River Dolphin Rescue: Our Animal Response Team in South America

Diverted waters, disappearing habitats

Bolivian river dolphins (Inia boliviensis), locally known as “bufeos,” are increasingly threatened due to shifting river waterways secondary to agriculture and dams. These humanmade blockages are causing bodies of water attached to the river to shrink and dry up. As a result, dolphins that once had access to the river are becoming trapped and exposed to large amounts of agricultural runoff, possibly containing high levels of chemicals and pollutants.

The Noel Kempff Natural History Museum and government of Bolivia were notified years ago by local villagers about a group of approximately 15 dolphins trapped within the lake, which was decreasing in size. After more than a year of planning, obtaining permits and assembling a team and equipment, the group of collaborators was ready to relocate as many dolphins as possible. Our goal was to perform health assessments on the dolphins, place satellite tags to track their movements and translocate them back to their native river, the Rio Grande.

The museum has been rescuing river dolphins throughout Bolivia for eight years, but never mounted a rescue of this magnitude. For the first time, the rescue work would include full veterinary health examinations to gather baseline data on their condition and assess how their health and well-being might have been affected by the constriction of their habitat in these isolated lakes.

As a zoo, wildlife and aquatic veterinary specialist in training, I worked alongside Dr. Ellen Bronson, Dr. Med. Vet., Diplomate of the American College of Zoological Medicine, of the Maryland Zoo in Baltimore. We performed full physical exams, blood evaluations, blowhole, genital and oral cell evaluations, and fecal parasite and infectious disease screenings. We also monitored the dolphins throughout collection and transport.

Into the rainforest

In late October, we gathered in the city of Santa Cruz de la Sierra. Our team of about 20 included biologists, forest firefighters, local villagers and even cooks! Over the course of several days, we planned the logistics of travel, camping, collection, health assessment and release of the dolphins.

After a bumpy 12-hour truck ride over highways and through rainforest, we arrived at our lakeside campsite at dawn—in time for the raucous wake-up calls of the beautiful blue-and-gold macaw population.

Surrounded by the sights of palm trees and lily pads and the sounds of frogs, howler monkeys and dozens of bird species, we built our tents under tarps tied between trees for extra shelter from heavy rainstorms. We established water supplies from a natural well dug into the ground and water tanks from nearby towns, and designated latrine and shower locations. Over the next couple of days, we prepared the boats, nets, trucks, release route and medical supplies. We talked to villagers about our project and asked for access to water towers as we drove through their communities with the dolphins.

Finally, we set out in four flat-bottomed boats on a 15-minute ride to a smaller channel on the north end of the lake. It used to connect to a larger lake but is now too shallow for dolphins, let alone boats, to travel through. Amazingly, as if in on the plan, the curious and gregarious river dolphins followed our boats to a small cove where we set up our laboratory. The team put out nets, making smaller areas around one or two dolphins, then entered the chest-deep water and slowly, quietly made a smaller circle around one dolphin.

Exam in an outdoor laboratory

On shore, we watched patiently, ready with all our equipment, including the mattresses in kiddie pools where the dolphins would lie during their exams. Slipping a soft net underneath a dolphin, the team lifted it into the boat to transport it to the laboratory. We were pleasantly surprised by how calm the dolphins remained throughout the procedure.

As soon as the dolphin was transferred to the laboratory, it was go time. Our goal was to be as complete and efficient as possible. Dr. Bronson and I divided duties to minimize the exam time. Biologists and other team members helped by safely holding the dolphins, keeping them moist, monitoring respirations, writing notes, taking photos and recording measurements.

Working quickly, we noted physical abnormalities such as scars or old, healed bone fractures; listened to the heart and lungs; did ultrasound scans to check for pregnancy and measure fat depths; collected blood from the ventral tail vein; took oral, genital and blowhole swabs for cell evaluation; collected a fecal sample; obtained a body weight using a scale built between two trees and recorded body measurements.

Dolphin differences

I expected these dolphins to be interesting, but I was astounded by their unique anatomy, tranquil personalities and striking differences from the marine cetaceans at Shedd.

They had unique coloring—varying mixtures of gray and pink that seemed to depend on age and size (younger/smaller, more gray; older/larger, more pink). Their laterally compressed bodies and long, flexible pectoral fins allowed them to lie easily on either their left or right side, differing from marine dolphins, which more easily lie on their stomach when out of water.

Living in muddy rivers, vision is less important, as evidenced by their small, simple eyes. Their tactile sense, however, is enhanced by vibrissae, or whiskers, along their entire beaks. In contrast, marine dolphins shed these hairs shortly after birth. Echolocation—cetaceans’ sonar—helps them navigate opaque waters and locate prey using their flexible melon. Inside their long mouth are many dark, cone-shaped sharp teeth surrounding a small, stubby tongue. Along the back is the small dorsal fin, which served as the location of satellite tag placement.

After completion of the exams, we moved each dolphin into a boat and transported them back to the camp. They were transferred onto a mattress in the bed of a small pickup truck outfitted with a tarp to hold water, like a kiddie pool, to keep them wet, and an overhead shade, along with a sheet placed over their bodies, to protect them from sunburn.

A team of four or five people including a veterinarian rode with each a dolphin during the 2½-hour, 33-mile drive to the river. The biggest relief was arriving safely at the release site with stable animals. We placed satellite tags on their dorsal fins and then released them into the Rio Grande.

Labwork by moonlight

Back at camp, we processed our samples by moonlight, among mosquitos, moths and crabs, until well past midnight, using a battery-powered microscope and centrifuge. We spent hours counting blood cells, scanning for fecal parasites, examining cells from the blowhole, genital and oral swabs, centrifuging and organizing samples for storage and preparing our materials for the next day’s adventure.

At the end of our time at the remote lake, we were able to rescue, examine and release six Bolivian river dolphins (one female, four adult males and one juvenile male), all deemed healthy based on their physicals and initial labwork.

On the return trip to Santa Cruz, we had another exciting encounter with wildlife: a Bolivian red rump tarantula. You know a spider is big when you spot it a football field away and have to stop the truck to let it cross the road!

Can we meet the ultimate challenge?

Nothing about this trip was easy, and our team overcame many challenges new to me: a delay in departure to the field due to a highway blockade; having to find a new release route to the river because our plan A “road” was washed out by rain; and learning how to keep refrigerated medical equipment cool for 10 days in the 90-degree jungle, how to turn a truck bed into a pool for better dolphin transport and how to push trucks out of the mud using palm fronds—all in Spanish. The dolphin collection and assessments turned out to be the smoothest part.

Each day I was impressed by this team’s strength, camaraderie, work ethic, passion, inventiveness and dedication to saving these incredible and threatened animals safely and successfully. We are hopeful that this project will continue with this wonderful collaboration because more dolphins need rescue.

Thank you for supporting Shedd Aquarium. You make it possible for the Animal Response Team to help animals in need around the globe, including the rare and charismatic Bolivian river dolphins!

—Dr. Julie Sheldon