Crabs do really well in the Pacific NW. I was wondering why no one has introduced lobsters either on purpose or just by releasing a store bought lobster. Apart from the ecological issues of introducin a non-native species, would this work?
My WAG is it’s the water temperature. The Gulf Stream plays a major role in keeping the North Atlanic waters warm, compared to the Pacific Northwest.
That could be. As cold as it is inside Cape Cod (the outside gets more of the Gulf Stream) , the Oregon coast is just ridiculous.
I don’t think it can just be temperature; there are lobsters in the North Sea (which doesn’t get much, if any benefit from the Gulf Stream) and even in sub arctic seas.
I couldn’t kind the information, but I’ll bet that it is mostly the temperature - to my knowledge, there are no other predators that would make life for lobsters more difficult up there.
We have a species of lobster living in Monterey (and south), but I don’t think you find them any further north. The waters around here are just a bit colder than in MA and ME, even though we’re quite a bit further south.
I googled to see if I could find the answer, but I got distracted with the following article:
“Furry ‘lobster’ found in Pacific”
Ah, that’s it. Lobsters would need fur coats to thrive in the Pacific Northwest, and most of those poor little guys just can’t figure out how to get one. 
The NW has the crabs, clams, and salmon - what do they need lobsters for?
Isn’t the Pacific very, very, very far from the Atlantic. Why would a species that evolved in the Atlantic necessarily have to be in the Pacific?
There are lobsters in the Pacific. The Pacific spiny lobster (genus Panulirus) ranges from Monterey, CA down into Mexico. AFAIK Atlantic Lobsters (Homarus) do not exist there.
I asked the owner of a dive shop (who’s degree is in marine biology) why lobsters didn’t live in the waters of the PNW. He said the waters were too cold for them.
Also the PNW is known for its several species of crabs. ISTM that lobsters and crabs fill a similar niche. (This is an assumption on my part.) With the large numbers of crabs, and they being of a similar size to lobsters and requiring similar resources, I think there’s just not a ‘place’ for lobsters. But from what I’ve heard, the water is just too cold.