of the Fishenj Board for Scotland. 49 



6. Special Statistics. 



As already mentioned, there are no statistics available which furnish the 

 particulars necessary to prove the benefit from sea-fish hatching. The 

 nearest approach to them perhaps are the statistics showing the catch of 

 cod and other fishes from the Christianiafjord over some 36 years, which 

 have frequently been referred to in connection with fish-hatching. These 

 statistics have never yet been published in a collected form, and I am 

 indebted to Mr. Knut Dahl for the detailed statement of them, which that 

 gentleman has kindly extracted from the various reports in which they 

 are contained, and which is subjoined here. They refer to two divisions 

 of Christianiafjord, the part within and the part without Drbbak, and to 

 the number of cod, whiting, and mackerel, and the weight of flat-fish, in 

 pounds, taken from these two areas and sold at the market of Christiania ; 

 the figures thus relate only to the sale in the fish-market, and do not show 

 the unknown quantity caught in the fjord and sold elsewhere in the dis- 

 trict. Probably a much more serious defect in these statistics from the 

 present point of view is that there is no information showing the amount 

 of fishing expended in the various years in relation to the quantity of fish 

 sold. It may well be that in a year when the quantity of fish was large 

 tlie quantity of fishing gear or the intensity of fishing was also great, and 

 the opposite. It may also be noted that the term "flat-fish" appears to 

 include several species, with the exception of halibut. 



The interest of the figures in relation to the question of fish-hatching 

 lies in the fact that for a number of years cod fry from the hatchery at 

 Flbdevig were placed in the fjord, and that since then the quantity or 

 number of cod taken from the fjord and sold at the market at Christiania 

 has steadily increased. Without particulars as to the relation between 

 the extent of fishing operations and the quantities caught in each year, it 

 would not be possible to establish the precise connection between the 

 liberation of fry, and the increase in the quantity of cod, but inasmuch as 

 the area of the fjnrd within Drobak is not very great, and it may be 

 supposed that the amount of fishing has a rough relation to the abundance 

 of fish in any year, a steady increase of the kind might ofi'er presumptive 

 evidence that the liberation of the fry was beneficial. Cod fry began to 

 be added in 1892,. usually from ten or fifteen to twenty millions annually, 

 and it will be seen from the table that in each year since the number of 

 cod taken from this part of the fjord and sold at Christiania has greatly 

 increased. Taking the average of each successive six years in the period 

 of 36 years we have the following : — 



of 



The statistics, however, include particulars as to other fishes besides the 

 cod, namely, whiting, mackerel, and " flat-fishes." The latter need not 

 be further referred to since several species are included, but those refer- 

 ring to whiting are important, and they show that the numbers of this 

 fish have increased in even greater ratio than the numbers of the cod. 

 The averages for the six-year periods are as follows : — 



