ROTHSCHILD: DEFINITION OF FISHING EFFORT 



400 hp 



II — .11 

 Good 



300 hp skippers 

 200 hp 



400 hp „ 



Poor 

 300hp snippers 



200hp 



EFFORT 



Figure 1. — Hypothetical relation between catch and ef- 

 fort for boats of varying horsepower and for "good" 

 and "poor" skippers. 



sically different in some important index in a 

 ratio of say 2: 1 may exhibit a range in catch-per- 

 input where the best boat is, say, 10 or more 

 times better than the poorest boat. The greater 

 effectiveness of some boats over other boats can 

 in large part be attributed to the skill of the skip- 

 per. This is ignored in many analyses primarily 

 because this question of skill has never been ap- 

 propriately formulated. In this section, we be- 

 gin to develop some examples which contribute to 

 the rudiments of analysis of the behavior of the 

 skipper as an input to the production function — 

 in terms of how a skipper perceives the fishing 

 environment — and then mention the problem of 

 the utility that the skipper places on the various 

 signals that he obtains from the environment. 

 We make a point of stressing that the relation 

 of the input vector to the output vector in the 

 fishing process is usually considered to be de- 

 terministic by students of the fishing process. 

 Another approach is to use an average vector 

 for inputs and assume an average vector for out- 

 puts. Unfortunately, it is unlikely that fisher- 

 men perceive the decision environment as either 

 deterministic or average and we make use of 

 this observation in our additional considerations. 

 In order to demonstrate these points we will 

 construct a branch of a very simple decision tree 

 which can serve as a framework for future anal- 

 ysis. The branch of the tree is shown in Figure 



2. This is the skipper's decision environment. 

 Nature deals the skipper good fishing, Oi or poor 

 fishing, G2. The skipper has an opportunity to 

 take a glimpse at the environment. This inter- 

 pretation of the glimpse is denoted by P{Oi\oj) 



where O; is his guess of 9; (j does not necessarily 

 have to equal ,) . If the skipper guesses Gi, then 

 he commits himself to a fishing operation, but if 

 he guesses §2, he moves to a less risky area and 

 fishes. In this less risky area, nature deals new 

 fishing conditions 0/ and O2'. The reward for 

 any particular fishing action is specified in Fig- 

 ure 2. We wish to use this model to show how 

 chance enters the decision process. 

 We set 



and examine three conditions: 



Condition I 



The skipper is perfectly skilled and thus 



P(ei 

 P{d'. 



ei) = PCGsIoo) = 1 andP(6,|G2) = 

 Oi) =0. The expected value of the branch 



$ 20 



(n) Nature's action 



(G) Glimpse - fisherman's interpretation 

 of nature's action 



Figure 2. — Branch of decision tree showing various 

 events and payoffs. (For a discussion of decision anal- 

 ysis see Raiffa, 1968.) 



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