(294) 



500 



400 



^ 300 



200 



100 • 



500 



400 



300- 



>T* 200- 



100 



FlG. 172A. Annual steady yield of plaice plotted against mesh at various fishing intensities. 



The yield per recruit ( Y W \R) as a function of t p ' for various values of F, to show how the 



height and location of the maximum changes with F. 



Fig. 172B. Eumetric Yield curve for plaice. If a change of mesh accompanies a change in 

 fishing intensity in such a way that each value of F is matched by the mesh that would 

 give the maximum steady yield at that value, the resultant curve of steady annual yield 

 per recruit (Y w jR) for plaice differs widely from that of Fig. 171c, particularly in having 



no maximum. 



Fig. 172c. An exercise in bionomics. Curve (a) is a eumetric curve in which steady yield 

 instead of being expressed in weight is now in money value, which is plotted against the 

 economic equivalent of intensity of fishing, namely, running costs. From those are derived 

 (6) the annual profit and (c) the profit expressed as a rate on running costs, which in many 

 situations bear a constant relation to capital outlay. 



MP = maximum profit point; ZP = zero profit point. 



