The Threats

River dolphins are under different anthropogenic threats, which may be diminishing their populations, among them we can mention:

DIRECT (BAIT, FOOD, POISONING)

As of 2000 there was no evidence that dolphins were deliberately hunted for use as bait. However, since then it it seems that this kind of activity is increasing and is one of the most important threats in Peru, Colombia and Brazil. In both these countries there is evidence that the river dolphins are used as bait to catch the “mota” fish (Calophysus macropterus) which is highly appreciated for its meat.

In Peru dolphins are considered by fishermen to be competitors for their catch and are consequently deliberately killed to reduce the dolphin’s encroachment upon their fishing waters. Dolphin mortality rates due to such practice are high in Peru and this type of threat is constant and relatively common. There are also recorded cases of deliberate poisoning of these mammals but most of these events are not known by the public or the authorities.

INDIRECT, INTERACTIONS WITH FISHERIES

Dolphins often become entangled in fishing nets while preying on fish and inevitably break the nets struggling to free themselves, resulting in economic losses to the fishermen who in turn prefer to kill them on sight.

Fishermen

BOAT TRAFFIC

It is well documented that non-regulated navigation on river where there are populations of aquatic species (specifically dolphins) has a detrimentally effect on their behavior patterns. Also there are injuries caused by accidents with boat propellers. Although noise pollution can be a threatening factor in behaviour and feeding strategies on river dolphins, no studies of these effects have yet been conducted in Peru.

Boat traffic

DOLPHIN PRODUCTS

Dolphin teeth and oil have been seen in some Iquitos markets in small quantities; dolphin meat however has never been seen observed for sale. There is no concrete evidence that dolphins were killed for these products. There does not appear to be any real demand for dolphin by-products.

OIL SPILLS AND POLLUTION

Although, there are reports that dolphins had been killed in oil spills around the Pacaya-Samiria Reserve in 1992 and 1994, there is not much objective documented evidence. However there was a recorder oil spill in June 2010 on the Marañón river which caused extensive contamination and loss of wildlife.

It’s difficult to measure concisely the negative impact of such events on the environment. Although there is no evidence to suggest that river dolphins have died as a direct result of oil spills, they are surely affected due to the destruction of their habitat and prey.

Pollution

OVERFISHING

Overfishing is evident in oceans, seas, lakes and rivers throughout the world and the rivers and tributaries of the Amazon are no exception. The reduction of food sources for the dolphins is a big concern, especially alarming is the disrespect and lack of concern for overfishing in pristine protected areas. This has a complete negative impact on the seasonal activities of the species and is leading to dilution of the species. Even more alarming are the illegal methods used to lay waste to the dolphin’s food source such as the use of nets, prohibited items or techniques (dynamite and poison etc).

Overfishing

TOURISM

Hopefully, tourism will increase public awareness about Amazon wildlife, such as the river dolphins. Tourism has a huge potential to bring economic change in the region including potential support for much needed research and conservation efforts. On the other hand, if not managed well, can have a negative impact on local people, the dolphins, and the environment. Tourism will need to be closely and carefully regulated and enforced if it is not to contribute to the degradation of the environment.

Boat traffic causes many problems to the environment and animal life in general, with the direct disposal of raw sewage into the lakes and rivers destroying pristine conditions and upsetting the stability of the ecosystem.  Boats traveling at high speeds with their electric generators and motors create air, noise and water pollution which further contribute to upsetting natures fragile balance.

USE AS PETS

River dolphins are not generally known to be used as pets, but there are reports of dolphins being hunted for tourist attractions where they are kept in captivity. Calves are especially vulnerable, many that are captured and placed in small ponds eventually die before maturity.

OTHER THREATS

Climate change, contamination with byproducts utilized in the mining of gold (specifically Mercury), hydroelectric dams and other big projects (Corina, railway train) are the main other threats to dolphin existence.

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