SEA-FISHERIES LABORATORY. 



317 



There can be no doubt that the experimental work 

 does indicate with a fair degree of certainty that 

 fluctuations in the abundance of fish on a ground are 

 the result of fluctuations in the regular migrations on to 

 that ground ; and also that these migrations are affected 

 by temperature-fluctuations, with regard to the number 

 of fish taking part in them and the dates at which the 



1901 , I90& . 1909 . 1910 . 1911 . 19 IE 



CaTch of Plaice 



J/0 

 100 



90 



3ea-Temf>era1ure in November 



Text-Fig. 5. Variations in the catch of plaice per day's fishing, and 



in the sea-temperature in November at hydrographic stations 5, 6 and 



7. The mean in each case is 100, the other figures represent the 



deviation above and below these means. 



migrations begin and end. The fact that the physical 

 and statistical data available fail to show this relation- 

 ship in a satisfactory manner is, no doubt, due only to 

 the inaccuracies, or insufficiency, of both these series of 

 data. The methods in use, both with regard to the 

 physical observations and the collection of the fishery 

 statistics, are quite satisfactory : the planning of the 



