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Part III. — Twenty -fourth Annual Report 



They formed a compact group (PI. XVII.) ranging from 148mm. to 

 192mm. 5}| to 7 T 9 ^ inches), the modal size was 167mm. (6 T 9 g inches), the 

 mean was 170mm., and the computed average 168 8mm., or inches. 

 These herrings were obviously the same series as those taken on 30th 

 May, that is, herrings in the fourth year, and thus, in all probability, 

 spring herrings somewhat over three years of age. 



The increment of length in the 29 days is, on comparison of the 

 modes, 7mm. to 8mm., on the means 6mm., and on the averages 69mm., 

 or a little over | inch. The rate per day, taking the increase at 7mm., 

 was 0241mm., and per month about 7 5mm., and this in the best period 

 for growth. If a similar rate is assumed for July and August, the 

 increase in the three best months of the year would amount to a little 

 over 22mm. Q inch), which contrasts with the growth of the w T hiting, as 

 indicated on a former page. 



If the group taken on 13th June is contrasted with the small herrings 

 got in the Bay of Nigg, Aberdeen, on the 19th June, referred to 

 previously, whose average was about 60mm., and which were also judged 

 to be autumn herrings, the growth in the two years is seen to amount 

 to about 80mm. (3 T \ inches). If, moreover, the herrings taken in 

 Aberdeen Bay on 30th May are contrasted with those taken at the 

 beginning of the same month (and year) in the Firth of Forth (both 

 being judged to be spring herrings, and the latter about thirteen months 

 younger), the differences are as follows: — On the modes 46mm., on the 

 means 47*5mm., and on the computed averages 48-5mm., showing a 

 mean difference of about 47mm. (l^ inches), or at the rate for the whole 

 period of 385 days of about • 122mm. per day, or 3*7mm. per month. On 

 5th July, 1901, eight herrings were taken in Aberdeen Bay, measuring 

 from 140mm. to 164mm. The modal size was 140mm., the mean 

 150mm., and the computed average was 1492mm., or 5J inches. They 

 belonged, no doubt, to the same series as that of 13th June. 



Some good collections of herrings were obtained in the Dornoch Firth. 

 On 9th February 8 ranged from 104mm. to 122mm., the mode and the 

 mean were 113mm., and the average was 112*4mm., or 4| inches. The 

 position of these is in February of the third year, i.e., nearly two years 

 old, if spring herrings, as they probably are. 



Sixteen obtained on 31st March ranged from 106mm. to 136mm. 

 (4 T 3 ^ to 5| inches), the mode being 112mm., the mean 121mm., and the 

 computed average 117*6mm., or 4£ inches. No doubt they represent 

 the same series as in February, and are about two years of age. 



Several collections were obtained in November. On 5th November, 

 1900, in from 7 to 10 fathoms, 4784 herrings were taken in a haul of 

 li hours' duration, of which 601 were measured. The smallest noted 

 was 73mm., and the largest 206mm., and the great majority ranged 

 about 11cm. to 11 '5cm. The first series is not fully represented, 

 probably because of the escape from the net of the smaller fishes. It 

 extended from 73mm. to about 97mm.; it might be 99mm.; the mean 

 was 85mm., and the computed average 90mm., but the herrings repre- 

 sent only part of a series (in their second year). The 2mm. arrangement 

 of the measurements at this place is as follows : — 



86-7 88-9 90-1 92-3 94-5 96-7 98-9 100-1 102-3 104-5 106-7 108-9 

 57798357 6 17 19 36 



The next series is taken as extending from 98mm. to 141mm. 

 (3 J to 5 T \ inches), but it may end about 13cm. or 13*5cm. The 

 arrangement of the 2mm. measurements is as follows: — 



124-5 126-7 128-9 130-1 132-3 134-5 136-7 138-9 140-1 142-3 144-5 



21 16 8243121 



