The initial claim of this article is that a Humpback Whale was found washed ashore in the Amazon River, confusing scientists.
The whale was initially discovered by conservationists from the group Bicho D'Agua as highlighted on their social media. Scientists were confused by the location of the whale as it was found "some 400 miles from its expected feeding grounds." Renata Emin, the president of Bicho D’Água, explained that upon examining the carcass of the whale she and her team hypothesized that the whale was “floating and the tide took it into the mangrove['s],” and when tide receded the whale died.
The initial claim of the article is true as verified by Bicho D'Agua's Facebook post, which can be referred to as a primary source, and was corroborated by trusted news sites like CNN and the NYT's. It is also true that at the time of the stories release scientists were still pursing information related to the incident, such as exact cause of death, “we are collecting information, identifying marks on the body, to determine if it was trapped in a net or hit by a boat.” This goes to support the secondary claim that scientists were still unsure of the exact reasoning behind the incident.