FWIW, it seems reasonably likely that fishing has increased fish populations on the whole, by disproportionately reducing the populations of more predatory species and increasing the populations of their prey. See Christensen et al., 2014(only considers fish, not invertebrates) andBell et al., 2018(very limited in regional representation).
In general, the effects of fishing on welfare seem quite morally ambiguous, when you consider the effects on population sizes across species, tradeoffs between species, uncertainty about whether their lives are overall bad or overall good:The moral ambiguity of fishing on wild aquatic animal populations.
FWIW, it seems reasonably likely that fishing has increased fish populations on the whole, by disproportionately reducing the populations of more predatory species and increasing the populations of their prey. See Christensen et al., 2014 (only considers fish, not invertebrates) and Bell et al., 2018 (very limited in regional representation).
In general, the effects of fishing on welfare seem quite morally ambiguous, when you consider the effects on population sizes across species, tradeoffs between species, uncertainty about whether their lives are overall bad or overall good: The moral ambiguity of fishing on wild aquatic animal populations.
I also suspect efforts to make fishing more sustainable actually just increase fishing, while outright bans seem politically infeasible; see my other recent post Sustainable fishing policy increases fishing, and demand reductions might, too.