There may be ethical issues around the fishing, but as far as cooking or selecting the food goes, the endangered-ness is pretty much irrelevant. Either you can find/source it or you can't.
The issues are also totally localized, making it a poor topic for discussion on a site targeted at a global audience.
Leaving aside the often dubious criteria used by governments and NGOs to attempt to classify "endangered species" and the even more dubious criteria used to determine the effectiveness of such measures, I really think that the whole thing is just too far-removed from our mission to be a central area of discussion.
Feel free to mention these things in answers, of course. I could foresee a question along the lines of "Why can't I find [Haddock] at the markets anymore?" And the correct answer might very well be, "[Haddock] was classified as an endangered species in [area], so very few markets there will sell it anymore." That's fine. But please no activism questions along the lines of "Is it ethical for me to be eating [Endangered Species]?" because honestly, that doesn't help further the site's aim of helping people to serve delicious meals.