XI 

 THE INTERNAL ECONOMY OF THE SEA 



NO one can forget the first sight of a big catch 

 laid out for sale at one of our chief fishing 

 ports. There are tons and even miles of fishes, 

 recently representing enormous locomotor power in 

 the sea, and soon to be transformed into likewise 

 enormous, though reduced, power of muscle-work 

 and brain-work on land. The sweepings go to feed 

 cattle and to fertilize the ground, and the total 

 supply is in such abundance that we stand wondering 

 at its continuance from day to day, year in year 

 out. What happens in the vast economy of the 

 sea? Who are the producers, the consumers, and 

 the middlemen? A well-known instance will 

 illustrate our inquiry namely, the demonstration, 

 offered some years ago by Dr. E. J. Allen, the 

 Director of the Marine Biological Station at Ply- 

 mouth, that there is a close correlation between tte 

 sunshine records for May and the quantity of 

 mackerel at Billingsgate. The rationale of this is 

 instructive. Mr. G. E. Bullen showed that there 

 is a correspondence between the catches of mackerel 

 during May and the amount of the Copepod plank- 

 ton (i.e. small Crustaceans of drifting habit) upon 

 which the mackerel for the most part feed. Then 



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