of the Fishery Board for Scotland. 19 



maturity. When calculated out it is found that approximately 24 per cent., 

 or about one quarter of the total marketable plaice, by weight, are under 

 the limit or immature. The proportion with the plaice varies greatly 

 according to the depth of water, and the figure given offers a contrast to 

 what obtains in the southern and eastern parts of the North Sea. 



Among lemon dabs all those classed as large, or firsts, are over the 

 biological limit of maturity, but a fair proportion of the second class, or 

 smalls, are immature, the percentage being about seven for the total 

 weight of the marketable fishes. 



Among witches, all those classed as firsts, or large, are over the limit 

 of maturity, and have either spawned or are large enough to do so. 

 Among the class of seconds, which range in size from a little over 8 

 inches to about 14 inches, with an average length of, approximately, 

 11^ inches, a considerable proportion are below the size of maturity, but 

 the percentage of the immature, by weight, of the total number of market- 

 able witches is only about 15. 



From the large size at which the cod first attains maturity, the 

 proportion of the immature that are marketable is very considerable. 

 Among boxed codlings one often finds a few which are over the 

 biological size at maturity, and measuring as much as 28 inches, the 

 selection as cod or codling on the part of the men on board the trawlers 

 often depending on the meagre or fat condition of the fish, as well as on 

 its length. Of all the cod and codling landed about 30 per cent., by 

 weight, are beloAv the biological size of maturity. 



With haddocks and whitings it is very difi'erent, since the market- 

 able size approximates to the size at which the fishes first become 

 mature. The calculations in regard to haddocks show that the 

 proportion of the marketable which are immature is very small, 

 amounting to only about 1 per cent, of the total quantity landed. This 

 is much under what one might expect from the statements made as to 

 the large quantities of undersized haddocks sometimes landed, but it is 

 the result of careful observations on a large number of fishes, both in 

 regard to size and weight. All the medium and large haddocks, or firsts 

 and seconds, landed are above the mature size, and the great majority 

 also of the small haddocks, or thirds. 



With the whiting the proportion of the immature among marketable 

 fishes is still less, and the quantity of small, or second class, whitings 

 brought to market by trawlers is inconsiderable, while the proportion 

 among those which are under the biological size of maturity is also 

 fractional. It may be said that practically all the whitings marketed by 

 trawlers are of adult size. 



It must be borne in mind in connection with this subject that the 

 limit taken is a biological one, having reference, not to the size of the 

 fish from the market point of view, but with reference to reproduction. 



With regard to the numbers, as apart from the weight, the calculations 

 show that, taking the mean of several years, the following represents 

 approximately the total numbers of the fish of the kinds named which 

 are brought to Aberdeen market:— Cod, including codling, 4,575,000; 

 haddocks, 110,000,000; whitings, 15,000,000; plaice, 2,400,000; lemon 

 dabs, 1,600,000; witches, 3,900,000; and dabs, 260,000. 



Investigations in the Moray Firth and Aberdeen Bay. 



I. 



The first of the series of investigations was made in the Moray Firth 

 in February, the steam trawler employed being the " Ben Edra," the trip 

 extending from the 7th to the 13th ; nineteen hauls of the net wer« 



