This is a good point - it seems not improbably that a whale's view of place would have more to do with their location in an oceanic current rather than their x, y coordinate in a plane. Sort of like if you describe your position within a car on a highway - you most naturally would say "im in the fast lane between shelbyville and springfield" rather than "i'm at lat/lng such-and-such"
So to attempt to find correlations with the whale's absolute position may (who knows!?) be looking for a signal the whale isn't sending.
Ocean currents and swells are also how ancient Polynesians navigated the ocean so precisely over such huge distances. They developed the ability to read them like maps. Unfortunately, these skills are almost totally extinct. I believe there's only one Hawaiian "master navigator" in the old ways left alive. That intelligent animals could also survive by using this information is not at all unbelievable. Very cool and interesting to think about.
So to attempt to find correlations with the whale's absolute position may (who knows!?) be looking for a signal the whale isn't sending.