low at the present time, a low which has brought the fishery to its present 

 grave crisis. 



b) This secular fluctuation corresponds to that which has occurred 

 in the same period in Portugal o And from the general indications which we 

 have it would appear that the fishery in Spain has also had in the last 

 century an analogous progress down to the present low pointj from which 



it has begun to recover only in the past two yearso 



This fact is quite important for us because it can be interpreted 

 in the sense that the Mediterranean tuna fisheries are subject to the same 

 general influences which determine analogous fluctuations of great ampli- 

 tude in the Atlantic fisheries, and that therefore the Mediterranean 

 fisheries are subject to the oceanographic influence of the Atlantic, 

 which can only be manifested in the influx of water from the Atlantic 

 through the Strait of Gibraltaro 



It is in fact not very probable, although still riot precluded, that 

 it is a question of influences of a meteorological or other nature, 

 operating synchronously but separately in the two regionso 



This is one of the many cases which show how useful would be an 

 oceanographic observatory at the Strait of Gibraltar j, the idea of which 

 was suggested by Steuer, which would gather data for the study of the 

 relations between the two seas and of the seasonal and annual variations. 



c) The secular fluctuation of the Lusitano-Mediterranean tuna 

 fisheries corresponds with the last secular fluctuation of the herring 

 fisheiy at BohuslSn , ^described by Pettersson and Johansen, except for a 

 lag of several years. 



And I note that the existence of these fluctuations has been 

 recognized for many centuries now (Ljungman). Pettersson relates it 

 to secular variations in the tides (ill years). Storrow has also occupied 

 himself with the question, placing in evidence analogous fluctuations for 

 other fishes. It is admitted, in any case, that these phenomena are 

 provoked by changes which take place successively and alternately in the 

 physical conditions of the waters. 



The analogy between the fluctuations of the Mediterranean tuna 

 fisheries and the herring fishery in the Skagerrak appears to conform very 

 well to the concept expressed above that our tuna fisheries reflect 

 Atlantic influences. And the proven antiquity of the phenomenon which 

 occurs in Scandinavia augments the probability that that of the tuna 

 fisheries has had a periodic character^ 



d) There are specific zones in which the overall effect of the 

 secondary fluctuationa of the tuna fisheries , at least those of a^ certain 

 Eimplitude , present a_ marked analogy. One of these zones embraces all of 

 Sardinia and Tunisia (Sicily with Favignana is separate from it although 

 very near). 



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