If their populations are being reduced, there will be fewer animals to suffer and I’d guess less overall suffering as a result. If you think they have overall bad lives or lives worth preventing, this would better, not worse.
And I don’t think there’s any feasible plan or path to improve their welfare on a similarly large scale, unlike for impoverished humans. Furthermore, the small and populous prey fish tend to have high mortality rates and short lives, which is a reason to believe their average welfare is negative (although possibly defeasible) that doesn’t apply to impoverished humans.
If their populations are being reduced, there will be fewer animals to suffer and I’d guess less overall suffering as a result. If you think they have overall bad lives or lives worth preventing, this would better, not worse.
And I don’t think there’s any feasible plan or path to improve their welfare on a similarly large scale, unlike for impoverished humans. Furthermore, the small and populous prey fish tend to have high mortality rates and short lives, which is a reason to believe their average welfare is negative (although possibly defeasible) that doesn’t apply to impoverished humans.