A bill to amend the Marine Mammal Protection Act of 1972 with respect to the number of marine mammals which may be taken, until January 1, 1979, incidental to the course of commercial fishing operations.

Amends the Marine Mammal Protection Act of 1972 to require the Secretary of the Interior or the Secretary of the department in which the National Oceanic and Atmospheric Administration is operating to issue permits for the taking, incidental to commercial tuna fishing operations, of specified numbers of certain stocks of marine mammals, during the period beginning May 1, 1977, and ending December 31, 1978.

Requires the Secretary to place an observer aboard fishing vessels engaged in fishing for tuna on porpoise until December 31, 1978.

Authorizes appropriations necessary to carry out this Act.