45 



enonnous area of the North Sea, which is at least twenty 

 times the size of the Irish Sea. 



Special vessels have, however, important work to do, 

 which will obtain for ns information supplementary to 

 that derived from the fishing fleets. They should be sent 

 to survey special grounds, to investigate spawning 

 grounds, nurseries where small fish congregate, and any 

 other areas of importance in connection with particular 

 problems. And when set on work of this kind no other 

 duties such as periodic cruises, mainly of hydrographic 

 importance, should be allowed to interrupt the progress 

 and continuity of these investigations. 



One of the chief features of the international scheme 

 is that all the vessels of the participating countries shall 

 undertake quarterly cruises along certain lines taking 

 hydrographic and other observations at fixed stations. 

 It is clear from the evidence given before the Ichthyo- 

 logical Committee that there is at least considerable 

 difference of opinion even amongst hydrographers as to 

 the value of the observations obtained on such cruises, 

 and what direct bearing they have upon the fishery 

 problems in which this country is really interested it 

 would be difficult to say. It may be practically impor- 

 tant, if any reliable conclusions can be drawn from 

 observations made three months apart, to the countries 

 bordering on the Baltic, and possibly to those interested 

 in the deep Norwegian Sea, to know something of the 

 movements of bodies of water differing very slightly in 

 temperature and in density ; but the influence of such varia- 

 tions upon the habits and abundance of the flat fish in our 

 shallow Noi-th Sea has still to be demonstrated, and must 

 at the best be so indirect, so slight, and so inconstant as 

 to be upset by storms, chance winds and floods bringing 

 an influx of fresh water from the rivers. 



