I work in the Alaska fishery and am typing this while sat in one of the largest fish processing facilities in the western hemisphere. I have the spare time beca

I work in the Alaska fishery and am typing this while sat in one of the largest fish processing facilities in the western hemisphere. I have the spare time because, well, there's no crabs coming in and everything else is mostly out of season. About half of the boats on Discovery belong to the company I work for, the largest in the US. So I'll take the opportunity to share some on-the-ground observations. Overfishing: It's not this. A billion crabs is north of 5 billion pounds, in other words on the order of 100x the US crabbing fleet's capability. I would hazard to guess there isn't enough crabbing gear on the planet earth to have achieved that catch. Foreign fleets: If this is the case, the real bad news is that the Rusky's and/or Chinese have developed cloaking device technology. Trawling: We're talking about the bottom-scrapers. They're new on the scene relative to the crabbers. Alaska allows 4 1/3 million crabs as bycatch (waste), amounting to ~20 million pounds, which would be a decent annual catch. Even though this is thought to interfere specifically with breeding grounds, it isn't enough to have caused this depopulation event. It's more than enough to piss of the crabbers though, since it actually is unfair. Disease: Is there a precedent in Earth's natural history of a 90% die-off in two years due to disease? We might have to go back to the meteor that killed the dinosaurs. Which brings us to: Climate change: There was a similar depopulation event in the early 80s. 1980 still holds the annual catch record at 200 million pounds (~40 million animals), a sustained harvest without noticeable impact on the stock. The waters warmed, population (and yield) suddenly tanked on a similar scale, and never recovered to anywhere near those levels. The basic ecological dynamic of a fishery is this: deep, cold, nutrient-rich waters are pushed by a current into a steep continental shelf, forcing them toward the surface where it fertilizes plankton, the foundation of sea life. The volcanic Aleutian archipelago is such a place, another notable one is Peru's fishery. A change in sea temperature can effect this dynamic, in addition to the breeding and general survival of crabs. However long it takes for the stock to recover (probably a long time, even if the environmental conditions do return to favorable), one outcome is almost a foregone conclusion: independent crabbers will have be forced out, and only the larger companies, with deeper pockets and more diversified across fish species, will survive, leading to another round of conglomeration.