It's ridiculous to diminish the plight of whales because smallpox are also nearly extinct. Go for "smallpox matter" instead, and see what people really think.
For what it's worth, I don't object to either "all species" or just whales. Regardless of whether someone is trying to protect all or focus their attention on one specific species, they're both working towards a good cause - though I do disapprove of the former trying to substitute the latter or vice versa.