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Thank you so much for celebrating Earth Day with us by spreading a little nature love through art. We are so excited about these creations:
Humpback whales (Megaptera novaeangliae) are large, majestic marine mammals that roam the seas worldwide. They are baleen whales, meaning they have baleen plates instead of teeth. Baleen is coarse and hair-like. It’s made of keratin just like our fingernails and hair! Humpbacks use their baleen to filter out food, like krill and small fish, from the water to eat. These gentle giants have long pectoral fins and a cute knobby head. They’re often seen breaching, or bursting through the surface with an explosive force and then coming back down with a huge SPLASH!
Western South Atlantic Humpback Whales
By: Kealy McNeal
Between the late 1700s and mid 1900s, hunters killed at least 300,000 humpback whales around the world. Some populations are still endangered because of their reduced numbers, but one humpback group in the western South Atlantic (WSA) has undergone a remarkable recovery - here is their story.
The whaling industry drove the western population of South Atlantic humpbacks right up to the edge of extinction (there would be none left). Whales were hunted for their meat and valuable blubber. Oil obtained from a whale’s blubber was burned in oil lamps until electric lights became popular. Whale bones were used to make a variety of useful products that today are made of plastic, such as fishing rods and ribs of an umbrella.
WSA Humpbacks
The WSA humpbacks spend their winters in mating and calving (where baby whales are raised) grounds off the eastern coast of South America, then migrate to feeding-grounds on the border of the South Atlantic and Antarctic Ocean, near South Georgia and the South Sandwich Islands for the summer months. Humpback whales feed on krill (small shrimp-like crustaceans) and small fishes by straining huge volumes of ocean water through their baleen plates.This particular population of humpbacks was hunted from the early 1800s onward, but it wasn’t until commercial whaling expand-ed further south during the early 1900s that the whales’ numbers were the most heavily impacted.
Photo: WSA humpback whale population range in the wintering grounds and areas for allocation of catches in the feeding grounds. Zerbini AN, Adams G, Best J, Clapham PJ, Jackson JA, Punt AE. 2019 Assessing the recovery of an Antarctic predator from historical exploitation.
Essential Fish Habitats
Scientists believe that this population of humpback whales was approximately 24,700 in 1904. By 1926, the population had plummeted to 700 and by 1958 only 440 individuals remained. They were able to estimate the population number based on the shockingly good records kept by the whaling industry.
What happened next saved these whales from certain extinction. Humpback whales have been legally protected from commercial whaling in the southern hemisphere since 1963. In 1982, the International Whaling Commission (IWC) decided there should be a pause in commercial whaling on all whale species for the 1985/1986 season onward. This pause is often referred to as the commercial whaling moratorium, and it remains in place today. This moratorium was adopted by all countries except Norway, Iceland and Japan, where commercial whaling is still observed. Since the moratorium was put in place all whale species, especially the population in western South Atlantic humpbacks appear to have reversed their downward population trajectory.
Photo: Underwater picture of humpback whale mother and calf. Picture taken off Brazil in September 2009. Photo Credit: L.Candisani/Courtesy Instituto Aqualie.
Scientists never really measured the population of the western South Atlantic humpbacks until the 1980’s, but it wasn’t until they conducted a proper assessment at the start of the 2000s, did they realize just how well they were recovering. Estimates of current population size, known as abundance estimates, are derived from a combination of fieldwork and computer modelling. Vessel-based and aerial sighting surveys, acoustic monitoring, and analysis of individual animal markings used independently or in conjunction with each other to count whales.
According to a study that was published in the journal Royal Society Open Science last year in 2019, by a team from the University of Washington, the population of humpback whales in this region is approximately 25,000.That means that the current population is estimated to be at 93 percent of its numbers prior to the exploitation by whalers. Researchers believe there is "a high probability" that the population will be "nearly recovered," meaning that it will have hit 99 percent of its pre-exploitation abundance, by 2030.
The Data
Look at the graph to the left and follow the blue line which represents the population of WSA humpback whales and observe the steep drop around the year 1910 when the red line spikes. The red line is the number of humpback whales caught by the whaling industry every year. Can you see what happened to the whales in 1982 when the moratorium was established? This graph even looks into the future — what does the whale population look like in 2030?
They are not out of the woods quite yet. Even though they have beat the odds and bounced back from the brink of extinction, these whales still have some obstacles to face. The threat of hunting has been replaced by the threat of competition for food and climate change, which may be impacting the distribution of krill, humpbacks’ most common food source.
As the population of humpbacks rises, so does the demand for their food. They not only compete with each other but with other species, like penguins and seals. An average humpback can eat 3,000 lbs of krill in just one day during the feeding season. At their present population size, humpbacks in this region consume 1.5 to 2.6 million metric tons of krill in a single season.
Although the near-term future for western South Atlantic humpback whales appears bright, scientists need to keep an eye on them and their food source. Nevertheless, this is very good news, providing clear evidence of how an endangered species can spring back from near extinction given the right policy changes, collective action, and management. Stories like this one, of the whales we know and love so well, should help us all have hope that through cooperation and work, we can conserve the many special things nature has to offer.
additional cool resources
Learn more about Humpback Whales
Where to See Humpback Whales!
Whale Songs
Why humpbacks sing is still a mystery. Researchers in Maui are trying to figure out the meaning of the whale’s song.