Because the internet is fueled by conspiracies and meaningless conjecture, the video’s comment section was flooded with suggestions as to what the huge fish might actually be. The public’s guesses -- such as “sturgeon,” “freshwater shark” and “alligator” -- were good intentioned, but totally wrong if you want to believe in river monsters.
Unfortunately, Alaska’s Department of Fish and Game had to investigate the mystery as if it wasn’t already an open and shut case. The BLM issued an update, writing that according to the investigation, the video probably shows "frazil ice stuck to a rope that is probably caught on a bridge pier." According to local reports in Alaska, fazil ice is "a kind of loose, slushy ice that forms on water."