What made billions of snow crabs disappear from the Bering Sea?

I have other thoughts. Let's assume the population numbers are correct. How could such change in numbers be accounted for? Global warming.....that's a stretch. Over fishing......there would have to be a lot more fishing going on than known. Our fleets are capable, with time, but would be hard to hide from the market. This is not due to over fishing. The markets would reflect that.

What about a virus or bacteria? A die off. Where's billions of bodies? The article applies the the Bering Sea. There are no fences. What about migration? A mass migration. Maybe they can graze the whole arctic. Maybe the resources or environment lured the crabs from the Bering Sea.

There have been histories where missing wildlife populations were found elsewhere.