The genus Eubalaena represents large baleen whales commonly known as right whales, a name rooted in the history of commercial whaling. These whales, which can reach lengths of up to 18 meters, were heavily targeted by whalers due to their slow speed and high blubber content, which caused their carcasses to float after death. This combination led to them being considered the “right” whale to hunt, pushing all populations toward collapse. Today, the three species within Eubalaena are among the most critically endangered cetaceans in the world. The modern threats they face are a direct result of human activity and prevent their recovery from historical lows.
Species and Distribution of Right Whales
The Eubalaena genus is composed of three recognized species, each occupying a distinct geographical basin. The North Atlantic Right Whale, Eubalaena glacialis, inhabits the western North Atlantic Ocean, migrating between feeding grounds off New England and Canada and calving grounds off the southeastern United States. The North Pacific Right Whale, Eubalaena japonica, is found in the North Pacific, primarily in the Bering Sea and the Sea of Okhotsk, and is the most sparsely distributed of the three. These two northern populations are separated by warm equatorial waters, which right whales cannot cross due to their thick insulating blubber layer.
The third species is the Southern Right Whale, Eubalaena australis, which is unique in its circumpolar distribution throughout the Southern Hemisphere between 20 and 60 degrees south latitude. This species migrates annually from its summer feeding grounds near Antarctica to warmer coastal bays off South Africa, Argentina, and Australia for calving. While the Southern Right Whale population is showing signs of recovery, the North Atlantic and North Pacific populations remain severely depleted. The scientific name Eubalaena itself translates to “good” or “true whale,” reflecting this geographic separation.
Unique Biological and Behavioral Traits
Right whales are easily identifiable by their rotund, dark bodies, which lack a dorsal fin, and their distinctive V-shaped blow that can reach five meters high. A unique physical characteristic is the presence of callosities, which are raised, rough patches of keratinized skin found primarily on the head. These patches are naturally dark but appear white or yellowish because they are colonized by tiny, shrimp-like crustaceans called whale lice, or cyamids. The pattern of these callosities is unique to each individual, allowing researchers to track and identify whales throughout their lives.
Right whales are filter feeders that use long, fine baleen plates hanging from their upper jaw to catch minute prey, mainly small copepods. Their feeding strategy, known as skim feeding, involves swimming slowly with their mouths open through dense patches of zooplankton. They must sustain their massive size and thick blubber layer, which can account for up to 40% of their body weight. Their slow reproductive pace makes population recovery difficult.
Females typically reach sexual maturity around nine or ten years of age and give birth to a single calf after an approximately one-year gestation period. Historically, the interval between successful births was about three to five years. However, due to nutritional stress and chronic injury from human interactions, the average calving interval for North Atlantic females has recently lengthened to six to ten years. This reduction in reproductive output is a major impediment to the species’ recovery.
Primary Factors Driving Endangered Status
Vessel collisions, or ship strikes, represent a major cause of serious injury and mortality, particularly for the North Atlantic Right Whale population. Right whales spend considerable time near the surface, often near major shipping lanes, making them vulnerable to impacts from large, fast-moving vessels. Collisions with vessels traveling at speeds greater than 10 knots are significantly more likely to be fatal.
Entanglement in commercial fishing gear, particularly the vertical lines connecting traps and pots to surface buoys, is the second primary cause of mortality. Over 85% of North Atlantic Right Whales show scarring from at least one entanglement event, and the severity has increased as fishing ropes have become stronger. Entangled whales often tow heavy gear for months, leading to chronic injury, infection, and exhaustion that prevents successful feeding and reproduction. This combination of vessel strikes and entanglement has driven an Unusual Mortality Event for the North Atlantic population since 2017.
Climate change has warmed the waters in historical feeding grounds like the Gulf of Maine, causing the copepods that right whales rely upon to shift their distribution northward. This forces the whales to follow their prey into less protected areas, such as the Gulf of St. Lawrence, where existing management measures are often insufficient. Ocean noise pollution from shipping, seismic surveys, and construction can mask communication sounds necessary for mating and feeding. This acoustic interference adds physiological stress and impairs the whales’ ability to navigate their environment.
Global Conservation and Recovery Strategies
Recovery efforts for the Eubalaena genus focus on mitigating the lethal impacts of vessel strikes and fishing gear. Regulatory measures in the US and Canada mandate seasonal speed restrictions of 10 knots or less for vessels 65 feet or longer in designated Seasonal Management Areas. Efforts are underway to expand these restrictions to smaller vessels and to create dynamic management areas activated by real-time whale sightings. Reducing vessel speed is recognized as one of the most effective ways to lower the risk of fatal collisions.
Technological solutions are being developed to reduce the risk of fishing gear entanglement, including the promotion of ropeless, or on-demand, fishing gear. This equipment allows fishermen to deploy and retrieve traps without leaving a permanent vertical line in the water column, often using acoustic signals to trigger retrieval. Other strategies involve using weak-link ropes designed to break away under less force, potentially allowing an entangled whale to free itself.
Monitoring programs use aerial surveys, dedicated vessel patrols, and acoustic buoys to detect the presence of right whales. These data trigger temporary closures of fishing areas or alert mariners to whales in their path. International cooperation between the United States and Canada is necessary, as the whales migrate across both countries’ jurisdictions, requiring coordinated conservation policies. These strategies aim to stabilize the population by reducing human-caused mortality and allowing the whales to recover their reproductive potential.