If you follow the link, the first paragraph says, “On World Fish Migration Day, thousands of organizations from around the world coordinate events around the common theme of connecting fish, rivers, and people”
Speaking of connecting fish and people, this thread popped into my head: https://forum.inaturalist.org/t/freshwater-fishes-a-big-observation-gap/ (almost 70 replies)
(I don’t see the thread suggested in the related topics below, but to me, it is related!)