THE AGE OF FISHES 189 



submarine shelf of the Grand Banks of Newfoundland and 

 the fishing grounds of New England. Here the arctic waters, 

 well laden with detritus and rich in fertihzer, meet the warm 

 waters of the Gulf Stream, and at this arctic front a great 

 swirling and stirring of waters takes place — just as the cold 

 fronts in the river of air bring about violent winds and storm. 

 This turbulent mixing of waters provides the proper conditions 

 of temperature and food for an outburst of plankton growth, 

 and the crop of ocean pasturage in turn supports the greatest 

 commercial fishery of the western Atlantic. The same benefi- 

 cial effects of arctic fronts have much to do with the living 

 wealth of fisheries elsewhere. The branches and tendrils of the 

 River near Iceland, in the Norwegian Sea, and in the still more 

 northerly Barents Sea, form growth-stimulating swirls of water 

 and bring fertility as a result of their conflict with colder 

 waters. 



Now we begin to see how the Ocean River brings life to its 

 fisheries by means of the perpetual conflict between the cold 

 arctic waters and the great warm flood of the Gulf Stream, and 

 how the pulses and changes in this ocean circulation have far- 

 reaching effects on our sea-food harvest. When we can tell 

 exactly how this happens, and when we can predict the effects 

 of weakened or increased flow in the River, we shall be closer 

 to predicting changes in the great fisheries and even in the 

 weather. Were we able to foresee changes in this pulse of the 

 ocean circulation, however, we should still be far from know- 

 ing their full effects on the commercial fish catches. 



These changes work in a complicated manner and their 

 results are sometimes paradoxical. The French scientist Le 

 Danois, and with him the American Columbus Iselin, have 

 suggested that a speeding up of the Gulf Stream flow may 

 bring colder instead of warmer water to the Atlantic fishery 

 grounds; it could happen in this way. When a current of water 

 increases its flow — as we have shown in an earlier chapter — 



