Optimum carrying capacity: 



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. (Marine Mammal Protec- 

 tion Act, 1972) 



Optimum sustainable population (OSP) : 



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. (Marine Mammal Protection Act, 1972) 



range of population levels with the upper limit 

 being the average carrying capacity of 

 the habitat and the lower limit at the 

 MSY level. (At present this appears to 

 best satisfy MMPA criteria of maximum product- 

 ivity, healthy state, health and stability of 

 the ecosystem, and maintenance of populations 

 as significant functioning elements within 

 the ecosystem. With more information, the 

 range could be narrowed.) (Marine Mammal 

 Commission, 1976, p. 7) 



a population size which falls within a range from 

 the population level of a given species or 

 stock which is the largest supportable within the 

 ecosystem to the population level that results 

 in maximum net productivity. (NMFS operational 

 definition 50 CFR 216.3) 



Optimum yield: 



the amount of fish (a) which will provide the 

 greatest overall benefit to the nation with 

 particular reference to production and recrea- 

 tional opportunities, and (b) which is prescribed 

 as such on the basis of maximum sustainable yield 

 from such fishery as modified by any relevant 



1-4 



