Information on the legalities of collection, uses, and sale of Alaskan fossilized ivory can be found here:

Bering Land Bridge National Preserve

http://www.nps.gov/bela/html/heritage.htm#ivory

The above discusses the laws regulating Alaska fossilized ivory as it relates to archaelogical sites.

The site below is a pdf site for the US Fish & Wildlife Service's Administration of the Marine Mammal Protection Act of 1972.

www.nctc.fws.gov/library/Pubs9/Marine_Mammal97.pdf