for cetaceans and pinnipeds other than walrus, while the 

 Secretary of Interior is responsible for all other marine 

 mammals (i.e., walrus, manatees, dugongs , sea otters, and 

 polar bears) . The Secretaries of Commerce and Interior have 

 delegated responsibilities to the NMFS and the U.S. FWS , 

 respectively. 



The Act created the Marine Mammal Commission and charged 

 it with overviewing all U.S. activities bearing upon the con- 

 servation and protection of marine mammals . The Commission 

 consists of three individuals, knowledgeable in the fields of 

 marine ecology and resource management , and is appointed by 

 the President. The Commission has an Executive Director and 

 staff, and a nine member Committee of Scientific Advisors 

 on Marine Mammals . 



The primary objective of the MMPA is to maintain the 

 health and stability of the marine ecosystem and, whenever 

 consistent with this primary objective, to obtain and main- 

 tain optimum sustainable populations of marine mammals. The 

 Act defines "optimum sustainable population" (OSP) as: 



"the number of animals which will result in 

 the maximum productivity of the population 

 or the species, keeping in mind the optimum 

 carrying capacity of the habitat and the 

 health of the ecosystem of which they form 

 a constituent element." 



"Optimum carrying capacity" is defined in the Act as : 



"the ability of a given habitat to support 

 the optimum sustainable population of a 

 species or population stock in a healthy 

 state without diminishing the ability of 

 the habitat to continue that function." 



The statutory definition of OSP has been interpreted in 

 regulations of the NMFS which define it for application in 

 the management context as follows : 



"Optimum sustainable population is a pop- 

 ulation size which falls within a range 

 from the population level of a given spe- 

 cies or stock which is the largest support- 

 able within the ecosystem to the population 



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