It's a very good question. It's important to make that distinction between the larval transport opportunity.... Of course, it's only a few weeks in a lobster's lifetime, but in that planktonic stage they have the potential to be transported tens or even hundreds of kilometres, depending on where they hatched and what the particular ocean currents were that they were entrained in.
For example, lobster larvae could be hatched off Grand Manan at the mouth of the Bay of Fundy and be transported easily down to Georges Bank. That's one opportunity. Then they settle to the seabed and are very cryptic until they are a few years old and become more mobile. By the time they are adults, they are capable of longer-distance movements. Again, the longest distance recorded has been on the order of about 100 kilometres in a year's time, but that's probably not the norm. Probably most of the stock would remain within 10 kilometres to 20 kilometres of where they settled.