234 DISCOVERY REPORTS 



Whereas February to April corresponds closely with the season of El Nino, this 

 counter-current has never been recorded south of Pisco : the squids on the other hand 

 do not appear to be stranded north of Arica. 



According to Wilhelm (1930) the squids enter the harbour alive and vigorous, and he 

 tells of a coasting steamer which meeting with a shoal in the open sea was unable to head 

 it off from Talcahuano Bay. His observations suggest that the animals are killed as a 

 result of battering against rocks and the quayside. The ovaries were spent, but since 

 the females are accompanied by males, immature individuals, and sometimes by hake 

 [Merluccius gayi), Wilhelm draws the tentative conclusion that the squids may have come 

 inshore to feed. 



The squids had been in Talcahuano a week or two and were already advanced in de- 

 composition when our ship arrived. At that date, the plankton in the bay showed no 

 signs of having been killed and water was not discoloured. We are therefore in agree- 

 ment with Wilhelm, that on the evidence at present available this migration is more 

 likely to have a biological than a hydrological cause. 



COMPARISON OF CONDITIONS ON THE 

 EAST AND WEST COASTS 



The further significance of conditions in the Peru Coastal Current may be 

 appreciated by comparing the west and east coasts of South America. Marine life on the 

 Patagonian continental shelf is relatively poorer. The area is bathed by the Falkland 

 Current which flows past the Falkland Islands northwards towards the South American 

 coast, in compensation, it is believed, for the Brazil Current, as the latter is deflected 

 eastwards. The Falkland Current thus converges with the coast, and although con- 

 siderable vertical mixing takes place over the Patagonian shelf, the circulation may be 

 expected to share some of the characteristics of a closed system. 



On the west coast, on the other hand, the Peru Coastal Current is essentially a single- 

 sided divergence line, and waters of different character, on the one hand from the deep, 

 on the other from the surface, are being constantly mixed together, drawn off, and their 

 place taken by fresh supplies. That areas of mixture are frequently of especial fertility 

 for the production of plankton has been emphasized by Hardy (1935) with reference to 

 the rich plankton found off South Georgia, where the waters of Weddell Sea and Bel- 

 lingshausen Sea origin mix. 



The importance of mixture may be seen in the Labrador Current. It compensates 

 for the Gulf Stream as the latter deflects eastward, and it has in consequence been 

 regarded as the analogue of the Falkland Current. The Labrador Current also converges 

 with the coast, yet the fisheries of the Newfoundland Banks are the symbol of very 

 fertile conditions. This finds a ready explanation when it is remembered that the 

 Labrador Current is not homologous with the Falkland Current. The Labrador 

 Current, having an Arctic origin, shares the fertility of polar seas, whereas the Falkland 

 Current is not Antarctic but sub-Antarctic, is an arm of the West Wind Drift and has 

 not experienced the vertical mixing of ice-laden water. 



