I'll take a stab at it, and then I'll pass it over to Bruce. He's more of an expert on this.
What I would do is compare that to land and what we do in farming. In farming, we typically replace an entire ecosystem. We take out whatever is there, till the soil, and then plant whatever we want. We're putting in a new ecosystem.
On the ocean, what bottom trawling does is that, at most, it modifies the ecosystem. It doesn't replace the ecosystem. It doesn't do the kind of damage to an ecosystem that we're doing on land in food production there.
If you want to compare it with food production, what we're doing with trawling is nowhere near as bad on the ecosystem as what we're doing on land.
The worst kind of fishery out there is not bottom trawling. There are places where dynamite is being used to fish. It's not as bad as some of these other places.