I'm actually pretty sure the high prices of lobster are entirely marketing-driven - we've made it a delicacy through demand, not through rarity. Lobsters themselves are still eminently common.

...and I just checked with Google, which says it's actually a mixed story. Some stocks are doing just fine, but others (especially the one in Southern New England) are collapsing, although this seems to be more due to environmental change than overfishing. Which is still a human-driven cause, heh.