I think, whether it's "endangered species" or not, still count as "cruel treatment" lor!
Just like, human is not endangered species at all and more likely over crowded tim la, we just can't kill some of us ga mah.
Oh no..... not again and again la............. ! We always hit the question whether to kill / eat animals is cruel or not ga la.... and even to kill (harvest) / eat plants could be cruel too la. Back to the most common answer: it's the way to kill / eat the animals to be judged cruel or not, not whether human kill / eat them or not lor.