He asked about fishing for them specifically. Not what if he accidentally catches one. I assumed he meant to keep and eat it and/or have it mounted, that's why I used the word 'take'. Why ask the question if you're just going to accidentally catch one then release it? What's to feel bad about?
How do you even catch and release a shark? Just cut the leader or is there a way to safely remove a hook. Do you even hook a shark in the mouth? The only shark fisherman I've ever talked to said they swallow the hook most of the time (I'm sure that varies by species though). A quick google search shows that there is some question about whether sharks can survive being released. So if that's what he's talking about, then fuck no. Either cut the line as soon as you realize it's a shark, or keep and eat the motherfucker.
Don't preach to me about the ecosystem. How about if humans just stop trying to play God and let the ecosystem take care of itself? You fucking people have no faith in Mother Earth. As humans, we need to stop wanton waste. I'm sure we agree on that much. But if a species like the mako or red wolf can't survive in the wild without heroic efforts on our part, then they need to die off.
