In July we received the sad news about nine river dolphins that had been trapped into a tributary river in Bolivia, which turned into a desperate situation for a group of people who tried to find a solution.

During the dry season, river dolphins of Bolivia are found in major rivers and tributaries where the levels of water are suitable. During the rainy season, water levels increase and river dolphins enter the various tributaries, now available, to feed. Many areas of Bolivia are suffering, as in many other countries, the clearing of forest to turn it into farmland. The river water is used for irrigation in these areas, thus smaller rivers are modified through a drastic reduction of its flow.

Such was the situation in Bolivia that water levels drop rapidly and the affluent where these dolphins, known in that area as bufeos, inhabited, was isolated due to the great amount of sediment deposited in the river's mouth at a time of flood, thus trapping dolphins with no way out of that tributary.

The group of dolphins trapped in the tributary, called Río Pailas, affluent of the Río Grande, one of the major Amazonian rivers of Bolivia, consisted of six adults, two calves and one juvenile. This dolphin, Inia geoffrensis boliviensis is one of the largest river dolphins and is strictly a freshwater dolphin. As we mentioned above, the sudden flood caused the blockade of the Pailas’s mouth, which resulted in a critical situation because of the forthcoming dry season when the flow decreases rapidly and rivers dry up, fearing that final destiny for these dolphins was death.

While weather conditions helped the situation, as cold weather extended a bit helping to slow down the arrival of the dry season, a group of researchers, in collaboration with WDCS and other organizations, was planning for weeks a possible rescue of the cetaceans. While they studied the way to carry out the rescue and relocation, the dolphins were continuously monitored to ensure their welfare.

Planning the rescue became a set of critical and extremely difficult decisions. Nearby areas where dolphins could be released are practically destroyed and there is almost no natural habitat due to changes in land for cultivation. Thus, in addition to the rescue there had to be a removal of animals, which should be planned carefully to minimize the stress of the dolphins.

Fortunately Enzo Aliaga-Rossel and a team of collaborators found appropriate sites for the release of the trapped group. This site was found downstream about 360 km north of the Santa Cruz city and was chosen because the families that live in that area have reported regular sightings of river dolphins and they also argued that there is an abundance of fish for this strip of river. For this, it was decided to capture the dolphins, transport them by truck to the Rio Grande and eventually move them by boat to the release sites.

A curious fact to highlight was the surprise of this group of people when, instead of the 9 dolphins they were planning to save, they finally rescued 20 individuals that had been trapped!

All these issues make us think on the long road we still have to investigate about this and many other species of cetaceans for which the information on their biology or distribution is scarce. Furthermore, this alerts us, once again, about the actions of human beings that cause changes on the Earth affecting the species that inhabit it.

We congratulate the group that with all its effort managed to save this group of dolphins

Source:

WDCS Latinoamérica