This might surprise you, but: not at all costs, actually.

While that may be true in principle, it seems likely to me that price is a very important factor for many or even most people, so much so that they don't look too closely at provenance. Were that not the case then I would expect the market for battery chickens to have dried up by now, for example.

True, only for a reasonable cost. The kind of prices that responsible and renewable fishing probably can't match.

Unless you live in the Maldives or Iceland:

https://en.wikipedia.org/wiki/List_of_countries_by_seafood_c...

commercial fishing is subject to an extreme form of "size" competition that is hard to fathom! many documented cases, in many language groups