o/ the Fisher ij Board for Scotland. 



393 



If this average and range be compared with those tor the corresponding 

 date at Aberdeen Bay and the deep water off Aberdeen, it will be seen 

 that the latter are larger, the difference in mean-size being over 13 mm. 

 and 6-7 mm. respectively. This is in agreement with the results derived 

 from the measurements of haddocks and long rough dabs, growth 

 in summer and autumn being less rapid in the deep water in the northern 

 part of the North Sea, as one might expect from the more tardy cycle of 

 temperature changes. Growth in winter and spring is, however, more 

 rapid in the deep water than near the shore ; but the evidence on this 

 point in the case of the whiting is slender, owing to the imperfection of 

 the hauls in May. If we assume that the conditions were essentially 

 similar in December 1900 as in December 1901, then we would have the 

 following ranges and averages for the respective dates, as computed from 

 the measurements and as amended : — 



The maximum size from the first to the third case increased by 46 mm., 

 and I have assumed an increase of 45 mm. for the minimum size in the 

 same period. The mean-size, uncorrected^ increased by 28-9 mm., and, 

 as amended, by 48-6 mm. in the 102 days to December. In Aberdeen 

 Bay, from 4th September to 17th December (in 1901), the apparent 

 increment amounted to 25*7 mm. and the amended increment to about 39 

 mm., so that during this period the rate of growth seems to be only 

 slightly more rapid in the deep water than in Aberdeen Bay. But the 

 average sizes, whether directly computed or amended, differ considerably 

 at the corresponding dates. In the beginning of September it was 96-2 

 (or 76-5) off the Shetlands, while in Aberdeen Bay it was 109-8 (or 940), 

 a difference of 13-6 (or 17-5 miu.); in the middle of December it was 

 125-1 mm. off the Shetlands, while in Aberdeen Bay it was 135-5 (133, 

 cd). It is not improbable that the spawning season in the two areas may 

 vary to some extent — and in that case the facts point to its being later in 

 the north — but it is pretty certain, I think, that the seasonable rate of 

 growth differs in the two regions. 



It would be of interest to test the relative increments during winter. 

 In Aberdeen Bay it amounted in the period from 17th-21st December 

 1900 (8059 fish) to 30th May 1901 (366 fish) to 17-1 mm. in the 160 days, 

 showing very slow growth, which, we may feel sure, was made up in April, 

 and especially in May. As stated, the collections from the deep water off 

 the Shetlands in May were imperfect ; but since a series begins before 

 250 mm. (extending to about 330 mm.), and the interval from the end of 

 the first series in December to the beginning of this series in j\Iay — five 

 months later — amounts to less than 86 mm. (thus excluding the possibility 

 of an intermediate series), it appears certain that the few whitings 

 obtained in May, ranging from 187 to about 230 mm., represent the first 



