The Blue Whale Is Extinction Prone for All of the Following Reasons Except
Blue Whale
Blue whale swimming in the ocean. Credit: NOAA Fisheries
Blue whale swimming in the ocean. Credit: NOAA Fisheries
About the Species
Blue whales are the largest animals ever to live on our planet. They feed almost exclusively on krill, straining huge volumes of ocean water through their baleen plates (which hang from the roof of the mouth and work like a sieve). Some of the biggest individuals may eat up to 6 tons of krill a day.
Blue whales are found in all oceans except the Arctic Ocean. There are five currently recognized subspecies of blue whales.
The number of blue whales today is only a small fraction of what it was before modern commercial whaling significantly reduced their numbers during the early 1900s, but populations are increasing globally. The primary threats blue whales currently face are vessel strikes and entanglements in fishing gear.
NOAA Fisheries and its partners are dedicated to conserving and rebuilding blue whale populations worldwide. We use a variety of innovative techniques to study, protect, and rescue these endangered animals. We engage our partners as we develop regulations and management plans that foster healthy fisheries and reduce the risk of entanglements, create whale-safe shipping practices, and reduce ocean noise.
Population Status
Blue whales were significantly depleted by commercial whaling activities worldwide. Today, blue whales are listed as endangered under the Endangered Species Act and protected under the Marine Mammal Protection Act. The latest stock assessment reports of blue whales include data for various stocks, including areas of the North Pacific and western North Atlantic Oceans.
Protected Status
ESA Endangered
- Throughout Its Range
CITES Appendix II
- Throughout Its Range
MMPA Protected
- Throughout Its Range
MMPA Depleted
- Throughout Its Range
Appearance
Blue whales have a long body and generally slender shape. Their mottled blue-gray color appears light blue under water—hence their name, the blue whale. The mottling pattern is variable and can be used to identify individuals.
Antarctic blue whales are generally larger than other blue whale subspecies. For example, in the North Atlantic and North Pacific, blue whales can grow up to about 90 feet and are over 100,000 pounds, but in the Antarctic, they can reach up to about 110 feet and weigh more than 330,000 pounds. Like many other baleen whales, female blue whales are generally larger than males.
Behavior and Diet
Blue whales sometimes swim in small groups but are more often found alone or in pairs. They generally spend summers feeding in polar waters and undertake lengthy migrations towards the equatorial waters as winter arrives.
Blue whales typically swim at about 5 miles an hour while they are feeding and traveling, but can accelerate to more than 20 miles an hour for short bursts. They are among the loudest animals on the planet, emitting a series of pulses, groans, and moans, and it is thought that in the right oceanographic conditions, sounds emitted by blue whales can be heard by other whales up to 1,000 miles away. Scientists think they use these vocalizations to communicate and—along with their excellent hearing—perhaps to sonar-navigate the dark ocean depths.
The primary diet of blue whales is krill—tiny shrimp-like animals, but fish and copepods (tiny crustaceans) may occasionally be part of the blue whale's diet. When blue whales hunt for food, they filter feed by swimming toward large schools of krill with their mouth open and closing their mouths around the krill while inflating their throat pleats. Once closed, blue whales then push the trapped water out of their mouth with their tongue and use their baleen plates to keep the krill trapped inside.
Where They Live
Blue whales are found in all oceans except the Arctic. They generally migrate seasonally between summer feeding grounds and winter breeding grounds, but some evidence suggests that individuals in certain areas might not migrate at all. Information about distribution and movement varies with location, and migratory routes are not well known. In general, distribution is driven largely by food availability—they occur in waters where krill are concentrated.
In the North Atlantic Ocean, their range extends from the subtropics to the Greenland Sea. Blue whales have been sighted in the waters off eastern Canada and in the shelf waters of the eastern United States.
Along the West Coast of the United States, eastern North Pacific blue whales are believed to spend winters off of Mexico and Central America. They likely feed during summer off the U.S. West Coast and, to a lesser extent, in the Gulf of Alaska and central North Pacific waters.
Blue whales with young calves are regularly observed in the Gulf of California (Sea of Cortez) from December through March. It is believed that this area is an important calving and nursing area for the species.
In the northern Indian Ocean, there is a "resident" population. Blue whale sightings, strandings, and acoustic detections have been reported from the Gulf of Aden, Arabian Sea, and across the Bay of Bengal. The migratory movements of these whales are largely unknown but may be driven by oceanographic changes associated with monsoons.
In the Southern Hemisphere, Antarctic blue whales occur mainly in relatively high latitude waters south of the "Antarctic Convergence" and close to the ice edge in summer. They generally migrate to middle and low latitudes in winter, although not all whales migrate each year. Pygmy blue whales (Balaenoptera musculus brevicauda)—a subspecies—are typically distributed north of the Antarctic Convergence and are most abundant in waters off Australia, Madagascar, and New Zealand. An unnamed subspecies of blue whale is found in the southeastern Pacific Ocean, particularly in the Chiloense Ecoregion, and migrates to lower latitude areas, including the Galapagos Islands and the eastern tropical Pacific.
World map providing approximate representation of the blue whale's range.
Lifespan & Reproduction
Blue whales' average lifespan is estimated at around 80 to 90 years. Scientists can estimate the age of whales by counting the layers of wax-like earplugs collected from deceased animals.
Scientists know little about the life history of the blue whale. The best available science suggests the gestation period is approximately 10 to 12 months. Weaning probably occurs at around 6 to 7 months on, or en route to, summer feeding areas. The age of sexual maturity is thought to be 5 to 15 years. Most reproductive activity, including births and mating, takes place during the winter. The average calving interval is probably 2 to 3 years.
Threats
Vessel Strikes
Vessel strikes can injure or kill blue whales. Vessel strikes have killed blue whales throughout their range, but the risk is much higher in some coastal areas with heavy vessel traffic, like ports and in shipping lanes, and from larger vessels and vessels traveling at high speeds.
Entanglement in Fishing Gear
Blue whales can become entangled in fishing gear, either swimming off with the gear attached or becoming anchored. Blue whales can become entangled in many different gear types, including traps, pots, and nets. Once entangled, whales may drag the attached gear for long distances, ultimately resulting in fatigue, compromised feeding ability, or severe injury, which may lead to reduced reproductive success and death.
Additional Threats
Additional possible threats to blue whales that are less understood include ocean noise, habitat degradation, pollution, vessel disturbance, and climate change.
Scientific Classification
| Kingdom | Animalia |
|---|---|
| Phylum | Chordata |
| Class | Mammalia |
| Order | Cetartiodactyla |
| Family | Balaenopteridae |
| Genus | Balaenoptera |
| Species | musculus |
Last updated by NOAA Fisheries on 04/21/2022
What We Do
Conservation & Management
All blue whales are protected under the MMPA and ESA. Our work strives to protect blue whales by:
- Reducing vessel strikes
- Responding to dead, injured, or entangled blue whales
- Reducing the effects from ocean noise
Learn more about our conservation efforts
Science
Our research projects have helped us better understand blue whales and the challenges they face. Our work includes:
- Stock assessments
- Environmental modeling to predict where blue whales are in near-real time
- Studying whales' habitat preferences and feeding ecology
- Conducting photographic and genetic identification
- Researching the acoustic environment of blue whales
Learn more about our research
How You Can Help
Keep Your Distance
Be responsible when viewing marine life in the wild. Observe all small whales from a safe distance of at least 100 yards by sea or land.
In Washington State inland waters, it is illegal to approach a killer whale within 200 yards. Please visit Be Whale Wise for more specific instructions.
Learn more about our marine life viewing guidelines
Report Marine Life in Distress
Report a sick, injured, entangled, stranded, or dead animal to make sure professional responders and scientists know about it and can take appropriate action. Numerous organizations around the country are trained and ready to respond. Never approach or try to save an injured or entangled animal yourself—it can be dangerous to both the animal and you.
Learn who you should contact when you encounter a stranded or injured marine animal
Reduce Speed and Be on the Lookout
Vessel collisions are a major cause of injury and death for whales. Here are some tips to avoid collisions:
Be Whale Aware. Know where whales occur (habitat).
Watch your speed in areas of known marine mammal occurrence. Keep speeds to 10 knots or less to reduce potential for injury.
Keep a sharp lookout. Look for blows, dorsal fins, tail flukes, etc. However, be aware that most captains report never seeing a whale prior to colliding with it.
Protect your boat, protect your passengers. Boats can be heavily damaged and even "totalled" after colliding with a large whale. Collisions can also injure passengers.
Keep your distance. Stay at least 100 yards away.
Stop immediately if within 100 yards. Slowly distance your vessel from the whale.
Learn more about vessel strikes
Report a Violation
Call the NOAA Fisheries Enforcement Hotline at(800) 853-1964 to report a federal marine resource violation. This hotline is available 24 hours a day, 7 days a week for anyone in the United States.
You may also contact your closest NOAA Office of Law Enforcement field office during regular business hours.
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Featured News
Science Overview
NOAA Fisheries conducts various research activities on the biology, behavior, and ecology of blue whales. The results of this research are used to inform management decisions and enhance recovery efforts for this endangered species.
Environmental Modeling
Scientists working on the WhaleWatch project are using advanced technologies to predict where blue whales are likely to be in near real-time off the U.S. West Coast. This near real-time information helps reduce human effects on whales by providing information on where the whales occur and hence where whales may be most at risk from threats such as vessel strikes, entanglements, and underwater noise. Scientists developed habitat-based model estimates of whale occurrence that combine satellite tracking of whales with information on the environment.
Learn more about the WhaleWatch project
Stock Assessments
Determining the size of the blue whale population—and whether it is increasing or decreasing—helps resource managers assess the success of the conservation measures enacted. NOAA Fisheries scientists collect population information on blue whales from various sources and present these data in annual stock assessment reports.
Shipboard Studies
NOAA Fisheries' research surveys investigate blue whales' habitat preferences and feeding ecology and collect photographs and genetic samples. Information from this research is used in management actions that protect the blue whale and reduce human-related deaths.
Acoustic Science
Other research is focused on the acoustic environment of blue whales. This research involves:
- Increasing our understanding of the basic acoustic behavior of blue whales
- Mapping the acoustic environment
- Assessing blue whale distribution
- Developing improved methods to locate blue whales using autonomous gliders and passive acoustic arrays
Learn more about acoustic science
Last updated by NOAA Fisheries on 04/21/2022
Source: https://www.fisheries.noaa.gov/species/blue-whale
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