This is from Release - The Newsletter of the Marine Mammal Center.
My comment: As a rule, you do not interfer when seeing a stranded marine mammal. We are not trained marine biologists and may do more harm than good.
From the newsletter - Marine mammals are wild animal and can transfer disease to humans and domestic pets. If you come accross marine mammals that seem injured or ill, you shold always call the local marine rescue group - their number is 415-289-7325 (24 hr. hotline in CA.)
The 1972 U.S. Marine Mammal Protection Act prohibits people from harming or disturbing marine mammals. That includes 'rescue' by non-licensed people such as jet skiers or beachcombers.