My guess is that the title that the submitter originally suggested (with dam info that is not in the original title) was over the 80-character limit for HN titl

My guess is that the title that the submitter originally suggested (with dam info that is not in the original title) was over the 80-character limit for HN titles, so they shortened it to the current existing (and confusing) title. For reference when it inevitably gets changed, it’s currently “Yangtze dam separates Paddlefish, largest, from spawn, now extinct”. Original title is: The Chinese paddlefish, one of world's largest fish, has gone extinct Subtitle is: Native to China’s Yangtze River, these fish grew 23 feet in length, but haven’t been spotted since 2003.