developed to understand the complicated and interrelated marine environ- 

 ment. As such, assessments depend upon the analysis of past information 

 and trends to predict future fisheries developments.^'^ 



Fishing activities have continually changed as technologies have de- 

 veloped. These changes force adjustments in past data analysis to reflect 

 future realities. Further, as fishing activities have varied, there exist 

 environmental fluctuations and trends that are yery long term in nature 

 and are, as yet, poorly understood. This understanding is extremely 

 difficult when technological changes continually perturb the time-stream 

 of data. 



Yet we have come to realize that, as awareness of the interrelatedness 

 of marine species has grown, the biological foundation of marine ecosystems 

 must be clearly understood. (^)* 



Fisheries managers are pressured to treat stock assessment information 

 with the same precision as other resource managers treat their data. How- 

 ever, while forest managers, for instance, can count the board feet of 

 available timber, or while mineral assessments are based on the premise of 

 a nonrenewable resource, fish populations cannot be counted. It is not 

 enough merely to discover that they exist in commercial quantity. The concept 



* Whereas initial assessments concentrated on single species — for at that 

 time single species were of major interest to harvesters — factory type 

 operations were often unselective and essentially "clear cut" the marine 

 biomass instead of "selective" fishing. While the implications of such 

 efforts are difficult to understand, it has become clear, at least on 

 Georges Bank through survey tows and other resource inventory methods, 

 that mixed fisheries may have a synergistic effect, reducing the level of 

 the biomass at a rate faster than one would assume. In 1972 ICNAF 

 scientists began to argue for the study of interspecies relationships, 

 clearly a far more complex undertaking than assessing one stock or another. 



