SCIENTIFIC WORK IN THE SEA-FISHERIES. 251 



of the results of these surveys, indeed, does not lead us to expect 

 , a solution of fisheries' problems from the hydrographers, how- 

 ever much we may appreciate their skilful and patient, though 

 expensive, labours in other respects. Therefore, grave doubt 

 was expressed, in 1901 and 1902, as to the propriety — at least, 

 so far as Britain was concerned — of making such observations so 

 prominent in the international scheme. 



The International Council has published four bulky quarto 

 Bulletins annually, besides other papers, giving hydrographic 

 details, temperatures, and tables of floating organisms. Few 

 important additions have been made to the latter — except the 

 long list of species of diatoms — since the subject was dealt with 

 for a whole year in St. Andrews Bay in 1888. The hydro- 

 graphical remarks merit careful attention, since the British 

 naturalists — from the experience acquired in these investigations 

 — state that they are within measurable distance of explaining 

 all the migrations of the fishes, as well as the fluctuations in the 

 fisheries, by such means. Further, that ordinary trawling ex- 

 periments are of little value, unless hydrographical, physical, 

 and chemical researches go with them ; that the changes in the 

 water cause the changes in the fishes which (species not men- 

 tioned) may be in one place in autumn and another in spring ; 

 in short, here to-day and away to-morrow to their special waters. 

 They narrate that, though the periodic Gulf Stream does not 

 reach the North Sea, yet Atlantic flooding into this area occurs at 

 the same time. There are, however, perturbations, the study of 

 which belongs to the future. Dr. Otto Pettersson, indeed, thinks 

 these disturbances show a two-yearly period — even and odd 

 years — the even with more temperate waters than the odd, and 

 accompanied by a warm-water area in the cold season — with a 

 failure in fishing. He adds that the winter Herring-fishery in 

 the Skagerak has returned with intervals, on the whole, of 111 

 years — since 859. Other hydrographic researches — such as 

 that of the Faroe-Shetland Channel and the Influence of the 

 East Islandic Polar Stream on the climatic changes of the 

 Faroe Isles, the Shetlands, and the North of Scotland— do not 

 seem to bear on the main point at issue, and the same may be 

 said of another on the compressibility of sea-water. 



So far as experience goes, it is scarcely possible to explain 



