of the Fishery Board for Scotland. 



329 



This series comprised 544 herrings, the mode was 115mm., the mean 

 1195mm., and the computed or arithmetical average 114*4mm. 

 (4^ inches). These were probably autumn harrings over two years of 

 age. There were also 9 herrings from 144mm. to 162mm. 



On the 11th November, 1903, in from 6 to 12 fathoms, 110 herrings 

 were caught. Of these 99 ranged from 79mm. to 109mm., the mode 

 uas 95mm., the mean 94mm., and the average 94 , 3mm., or 3| inches. 



On the following day (12th) 1336 herrings were taken in from 6 to 

 10 fathoms, and all measured. The first series, comprising 1234 herrings, 

 apparently ranged in length from 79mm. to 133mm. (3g to 5| inches) ; 

 the series might, however, terminate about 133mm or 136mm. or 

 138mm. The above range (54mm.) is greater than usual. On the 

 other hand, the series might not begin till about 83mm. or 85mm. 

 There is not uncommonly a difficulty in assigning the position of the 

 odd fish at the beginning or end of a series, which may belong to 

 different groups, but the influence on the average size is quite unappre- 

 ciable, while the mode is unaffected. The 2mm. arrangement at the 

 beginning of the series on 11th and 12th November is as follows: — 



79-80 81-2 83-4 85-6 87-8 89-90 



11th 1 5 9 9 9 



12th 2 2 3 9 15 22 



The most appropriate interpretation is that the series begins at 84mm. 

 and extends to 133mm. (3f to 5^ inches). The modal size is 105mm., 

 the mean 108 - 5mm., and the average 105'4mm., or 4^ inches. These 

 herrings are doubtless autumn herrings, two years and a few months old. 



Most of the remaining herrings in the collection, viz., 87., measured 

 from 161mm. to 198mm. (6f to 7 T § inches), the mode being 175mm., 

 the mean 180mm., and the computed average 1791mm., or a trifle over 

 7 inches. The group is only partially represented, but as the difference 

 from the other and younger group amounts to over 70mm., it is evident 

 that they do not represent that series when one year older. They are 

 apparently spring herrings, about three years and seven months old, 

 members of the group present in the collection from the Dornoch Firth 

 on 15th December, and in that taken at Burghead Bay in December, 

 referred to below. 



The herrings between 133mm. and 162mm. numbered 15, from 

 134mm. to 152mm., and they belong to another group, viz., that shown 

 in the December collection from Aberdeen Bay. 



A large number of herrings were taken on 25th December in the 

 Dornoch Firth in another year. The youngest series comprised 1769 

 fishes, measuring from 98mm. to about 144m in. (3^ to §\\ inches) ; the 

 modal size was 119mm. (4^i inches), the mean w T as 121mm., and the 

 computed average 122*4mm. (4^| inches). 



These are autumn herrings, two years and some months old. The 

 size of the corresponding group taken on 12th November, and described 

 above, was 105mm., while here, 43 days later, it is above 14mm. higher. 

 The amount is too much to be accounted for by increment of growth 

 in the interval ; and the explanation is probably to be found in the fact 

 that the collections belong to different years (1900 and 1903) there 

 being, doubtless, as with other fishes, a variation in the growth in 

 different years. 



Only a few belong to the second series (represented in Aberdeen Bay 

 in the same month), viz., 172, ranging from 145mm. to 178mm. 



A third group is better indicated by 41 herrings from 182mm. to 

 217mm., the modal size being about 196mm., and the average 190'8mrn., 

 or a little over 7 inches. 



