Rescuing River Dolphins With the Help of Satellites
Written by the research team at the Instituto Araguaia
The Araguaia river dolphin (Inia araguaiaensis) is one of the most endangered dolphins on Earth. Uniquely adapted to shallow waters, it only occurs in the Araguaia river of central Brazil and its tributaries. Perhaps fewer than 1000 remain, a dwindling population threatened by dams, overfishing, and killings by fishermen, who see them as competitors.
Instituto Araguaia is a local Brazilian non-profit that works to save the Cantão ecosystem, where the Amazon flooded forest meets the Cerrado — the most biodiverse savanna on Earth. Located along the mighty Araguaia river, Cantão Park is the best remaining refuge for the Araguaia river dolphin, as well as other endangered river species like giant otters, river turtles, and the great arapaima, the world’s largest freshwater fish.
From our base deep in the park, we help protect critical habitat and we monitor the top predators, including the dolphins. They are truly unique and amazing: in the wet season, they chase fish among submerged tree trunks, deep in the flooded forest; in the dry season, they can belly crawl from pool to pool over sandbanks as shallow as 20 cm in search of prey. No other dolphin does this. When they do this, they sometimes fall prey to jaguars, the most aquatic of all big cats, which pounce on them from the riverbanks!
But this unique behavior also puts the dolphins at risk from unnatural causes: tributaries of the Araguaia to the south of Cantão are being dammed and pumped nearly dry for large-scale agriculture. River dolphins become trapped in dwindling pools, where they can overheat and run out of fish prey before the floods return. This year, a dozen dolphins had to be rescued, and at least three died before they could be saved. With so few remaining in the wild, every individual counts. But capture and translocation in the tropical heat are also risky and traumatic for this delicate species.
Instituto Araguaia must monitor groups of at-risk dolphins throughout the dry season, so that we can identify and rescue only those in imminent danger. The best and most cost-effective way to accomplish this is with real-time, high resolution satellite imagery, so that we can watch drying stretches of river where we know dolphins are trapped, spread out over hundreds of kilometers, without having to send out a ground team over the bad or nonexistent roads. This is where our partnership with Planet comes in.
Since our partnership began, Instituto Araguaia’s scientists and rangers have been using Planet imagery for a wide variety of purposes related to research and conservation. We have used them to detect illegal deforestation and unlicensed construction in the park’s buffer zone; and to better understand the monthly changes in river dolphin and giant otter habitat, as the river levels rise and fall.
Recently, we discovered that we can even use Planet to map the distribution of high and low ground in the nearly flat Cantão floodplain. For half the year, most of the park is flooded, as the Araguaia rises 6 to 8 meters during the rainy season. The few remaining areas of “high” ground become extremely important, as all the park’s terrestrial species become crowded in the 10–20% of the area that remains above water. These higher spots are no more than 1–2 meters above the rest, but they are ideal for setting camera traps. Knowing where to find them enables us to get images of jaguars, ocelots, and giant otters deep in the flooded forest, and for all three species we can identify individuals, and thus study the population.
But due to the dense rainforest canopy, it is impossible to even see the ground from above, let alone measure elevation with enough precision to find high ground. With Planet, however, we can look at images taken during the precise 5–8 day period in August (dry season) when the yellow ipê tree (Handroanthus) loses its leaves and flowers, dotting Cantão with its gorgeous flaming yellow crowns. Planet imagery has enough resolution to show each individual tree, and since ipê only grows on high ground, to locate every spot of high ground in the vast Cantão wilderness, however small and deep in the forest. This represents tremendous scientific power, allowing us to monitor and understand the ecosystem in ways that were unimaginable just last year, when access to real-time, on-demand, high-resolution imagery was simply not possible for scientists in the field.
Not long after the above image was taken, we were called upon to help assess whether a group of river dolphins trapped behind an irrigation dam in a river south of Cantão needed to be rescued. Capture and relocation is a last resort, as it is very stressful and risky for the animals, but in this case we could see it had to be done, as water levels were dropping daily. When it became evident that the remaining pool of water was not enough for the dolphins to survive until the floods returned, it was time for action! Take a look at what we did:
The rains have returned now, and the waters are rising, but we are readying ourselves for the next dry season, when new irrigation projects will mean even more danger for the dolphins. We have identified a number of locations where dolphins may be at risk. Thanks to Planet, will be able to monitor them all on a daily basis next dry season, and to organize timely rescues if necessary. Planet’s support is really revolutionizing the way we work with endangered species and ecosystem management — and it seems that every day we come up with a new application!
For more information visit www.araguaia.org and www.planet.com.
