EDIS asked me to comment on modeling from the standpoint of the research 

 administrator. The bulk of the effort in the Fisheries Center is essentially 

 ecological. We have a particular focus on the resources utilized by man. For 

 each of our very large ecosystems we really have only one model and this model 

 often drives our entire program. Each Fishery Research Center is concerned 

 with one or two very large ecosystems of varying complexity and size. These 

 VLE's, as we call them, don't have hard boundaries, of course. For us, modeling 

 is a continual process — a way of life not, unfortunately, marked by continued, 

 steady progress, but rather a process that leads to questions as well as answers 

 and tends to vary in intensity through time. 



One continuing problem that we have is that of deciding how much centralized 

 effort to put into modeling at any one point in time. In general each scientist 

 models his own specific element of the work. There is a need, however, for the 

 integrative modeling effort. There is a marked tendency to centralize this 

 effort. Unfortunately, all too often such centralization leads to the development 

 of one general model driven by a single dominant personality. While it may 

 seem more efficient to proceed this way, it can lead to serious difficulties 

 because of the limited grasp of the complexity of an ecosystem by any one 

 individual and by the pulsating and varied nature of opportunity to make 

 advances. It is better, in my opinion, to proceed somewhat more slowly by 

 rotating the involvement of individuals dealing with these more general models. 

 This has the benefit of varying the effort commensurate with the opportunity to 

 make specific advances and does not result in a model frozen in the image of 

 one individual. 



Change is the name of our game. The situation that we are dealing with is 

 dynamic and, to some degree, intractable to deal with because of the logistics 

 of sampling the ocean. Almost all of the decisions that are made with respect 

 to resources events are based on our ability to measure change, not absolutes. 

 Our fundamental problem is one of specifying rates. 



The first version of our model, possibly it is the first ocean model, was 

 published by George L. Clark in 1948 in a paper entitled "The Dynamics of a 

 Marine Ecosystem."! The present model is about the fifth generation of this 

 model. It has improved with each succeeding year as more and more data accumulates 

 and interactions become clearer. At the present time it is relatively robust 

 at the two ends — that is, we know a great amount about the initial energy inputs 

 and primary production, and the outputs, that is, the fish and other resource 

 populations. The internal anatomy is still unclear although even here rapid 

 advances are being made. 



The general robustness of the model, even in its third generation, was 

 sufficient to convince us and others that the only solution to the problem 

 created by the massive foreign fishing effort off our shores was to impose an 

 overall biomass quota. We had enough information, for example, to convince 

 others that we had a sausage machine that produced at a reasonably well defined 

 rate, although we couldn't specify precisely the type of sausage that might be 

 produced at any one time. Such a biomass limit was imposed, an impressive 

 'first' in the history of ocean management. 



1 Ecological Monographs, vol. 16, no. 4, pp. 321-335. 



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