of the Fisheri/ Board for fScotland. 409 



March to 20th May, 71 days, the apparent increase was 24*4 mm., or on 

 the amended average 32-4 mm. The iucrea.se in length in the whole 

 period from the beginning of September till the tliird week in May 

 amounted to about 109 mm., or i-f^ inches. 



The increase in the second series over the whole period was 72*5 mm. 

 (2g inches), or with the amended avei'ages 63-5 mm. (2| inches), while 

 the apparent increment in the third series was 40"7 mm., or 1| inches. 



The differences between the average size of the various series may now 

 be considered. The mean length of the haddock at Aberdeen when one 

 year of age we have seen to be about 7^ inches, but the growth in length 

 during the second year is less. The mean of the differences between 

 the average size of the first and second series in twelve collections in 

 the autumn of 1900 was about 4f inches. The mean of the thirteen 

 hauls in 1901 in which the series were represented was 108 mm. or 

 4^ inches, which represents the apparent average growth from the first 

 to the second series in the course of a year. The difterence varies 

 considerably according to the time of year, being between 130 and 

 134 mm. in July, when the first series appears, and diminishing in the 

 latter part of the year, owing to the relatively more rapid growth of the 

 first series. And since the growth during the first year in the deep water 

 off the Shetlands is less than at Aberdeen, while it is relatively greater 

 in the second year, the difference between the averages is greater, the mean 

 of the five cases having 126"2 mm., or |f inches. 



The growth in length from the second to the third series is slower. At 

 Aberdeen the mean of ten cases in 1901 was 95*5 mm., or 3| inches; 

 in several of these instances, however, the number of haddocks was small 

 and the larger ones not proportionally well represented. In the deep-sea 

 haddocks practically the same difference was shown, the mean of the four 

 cases being 94"9 mm. 



The growth in length from the third to the fourth series is less pre- 

 cisely determined. The eight cases at Aberdeen in which comparison can 

 be made gives a mean uf 81'3 mm., or 3^^^ inches. In four cases in the 

 Moray Firth the mean amounts to 85 •! mm., or 3| inches. 



I have represented in the curves on Plate XXI. the average growth of 

 the haddock at Aberdeen and in the deep water off the Shetlands ; in the 

 former case by taking the mean of the measurements for the bay and the 

 deeper water offshore, while in the latter case the measurements them- 

 selves are represented. The averages for Aberdeen Bay and oil' Aberdeen 

 coincide very closely for the young haddocks from July, in which they 

 were first caught, until the following summer, when they were over a 

 year old, but in the autumn and winter the averages vary and diverge, 

 owing, as explained, to the unequal representation of the larger fishes, but 

 the curve substantially represents the size at different periods. 



The following Table is based upon the curve, and represents the 

 approximate mean length and w^eight of the haddock when one, two, and 

 three years old at Aberdeen and in the deep water of the northern part 

 of the North Sea respectively, as well as the approximate range of length 

 and weight in the same series in the early part of April. The weights 

 are derived from a curve formed by weighing a large number of haddocks ; 

 its accuracy is greater for the smaller-sized fishes than for the larger, of 

 which fewer were weiehed. 



[Table. 



