400 Fart III. — Twentieth Annual Report 



male whiting (all sizes together) closely correspond (that of 423 males 

 examined being 11 '29 inches, that of 895 females 11'78 inches) there do 

 not appear to be exact observations as to the average size at first-maturity 

 in the two sexes. 



From the investigations detailed in this paper it appears that some 

 whitings, before the conclusion of the spawning season in the year after 

 that in which they were themselves born — i.e., when they are a little over 

 one year of age — may attain a size about equal to the size above stated at 

 which maturity is first reached. But the size of the whitings at corres- 

 ponding ages may, as we have seen, differ considerably in different places, 

 and the size at which maturity is attained will, no doubt, differ in 

 the same way. Such cases, however, of large whitings one year 

 old are exceptional, and represent only the few biggest fish of the 

 generation ; while the average size, and still more, of course, the minimum 

 size, of the series arc very much lower. In Aberdeen Bay, for example, 

 whitings one year old may vary from about 3| inches to 7i inches, the 

 average size being 5| inches. In the Firth of Forth the range is from 

 about 2| inches to 6| inches, the average being 4^ inches. The 

 whitings from the deep water off the Shetlands (according to the com- 

 putation previously made, grow more quickly during winter and 

 spring, and may be regarded as ranging in May from about five to nine 

 inches, with an average of se^■en inches ; but further observations are 

 required in this case. There is little doubt that none of these whitings 

 spawn at the sizes stated — i.e., when one year old. 



When two years old the whitings at Aberdeen range from about seven 

 and three-quarter inches to over twelve inches, the average size being 

 about 9|- inches. In the Forth they are somewhat smaller, ranging from 

 under seven to nearly llg inches, the average size being about 8|- inches. 

 It is this series, then, I think without any doubt, that must be regarded 

 as that which spawns for the first time ; and on the assumption discussed 

 elsewhere (p. 359) it is probable that all the whitings spawn when two 

 years old, the larger fishes probably earliest in March, and the smaller 

 towards the end of the spawning season in June, when they will have 

 added considerably to their length. One would expect to find 

 therefore, among these spawning whitings a variation in the size at 

 first-maturity corresponding to the limits of the group — i.e., from about 

 eight to over twelve inches. 



I have given in the following Table the approximate length and 

 weight of the whitings at one and two years of age in the localities 

 referred to : — 



[Table. 



