rround a horizontal aitisc j- great difficulty is the pollution of 

 the water. Even if the v/atcr is constantly reneriTed, many food 

 remains, shells afttr the shedding, excreraents, etc.,, VYill be 

 gathere'l. In order to remove these things, small air bubbles are 

 forced into the hose leading to the apparatus. This happens tv/ice 

 per 24 hoiurse These air bubbles attach themselves to all pollut- 

 ing particles and couse the latter to rise to the siu'faceo They 

 are simply remox'ed by means of a fine dip net. Also nil the 

 strainers for the outlets must be kept constantly clean- 

 In each of these aquaria it is -Tossible to rear about 5,000 

 larvae to the bottom stage at a time; the percentage is dependent 

 upon the number of lai-vac in the boXj - tlie denser population, the 

 smaller nercentage. One might count on a profit of 20 to 40 per 

 cento The tem.peroture and the degree of salinity of the sea water 

 are of gret t importance. At Fl;(devigen vie always tal:e the sea 

 water from a depth of four meters; this lias alv/ays proved salt 

 enough, ^vs is known, the degree of saltness increases as vre go 

 deeper T On the other hand it appears that the temperature might 

 fall so much that the development of the larvae is hampered and 

 the death rate increases© This is due to the fact that tlie larvae 

 vfhich are in the process of changing shells, are hindered in their 

 production of shell oy the low temperaturco Yfe can avoid this 

 difficulty by using a large v;ater reser^/oir - but this is rather 

 expensive© 



Yflien the larvae have reached the bottom stage they are very 

 easy to recognize on account of their long claws which are stretched 

 forw-ard. They rir-e then picked up, counted and transferred to cle^.n 

 aqurria v/here there is a very weak c;irrent» During the first time 

 the larvae, swim quickly around near the surface, but after having 

 been fed for some days, they start settling dovm on the bottom and 

 the sides of the aquariumc NavT they are ready to be liberated in 

 the sea. 



The transportation is partly made in the sane tubs, v;hich are 

 used fcr transportation of cod young; these' are square wooden boxes 

 0e73 X 0»80 meters and 0.56 meters deep, in which is installed a 

 somev/hat smrdler inner box with walls of wax cloth in order to pro- 

 tect against the rolling of the vessel, and with a fine screening 

 m.esh (cloth) in the br-ttom which i.rkes the renewal of the v/ater 

 possible during the transportatioiio On lon;';er trips, hove^-er,, the 

 transportation must take plaoe in especially designed tubs with 

 constantly circulating water - in rccordance v/ith the principle used 

 in the rearing stations We have made two successful experiments 

 v.rith transportation as for as to the Oslof jord. 



In this way the technical problems both as to the rearing and 

 the transpirtation have been solved. The question is now to find 

 out hovj- economical the rerr ing mii.ht be d.one^ This depends upon 

 whether one has means for full production so thai; the possibilities 



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