CHAPTER 13 



Plankton (IS food for man. and the possihilitics of jcrtilizing the sea 



If so much life in the sea depends on plankton, it is very natural to ask 

 if plankton cannot be caught commercially, perhaps for human food, 

 perhaps to supplement animal feeding stuffs, and so to lead to increased 

 supplies of human food. 



On page 136 it was stated that the total annual production of green 

 plants in the sea amounted to 150,000 million tons, which yields only about 

 30 million tons, or 0-02 per cent, on the world's fish markets. Can we not 

 use some of the 99-98 per cent of this lost production? Properly treated, the 

 plants could form excellent silage. Or even if we reduce this surplus to one- 

 tenth or even one-hundredth and concentrate on catching only the zoo- 

 plankton, this should leave us some 1,500 million tons a year to tap. Certainly 

 there is plenty of plankton in the sea to be had for the taking — but can we 

 take it? 



Collecting marine plankton for food can be considered under two quite 

 separate topics: as an emergency food for shipwrecked mariners, and as an 

 economic proposition aimed at feeding the world's ever-increasing 

 populations. 



The shipwrecked mariner in his lifeboat or on his raft needs to eke out 

 his existence, to remain in suthcient health long enough to be rescued and 

 enable him to recover completely. His main needs, apart from protection, 

 are water, food and vitamins. Plankton can supply all these, not ideally, 

 possibly somewhat dangerously — but the alternative is so much worse ! Dr. 

 Alain Bombard cast himself adrift in the Atlantic in 1952 to prove to others 

 that man could survive under such conditions, living exclusively on what 

 he could get from the sea, for much longer than the normally expected 

 ten days. He advocated small doses of sea water during the first few days, 

 and while the body still possessed its normal water content, but beyond this 

 first period taking any sea water can only make things worse. Sea water 

 contains about }h per cent salt, while the kidneys can only deal with a 

 little over i per cent, and this figure is soon reached in the blood if natural 

 water losses are not replaced. Taking more salt can then be fatal due to acute 

 nephritis. Dr. Bombard's idea was that as the normal blood contains less 

 than I per cent of salt it can accept sea water with its essential liquid until 

 the limit of salt concentration is reached — but not beyond it — thereby 

 delaying the first onset of dehydration. 



162 



