You can't make the case that lobsters are threatened by fish farms or anything else when each successive year brings a new record harvest of lobsters.
Unless, of course, the harvests are a product of industry pressure in the face of contradictory scientific opinion which would lead to the natural conclusion that the lobsters are being codded. Even if that weren't the case, the harvest is on a trajectory that will eventually land it there. Spiraling industry capacity chases ever-increasing harvests which chase ever-increasing industry capacity, pressure mounts to keep the over-capacity running, stocks start to respond to excessive harvests, competition for the declining numbers gets fiercer and over-harvesting climbs further until the whole thing collapses. It's not like we haven't seen the pattern before and in the same region.
But of course, we all know it's the fish farms fault.