Are Dolphins Endangered? They Are and the Sad Reasons Matter
Are dolphins endangered? Several species and subspecies of dolphin are threatened and the reasons are all man-made. Many human activities, whether done intentionally or by accident, have adverse environmental impacts and result to the decline of dolphin population and increase their risk of becoming extinct.
Animals across the world, including dolphins, are facing issues that threaten their existence. In 2006, a freshwater species of dolphin was declared functionally extinct. Its extinction was mainly attributed to the destruction of its habitat.
The last known encounter of these dolphins was in 2002. Although more recent sightings have been reported, none of them were verified.
Why are dolphins endangered? What is causing the steady decline of their population?
What Being Endangered Means - Nine Categories of Conservation Status
The International Union for Conservation of Nature (IUCN), an international organization that focuses on conservation and sustainability, founded in 1965 the IUCN Red List of Threatened Species. Also called the IUCN Red List, it’s the most comprehensive record of the conservation status of plants, animals, and fungi. The conservation status indicates whether a species is already extinct or how likely an existing group will go extinct sometime in the near future.
The IUCN Red List classifies species into nine categories based on factors such as population size, rate of population decline or growth, breeding success rates, geographic distribution, known threats, and actions being taken to protect the species.
The nine categories of conservation status are:
- Least Concern (LC) - widespread and abundant; lowest risk of becoming endangered
- Near Threatened (NT) - most likely to be endangered
- Vulnerable (VU) - high risk of becoming endangered
- Endangered (EN) - high risk of becoming extinct
- Critically Endangered (CR) - very high risk of being extinct
- Extinct in the Wild (EW) - surviving individuals are found only in captivity
- Extinct (EX) - no known surviving individuals
- Data Deficient (DD) - risk of extinction not assessed due to insufficient data
- Not Evaluated (NE) - hasn’t been evaluated yet against the criteria
The Endangered Dolphins
In a broader sense, the term "endangered" is used to describe species listed as Vulnerable, Endangered, and Critically Endangered.
There are at least 36 known species of dolphins and a few more different subspecies. According to the IUCN Red List, 5 species and 6 subspecies of dolphins are endangered.
Baiji / Yangtze river dolphin
Yangtze River, China
* considered extinct after researchers failed to locate a single dolphin
coastal waters of North Island, New Zealand
* one of the two smallest known dolphin species along with Hector's dolphin * one of the rarest type of dolphin with a population of less than a hundred
Ganges river dolphin
Ganges and Brahmaputra Rivers of India and Bangladesh
* with current population of less than 2000 * essentially blind
Indus river dolphin
Indus River in Pakistan
* can only detect light intensity and color * often swims on its side
waters of New Zealand
* named after James Hector, the first person to study their species
Atlantic humpbacked dolphin
coastal waters along Morocco to Angola
With a hump on where the rounded dorsal fin is
Quite shy; avoids boats and contact with humans
rivers, lakes, coasts, and estuaries in South and Southeast Asia
Reproduces a single offspring every 2 to 3 years
One of the primary causes of death is drowning in fishing nets
La Plata river dolphin or Franciscana
southeastern South America
Has the longest beak in proportion to its body size among cetaceans
The only type of river dolphin that also lives in saltwater estuaries and the ocean
Black Sea bottlenose dolphin
The male usually grows larger than the female unlike other dolphin species
Extremely curious and excited to be in contact with humans
Black Sea common dolphin
Avoids seawaters with low salinity
With distinctive color pattern and color bands on its sides
Eastern spinner dolphin
Eastern Pacific Ocean, coastal waters of Central America and Mexico
Stays in deep water during the day unlike other spinner dolphins
Spins on its axis after leaping high out of water
While the number of threatened species seems small, it should be noted that not much is known about one-third of the dolphin species. And it’s not impossible that they could also be endangered. Being classified as either Data Deficient or Not Evaluated means that there’s no urgency to implement actions geared toward their protection and conservation.
In some cases, a species under a less critical status have subspecies or subpopulations that are under more serious threat. One example of this is the Irrawady dolphin. While the species is considered vulnerable, five of its many subpopulations are critically endangered.
Another example is the common bottlenose dolphin. It’s classified under Least Concern but one of its subspecies is endangered. In addition, two of its subpopulations are categorized under Vulnerable and Critically Endangered.
Why Are Dolphins Endangered?
Dolphins in the wild face natural threats. They serve as prey to a few top predators, essentially orcas and some larger sharks. They also have to compete with these predators for food.
But the biggest threat to dolphins is man. For a couple of centuries, human activities have dramatically altered the environment. Their related impacts have significantly added to the risks that dolphins have to contend with.
The adverse effects of climate change are felt by many marine animals including dolphins. The rising water temperatures affect the ocean currents altering migratory pathways, feeding grounds, and prey distribution. Scientists and conservationist are concerned that dolphins won’t be able to adapt to these conditions fast enough to sustain their populations.
The rising sea levels due to thermal expansion and melting of ice sheets is also detrimental to some dolphins. Those species that live in brackish waters - areas where rivers meet the oceans - are losing their habitat.
Chemical and Debris Pollution
Oil and chemical spills contaminate and destroy the natural habitats of dolphins. Microplastics and other debris, which are known to absorb toxic persistent organic pollutants (POPs), have been found inside the stomach of dead dolphins and other animals.
These pollutants are believed to weaken the dolphins’ immune system. They also result to an increase of infant mortality rates. Moreover, the effects of contamination on them are compounded as they eat other contaminated marine animals.
Sea Traffic and Noise Pollution
Dolphins rely heavily on their sense of hearing. In murky or dark waters, they use echolocation to protect themselves from predator, navigate, locate their prey, and hunt.
Sounds coming from shipping, seismic testing and offshore drilling for oil and gas exploration, military activities, and ocean research contributes to noise pollution that affects dolphins. They can cause confusion or actual impairment of the dolphins’ hearing. It’s believed to be the main cause of mass stranding of dolphins, which can possibly lead to their death.
Dolphin hunts are commonly practiced in Japan and the Faroe Islands, but they’re also done in countries throughout Central and South America, South Pacific, and West Africa. Most of them harvest dolphins for food despite the fact that their meat contains toxic levels of substances such as mercury. Others, mainly fishermen, believe that dolphins destroy their fishing nets or compete with them.
Modern techniques employed by large commercial fishing vessels are a lot more efficient than those used a century ago. As a consequence, the number of traditional dolphin preys have been significantly reduced.
Dolphins are also vulnerable to entanglement in commercial and discarded fishing gears. Dolphins can’t breathe underwater. Thus, getting entangled leads to drowning and their death.
Tuna fishing is often associated with large numbers of dolphin deaths. Yellowfin tuna is commonly caught through indiscriminate capture. Because several species of dolphin swim with schools of yellowfin tuna, massive numbers get caught along with tuna, and they are eventually exterminated.
River dolphins are most susceptible to habitat loss. Living in highly populated regions, their existence is constantly threatened by humans either on purpose or by accident. In addition, construction of dams and other waterfront development drastically alters and destroys their habitat.
Dolphins are captured for research and entertainment purposes. With tourist attractions offering the chance to interact and swim with dolphins becoming more popular, more have been brought to captivity.
Conservationists claim that the removal of dolphins from their natural habitat and the transportation lead to more deaths. Even if they survived the process, they are exposed to several diseases in captivity tanks.
What You Can Do
Humans are the main reason why the numbers of dolphin species are continuously decreasing. Although conservation requires immense global effort, you can choose to not add to the problem, and become part of the solution by doing these things:
- Become more responsible and actively recycle for less waste
- Do not patronize tourist attractions that offer irresponsible animal interactions
- Lower your carbon emissions to reduce global warming by opting for environmentally-friendly vehicles
- Participate in government and private conservation efforts
- Encourage your family, friends, and other people to do the same
Raise awareness and let other people know about endangered dolphins by sharing this article on Facebook, Reddit, Pinterest, or Twitter.
- Why Are Dolphins Endangered? By Whale Facts - https://www.whalefacts.org/why-are-dolphins-endangered. Retrieved on May 5, 2019
- IUCN Red List Categories and Criteria, By iucnredlist - https://www.iucnredlist.org/resources/categories-and-criteria. Retrieved on May 5, 2019
- Dolphin Threats, By seethewild - https://seethewild.org/dolphin-threats/. Retrieved on May 5, 2019