Fishing has a great importance to the socioeconomic development of the Amazonian riparian communities, which have a local knowledge on the environment, its fauna and flora. This knowledge is of paramount importance for the management and conservation of fish stocks and species that interact with the fishing activity, such as the populations of gray porpoises (Sotalia sp.) and pink porpoises (Inia geoffrensis). Therefore, to register local ecological knowledge and the interaction of porpoises with fishing on the coast of the state of Para, Brazil, 82 semi-structured interviews were carried out in 3 different colonies of fishermen: colony Z-1 (Soure), colony Z-7 (Maracana), and colony Z-23 (Colares). The species Sotalia sp. had a strong social structure, it can be observed in the region both during the dry and rainy seasons, while the species I. geoffrensis didn’t present a social structure, it’s observed in the region especially during the rainy season. The pink porpoise showed a larger interaction with fishing than the gray porpoise, however, this interaction was particularly detrimental to the activity, while the gray porpoise showed both a beneficial and a harmful interaction with fishing. The incidental capture of porpoises primarily occurred through nets and trawls, harming their populations. Captured animals were mostly released, however, there were records of consumption for food, use as bait, and selling of the animal’s eyes. This information will constitute the basis for further studies on the biology, ecology, and estimate of the mortality of porpoises on the Amazon coast. Management measures should be adopted, along with the communities studied, for the conservation of these animals in the region.