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in mind, that according to the general experience, about 20 years ago, when steam 

 trawhng was commenced, these very large and old plaice were caught in much greater 

 quantity, both relative and absolute, than is now the case. The extremely intensive 

 fishing of the Iceland grounds, which are of very restricted extent, has evidently already 

 eliminated a great part of the superfluity of large, old plaice, the so called accumulated stock, 

 and reduced the composition of the stock to something similar to that of the North Sea. 

 There can however be no doubt, that the Icelandic plaice even now reach a greater age 

 than those of the North Sea, which is evidently a sign of more primitive conditions 

 prevailing. 



If we examine the composition of the landings from Iceland with regard to sex, 

 and compare with the conditions in the North Sea, a greater and very remarkable 

 difference is noticed, viz., an extraordinarily large majority of males as compared to 

 females. Of 11,675 Icelandic plaice examined with regard to sex, not less than 70 "/o 

 were male, and only 30^/0 female; a proportion which, at least in the southern 

 North Sea, is only found on the spawning grounds at spawning time, otherwise males 

 and females are as a rule caught there in equal numbers. In the northern North Sea, as 

 far as investigations have been carried out, e. g., in the Moray Firth, we find that 

 somewhat similar conditions to those of Iceland waters prevail, the males here outnum- 

 bering, from 18 cm. upwards, the females in a proportion of 54 : 46. If we compare, 

 as is most correct, only the higher parts of the series of measurements from 33 cm. 

 and upwards, which is the value of greatest density in the Iceland series, then the 

 proportion in number of male and female plaice of 33 cm. and upwards in the North 

 Sea about 40 : 60, in Iceland waters 66 : 34. Among plaice of 40 cm. and upwards we 

 have for the North Sea 18 : 82, for Iceland 47 : 53, while plaice of 50 cm. and upwards, 

 i. e., abt. 9 years old or more, appear in the proportions of 10 : 90 for the North Sea, 

 and 30 : 70 for Iceland. Thus ive see, that in Iceland waters a great many more males 

 reach an advanced age than is the case in the North Sea. Of all male plaice over 

 32 cm. in the North Sea, only about 1^2 ''/o reach a length of 50 cm. or more; in 

 Iceland waters about 4 "/o. Of females of the corresponding size class in the North Sea 

 about 8 "/o reach a length of 50 cm. and more, in Iceland waters about 25 "/o. 



The male plaice thus reach a considerably larger size on the Iceland fishing grounds 

 than in the North Sea, and naturally also a correspondingly greater age. 



A further, and very characteristic difference in the proportions of the sexes in the 

 North Sea as compared with Iceland is the fact that the point of intersection of the 

 curves of sex for Iceland occur at a considerably higher length than for the North Sea. 

 In the southern North Sea this point of intersection, i. e., the length at which male 

 and female appear in equal numbers, is about 24 cm., in the Scottish fiords about 

 37 cm. and for Iceland about 44 cm. 



It is probable that these remarkable differences between the plaice stock of the 

 Iceland fishing grounds and that of the North Sea with regard to the proportions of 

 the sexes, indicate that the Iceland stock is in a more primitive and natural state, that 

 of the North Sea being more strongly aftected by fishery. When a primitive, little 

 fished stock is so intensively fished that a decrease in the density, i. e., an absolute 

 reduction in the size of the stock takes place, and when this is chiefly due to the fact 

 that the older fish are taken in relatively greater quantities than the small, which is 



