Panel A - Ecosystem Modeling as a Fisheries Management Tool 



Panelists: Marvin Grosslein, Chairman 

 Sharon LeDuc, Chairman 

 Kenneth Dixon 

 John Finn 

 Brenda Nor cross 

 Robert Pedrick 

 Mark Reed 

 Stephen Re illy 

 Peter Saunders 

 William Schaaf 

 Michael Sissenwine 

 Nancy Pola Swan 



I. INTRODUCTION 



The focus of the Panel was on major fishery management concerns and the 

 role of numerical models in providing the information necessary to meet these 

 concerns or needs. First, the Panel outlined fishery management needs and 

 the general kinds of models currently used to meet those needs. The utility of 

 these models was discussed, and an attempt was made to assign priorities to 

 future research in terms of potential for improvement in predictive capability. 

 No attempt was made to prepare a complete list of all the variations of models — 

 just the general types of models. 



Next, the Panel discussed the role of ecosystem models in fishery management, 

 There was general recognition by the Panel that full-scale mechanistic ecosystem 

 models (i.e., involving quantitative and dynamic linkages among all the principal 

 physical and biological processes which control organic production in the 

 aquatic environment) are not being widely used for fishery management. This is 

 because quantitative knowledge of the natural ecological mechanisms which 

 control fish production is still very limited; in particular, the factors which 

 control survival in the first year of life of fishes are not well understood, 

 and this is the life stage when mortality is both high and variable. The Panel 

 considered the critical role of the recruitment process in driving fishery 

 fluctuations and discussed the importance of modeling in helping to clarify 

 this process. 



II. FISHERY MANAGEMENT NEEDS VERSUS MODELS IN CURRENT USE 



The products of ecological models in current use which meet basic needs of 

 fishery managers can be put into three general categories: 1) short-term 

 projections of fishable stock, 2) long-term harvest strategies, and 3) environ- 

 mental quality. A brief outline was constructed of the various types of models 

 relative to these categories. 



Short-Term Stock Projections 



The basic tool of the fishery manager is still the traditional single 

 species population dynamics model which can yield good forecasts of fishable 



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