94-97% Collapse In Amazon Dolphin Numbers In Mamiarua Reserve From 1997 To 2017

Both species of Amazon river dolphin appear to be in deep decline, according to a recent study. Boto (Inia geoffrensis) populations fell by 94 percent and Tucuxi (Sotalia fluviatilis) numbers fell by 97 percent in the Mamirauá Reserve in Amazonas state, Brazil between 1994 and 2017, according to researchers.

Difficult to detect in the Amazon’s murky waters, both species are listed as “Data Deficient” by the IUCN. But researchers maintain that if region-wide surveys were conducted both species would end up being listed as Critically Endangered.

The team noticed scars from harpoon and machete injuries on the dolphins they caught. Interviews with fishermen confirmed the team’s suspicions: dolphins were being hunted for use as bait. The mammals also get entangled in nets and other fishing gear, are hunted as food, eliminated as pests, and suffer mercury poisoning.

Researchers believe the passage and enforcement of new conservation laws could save Amazon river dolphins, and halt their plunge toward extinction. But a lack of political will, drastic draconian cuts to the Brazilian environmental ministry budget, and continued illegal dolphin hunting and fishing make action unlikely for now.

EDIT

https://news.mongabay.com/2018/06/hunting-fishing-causing-dramatic-decline-in-amazon-river-dolphins/