490 REPORT ON TRAWLING AND OTHER INVESTIGATIONS 



for plaice of the smaller size-group would probably, indeed, slightly 

 exceed the figure assigned, since, as pointed out in the previous section, 

 relatively few of the 8-inch fish were recovered, and we have seen in 

 this section that the rate of growth was inversely proportional to the 

 original size of the fish. 



This experimental result agrees with the evidence of the trawling 

 records. Station VII. in Teignmouth Bay is the chief rearing-ground 

 for small plaice, and a representative haul on that station on October 

 9th (Table D, haul 7) shows that intervals of 4 inches and about 

 3 1 inches separated the sizes at which the plaice were most abundant, 

 viz. 4 inches, 8 inches, and 11 or 12 inches. These sizes, according to 

 Petersen's method, may be taken as the average sizes of plaice of suc- 

 cessive yearly groups, and the intervals between them as the annual 

 increments of growth (cf. also Torbay, same table, Station IV., hauls 

 1, 4, 8, and 34). 



Section III. 

 The Reproduction of the Fiat-Fishes. 



H. M. Kyle, M.A., D.Sc. 



1. SPAWNING PERIOD OF THE PLAICE. 



" The spawning periods of the food-fishes have been fully ascertained 

 for the east coast of Scotland by Dr. Fulton and other Scottish workers, 

 and the present occasion afforded a good opportunity of determining the 

 spawning time of the plaice on the south-west coast of England. Mr. 

 Cunningham's work, published in previous numbers of this Journal, and 

 in more compendious form in his book on Marhctalle Marine Fishes, 

 covers the whole field of fishery investigation, and forms therefore an 

 excellent basis for more definite and detailed research. The spawning 

 period of the plaice, for example, is given as January, February, and 

 Marcli for tlie North Sea and English Channel, and in a general way 

 this is (^uite correct, but it is somewhat vague. The plaice of the 

 Bristol Channel also spawn during the months mentioned, but on the 

 whole later than those of the English Channel. It is evident, therefore, 

 that we must ascertain the periods at which most plaice are spawning 

 or have spawned, in other words the maximum spawning period as it 

 is generally called. The difficulties in the way of ascertaining this 

 accurately arise from the facts that all fish do not spawn exactly at tlie 

 same time, and that one fish may take two or more weeks in getting 

 rid of all its spawn. We cannot, therefore, delimit the maximum 

 spawning period to less than two to three weeks, and if we allow for 



