q/ ihe Fishery Board for Scotland. 



385 



These increments are greater in relation to the period than is shown 

 in he fisli from the Clyde ; and the annual increment deduced from 

 comparison of the mean-size of this and the preceding series is, as 

 already indicated, considerably greater also. Thus, for the fish off the 

 Shetlands we have annual increments in millimetres ns follows: — 



31st August. 

 54-9 



4tli Sept. 

 55-2 



16 til to 19th Oct. 

 53-1 



19th May. 

 58-3 



11th Dec. 1901. 

 47-0 



The mean increase in a year between this series and the younger one 

 is therefore about 53'7 mm. (2^ inches), or 22-2 mm. (| inch) more than 

 the yearly gi-owth in the corresponding series in the Clyde. The 

 averages in the hauls oflf Aberdeen indicate the following annual 

 increments in millimetres : — 



21st August. 

 66-5 



28th November. 



58-7 



16th December. 

 63-7 



The mean increase in a year in these cases is about 63'0 mm., or 2| 

 inches. 



In the Firth of Forth the annual increment of growth is still 

 greater, i.e. growth is more lapid, as I haA-e already shown (p. 378), 

 the mean increase from the previous series to this (in May, July, and 

 August) being about 69-8 mm., or, excktding the two instances in 

 May (five fishes) 70-7 mm. (2| inches), more than double, therefore, the 

 growth of the corresponding series in the Clyde. The average size of 

 this series at nearly corresponding dates in the various localities shows 

 the same thing, as indicated below : — 



Finally, the older series which are present in the Clyde hauls show 

 the same tardy growth compared with the East Coast fish, the incre- 

 ments in the interval between the various dates above-mentioned, from 

 1st August to 3rd April, being for the third series 1-3 mm., 1-4 mm., 

 1"8 mm., O-f) mm., and 4-7 mm. respectively, or a total growth in the 345 

 days of 9-7 mm. (| inch). The apparent annual increments of growth 

 between this and the second series are respectively 30-6, 32-0, 29-8, 

 29'9, and 32-2 mm., or a mean of about 30-5 mm., or \-^^ of an inch. 



From the facts above described it is clear that the growth may be 

 very diiferent in diflerent places. At approximately the same age the 

 long rough dab is larger, and grows quicker, in the Firth of Forth 

 than in the deep water oft' Aberdeen ; it is larger and grows quicker 

 in the latter locality than in the deep water off the Shetlands, while it 

 is still smaller and grows less quickly in the Clyde. The difference 

 2a 



