicate that certain rorquals within the family Balaenopteridae, such as the humpback whale (Megaptera novaeangliae) and the fin whale (Balaenoptera physalus), share a closer phylogenetic relationship with the gray whale than with other rorquals, including minke whales. This revised classification has been adopted by the American Society of Mammalogists.

In 1865, John Edward Gray established a distinct genus for the gray whale, naming it in honor of the physician and zoologist Daniel Frederik Eschricht. The common name of the whale is attributed to its characteristic coloration. Gray utilized subfossil remains of now-extinct gray whales found along the Atlantic coasts of England and Sweden to formulate the initial scientific description of a species then believed to exist exclusively in Pacific waters. The living Pacific species was subsequently described by Cope in 1869 as Rhachianectes glaucus. By the 1930s, skeletal comparisons demonstrated the Pacific species' identity with the Atlantic remains, leading to the general acceptance of Gray's nomenclature. Although anatomical data cannot definitively prove the identity between historical Atlantic and contemporary Pacific populations, the gray whale's skeleton is uniquely distinctive and readily distinguishable from all other extant whale species.

Numerous other appellations have been historically applied to the gray whale, including desert whale, devilfish, gray back, mussel digger, and rip sack. The designation Eschrichtius gibbosus is occasionally encountered, its usage contingent upon the acceptance of a 1777 description by Erxleben.

Taxonomic history

Several 18th-century authors referred to the gray whale as Balaena gibbosa, or the "whale with six bosses," a description seemingly derived from a concise note by Dudley in 1725:

The Scrag Whale, closely related to the Fin-back, is distinguished by a ridge on the posterior part of its back, which features approximately six knobs or knuckles instead of a dorsal fin. It resembles the right whale in its overall form and oil production; its bone is white but does not split.

The gray whale was initially identified as a distinct species by Lilljeborg in 1861, based on a subfossil discovered in the brackish Baltic Sea. This specimen was believed to originate from the now-extinct North Atlantic population. Lilljeborg, however, classified it as "Balaenoptera robusta," a rorqual species. In 1864, Gray recognized that the specimen's rib and scapula differed from those of any known rorquals, leading him to establish a new genus, Eschrichtius. Subsequently, Van Beneden and Gervais in 1868 concluded that the bones described by Lilljeborg could not belong to a living species but resembled fossils Van Beneden had previously documented from Antwerp's harbor (most of his named species are now considered nomina dubia). Consequently, they named the gray whale Plesiocetus robustus, thereby rendering Lilljeborg's and Gray's classifications synonymous.

Charles Melville Scammon provided one of the earliest accounts of living Pacific gray whales. Despite his involvement in whaling activities that nearly led to their extinction in the lagoons of the Baja California Peninsula, his name remains closely linked to the species' description. During this period, the extinct Atlantic population was taxonomically distinguished as a separate species (Eschrischtius robustus) from the extant Pacific population (Rhachianectes glaucus).

Taxonomic classification became increasingly complex during the 19th century, as scientists frequently introduced new species, such as Eschrichtius pusillus, E. expansus, E. priscus, and E. mysticetoides, often relying on incomplete specimens. This led to taxonomists inconsistently and incorrectly interchanging various generic and specific names, including Agalephus gobbosus, Balaenoptera robustus, and Agalephus gibbosus. The situation was further complicated until the 1930s, when it was definitively established that the extinct Atlantic population and the extant Pacific population constituted a single species, leading to the proposal of the new combination Eschrichtius gibbosus.

Description

The gray whale exhibits a dark slate-gray coloration, adorned with distinctive gray-white patterns that are scars from parasites shed in its cold feeding grounds. Individual whales are commonly identified through photographic documentation of their dorsal surface, by matching these unique scars and patches, whether from detached or still-attached parasites. Possessing two blowholes atop its head, the gray whale can produce a characteristic heart-shaped blow at the surface during calm atmospheric conditions.

Gray whales range in length from 4.6–4.9 meters (15–16 feet) for newborns to 11–15.2 meters (36–50 feet) for adults, with females generally being marginally larger than adult males. Newborns display a darker gray to black hue. A mature gray whale can attain a weight of 40–45 tonnes (44–50 short tons), though the typical range is 15–33 tonnes (17–36 short tons), positioning them as the ninth largest cetacean species.

Distinguishing features of the gray whale from other mysticetes include its baleen, which is described as cream, off-white, or blond and is notably short, with the beard plate extending 5–40 cm (2.0–15.7 inches) in length. The upper jaw features small depressions, each containing a single stiff hair, discernible only upon close examination. Unlike related rorquals, its head's ventral surface lacks numerous prominent furrows, instead presenting two to five shallow furrows on the underside of its throat. The gray whale also lacks a dorsal fin, possessing instead 6 to 12 dorsal crenulations, or "knuckles," which are raised bumps along the midline of its posterior quarter, leading to the flukes; this formation is termed the dorsal ridge. The tail measures 3–4 meters (10–13 feet) across, is deeply notched centrally, and tapers to points at its edges. The gray whale's penis can extend to at least 1.7 meters (5 feet 7 inches). Its typical movement speed is slow, approximately 5–8 km/h (3–5 mph), but it can accelerate to 16–17.5 km/h (10–11 mph) when threatened.

A documented instance of aggressive interspecies interaction between a North Pacific right whale and a pod of gray whales off California represents the sole recorded case of potential interspecies aggression among baleen whales. Conversely, social behaviors between these two species have been observed near Sakhalin.

Pacific Groups

The two populations of Pacific gray whales (Eastern and Western) exhibit distinct morphological and phylogenetic characteristics. Beyond genetic distinctions, confirmed variations between these populations encompass proportions of various body parts, body coloration (including skeletal features), and the length ratios of flippers and baleen plates. Some researchers propose that the ancestral Eastern and Western groups may have been considerably more divergent than previously assumed, potentially warranting classification as distinct subspecies. The extinction of the original Asian and Atlantic populations complicates efforts to identify unique characteristics within those historical stocks. Nevertheless, recent observations have documented certain whales displaying distinctive, blackish body coloration. This observation aligns with DNA analysis from the most recently recorded stranding event in China. Furthermore, discrepancies were noted between specimens originating from Korea and China.

Populations

North Pacific

The Pacific Ocean hosts two recognized populations: a critically small population, whose migratory path is hypothesized to extend between the Sea of Okhotsk and southern Korea, and a considerably larger Eastern Pacific population, estimated at approximately 27,000 individuals, which migrates between the waters off northern Alaska and Baja California Sur. During this migration, mothers, typically accompanied by their calves, often remain close to shore within shallow kelp beds. Their fierce defense of their young against attacks has led to the gray whale being colloquially known as the "devil fish."

Despite extensive conservation efforts over several years, the Western population has exhibited a remarkably slow growth rate, likely attributable to its inherently low reproductive rate. The population reached its nadir in 2010, with no new reproductive females documented, bringing the total observed reproductive females since 1995 to a minimum of 26. Even a marginal increase in annual female mortality could precipitate a decline in this subpopulation. Nevertheless, by 2018, evidence suggested a notable increase in the Western population's numbers, particularly in the waters surrounding Sakhalin Island. Consequently, the IUCN revised the population's conservation status from 'critically endangered' to 'endangered'.

North Atlantic

Gray whales became extinct in the North Atlantic during the 18th century. Historically, they were seasonal migrants to coastal waters on both sides of the Atlantic, encompassing areas such as the Baltic Sea, the Wadden Sea, the Gulf of St. Lawrence, the Bay of Fundy, Pamlico Sound, and potentially Hudson Bay. Radiocarbon dating of subfossil and fossil remains from European coastal regions (Belgium, the Netherlands, Sweden, the United Kingdom) corroborates this historical presence, with whaling identified as a probable cause for the population's extinction. A 2025 study concluded that gray whales were extirpated from the eastern North Atlantic between the 12th and 14th centuries. This extirpation was attributed partly to environmental factors, coinciding with the end of the Medieval Warm Period, and partly to medieval whaling, which was at its peak during this period. In 1997, remains from the Roman epoch were discovered in the Mediterranean during the excavation of the ancient harbor of Lattara near Montpellier, France. This discovery prompted inquiries into whether Atlantic gray whales migrated along the European coast, from the Wadden Sea to calving grounds in the Mediterranean. A 2018 study, employing ancient DNA barcoding and collagen peptide matrix fingerprinting, confirmed that Roman-era whale bones found east of the Strait of Gibraltar belonged to gray whales (and North Atlantic right whales), thereby verifying the historical presence of gray whales in the Mediterranean. Likewise, radiocarbon dating of subfossil remains from the American East Coast indicates the presence of gray whales in that region at least until the 17th century. This population's range extended at least from Southampton, New York, to Jupiter Island, Florida, with the latest evidence dating to 1675. In his 1835 historical account of Nantucket Island, Obed Macy documented that prior to 1672, a whale identified as a "scragg" entered the harbor and was subsequently hunted and killed by the early colonists. A. B. Van Deinse suggests that the "scrag whale," a species described by P. Dudley in 1725 as being targeted by early New England whalers, was almost certainly the gray whale.

Gray whales have been occasionally observed in the Atlantic Ocean and Mediterranean Sea since the 2010s, with notable sightings off the coasts of Israel and Namibia. These individuals are presumed to be migrants from the North Pacific population, traversing the Arctic Ocean. A 2015 DNA analysis of subfossil gray whales suggested that such migrations might not be historically unprecedented. The study proposed multiple gray whale migrations between the Pacific and Atlantic over the last 100,000 years, with the most recent large-scale event approximately 5,000 years ago. These migratory periods correlated with comparatively elevated Arctic Ocean temperatures. In 2021, a single gray whale was sighted in Rabat, Morocco, subsequently followed by observations in Algeria and Italy. In March 2024, researchers from the New England Aquarium documented a gray whale approximately 30 miles (48 km) south of Nantucket, Massachusetts.

Pre-Whaling Population Abundance

Employing a genetic methodology, researchers estimated pre-whaling abundance using samples from 42 gray whales. Their analysis of DNA variability across 10 genetic loci indicated a historical population size ranging from 76,000 to 118,000 individuals, which is three to five times greater than the average census size recorded up to 2007. The National Oceanic and Atmospheric Administration (NOAA) has conducted gray whale population surveys since at least the 1960s. NOAA reports that the most recent population estimate from 2007 was approximately 19,000 whales, with an 88% probability that the population has reached its "optimum sustainable population" size, as defined by the Marine Mammal Protection Act. It is hypothesized that significant alterations to the ocean ecosystem since the pre-whaling era render a return to historical population levels impractical. Current population levels are constrained or threatened by factors such as ship strikes, entanglement in fishing gear, and shifts in sea-ice coverage linked to climate change.

Population Integration and Recolonization

Multiple gray whales observed off Sakhalin and the Kamchatka Peninsula have been confirmed to migrate eastward across the Pacific, integrating with the larger eastern population. In January 2011, a gray whale previously tagged within the western population was tracked eastward to the range of the eastern population off the coast of British Columbia. Recent analyses of stranded or entangled specimens suggest that the original western population may be functionally extinct. Consequently, all gray whales observed along Japanese and Chinese coasts in contemporary times are potentially vagrants or recolonizers originating from the eastern population.

In the mid-1980s, three gray whale sightings occurred in the eastern Beaufort Sea, extending their known range at the time by 585 kilometers (364 mi) eastward. A recent increase in sightings has been confirmed in Arctic regions within the historical range of Atlantic stocks. These observations are particularly notable in several locations in the Laptev Sea, including the New Siberian Islands in the East Siberian Sea, and near the Franz Josef Land marine mammal sanctuary, suggesting potential early recolonization efforts. These individuals exhibited a darker body coloration compared to those observed in the Sea of Okhotsk. In May 2010, a gray whale was sighted off the Mediterranean coast of Israel. Speculation suggests this whale traversed from the Pacific to the Atlantic via the Northwest Passage, as an alternative route around Cape Horn would not align with the species' established territory. Gradual melting and recession of Arctic sea ice, with extreme loss recorded in 2007, rendered the Northwest Passage "fully navigable." The same individual was subsequently sighted on May 30, 2010, off the coast of Barcelona, Spain.

In May 2013, a gray whale was observed off Walvis Bay, Namibia. Scientists from the Namibian Dolphin Project confirmed the whale's identity, marking the sole documented sighting of this species in the Southern Hemisphere. Photographic identification indicates that this individual differs from the one sighted in the Mediterranean in 2010. As of July 2013, the Namibian whale continued to be observed regularly.

In March 2021, a gray whale was sighted near Rabat, the capital of Morocco. In April, further sightings were reported off the coasts of Algeria and Italy.

In December 2023, a gray whale was observed off Sunny Isles Beach, Florida.

Genetic analysis of fossil and pre-fossil gray whale remains in the Atlantic Ocean indicates multiple dispersal waves from the Pacific to the Atlantic, linked to successive periods of climatic warming during the Pleistocene (prior to the last glacial period) and the early Holocene (following the opening of the Bering Strait). These findings, coupled with recent sightings of Pacific gray whales in the Atlantic, suggest that another range expansion into the Atlantic may be commencing.

Life History

Reproduction

Breeding behavior is intricate, frequently involving groups of three or more individuals. Both male and female whales attain sexual maturity between six and twelve years of age, with an average onset at eight to nine years. Females exhibit highly synchronized reproductive cycles, entering oestrus from late November to early December. During the breeding season, females commonly engage with multiple mates. This singular ovulation event is thought to align with the species' annual migratory patterns, facilitating births in warmer aquatic environments. While most females reproduce biennially, annual parturition events have been documented. Males similarly undergo seasonal physiological alterations, including an increase in testicular mass that corresponds with the female oestrus period. Instances of male aggression towards parous females have been reported, occasionally leading to injury or mortality. Presently, no live twin births have been recorded, though a case of twins in utero has been documented.

The gestation period for gray whales is approximately 13 1⁄§34§ months, with females typically calving every one to three years. During the latter half of gestation, the fetus undergoes accelerated growth in both length and mass. Mirroring the restricted breeding season, the majority of calves are born within a six-week window centered around mid-January. Calves are typically born tail-first, measuring approximately 14–16 ft in length and weighing around 2,000 lbs. Lactation by females persists for approximately seven months post-parturition, after which calves are weaned and maternal investment gradually diminishes. The shallow lagoon environments utilized for reproduction are thought to provide protection for newborns against predators such as sharks and orcas.

On 7 January 2014, a pair of conjoined twin gray whale calves, either stillborn or aborted, were discovered deceased in Laguna Ojo de Liebre (Scammon's Lagoon), situated off Mexico's west coast. The twins were conjoined ventrally.

Feeding

Gray whales primarily consume benthic crustaceans, including amphipods and ghost shrimp, by turning onto their side and scooping sediments from the seafloor. This specialized feeding strategy renders gray whales among the most dependent baleen whale species on coastal marine environments. As a baleen whale, it possesses baleen plates (whalebone) that function as a sieve, filtering small marine organisms, such as amphipods, along with sand, water, and other particulate matter. Near Vancouver Island, gray whales frequently prey on shrimp-like mysids, and their presence in substantial numbers correlates with mysid abundance. Although mysids are a preferred prey, gray whales exhibit opportunistic feeding behavior, readily transitioning between planktonic and benthic foraging. During planktonic feeding, gray whales either roll onto their right side with their fluke remaining above the surface, or they employ a skimming technique, similar to other baleen whales, by swimming with an open mouth at the surface. This skimming behavior appears predominantly utilized when gray whales target crab larvae. Additional dietary components encompass polychaete worms, herring eggs, diverse larval forms, and small fish.

Gray whales exhibit benthic feeding behavior, involving dives to the ocean floor where they roll onto their side—typically favoring the right side, similar to blue whales—to suction prey from the seabed. While planktonic feeding is preferred in their primary feeding grounds, benthic foraging occurs along their migration routes in shallower waters. The species primarily feeds in northern waters during summer months, supplementing this with opportunistic feeding during migration, largely sustained by substantial fat reserves. This opportunistic feeding strategy may also stem from population growth, leading to increased competition and a broader utilization of available prey resources. Migratory feeding areas reportedly encompass the Gulf of California, Monterey Bay, and Baja California Sur. Gray whale calves consume 50–80 lb (23–36 kg) of their mothers' milk, which contains 53% fat, daily.

The primary foraging habitat for the western Pacific subpopulation is the shallow continental shelf (5–15 m (16–49 ft) deep) off northeastern Sakhalin Island, specifically near the southern part of Piltun Lagoon, where amphipods and isopods constitute the principal prey. Occasionally, these whales utilize an offshore feeding ground located 30–35 m (98–115 ft) deep southeast of Chayvo Bay, primarily consuming benthic amphipods and cumaceans. Although some gray whales have been observed off western Kamchatka, all individuals photographed in that region have also been identified in the Piltun area.

Migration

Predictive distribution models suggest that the gray whale's overall range during the last glacial period was more extensive or shifted southward, potentially allowing for habitation in areas currently devoid of the species, such as the Southern Hemisphere, South Asian waters, and the northern Indian Ocean, owing to favorable environmental conditions at that time. Future range expansions are anticipated due to population recoveries and recolonization efforts, with projected distributions exceeding current extents. The gray whale undertakes the longest migratory journey of any mammal.

Eastern Pacific population

Annually in October, with the southward progression of northern ice, small groups of eastern gray whales from the eastern Pacific embark on a two- to three-month southward migration, covering 8,000–11,000 km (5,000–6,800 mi). This journey originates in the Bering and Chukchi Seas, traverses the western coasts of Canada, the United States, and Mexico, and concludes in the warm-water lagoons of Mexico's Baja California Peninsula and the southern Gulf of California.

Migrating continuously, day and night, gray whales maintain an average speed of 8 km/h (5 mph), covering approximately 120 km (75 mi) daily. This extensive round trip, spanning 16,000–22,000 km (9,900–13,700 mi), is considered the longest annual migration undertaken by any mammal. From mid-December to early January, most individuals are typically observed between Monterey and San Diego, including locations like Morro Bay, often visible from coastal vantage points. The whale watching industry facilitates opportunities for ecotourists and marine mammal enthusiasts to observe migrating gray whale groups.

Eastern gray whales commence their arrival in the calving lagoons and bays along the west coast of Baja California Sur between late December and early January. The three most frequented locations include San Ignacio, Magdalena Bay (situated to the south), and Laguna Ojo de Liebre (located to the north), which was historically referred to as Scammon's Lagoon, named after whaleman Charles Melville Scammon, who identified these lagoons in the 1850s and engaged in gray whale hunting.

Historically, gray whales extended their range into the Sea of Cortez and along the Pacific coasts of continental Mexico, reaching as far south as the Islas Marías, Bahía de Banderas, and the Nayarit/Jalisco regions. Additionally, two contemporary calving grounds existed in Sonora (Tojahui or Yavaros) and Sinaloa (Bahia Santa Maria, Bahia Navachiste, La Reforma, Bahia Altata) until their abandonment in the 1980s.

The initial arrivals typically consist of pregnant females seeking the protective environment of the lagoons for parturition, alongside solitary females in search of mates. By mid-February to mid-March, the majority of the population has converged in these lagoons, which then become active sites for nursing, calving, and mating among gray whales.

During February and March, the initial gray whales to exit the lagoons are typically males and females that are not accompanied by new calves. Pregnant females and lactating mothers, along with their newborns, constitute the final group to depart, delaying their departure until their calves are adequately prepared for the migration, generally occurring from late March to mid-April. Occasionally, some mothers may extend their stay with their young calves into May. Whale watching activities in Baja's lagoons are notably popular, primarily due to the whales' frequent proximity to boats, which allows tourists to interact physically with them.

By late March or early April, the migrating gray whales become visible along the coast extending from Puget Sound northward to Canada.

Resident Populations

Approximately 200 gray whales constitute a resident population that remains along the eastern Pacific coast, spanning from Canada to California, during the summer months, foregoing the extended migration to Alaskan waters. This specific summering group is designated as the Pacific Coast Feeding Group.

The historical or contemporary existence of analogous resident groups within the western gray whale population remains largely unconfirmed. Nevertheless, evidence from whalers' logbooks and scientific observations suggests that year-round occurrences in Chinese waters, particularly within the Yellow and Bohai basins, likely served as summering grounds. Historically, well-documented catches indicate that gray whales frequently remained for several months in various enclosed waters, with specific records from the Seto Inland Sea and the Gulf of Tosa. Previous feeding areas extended across significant portions from mid-Honshu to northern Hokkaido, and whales were documented during most annual seasons, including wintering periods, along the eastern coasts of the Korean Peninsula and Yamaguchi Prefecture. Recent observations further support the potential for historical resident whale populations: for instance, a group of two or three individuals was observed feeding near Izu Ōshima for nearly a month in 1994; two solitary whales resided in Ise Bay for approximately two months in the 1980s and again in 2012. Furthermore, in 2014, the first confirmed living individuals within Japan's Exclusive Economic Zone in the Sea of Japan, comprising a cow-calf pair—the first such sighting since the cessation of whaling—remained along the Teradomari coastline for about three weeks. One of these individuals subsequently returned to the same coastal area at the identical time of year in 2015. A review of other observations across various Japanese coasts and islands during 2015 suggests that spatial or seasonal residencies, whether temporary or permanent, were historically prevalent throughout many regions of Japan and other coastal areas of Asia.

Western Population

The contemporary western gray whale population primarily summers in the Sea of Okhotsk, specifically off the Piltun Bay region on the northeastern coast of Sakhalin Island, Russian Federation. Sporadic sightings also occur off the eastern coast of Kamchatka, Russian Federation, and in other northern Okhotsk Sea coastal waters. Their migration routes and wintering grounds remain largely undetermined, with recent data limited to infrequent observations along both the eastern and western coasts of Japan and the Chinese coast. Prior to 2016, gray whales had not been documented near the Commander Islands. Based on photo identification data collected off Sakhalin Island and Kamchatka, the northwestern Pacific population is estimated to comprise approximately 300 individuals.

The Sea of Japan was historically not considered a migration route for gray whales until multiple entanglement incidents were documented. No confirmed records of the species on Kyushu had existed since 1921. Nevertheless, numerous whale sightings were reported along the Genkai Sea off Yamaguchi Prefecture, within Ine Bay in the Gulf of Wakasa, and near Tsushima. Gray whales, alongside other cetacean species like right whales and Baird's beaked whales, were frequently observed off the northeastern coast of Hokkaido, specifically near Teshio, in Ishikari Bay near Otaru, around the Shakotan Peninsula, and among islands in the La Pérouse Strait, including Rebun Island and Rishiri Island. These regions potentially served as feeding grounds. Additionally, shallow, muddy areas conducive to whale feeding are present off Shiretoko, notably at Shibetsu, the Notsuke Peninsula, Cape Ochiishi on Nemuro Peninsula, Mutsu Bay, along the Tottori Sand Dunes, within the Suou-nada Sea, and in Ōmura Bay.

The precise historical calving grounds remain undetermined, though potential locations include the southern Chinese coasts, specifically from Zhejiang and Fujian Provinces to Guangdong, with particular emphasis on areas south of Hailing Island and near Hong Kong. Further possibilities encompass Daya Bay, Wailou Harbour on the Leizhou Peninsula, and regions extending southward to Hainan Province and Guangxi, especially around Hainan Island. These identified areas represent the southwestern extremity of the species' documented range. It is uncertain whether the whales' historical distribution extended further south into the Gulf of Tonkin. Furthermore, the existence of historical calving grounds on Taiwan and the Penghu Islands (supported by some fossil records and captures), as well as any presence in areas beyond the known ranges, such as off the Babuyan Islands in the Philippines and in coastal Vietnamese waters within the Gulf of Tonkin, is also unknown. A single confirmed instance of accidental mortality for this species in Vietnam occurred in 1994 at Ngoc Vung Island, off Ha Long Bay; the skeleton is currently displayed at the Quang Ninh Provincial Historical Museum. Notably, gray whales have been observed in the Taiwan Strait in recent years.

The historical existence of winter breeding grounds beyond the Chinese coasts remains speculative. For instance, it is not established whether these whales frequented the southern coasts of the Korean Peninsula, including areas adjacent to Jeju Island, Haiyang Island, the Gulf of Shanghai, or the Zhoushan Archipelago. In Japan, there is no substantial evidence of historical presence south of the Ōsumi Peninsula, with only one skeleton having been discovered in Miyazaki Prefecture. While Hideo Omura once proposed the Seto Inland Sea as a historical breeding ground, this hypothesis is supported by only a limited number of capture records, despite confirmed migrations into the sea. Recent genetic and acoustic investigations indicate the presence of several wintering sites for western gray whales, including locations in Mexico and the East China Sea. Nevertheless, their specific wintering behaviors within the western North Pacific are still inadequately understood, necessitating further research.

Recent Migratory Patterns in Asian Waters

Despite South Korea's substantial conservation efforts for the species among Asian nations, no confirmed sightings have been reported along the Korean Peninsula or within the Sea of Japan in recent years.

The last confirmed observation in Korean waters involved a pair of whales sighted off Bangeojin, Ulsan, in 1977. Preceding this, five animals were captured off Ulsan in 1966. A potential sighting of a whale within the port of Samcheok was reported in 2015.

Since 1933, a total of 24 records, encompassing sightings, strandings, intentional hunts, and bycatches, have been documented along Chinese coasts. The most recent confirmed occurrence of the species in Chinese waters during the 20th century was a stranded semi-adult female in the Bohai Sea in 1996. The sole record for Chinese waters in the 21st century involved a fully-grown female that died from entanglement in Pingtan, China, in November 2007. Subsequent DNA analysis suggested that this individual likely originated from the eastern population rather than the western.

Significant observations of living whales post-1980s include a group of 17 or 18 individuals sighted along Primorsky Krai in late October 1989, preceded by a report of a pair in the same area in 1987. Another notable record involved 14 whales in La Pérouse Strait on June 13, 1982, with an additional sighting of a pair in this strait in October 1987. More recently, in 2011, the presence of gray whales was acoustically detected in the pelagic waters of the East China Sea, situated between Chinese and Japanese territories.

Since the mid-1990s, the majority of confirmed records of living gray whales in Asian waters have originated from Japanese coasts. These records comprise between eight and fifteen sightings and stray observations, which include unconfirmed reports, re-sightings of the same individuals, and one instance of mortality due to net-entanglement. The most significant of these observations are detailed subsequently:

• In 1994, the feeding activities of a group comprising two or three whales, which remained near Izu Ōshima for approximately one month, were documented underwater by multiple researchers and whale photographers.
• A pair of emaciated juvenile whales was observed off Kuroshio, Kōchi, in 1997. This location is notable for its whale-watching tourism, primarily focused on resident and sub-resident Bryde's whale populations. The sighting was considered atypical due to its occurrence at a mid-latitude during the summer season.
• In May 2003, another pair of sub-adult gray whales was confirmed swimming near the mouth of the Otani River in Suruga Bay.
• A subadult whale that remained in Ise and Mikawa Bay for approximately two months during 2012 was subsequently identified as the same individual previously sighted off Tahara, near Cape Irago, in 2010. This observation marked the initial documented instance of a consistent migration originating from Russian waters. The juvenile whale sighted off Owase in the Kumanonada Sea in 2009 could not be definitively linked to the same individual. The Ise and Mikawa Bay region stands as the sole Japanese coastal area with multiple documented occurrences since the 1980s, including a fatal entanglement in 1968, a brief residency in 1982, and a self-extricating entanglement in 2005. Historically, this region also initiated commercial whaling activities. Additional locations reporting multiple sightings or strandings in recent years encompass the Kumanonada Sea off Wakayama, the Oshika Peninsula in Tōhoku, and coastal areas adjacent to Tomakomai, Hokkaido.
• The initial confirmed observation of live gray whales in Japanese waters of the Sea of Japan since the cessation of whaling activities was documented on April 3, 2014, at Nodumi Beach, Teradomari, Niigata. Two individuals, measuring ten and five meters respectively, remained in proximity to the Shinano River mouth for a period of three weeks. The determination of whether this constituted a cow-calf pair, which would represent a novel record for Asia, remains unconfirmed. Prior modern records within the Sea of Japan exclusively comprised by-catch incidents.
• One individual from the aforementioned pair reappeared at the identical beaches during the same annual period in 2015.
• A juvenile whale, potentially accompanied by a larger individual, was present in Japanese waters between January or March and May 2015. This marked the initial confirmed presence of the species around Japan's remote oceanic islands. One or more individuals initially frequented the waters surrounding Kōzu-shima and Nii-Jima for several weeks, subsequently moving to areas adjacent to Miho no Matsubara and behind the Tokai University campus for an extended period. The same individual may also have been sighted off Futo. This whale was subsequently identified as the same individual previously documented off Sakhalin in 2014, representing the first re-recording of a single individual across distinct Asian locations.
• In March 2015, a juvenile whale was observed by land-based fishermen at Cape Irago.
• One individual from the aforementioned pair was observed off southeastern Japan in 2015, subsequently reappearing off Tateyama in January 2016. Nana Takanawa confirmed the whale's identity through photographs taken of the same individual on Niijima in 2015. The same individual was likely sighted off Futo and, approximately thirty minutes later, off Akazawa beach in Itō, Shizuoka, on the 14th. Subsequently, the whale remained near a pier on Miyake-jima and later at Habushi beach on Niijima, the identical beach where the individual had been present the preceding year.
• A nine-meter (30 ft) whale stranded near Wadaura on March 4, 2016. Post-mortem examinations suggested this individual was distinct from the previously mentioned animal.
• A seven-meter (23 ft) carcass of a juvenile female whale was initially reported floating near Atami on April 4, subsequently washing ashore at Ito on April 6.
• As of April 20, 2017, one or more whales had been present within Tokyo Bay since February; however, at one juncture, another whale, whose identity relative to the initial sighting remained unconfirmed, was observed off Hayama, Kanagawa. The precise number of whales involved in these sightings remains ambiguous, with fishermen reporting two individuals and the Japanese coast guard reporting three on either the 20th or 21st.

Whaling

North Pacific

Eastern population

Adult gray whales face predation exclusively from humans and orcas, with orcas representing the more significant threat. The remains of a 14-meter (46 ft) adult female gray whale, presumed to have been consumed by an orca, were previously discovered. Indigenous hunters, including communities on Vancouver Island and the Makah in Washington, have historically pursued gray whales.

Commercial whaling targeting this species by European entities in the North Pacific commenced during the winter of 1845–46, when two United States vessels, the Hibernia and the United States, commanded by Captains Smith and Stevens, captured 32 individuals in Magdalena Bay. Additional vessels subsequently engaged in whaling during the subsequent two winters, after which gray whale hunting in the bay was largely discontinued due to "the inferior quality and low price of the dark-colored gray whale oil, the limited quality and quantity of whalebone derived from the gray whale, and the inherent hazards associated with lagoon whaling."

The practice of gray whaling in Magdalena Bay experienced a resurgence during the winter of 1855–56, primarily driven by vessels from San Francisco, notably the ship Leonore, commanded by Captain Charles Melville Scammon. This period marked the commencement of an 11-winter span, from 1855 to 1865, designated as the "bonanza period," during which gray whaling activities along the Baja California coast reached their zenith. Whales were harvested not only within Magdalena Bay but also by ships positioned along the coastline from San Diego southward to Cabo San Lucas, and from established whaling stations extending from Crescent City in northern California down to San Ignacio Lagoon. Concurrently, vessels operating in the Gulf of Alaska, the Sea of Okhotsk, and the Western Arctic, primarily targeting right and bowhead whales, would occasionally capture a gray whale if the preferred species were unavailable.

In December 1857, Charles Scammon, aboard the brig Boston and accompanied by his schooner-tender Marin, navigated into Laguna Ojo de Liebre, also known as Jack-Rabbit Spring Lagoon, and subsequently renamed Scammon's Lagoon by 1860. This expedition led to the discovery of one of the gray whale's final sanctuaries, where he captured 20 whales. The subsequent winter (1858–59) saw his return with the bark Ocean Bird and schooner tenders A.M. Simpson and Kate. Over a three-month period, this operation resulted in the capture of 47 female whales, producing 1,700 barrels (270 m§1011§) of oil. During the winter of 1859–60, Scammon, once more commanding the bark Ocean Bird alongside several other vessels, entered San Ignacio Lagoon to the south, where he identified the last known breeding lagoon for the species. However, within merely a few seasons, this lagoon was almost entirely depleted of whales.

From 1846 to 1874, an estimated 8,000 gray whales were harvested by American and European whalers. More than half of these captures occurred within the Magdalena Bay complex, encompassing Estero Santo Domingo, Magdalena Bay proper, and Almejas Bay, as well as by shore-based whalers operating in California and Baja California.

A subsequent, less extensive, and shorter period of gray whale hunting transpired in the eastern North Pacific. Between 1919 and 1926, only a limited number of whales were captured from two whaling stations situated along the California coast, with an additional capture attributed to a single station in Washington from 1911 to 1921. Across the entire west coast of North America, a total of 234 gray whales were harvested between 1919 and 1929. British Columbian stations accounted for merely a dozen or so captures, almost exclusively in 1953 at Coal Harbour. A whaling station in Richmond, California, reported catching 311 gray whales for "scientific purposes" from 1964 to 1969. The Soviet Union captured 138 gray whales between 1961 and 1972, despite initially reporting no such takes. Another notable catch occurred over two seasons by the steam-schooner California off Malibu, California. During the winters of 1934–35 and 1935–36, the California anchored off Point Dume in Paradise Cove, where it processed gray whales. By 1936, gray whales received protected status within the United States.

Western Population

Japanese whaling operations targeting gray whales commenced in the 1570s. Records indicate that 169 gray whales were captured at Kawajiri, Nagato, between 1698 and 1889, while 201 were taken at Tsuro, Shikoku, from 1849 to 1896. Additionally, American and European whalers likely harvested several hundred more in the Sea of Okhotsk from the 1840s through the early 20th century. During the 1890s, whalers in Japan captured 44 gray whales using nets. However, the most significant impact occurred between 1911 and 1933, when Japanese whalers killed 1,449 individuals following the establishment of multiple Japanese whaling stations on the Korean Peninsula and along the Chinese coast, including sites near Daya Bay and on Hainan Island. By 1934, the western gray whale population was critically endangered, approaching extinction. From 1891 to 1966, an estimated 1,800–2,000 gray whales were caught, with annual peak catches ranging from 100 to 200 during the 1910s.

By 2001, the Californian gray whale population had expanded to approximately 26,000 individuals. Conversely, as of 2016, the population of western Pacific gray whales, found in the seas adjacent to Korea, Japan, and Kamchatka, was estimated at only 200.

North Atlantic

The North Atlantic gray whale population is believed to have faced extirpation during the 18th century. Indirect evidence suggests that intensified whaling operations in the 17th and 18th centuries correlated with the disappearance of this population. A. B. Van Deinse identified the "scrag whale," documented by P. Dudley in 1725 as a target for early New England whalers, as highly probable to be the gray whale. Obed Macy, in his 1835 historical account of Nantucket Island, recorded an incident in the pre-1672 colony where a "scragg" whale entered the harbor and was subsequently hunted and killed by settlers. Gray whales, known in Icelandic as sandlægja, were also documented in Iceland during the early 17th century. It is hypothesized that the species was hunted to extinction in the eastern North Atlantic between the 12th and 14th centuries, having been the second most prevalent whale taxon identified at European archaeological sites through the medieval era. The historical viability of commercial whaling operations within the Mediterranean basin has also been considered.

Conservation Efforts

Since 1949, the International Whaling Commission (IWC) has afforded gray whales protection from commercial hunting, resulting in a cessation of large-scale harvesting.

Nevertheless, restricted gray whale hunting has persisted, predominantly in Russia's Chukotka region, a significant summering ground for the species. This activity is sanctioned under an "aboriginal/subsistence whaling" exemption to the commercial hunting prohibition. Anti-whaling organizations have contested this practice, asserting that the whale meat is not utilized for traditional indigenous consumption but rather to sustain animals in state-operated fur farms. They highlight a substantial increase in annual catch figures during the 1940s, coinciding with the establishment of these state-run fur farms in the area. While the Soviet government refuted these allegations until 1987, the Russian government has recently acknowledged the practice. The Russian IWC delegation maintains that the hunt is justifiable under the aboriginal/subsistence exemption, as the fur farms contribute a vital economic foundation for the region's indigenous inhabitants.

The current annual quota for gray whale harvesting in the region is set at 140 individuals. Following an accord between the United States and Russia, the Makah tribe of Washington asserted a claim for four whales from the IWC quota established during its 1997 meeting. However, aside from one gray whale taken in 1999, the Makah people have been precluded from hunting due to a series of legal challenges. These culminated in a December 2002 United States federal appeals court ruling that mandated the National Marine Fisheries Service to develop an Environmental Impact Statement. Notwithstanding this judicial decision, on September 8, 2007, five members of the Makah tribe killed a gray whale using high-powered rifles. The whale succumbed within 12 hours, sinking as it moved offshore.

As of 2018, the International Union for Conservation of Nature (IUCN) classifies the gray whale as a species of least concern regarding its conservation status. Nevertheless, the distinct subpopulation inhabiting the northwest Pacific is designated as critically endangered. Furthermore, the U.S. government's National Marine Fisheries Service lists the northwest Pacific population as endangered under the U.S. Endangered Species Act. In 2011, the IWC Bowhead, Right and Gray Whale subcommittee reaffirmed the substantial conservation risk faced by western gray whales, attributing it to the population's diminutive size and potential anthropogenic influences.

Initial observations of gray whale migrations along the Pacific Coast were conducted by Marineland of the Pacific in Palos Verdes, California. The Gray Whale Census, an official initiative, has continuously monitored the population and migratory patterns of the Pacific gray whale since 1985, making it the longest-running census for this species. Volunteers involved in the census record data from December 1 through May, operating daily from dawn to dusk, to track the number of gray whales traversing the waters off Los Angeles. Data collected from this census is disseminated via the American Cetacean Society of Los Angeles (ACSLA).

Both South Korea and China classify gray whales as species of significant conservation concern. In South Korea, the Gray Whale Migration Site was designated as the 126th national monument in 1962; however, illegal hunting has subsequently occurred, and no recent sightings of the species have been reported in Korean waters.

Rewilding Proposal

In 2005, two conservation biologists advanced a proposal for the translocation of 50 gray whales from the Pacific Ocean to the Atlantic Ocean. Their rationale posited that, given the recovery of Californian gray whale populations to viable levels, surplus individuals could be relocated to re-establish the extirpated British population. As of 2024, this initiative remains unimplemented.

Threats

The Government of Canada's Management Plan for gray whales identifies several threats to the eastern North Pacific population. These include heightened anthropogenic activities within their Mexican breeding lagoons, climate change, acute noise pollution, toxic spills, aboriginal whaling practices, entanglement in fishing gear, vessel collisions, and potential consequences stemming from fossil fuel exploration and extraction.

Western gray whales confront substantial threats to their future survival, including extensive offshore oil and gas development initiatives proximate to their summer feeding grounds and lethal net entrapments occurring off Japan during migratory periods. Furthermore, considerable nearshore industrialization and shipping density along the migratory corridors of the western gray whale population present additional hazards, elevating the probability of exposure to vessel collisions, chemical contamination, and pervasive anthropogenic disturbance.

Of particular concern is offshore gas and oil development in the Okhotsk Sea, situated within 20 km (12 mi) of the primary feeding ground located off northeast Sakhalin Island. Activities associated with hydrocarbon exploration, such as geophysical seismic surveying, pipeline installation, drilling operations, heightened vessel traffic, and potential oil spills, collectively represent significant threats to western gray whales. Acoustic disturbance from underwater industrial noise has the potential to displace whales from essential feeding habitats. Furthermore, physical habitat degradation resulting from drilling and dredging activities, coupled with the potential effects of oil and chemical spills on benthic prey communities, also necessitates serious consideration. Consequently, the western gray whale population is classified as endangered under IUCN criteria.

During the 2000s, four female gray whales, including a cow-calf pair, were ensnared and perished in nets along Japanese coastlines. In the 1990s, a deceased whale, suspected to have been harpooned by dolphin hunters, was documented on Hokkaido. Additionally, whale meat offered for sale was identified in Japanese markets.

The year 2019 witnessed an unprecedented number of gray whale strandings and mortalities, with 122 incidents recorded in United States waters and 214 in Canadian waters. Post-mortem examinations of some specimens indicate that the cause of death is attributable to suboptimal nutritional status. A prevailing hypothesis suggests that a subset of these strandings correlates with alterations in the abundance or quality of prey in Arctic feeding grounds, leading to inadequate foraging. Certain researchers propose that diminished sea ice coverage has impeded the fertilization of amphipods, a primary food source for gray whales, compelling them to consume less nutritious krill as an alternative. Further investigation is imperative to fully comprehend this complex phenomenon.

Recent research indicates a potential correlation between solar activity and gray whale strandings. Specifically, periods characterized by a high prevalence of sunspots corresponded to a fivefold increase in the likelihood of gray whale strandings. One proposed explanation for this phenomenon is that solar storms emit substantial electromagnetic radiation, potentially disrupting Earth's geomagnetic field and/or the whales' capacity to perceive it. This mechanism might also extend to other cetacean species, including sperm whales. Nevertheless, insufficient empirical evidence currently exists to definitively establish that whales employ magnetoreception (the biological ability to sense a magnetic field) for navigation.

Orcas are recognized as primary predators of gray whale calves. Typically, three to four orcas collaborate to separate a calf from its defending mother by ramming it from below. Observations have documented humpback whales defending gray whale calves against orca attacks. During the northbound migration, orcas frequently enter Monterey Bay to intercept gray whales, specifically targeting females accompanied by newborn calves. Their strategy involves separating the calf from its mother and submerging it to induce drowning. This drowning tactic is also employed by orcas against adult gray whales. Approximately 33% of gray whales born annually are estimated to succumb to predation.

Captivity

Due to their substantial size and migratory requirements, gray whales have seldom been maintained in captivity, and then only for limited durations. The inaugural gray whale held in captivity, named Gigi, was captured in Scammon's Lagoon, Baja California, in 1965 and succumbed to an infection two months subsequent to her capture. A second gray whale, Gigi II, captured from the same lagoon in 1972, was released a year later when her growth rendered the existing facilities inadequate. The third documented gray whale, J.J., initially beached herself in Marina del Rey, California, in 1997, necessitating her transfer to SeaWorld San Diego. Following a 14-month period, she was released due to her increasing size, which exceeded the capacity of the available facilities. Upon her release, J.J. weighed 19,200 pounds (8,700 kg) and measured 31 feet (9.4 m), making her the largest marine mammal ever maintained in captivity.

Gray Whale Cove State Beach

• Gray Whale Cove State Beach
• Gray Whale Ranch
• List of cetaceans
• Cryptolepas rhachianecti (a barnacle species inhabiting gray whales)

References

Sources

• Anderson, J. (1746). News from Iceland, Greenland and the Davis Strait (in German). Hamburg: Published by Georg Christian Grund, Bookseller.Barnes, L. G.; McLeod, S. A. (1984). "The Fossil Record and Phyletic Relationships of Gray Whales." In Jones, M. L.; Swartz, S. L.; Leatherwood, S. (eds.). The Gray Whale: Eschrichtius Robustus. Academic Press. pp. 3–28. ISBN 978-0-08-092372-7.Brisson, M. J. (1762). Animal kingdom distributed into 9 classes, or, Methodical synopsis (in Latin and French). Leiden: At Theodorus Haak. OCLC 13184910.Erxleben, J. C. P. (1777). System of the animal kingdom by classes, orders, genera, species, varieties, with synonymy and history of animals. Class 1: Mammalia (in Latin). Leipzig: Weygandianis. OCLC 22224991. OL 23666710M."Eschrichtius Gray 1864 (gray whale)." Fossilworks. Archived from the original on 2022-08-18. Retrieved 2021-12-17.Lilljeborg, W. (1861). Overview of the Cetacean Mammals (Cetacea) found in Scandinavia (Sweden and Norway) (in Swedish). doi:10.5962/bhl.title.15843. OCLC 670223335.Scammon, C. M. (1874). "The California Gray Whale." In The marine mammals of the north-western coast of North America. San Francisco: John H. Carmany and Co. pp. 20–33.Van Beneden, P. J.; Gervais, P. (1868). Osteography of living and fossil cetaceans, including the description and iconography of the skeleton and dental system of these animals; as well as documents relating to their natural history. Paris: A. Bertrand. doi:10.5962/bhl.title.9521."P. J. Van Beneden and P. Gervais 1868." Fossilworks. Archived from the original on 2021-08-21. Retrieved 2021-12-17.Jones, Mary Lou; Swartz, Steven L.; Leatherwood, Stephen (1984). The Gray Whale: Eschrichtius robustus. Academic Press. p. 600. ISBN 978-0-12-389180-8.
  • Jones, Mary Lou; Swartz, Steven L.; Leatherwood, Stephen (1984). The Gray whale: Eschrichtius robustus. Academic Press. p. 600. ISBN 978-0-12-389180-8.Rice, Dale W.; Wolman, Allen A. (April 30, 1971). The Life History and Ecology of the Gray Whale: Eschrichtius Robustus, Special Publication No. 3. The American Society of Mammalogists. p. 152.Swartz, Steven L.; Jones, Mary Lou (June 1987). "Gray Whales." National Geographic. Vol. 171, no. 6. pp. 754–771. ISSN 0027-9358. OCLC 643483454.Sumich, James (2014). E. robustus: The Biology and Human History of Gray Whales (1st ed.). Whale Cove Marine Education. p. 199. ISBN 978-0-692-22542-4.
    • Cooke, J.G. (2018). "Eschrichtius robustus". IUCN Red List of Threatened Species. 2018 e.T8097A50353881. doi:10.2305/IUCN.UK.2018-2.RLTS.T8097A50353881.en. Retrieved 2 April 2024.
    • Cooke, J.G. (2018). "Eschrichtius robustus". IUCN Red List of Threatened Species. 2018 e.T8097A50353881. doi:10.2305/IUCN.UK.2018-2.RLTS.T8097A50353881.en. Retrieved 2 April 2024.Source: TORIma Academy Archive