An interesting article, if a tad grim. It's hard being a baby seal.
I do suspect that the author of the article is a landsman who doesn't really understand the mechanics of how tides work. The article says the orcas beach themselves at high tide. This makes no sense, as the falling tide would leave them completely stranded. I suspect that what happens is that the orcas beach themselves on a rising tide, so that the incoming tide will float them off. After all, these are highly intelligent sea creatures, and one would expect them to have an advanced understanding of the tides.
I was particularly intrigued to read that this deliberate beaching behavior is seen nowhere else in the world.