I'm looking for a horror/science fiction story involving orcas/killer whales. It was written by someone who was either a marine biologist or someone who used to work with cetaceans, and in their author notes they actually interviewed people who used to work with orcas at Seaworld in order to get an idea of what orcas were like.
The plot of the story was that humanity finally cracks the communications barrier between humans and orcas, but to our horror instead of being a peaceloving society who was interested in sharing culture and knowledge between species, the orcas were a barbaric species rules by cruel matriarchs that practiced slavery. Even worse, rather than being horrified at how humans treated orcas in marine parks, the orca matriarchs applauded such behavior to humanity's collective horror, and even worked out an agreement where they sold enslaved baby orcas that they captured as prisoners of war (based on what the author noted is an IRL phenomenon where baby orcas have a tendency to mysteriously disappear and marine biologists don't know why). There was a subplot in the story where a human paid a marine park money in order to shoot a baby orca (who was shown from their point of view to be a child or have the mind of one).
Part of the reason the orca matriarchs did this was that humans had destroyed the populations of marine mammals they depended on for food, and the orcas sold baby orcas in exchange for the humans allowing them to eat those tasty, tasty PETA protesters and similar people. There was a part where members of a PETA-esque group and several New Agers or environmentalists were shipped out to a platform believing they were on an orca-viewing cruise, only for the platform to be dropped into the water and it was strongly implied the orcas ate them all. The overall horror element of the story was the subversion of the expectation that if we ever crack the species communication barrier other animals would be friendly and welcoming, when it could be that by our standards other species hold practices that we consider barbaric and cruel.
I remember this story was online somewhere. However, I can't find this story anywhere. When I look up orcas in horror and science-fiction I either get links to Blackfish or the 1977 horror movie Orca.