42 FISHERIES OF THE NORTH SEA 



is this reproduction that it would be useless 

 to try to give correct figures ; sufficient to 

 say the numbers involved are almost in- 

 calculable. As soon as these fry emerge 

 from the egg, the first and last problem 

 they have in life is to eat and avoid being 

 eaten. That is the first law of nature 

 in the ocean. The voracity of fish is extra- 

 ordinary ; often they will swallow other 

 fish until their stomach is distended to 

 such an extent that they fall an easy prey 

 in turn to larger fish. Many can eat other 

 fish bigger than themselves ; others, if 

 they cannot manage the whole of their 

 prey will swallow half, and when that is 

 digested draw in the other half, which in 

 the interval was sticking out of the mouth 

 of the victor. To protect themselves they 

 move about with the utmost rapidity, or 

 hide by mimicking the waving sea grasses 

 or disguising themselves as part. of the sea- 

 bed. The sole adopts the colour of the 

 sand in which it lives ; plaice and dabs are 

 darker when caught on the Icelandic banks, 

 where the bottom is black and muddy ; 

 in the North Sea, where the bottom is sandy, 

 they are lighter. The haddock and herring 



