required for developing a broader ecosystem oriented theo- 

 retical basis for fisheries management were determined. In 

 addition, means of influencing the fishery management plan 

 development process, and consequently plan contents, based 

 on aspects of the day to day operations of the councils were 

 evaluated . 



The first draft of the report was submitted in January 

 of 1979 to the Marine Mammal Commission as well as to sev- 

 eral of the individuals contacted in the fall of 1978. In 

 August of 1979, following internal review, the Commission 

 submitted the draft report for review to the Executive Di- 

 rectors of the eight councils, to the Director of the U.S. 

 Fish and Wildlife Service (U.S. FWS) and to the Assistant 

 Administrator for Fisheries of the NMFS . Comments received 

 from the councils, the FWS and many different units of the 

 NMFS as of December 1979 were incorporated into a subsequent 

 draft and the final report. 



III. RESULTS 



In order to place the information collected through this 

 study in proper perspective, the concept of MSY is discussed 

 first. The MSY concept is central to traditional fisheries 

 management, related to the selection of optimum yield as re- 

 quired by the FCMA, and part of each fishery management plan. 

 The characteristics of MSY-oriented management are compared to 

 those of a broader based ecosystem level perspective, and modi- 

 fication of the underlying theory is recommended as a means 

 for initiating an ecosystem approach to fishery conservation 

 and management . 



CONCEPT OF MSY 



Traditional fisheries management has been based upon the 

 concept of maximum sustainable yield, defined as "the greatest 

 harvest that can be taken from a self -regenerating stock of 

 animals year after year while maintaining constant average 

 size of that stock" (Holt and Talbot, 1978). A different level 

 of sustainable yield is associated with each level of popula- 

 tion size for a particular stock, assuming a constant environ- 

 ment. The highest of this set of possible sustainable yields 

 is the maximum sustainable yield, associated with one particu- 

 lar population level. MSY is also the greatest of the set of 

 Equilibrium Yields (EYs) , which are harvest levels that allow 

 the stock to remain at the same level of abundance. 



The concept of MSY depends on some highly simplified as- 

 sumptions about the way in which the population under exploita- 

 tion will behave. These assumptions include that the stock is 



