I don't know if there's evidence of targeting as much as there's evidence of being selective about what's consumed. Seals and sea lions tend to rip the bellies out of fish and like to consume the roe.
We do see species-specific targeting. My experience is in Cowichan Bay. It occurs elsewhere, but in Cowichan Bay specifically sea lions and seals will swim through a school of chum salmon in order to target a coho or a chinook. That's been observed many times.