Yes, because gravity waves are a recent phenomena. We just happened to come up with a way to detect them around the same time they caused mass whale beachings.
Your idea has some real cause and effect issues.
So, I wasn't saying that the gravity waves were the cause. I personally think a lot of sea life is getting sick, and being driven from deep water, by settling radiation from Fukushima.
But, the proximity of the two things made me wonder if a biological species could have sensory perception able to feel such vibrations in some way. The way birds and whales feel the magnetic field, or how my inner ears are more sensitive than others so I feel amen process changes in barametric pressure and movement differently than my former coworkers did.
The possiablity exists that some critter out there has evolved a way to feel them even if it hasn't a clue what it is.