NATURE ADRIFT 



When the extra fertUizer is used up, the organisms of the red-tide die off in 

 their milhons and milhons and things gradually return to normal. If there is 

 fertilizer to spare, how much better to put it on the land and increase our 

 crops under proper control with a reasonable hope of a fair economic ^return 

 and extra food for the world ! hideed, there is so much rich fertilizer unused 

 in the deep oceans that if we could do so it would be better to extract it from 

 the sea instead of putting it back. 



A more hopeful way of fertilizing the sea would be to increase the turn- 

 over between the nutrient rich deep layers and the depleted surface layers, 

 especially in the warmer oceans. This is not a biological problem, but an 

 engineering one, and not within the scope of this book which is, however, 

 sufficiently ecological to remind the reader that transference by the bucketful, 

 or even by the million gallons, is neither here nor there. 



This rather discouraging chapter does not mean that all efforts to improve 

 marine fisheries by artificial means are doomed to failure. In Chapter lo it 

 was emphasized that the greatest loss offish occurred in the planktonic stages. 

 If we can rear fish beyond that stage, simply by giving them enough food 

 and protecting them from their natural enemies, we could increase the 

 potential fish stocks — provided there is sufficient natural food for them where 

 they are to be liberated. Another way of doing much the same thing is by 

 catching large numbers of young fish in their natural nurseries and trans- 

 planting them to places where the food is more plentiful than it would be 

 where the fish would normally migrate to. This has been done for a number 

 of years in the North Sea, taking young plaice to the Dogger Bank which 

 provides a better natural food supply than the shallow sandy shores of the 

 continent. It would help, too, if we can increase the available food by re- 

 ducing the numbers of other less valuable species eating the same foods. 

 This could be a way of getting more human food out of the sea, but the 

 economics depend on the ratio between the increased value of the fish caught 

 and the cost of rearing and transplanting the fish, or the cost of the 'weeding' 

 operations. 



The world's population is increasing at a frightening rate, and increased 

 populations mean increased need for food. The sea is an important source 

 of this food and will give better and better yields as we learn more and more 

 about it, and learn to exploit it in a controlled and rational way. This means 

 the international co-operation of biologists, chemists, physicists, engineers, 

 statisticians, politicians, fishermen and all the various ancillary vocations and 

 trades. It can be done and, gradually, it is being done. 



This book is about plankton, and the part plankton plays in this problem, 

 it is not a book on the economics of world population. Nevertheless, plankton 

 forms a natural community of living things and its study is bound to show 



170 



