1998 



OUR LIVING OCEANS 



1976 MFCMA 



1996 MSFCMA 



Table 1 



Definitions of optimum yield 

 in the Fishery Conservation 

 and Management Act (em- 

 phasis added). 



"... the amount of fish - 



(A) which will provide the greatest overall benefit to 

 the Nation, with particular reference to food 

 production and recreational opportunities, and 



". the amount of fish which - 



(A) will provide the greatest overall benefit to the 

 Nation, particularly with respect to food production 

 and recreational opportunities, and taking into 

 account the protection of marine ecosystems. 



(B) which IS prescribed as such on the basis of the 

 maximum sustainable yield from such fishery, as 

 modified by any relevant economic, social, or 

 ecological factor," 



(B) IS prescribed as such on the basis of the 

 maximum sustainable yield from the fishery, as 

 reduced by any relevant economic, social, or 

 ecological factor, and 



(C) in the case of an overfished fishery, provides for 

 rebuilding to a level consistent with producing the 

 maximum sustainable yield in such fishery." 



is in an "overfi.shed condition." The harvest (tar- 

 get) control rule (dasiied line) is designed to 

 achieve OY, which in this example pertains to 

 maintaining a balance between achieving high 

 yields and avoiding overfishing; it the stock size is 

 below its MSY level, the decreasing target fishing 

 mortality allows tor rebuilding back to the MSY 

 level. Specifying limit and target harvest control 

 rules that are compatible with the National Stan- 

 dard Guidelines can be a complicated exercise that 

 should take into account the biology of the 

 stock(s), the characteristics oi the fisheries (e.g. gear 

 selectiviry), the ability to assess the stock's status 

 and productivity, and the relative importance to 

 be assigned to the various management objectives. 

 Restrepo et al. (1998) provide technical guidance 

 for defining limit and target harvest control rules 

 that arc in accordance with the Guidelines, and 

 where, in the spirit ot the Precautionary Approach, 

 resource conservation takes precedence over other 

 management objectives. 



RISK AVERSION 



I he concept ot risk aversion has a lona, theo- 

 retical tradition in fisheries, although it is not tre- 

 qiientl)- applied in practice. Risk-averse manage- 

 ment means that when there is greater uncertainty 

 regarding the status or productive capacit\' ot a 



stock, greater caution is used in setting target catch 

 levels. In the context of the Precautionary Ap- 

 proach, risk-aversion is the mechanism tor revers- 

 ing the burden ot proof 



For example, consider the case in which man- 

 agers wished to define the average OY as landings 

 close to MSY, MSY being a limit reference point 

 (not to be exceeded with any substantial probabil- 

 ity) and OY being the target reference point (to 

 be achieved on average). A risk- averse Precaution- 

 ar\' Approach would set OY below MSY as a func- 

 tion ot iincertaint)', viz: the greater the uncertainrv, 

 the greater the distance between the two. In this 

 example, onh- in the case ot pertect knowledge (tor 

 both MSY and stock status) and pertect compli- 

 ance could OY be set exactly at MSY. In the ex- 

 ample ot Figure 2, the 2S'!'b ditterence between 

 the limit and target at high stock si/cs provides 

 tor a safety margin to guard against uncertainty in 

 perceived stock status, in implementation ot man- 

 agement controls, and in natural abundance fiuc- 

 tuations. 



Scientific analvses underpin the Precaution- 

 ary Approach in that they are- the basis for deter- 

 mining reference points, assessing stock abundance 

 and exploitation levels, quantif\'ing uncertainty, 

 and assessing the risk associated with different 

 management options. I he second National Stan- 

 dard in the MSFGMA states that: 



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