Chinook Salmon Vanish Without a Trace

From the NYTimes.com: Chinook Salmon Vanish Without a Trace

Where did they go? The Chinook salmon that swim upstream to spawn in the fall, the most robust run in the Sacramento River, have disappeared. The almost complete collapse of the richest and most dependable source of Chinook salmon south of Alaska left gloomy fisheries experts struggling for reliable explanations — and coming up dry.

This is frightening.  When something that’s been around for years and suddenly disappears.  It’s a signal that something is wrong.  The problem is that there are a lot of questions and possible causes, but they’re not exactly sure what happened.