Unit of Time 



The biologist and the economist will be 

 naturally inclined to use different units of time 

 (time at sea for the second and time fishing for 

 the first). Anyway, the distance to the grounds 

 will have an opposite effect for both researchers, 

 the longer the distance, the higher the costs or 

 the fishing effort for the economist; the shorter 

 the distance the higher the impact on the fish 

 stocks, or the fishing effort for the biologist. 



The conclusion is obvious. There cannot be 

 such a unit as a unit of fishing effort. Fishing 

 effort is a complex concept; it is a ratio or a 

 relationship between different units. To assume 

 that it can be defined once and for all and be 

 used indifferently by researchers of both dis- 

 ciplines, economics and biology, is a complete 

 mistake. Each time that the concept of fishing 

 effort is utilized it should be made clear what 

 it really means. Attached to a stock or fishing 

 technique, its value is limited to this stock or 

 technique. Given in money terms its compar- 



ability is attached to the economic systems of 

 which it forms part. 



CONCLUDING REMARKS 



A substantial complexity is the consequence 

 of the impossibility of building up a complete 

 bioeconomic model, of the difficulty of converting 

 to economic measurement the ratios used by a 

 number of biologists, of the lack of a clear 

 understanding of what fishing effort is, of the 

 impossibility of forecasting the pattern of 

 recruitment of the fish stocks. To overcome this 

 complexity it does not seem that one can in- 

 definitely rely upon equations which, whether 

 they are Schaefer's or Beverton and Holt's, are 

 mostly used analytically to give account of 

 past developments but cannot make apparent 

 the mechanisms through which future develop- 

 ments are taking place. Figure 5 shows that 

 these biological equations only concern the 

 squares 1, 2, and 3 when a complete simulation 



BIOLOGICAL RESEARCH 

 (by fish stock) 



ECONanC RESEARCH 

 (by fishing fleet) 



Actual vessels 

 catch rates 



Direct assessnents 

 e.g. by accoustic 

 methods ■. 



Corrected for 

 standard vessels 



Assessments of 

 mortalities and of the 

 size of the fish stock 



Growth and recruit- 

 ment observations 



Forecasts of the 

 future stock and 

 mortalities 



Market 

 assessments 



Existing 

 fishing fleets 



Economic assessment 

 of the past and 

 present situation 



Expected 

 changes in the 

 markets 



Expected 

 changes in the 

 fleet 



Necessary 

 adaptation 

 leading to 



New market 

 conditions 



Redevelopment 

 of the fleet 



Figure 5. — A simulated flow chart of a fishery. 

 102 



