Things are changing in the ocean.  The change in temperatures at all will affect the ocean flows and currents and will affect the animal behavior.  Also, the mammal groups are like anything else they have their own hierarchy.  When they lose for natural or predation reasons the older seasoned travelers among them they will rely upon the "new" pack leaders about where to pull out.  They may be stressed herds at this time for temperature and other toxins and stress in their usual routes.  The waters are noisier, different temps which will affect the marine bio columns, the locations where the waters mix.  The "testing" done by humans may be interfering.  The animals don't read newspapers about where they are supposed to go.  They just respond to their own stimuli.  They have true freedom.