Cetaceans are an order of aquatic mammals that include 90 species of whales, dolphins and porpoises. They are known for high intelligence and complex social behaviors. Cetaceans live in all of the world’s oceans and some rivers. Some species live in very specific regions, while others migrate over thousands of miles through the ocean.
The smallest cetacean is the vaquita at 120 pounds (54kg) and 4.5 feet (1.4m) long. The largest cetacean species is also the largest animal that has ever lived on Earth, the blue whale. The largest one ever recorded was 33.5m long (over 110 feet); they weigh up to 199 tons.
Of the 90 species of cetacean, 32 are listed as threatened, vulnerable or endangered. Four of these are critically endangered: the Yangtze River dolphin, the vaquita, Atlantic humpback dolphin, and North Atlantic Right whale.
Cetaceans benefit the ocean and its many ecosystems in several ways as are helping in the fight against climate change.
First, cetaceans modify the habitats in which they live. And since many species migrate over thousands of miles each year, that can have a huge impact. Whales and dolphins feed at varying depths but generally eliminate waste at the surface. Their waste provides nutrient fertilization to ecosystems at various depths below; increasing the growth of phytoplankton, benefitting the food chain and renewing fish stocks.
Moreover, when whales die, their massive bodies often fall to the sea floor. If they reach the deep sea (below 1000m (3300 ft), the whale carcass, and eventually the skeleton, create a localized ecosystem that supports deep sea creatures for years or even decades.
Not only do cetaceans fertilize marine ecosystems, but they help to absorb carbon. On average a whale, over its lifetime, captures the same amount of carbon as 1000 trees. When they die and sink to the ocean floor, that carbon remains locked away from the atmosphere; they are natural carbon dioxide regulators.
For centuries, whales were hunted throughout the ocean. By the mid 1900’s many species were nearing extinction. In 1986, an international moratorium was placed on whaling. Most countries in the world stopped hunting whales although Iceland, Norway, and Japan have done so since that time. However, in 2017, for example, just under 1500 whales were hunted worldwide, compared to as many as 50,000 annually in years before the ban. Since that time, whaling is no longer a major threat to cetaceans, but other threats endanger the lives of these marine mammals.
Entanglement in fishing gear is the leading threat for whales and dolphins worldwide; responsible for approximately 300,000 deaths per year. Some nets or lines are huge and difficult to avoid. Others are thin and difficult to see. When cetaceans are entangled in either and unable to escape, they die a slow death through either suffocation or starvation. The critically endangered right whale population migrates along the east coast of the US and Canada avoiding the 1 million fishing lines they pass along the way; 84% of all right whales have been entangled in these lines at least once.
A heartbreaking example of the devastation of entanglement is the vaquita, the smallest cetacean species. Vaquita live exclusively in the Gulf of California off of Mexico. Fishermen use gill nets to catch totoaba, a fish species, prized in China. Due to their similar size, vaquita are often caught and trapped in these nets and suffocate. The amount of entanglement is so great that fewer than 10 individuals remain alive, a 98.6% decline in just 10 years.
Bycatch refers to unwanted fish or other marine creatures inadvertently caught while targeting another species. Since dolphins are often found near schools of tuna, fishermen search for dolphins to find the tuna they are seeking. Historically, they would place their nets in a circle around the group in hopes of catching tuna inside, without regard for any dolphins also caught. Fortunately, companies are monitoring fishing methods and reporting which brands of tuna are “dolphin-safe,” which has reduced, but not eliminated dolphin bycatch.
Shipping traffic increased 300% between 1992 and 2013, and continues to increase annually by 2-3%. And it’s not just more ships, but larger and faster ones. Many of the busiest shipping lanes worldwide overlap with cetacean feeding, breeding, and traveling routes. Since cetaceans are mammals and must come to the surface to breathe, there is an increasing danger of collision with ships; especially as there are more ships that are moving faster. Ship strikes are one of the leading causes of death, especially in large whale species. The exact numbers of fatalities are unknown since most of the corpses sink to the ocean floor rather than washing ashore.
Like many other marine animals, whales and dolphins accidentally swallow plastic debris, either as part of filter feeding, or mistaking it for squid or other food. Once ingested, this plastic can cause fatal internal injuries, can break down and release toxins into the animal’s body, or can fill the stomach causing a false feeling of being full. One stranded sperm whale was found to have 135 plastic bags and other plastic items in his stomach when he died.
Noise pollution also threatens the existence of cetaceans. Large ships and boats make a tremendous amount of noise that falls into the same frequency range as their communication. Since sound plays a vital role in the life of whales, dolphins, and porpoises, noise pollution is one of the most prevalent dangers facing them.
Climate changes can affect cetaceans in several ways: from changes in temperature, to the loss of polar habitats, to changes in currents and migration patterns. Global warming particularly affects bowhead, narwhal, and belugas, who live year-round in arctic waters. However, krill, tiny shrimp which are a primary food source for many large cetaceans, also rely on cooler temperatures and are in decline.
Pressure Your Government to Change Regulations in the Shipping & Fishing Industries
Governments must work together to minimize entanglements and ship strikes to protect endangered cetaceans.
Reduce Your Carbon Footprint
Support Organizations that Advocate for Cetaceans
There are many organizations lobbying for cetaceans. They need your support. Captive cetaceans need a voice, but those in the wild also need regulations to protect them from human-induced threats. Use your voice and spread the word.
Many organizations do amazing work to educate people about the importance and the threats to cetaceans and their habitats. Learn more about some of these organizations, their work, and what you can do:
Indo-Pacific Humpback Dolphins, Hong Kong
There are approximately 2000 of this dolphin species left in the wild; they have seen an 80% drop in population in the last 15 years. However, thanks to travel restrictions during 2020, the waters around Hong Kong, usually teeming with high speed ferries, have seen a 30% resurgence in sightings of these dolphins.
South Atlantic Humpback Whale Recovery
In the 19th and 20th centuries, the humpback whale was hunted to near extinction. Since the whaling ban in 1986, South Atlantic humpback whales now number over 24,900, compared to 440 animals in 1958. This population has recovered to 93% of their pre-whaling numbers.
Whale Safe, Whale Detection System
Whale Safe is a new technology developed to help reduce cetacean ship strikes. The system produces daily alerts of the likelihood of encountering whales on a given day in a given location. The system uses a combination of whale sightings, underwater acoustic detection, and habitat suitability to predict whale locations. As an added bonus, it grades shipping companies on whale safety to incentivize companies to do the right thing, and publicly recognize those that do.
Salt Mining San Ignacio Lagoon, Mexico
In March 2000, Mitsubishi planned to build the world’s largest industrial salt mining factory in a breeding and calving lagoon for Pacific grey whales. Due to massive campaigns by environmental groups in Mexico and around the world, the Mexican government abandoned the plan; reminding us that we have a voice and should use it!
Canada Bans Captive Whales and Dolphins
In 2019, Canada’s parliament passed legislation preventing whales, dolphins, and porpoises from being bred or held in captivity bowing to public pressure.