"Plastics kill 1.5 million marine animals each year."
I can't seem to find any reference to support this claim, let alone details about how many different species are aggregated in this number, or ultimately how many of each individual species die from plastics. (I'd certainly be willing to settle for a genus or family breakdown - asking species can often be quite demanding.)
Considering that much of the published hype regarding oceanic garbage patches can be effectively debunked, I would expect that that is also the case with this number.
Certainly trash in the ocean is wrong, plastic or otherwise. But the solution will be to not put it there in the first place.