of the Fishery Board for Scotland. 



63 



appeared to have just left the immature group. Ninety-two herrings, 

 19 to 28 cm. long, in June were not classified ; they were probably 

 composed of immature and winter-spent herrings. 



The first point to be determined is the smallest size of maturity. For 

 this purpose attention may be directed to the winter-spawners, which are 

 shown in " Fulls," Table, p. 60; Developing, Table, p. 61 ; Spents, Table 

 p. 61. The winter-fulls are seen in February to vary in length from 17 

 to 34 cm. The developing winter-spawners range from 17 to 29 cm., 

 while the spents in February, March, and April range from 19 to 32 

 cm. in length. The smallest size of the winter-spawning herring at 

 maturity is 17 cm. 



The upper limit of the first spawning group may be got from a study 

 of the Tables of Immature herrings, p. 59, and of the Immature develop- 

 ing herrings, p. 60. The immature winter-spawners, which will become 

 ripe for the first time in February, leave the immature group during the 

 previous summer. In June the upper limit was 28 cm. ; in August the 

 upper limit of the specimens obtained was 25 cm. In July a few imma- 

 ture developing herrings measured from 26 to 30 cm., and in August the 

 same class was represented by the series 17 to 28 cm. The immature 

 developers soon become merged in the developing winter-spawning group. 

 Taking 30 cm. as the upper limit of the immature developers in August, it 

 may be taken for granted that the fish of that size will by February have 

 grown in length. In March and April the full herrings were from 20 to 

 29, 31 cm., and 20 to 29 cm. respectively. I take 30 cm. as the upper 

 limit of the first spawning group. 



The first spawning group of winter-spawners may therefore be taken as 

 from 17 to 30 cm. 



It is now necessary to determine the lowest size of this group when it 

 is a year older and is spawning for the second time. During the year the 

 winter-spents have been traced for several months, vide Table, p. 61, In 

 June they measured from 19 to 31 cm., in July from 18 to 30 cm., in 

 August from 21 to 32 cm. Beyond the last-mentioned month the spents 

 were not recognisable, but were included in the developing winter- 

 spawners. The developing winter-spawners measured in September 21 to 

 29 cm., in October 20 to 33 cm., in November 17 to 31 cm., in December 

 18 to 32 cm. These lots of fish probably include both first and second 

 spawning groups. In January most of the winter-spawners were full. 

 They measured 22 to 32 cm., while the developing members measured 

 from 19 to 26, 33 cm. In October the full herrings measured 23 to 32 

 cm., in November 23 to 32 cm., in December 22 to 32 cm. I regard the 

 sizes 22 to 32 cm. as representing the second-spawning group. There 

 would appear to be an indication, as Smitt says, that the herrings which 

 spawn early in the winter have spawned before, while those which spawn 

 at the end of the season are spawning for the first time. 



So far as the material goes, a similar relationship i« shown in the 

 summer-spawning group. The immatures that are to spawn in summer 

 leave the immature group in winter. The immatures in winter do not 

 seem to be so large as those of summer. The largest sizes were 23 and 

 25 cm. for immature, and 26 cm. for an immature developing. The 

 immature developers in February were from 17 to 26 cm. But in 

 January the representatives of this stage measured from 15 to 24 cm. 

 And judging by the amount of fat present in the immature herrings 1 3 

 to 23 cm. in length in February, it was indicated that these herrings 

 would soon leave the immature group and would probably spawn during 

 the summer, vide p. 56. It is therefore probable that 17 cm. is 

 not, during February, the lowest limit of the first summer-spawning group. 

 In July the summer-spawners measured from 21 to 33 cm. I do not 

 think the smallest mature herrings are represented in this sample. The 



