Crab Boil & Fish Boil & Shrimp Boil (1959)

[Clai Rice]

Some preliminary results from NewspaperArchives.com gets earlier citations
for all three terms.  Since I don't have a subscription I can't confirm the
larger contexts, though they kindly provide a little snapshot of half a
column width that helps ascertain that the terms are the ones we are looking
for.  Barry or some other subscriber will have to verify them:

CRAB BOIL:
News, Frederick, Maryland, Wed. 18 March 1896

...to a July oyster roast, ... "grand crab boil" is in the air

SHRIMP BOIL:
Chronicle Telegram, Elyria, Ohio, Mon 27 June 1949

...regional specialties as low c... shrimp boil, gumbo, blac...

FISH BOIL:
Sheboygan Press, Sheboygan, Wisconsin, Mon, 26 July 1954
...will proceed north...Michigan, stopping...Park for a fish boil...