326 



Part III. — Twenty-fourth Annual Report 



These herrings, as the other collections and measurements show, are 

 in their third summer, and are spring herrings a little over two years 

 of age. 



To this series also belong nine herrings taken by the Garland on 16th 

 May, measuring from about 9cm. to 12cm. 



In July in the same year a small collection of herrings was secured. 

 There were only eight of them, ranging in size from 109mm. to 137mm., 

 the mean being 123mm. and the average 125'4mm. (4]^ inches). 



In Aberdeen Bay some large collections of herrings at a corresponding 

 stage were obtained. On October 1 8th they numbered 444. There was 

 one at 85mm. (3| inches), the next being 96mm.. and the group to 

 which the latter belonged extended to about 141mm. It contained 429 

 herrings, the modal size of which was 115mm., the mean was also 

 115mm. (4| inches), and the average was 1 17'5mm., or 4g inches. These 

 herrings were thus of almost the exact size of the group caught in the 

 Forth in May, and may be referred to the autumn series, somewhat over 

 two years old. The group might terminate at a slightly smaller size 

 than that indicated, e.g., 137mm.; on the other hand, there were five 

 herrings measuring 143mm. to 145mm., three from 151mm. to 154mm., 

 and one at 164mm. It is possible that the first five belong to the 

 group, but the balance of evidence is against the supposition ; in any 

 case, the mode and average would not be appreciably affected. All the 

 herrings referred to probably belong to a group, extending in this case 

 from 143mm. to 187mm. 



Another large collection obtained on 31st October, but in the previous 

 year, was made up of younger herrings. The curve of trie measurements 

 (see Plate XVII.) is slightly irregular, there being a small depression at 

 about 7"5cm., and two slight cusps at 7cm. and 8cm. Consideration of 

 other cases shows that the group extends to about 9 '5cm., and is really 

 one. The 650 herrings contained in it extend from 52mm. to about 

 95mm. (2^ to 3| inches) ; the chief mode is at 8cm. (3J inches), the 

 mean at 73mm. (2| inches), and the average at 77 8mm., or 3 T L inches. 

 These herrings are obviously those of the year before, and autumn 

 herrings, so that they would be about 13 to 15 months old. The 

 difference between this group and the group of the 18th (in the following 

 year), both of which are supposed to be autumn herrings, is, on the 

 modes 35mm., on the means 42mm., and on the averages as computed 

 39 , 7mm., the mean of the three being 38*9mm. (ly^- inches). The mode, 

 as we have seen, is not regular in the collection of 31st, and is better at 

 7*5cm., which would make the difference 40mm. and the mean of the 

 three comparisons 40"6mm., or lg inches, representing a year's growth. 



The next group consisted of 179 herrings from about 96mm. to 

 143mm., but the larger individuals are not well represented. They 

 appear to belong to the corresponding group so well shown in the 

 collection of 18th October. There was a single herring at 157mm. 



On November 6th and 9th, in three different years (1900, 1901, 19<>3) 

 small collections were obtained, which may be combined and sum- 

 marised. Seven measured from 75mm. to 100mm., the computed 

 average being 87'7mm. (3 T 7 ^ inches) ; 48 ranged from 102mm. to 143mm. 

 (4 to 5| inches), the computed average being 125mm. (4|^ inches). 

 There were also two herrings 185mm. and 188mm. 



On 12th December, six herrings measured from 97mm. to 124mm. (3 T f 

 to 4J inches), the mean size being 110'5mm. and the average 109*3mm. 



On 19th December, six, measuring from 78mm. to 95mm. were 

 caught, the average size being 90*5mm., or 3 T 9 ^- inches; there were also 

 five ranging from 110mm. to 131mm., the average being 120mm., or 

 4| inches. 



