SEA-FISHERIES LABORATORY. 213 



At the beginning of these investigations I considered 

 it important to study the question, whether the natural 

 production of fry was great or insignificant in the 

 localities in question. To this end I have from Kisor 

 gathered statistical reports on the quantity of cod caught 

 in the Sondeledfiord. 



By comparison of this material with the result of 

 marking experiments (proportion of recaptures to number 

 of marked fish) the conclusion may safely be drawn, 

 that even in a small fiord like the Sondeledfiord tens of 

 thousands of cod spawn every year, while the Flodevigen 

 hatchery yearly manipulates the roe of about 500 cod 

 (males and females) and distributes the hatched larvae 

 over the whole of the Skagerrak coast. The number of 

 spawning cod on this coast is indeed to be counted in 

 millions. 



By making uniform hauls with a tow-net (see above) 

 I have endeavoured to study the quantitative occurrence 

 of eggs and larvae of the cod. By these tow-nettings it 

 was found that the eggs of the cod may occur in such 

 numbers in the upper layers of the Sondeledfiord that 

 up to 4,000 cod eggs may be obtained in five minutes' 

 tow-netting. A calculation based upon the supposition 

 that the number of eggs gathered by a series of tow- 

 nettings in the spring, 1904, down to 10 metres in four 

 different stations, represent approximately true values for 

 the whole of the inner fiord, gives very large figures. 

 Indeed, we get figures so great, that we may safely draw 

 the conclusion, that even the interior of the Sondeledfiord, 

 an area not exceeding five square kilometres, may in one 

 single day contain more eggs than the Flodevigen 

 hatchery produces in the whole season. And these 

 quantities of eggs, the number of which may be calcu- 

 lated at a certain time in a fiord, are, of course, not the 



