Pink Amazon River Dolphin may disappear within ten years in the Amazon
Research team rushes a pink  Amazon River dolphin pup back to the water after rapid capture for collection of biological material. Photo: Ampa

The pink Amazon river dolphin (Inia geoffrensis) is found only in the Amazon and Orinoco Rivers and tributaries. This beautiful and intriguing mammal can become a regional folklore character in the not so distant future. This, according to Nívia do Carmo; a Brazilian researcher and fellow at the National Institute for Amazonian Research ( INPA ). If the killing of pink Amazon River Dolphins by fishermen at the riverine communities continues at its current rate, the dolphin may become extinct within ten years.

Study says 10 % of the Pink Amazon River Dolphin population is hunted every year in the Brazilian Amazon. Dolphins are killed to be used as bait to catch catfish.

catfish caught using dolphin meat
Catfish caught using dolphin meat as bait. Photo; Ampa

According to Nívia do Carmo, the number of pink Amazon River dolphins is decreasing rapidly due to the intensive hunting for bait. Pink dolphins are killed, cut into pieces and put in cages to attract catfish, which is subsequently trapped in the cages. Local fishermen assure that when it comes to bait for catfish, nothings comes close to the meat of a pink Amazon River Dolphin. In Mamirauá, a intensively studied wildlife management area located 600 km from the city of Manaus, it has been estimated that about 1,350 dolphins are killed every year. This is about about 10 % of estimated Pink Amazon River dolphins estimated to occur in the region.

There are two species of Amazon River Dolphins. The pink Amazon River dolphin and gray Amazon river dolphin (sotalia fluvialis). The Gray Amazon River dolphin occurs in the same rivers alongside their pink cousins. However, gray river dolphins tend to favor smaller tributaries, and unlike the friendly pink dolphins, gray river dolphin keep themselves away from boats and the harpoons used to capture them.

sotalia_fluviatalis_gray amazon river dolphin.
Gray Amazon River dolphin is the other dolphin in the Amazon basin.

The switch from subsistence to commercial fishing among local fishermen has worsened the problem. Stimulated by economic incentive, local fishermen will fish as much catfish as they can to be sold in the city of Manaus. Large refrigerators boats will provide ice to local fishermen to preserve the fish before it is shipped to the city for consumption. In exchange, local fishermen get merchandise and money.
Populations of the Pink Amazon River dolphin cannot keep up with the intensive hunting largely due to its low rate of reproductive productivity. A pup dolphin takes seven years to attain sexual maturity or become pregnant. Females go through a gestation period of seven months, and take care of a cub for five years before becoming sexually receptive and pregnant again.

Effects in nature

Pink Amazon River Dolphins are top predators in the Amazonian aquatic ecosystems they live. They feed nearly exclusively on fish. Among other functions in the ecosystem, dolphins will consume weak and diseased fish keeping potential disease outbreaks at bay. If dolphins disappear the balance of the ecosystems could break down in unforeseeable ways. Moreover, other large predator would likely occupy the vacant ecological niche. Such top predator may be caimans or other Amazonian large predator.

Pink Amazon River Dolphin.
Adult pink Amazon River dolphin. Foto: Yasuyoshi

The regional government is working on a campaign that seeks to educate local people on the effects of overhunting dolphins. This campaign is based on stories with elements and consequences local fishermen can relate and understand. The ultimate purpose is not preventing local people from subsistence fishing or hunting, but finding alternatives that allows them to use their resources in a sustainable manner.

In another measure the local natural resource agency has banned the commercialization of catfish in supermarkets in the city of Manaus. A 6-month moratorium is in place until research on dolphin populations and catfish fishing yields results that enable the crafting of management policies.

SOURCE [G1 Amazonas – OGlobo Brazil]

The Pink Amazon River Dolphin may disappear within ten years in the Amazon