6 — 



If we consider the argument in favour of hatching, which is taken from the statistics 

 of the Christiania Fish Marlcet, it is easy to see the reason why this has not been 

 convincing. 



From the year 1872 the police office in Christiania has icept a record of fish sold 

 in the fish market from the fjord inside Drobak, from districts outside Drobak, and finally 

 from Sweden and Denmark. When employing these statistics for biological purposes 

 we must above all remember, that its figures only refer to the sale of fish in 

 the fish market. As regards the inner fjord we must specially notice that a considerable 

 source of error is to be found in the fact, that an unknown quantity of fish is caught 



SS-Q 



/87i-7i 7t-7S76 77-78 7?SOÔ/'6Z-85SfSS86d788-8?70f/?Zf57f 7596 ?7?8??/?m/ûZ03O9ÛS 06 



CocL Matkerel Whilma 



Fig. 1. Diagram showing the number of cod, mackerel and whiting sold in the Christiania 

 Fish Market from the fjord inside Dr0bak in the years 1872—1906 (in thousands). 



in the fjord and sold elsewhere in the districts or to the town itself without passing 

 through the fish market. 



The diagram Fig. 1 records the number of cod, whiting and mackerel sold in the 

 fish market in Christiania in the years 1872— 1906. 



Regarding the cod we see that there have evidently occurred 3 periods with high 

 values, viz: one period in the seventies terminating in a minimum in the early eighties, 

 then a shorter period of rise in the eighties with a subseqent minimum towards the 

 end of the decade. The liberation of cod larvae began in 1892 and was succeeded by 

 a rise in the nineties and the beginning of the present century. 



A glance at the curves for mackerel and whiting is sufficient to show, that the rise 

 in the number of cod during the last 12 or 13 years cannot be taken as a proof of the 



