The critically endangered pink river dolphin could be threatened by the end of a fishing ban in Brazil

• The Amazon river dolphin, known for its pink color, is a critically endangered species of freshwater dolphin.
• A ban on hunting catfish was lifted in Brazil last month, leading researchers to fear that poachers will kill river dolphins to use as bait.
• The dolphins, or botos, hold a special place in local culture, with one legend saying the dolphins turn into humans walk ashore at night.
• View more episodes of Business Insider Today on Facebook.

The end of a local fishing ban in Brazil may signal good news for fishermen — but researchers are afraid it will spell disaster for a rare species of dolphin.

The Amazon river dolphin, or boto, is critically endangered, with a population somewhere in the thousands. Known for their distinctive pink color, the freshwater dolphins have seen their population dwindle by 94% since 2000, according to one estimate, because of pollution and poaching.

Now, some are concerned that botos face another existential threat.

Last month, a legal moratorium on hunting catfish was lifted, leading researchers to fear that poachers will now hunt and kill dolphins to use as bait — a practice that poachers already did illegally. They also killed the dolphins to prevent them from raiding fish from their nets.

The catfish ban, put in place in 2014, was a victory for scientists. But now they fear the dolphins will be decimated, since before the ban, an estimated 2,500 dolphins were being killed each year for bait.

"We don't want the dolphins to become just a legend of the Amazon," said Vera da Silva, a researcher at Brazil's Mamirauá Sustainable Development Reserve. "We want them to exist for a long time."

Environmentalists at the Mamirauá reserve in the state of Amazonas have been fighting the local fishing industry for decades. Da Silva's team tracks the local boto population's size and health by catching the dolphins with nets and bringing them back to the lab, where they are examined, measured, and then marked prior to release.

The researchers' work is cut out for them. Rebuilding a population depends on a species' reproductive cycle, and in the case of dolphins, the process is longer than usual — mother dolphins' pregnancies last 13 months, and they nurse for two years. As a result, females only reproduce every three to five years.

To people of the Amazon, botos hold a special importance. Local legend says the creatures have magical powers, including the ability to come ashore at night as humans. Some indigenous people believe killing or eating a river dolphin brings years of bad luck.

"I never stop being amazed by them. They are fascinating animals," da Silva said.

''We have the duty and obligation, not only as biologists, but as a society, to preserve and maintain mainly the endangered species, which we know will disappear from the Amazon and from the world. Every time an animal species disappears, humanity certainly loses out."