316 TRANSACTIONS -LIVERPOOL BIOLOGICAL SOCIETY. 



point at which the two curves cross is rather different 

 in each, and the difference between the temperatures 

 read off from the curves for any date is not always the 

 same. But no certain relationship between these 

 temperature fluctuations and the fishery fluctuations" can 

 be deduced. There ought to be some relationship, and 

 the fact that it cannot be seen is not to be explained in 

 any other way than by supposing that the hypothesis of 

 temperature-adaptation by migration is not true, or that 

 the temperature data, and the fishery statistics, are too 

 inaccurate to exhibit it. '! 



The years 1909 and 1910 were years of low range of 

 temperature at Nelson Buoy : the latter was 12'5° in 

 1909 and 121° in 1910. These also were years in which 

 the plaice fishery in Bed Wharf Bay was relatively good. 

 The years 1911 and 1912 were years in which the range 

 of temperature was high : it was 14'25° in the former and 

 13'0° in the latter, and they were also years in which 

 the fishery in Red Wharf Bay was relatively poor. 



In fig. 5 the fluctuations of temperature at hydro- 

 graphic Stations 5, 6 and 7, in the month of November, 

 are compared with the mean daily catch of plaice, in 

 cwts., in the Red Wharf Bay area during the last two 

 months of the year. Here there does seem to be a 

 relationship. The years of low temperature are good 

 fishery years, and vice versa, and the correspondence is 

 quite good — indeed, it is all that could be desired — 

 except for the year 1912. In that year the catch of 

 plaice ought to have been better than that of 1911, since 

 the temperature had fallen, yet the opposite is the case. 

 If, however, we suppose — what, indeed, is very probably 

 the case — that the exceptionally bad weather of the 

 latter part of 1912 affected the fishing by preventing the 

 smacks from going to sea, then the relationship would 

 hold good. 



