I 



IN THE BAYS ON THE SOUTH-EAST COAST OF DEVON, 475 



Changes of this kind may possibly, after a series of years, bring about 

 a nett result to the advantage of the dab ; but, as the spawning season 

 of the dab does not precisely coincide with that of the plaice, a 

 detailed examination of the fluctuations of the dab in relation to the 

 physical conditions prevailing during the various spawning seasons is 

 necessary before any such difference can be attributed with confidence 

 to the differential effects of protection on dabs and plaice respectively. 

 The only point established by the investigations as regards the dab 

 is that this species is subject to even greater fluctuations in abundance 

 than the plaice. 



8. In spite of the seasonal and annual fluctuations to which the 

 numbers of flat-fish in the bays are subject, it is clear that there is 

 an essential difference between Start Bay and the other bays to the 

 northward as regards the normal proportions of large and small fish. 



The following table shows the extent of the seasonal fluctuations in 

 the percentage of plaice of different sizes for each bay, as shown by the 

 quarterly averages of the Oithona's records. 



start Bay. Torbay. Teignmouth Bay. 



Length of fish. Per cent. Per cent. Per cent. 



T^„,of„.. / 0-'? ins. ... 1-13 ... 33-77 ... 43-88 

 Immature ^ _. jg_53 ^__ ^_^^ ___ 3_34 



/ 0-7 ins 

 I 8-11 „ 



{ 



Mature... "I 15 j^s. and above' 11-34 ... 5-11 ... 4-16 



Start Bay showed a preponderance of mature plaice at all seasons of 

 the year, and an insignificant proportion of small plaice below 8 inches 

 in length {never more than one-eighth of the total number present). 

 On the other hand, Torbay and Teignmouth Bay always showed a pre- 

 ponderance of immature plaice, while the proportion of the smallest 

 fish below 8 inches was never less than one-third, and sometimes (i.e. 

 during the winter quarter) exceeded three-fourths of the total number 

 present. 



9. The following table shows the average percentage of plaice of 

 each size in the three bays, irrespective of seasonal differences, as 

 shown by the two series of experiments respectively. 



Thistle and Busy Bee, 1895-8. Oithona, 1901-2. 



Thus the preponderance of large plaice over small in Start Bay, 

 and of small plaice over large in the other bays, was even more marked 

 during the Oithona's investigations than during the earlier series of 



