The Herring 



conditions did in fact alter, the new interpretations served as an 

 indicator of the magnitude of these hydrographic alterations . And 

 very considerable they must have been, so immense that Jan found 

 himself being continually annoyed by journalists who occasionally 

 turned their interest to the fish-trade and discovered in the north- 

 ward extensions of the great cod grounds a prognosis for a revolu- 

 tion in the climatic conditions of the northern hemisphere. Not 

 that they were wrong : it was simply that they had no idea them- 

 selves whether they were right or wrong and there was no way of 

 proving the case one way or another. Certainly it was true that 

 the cod did appear to be moving north into waters that would have 

 been too cold for it twenty years earlier, waters that were warm- 

 ing slowly as the Swiss glaciers melted and the great Arctic ice 

 mass also gave signs of diminishing. But very little was known 

 about the past history of these waters or of the cod population 

 that they were now supporting because these waters had been be- 

 yond the range of medieval navies and the sail fishing boats of later 

 years. It was quite possible that there was a short cycle of warm 

 and cold years, a twenty, thirty or fifty year cycle that had been 

 going on unobserved until the general adoption of steam and diesel 

 power had brought these fishing areas into the range of the otter 

 trawl. But the movements of the herring were known, roughly 

 admittedly but still kno\^'Tl, and, if hydrographic conditions could 

 be deduced from these movements, then there was a good deal of 

 evidence for a fifty year cycle and the cod populations might well 

 be in full retreat by 1980. The weather would not change, not 

 anyhow in such southern regions as the British Isles : for there had 

 to be a lot of melting in the ice cap before latitude fifty-five felt 

 the effect. 



Yet still, there had been the Hanseatic League : there had been 

 herring hosts in the Baltic, numbers such as would be unthinkable 

 under present conditions. And simultaneously, the climate of 

 England had allowed vines to grow in Kent and British wines had 

 been cellared. Since the herring was a cold water fish it could not 

 have flourished around the British coasts at that period . So Camden 



191 



