Local vs. Remote matters because the remote guys give zero fucks about the state of the fishery, or any other resource.
For example, as a consumer, we in aggregate give zero shits about the oppressed seamstress in Bangladesh who is essentially a slave making our t-shirts for pennies. But if somebody kicks a dog, it will generate a massive outcry. We relate to the dog, who could be our own dog, but don't relate to the seamstress.
The control remains local because that where the resource is. It's about local vs remote ownership.
Efficiency of scale does not increase the carrying capacity of the local areas. Further prices are mostly dictated by availability not operations costs. So, maximizing the average catch size long term is vastly more important than minimizing operating costs.
OK, but that's not really a full accounting of the tradeoff being made. Preventing "outside" or "non-local" fishing does have the advantage of privileging local stakeholders over remote capitalists - but it also privileges local stakeholders over remote _customers_. If economies of scale allow a commercial fishing operation to cut final prices by 10%, then on the margin you're going to see about 10% more lobsters being sold, which means that 10% more people get to eat lobster than would be able to do so under this regime.
And maybe that's fine! I'm not saying we shouldn't make this tradeoff. But consumer surplus is generally ignored in this kind of calculation, as if the value of the lobsters were a zero-sum game in which we split things up between Small Local Good Guys and Rapaciously Greedy Outside Capitalists, and that doesn't tell the whole story.