35 



Thus the eggs and pelagic yomig of the whiting appear later in fJie Danish 

 ivafers than tJiose of the cod, and it is this circumsfance which determines the distrihu- 

 fion. In the section on the cod I have shown, how the eggs and pelagic young 

 of this species are carried away from the intermediate parts of tlie Danish waters. 

 The eause of this was sliowu to be the curreuts, and the bottom-stages were thus 

 lackiug in certain regions. On account of the later appearance of the whiting 

 eggs and young, otlier hydrographic conditions determine their distribution. I shall 

 uow describe the progress of these. conditions in 1904. 



Af the end of June a great change in the hydrogrnphic conditions tooh place. 

 Concerning this I find the following in the journal, noted on June 30th: 



In the second half of June we had a hard noith-Tve.sfcerly storm, which brought very 

 salt water right down into the Great Belt. In consequence of this we had an unnsuallv high 

 level of water, which even rendered difflcult our investigations of the occurrence of the flat-lish 

 young on the coasts of the Great Belt and western Baltic, and obliged us to go in waist-deep at 

 piaces where we were accustomed merely to wade. AVitb the salt water came numerous speci- 

 mens of Cyanea caj), and Bolina, which we had not previously seen in the Great Belt in summer, 

 became so common as to be a great nuisance in our investigations with the young fish trawl, 

 enveloping the young captured and making the trawl slimy and close. 



This appearence of salt water can be distinctly traced by looking at Tab. 1, 

 where the hydrograpliical changes can easily be followed, e. g. in the Great Belt, 

 by looking down the Table. 

 We find there: 

 D. 27—5—04. S. E. of Sprogø, 20 fm. Surface salinity 12.^ %„ 



D. 30—6—04. Off Nordenhuse, 11 fm. - — 15.^ »/„„ 



D. 28—6—04. Spodsbjærg in N. W. to N., 1' , miles, 14 fm. — 21., %„ 



The two piaces first named lie in the northeru Great Belt, the third in 

 the southern. The great increase observed in the salinity is thus the more striking. 

 An even better notion of the abnormal hydrographic conditions at the end of June 

 will be obtained by looking through the "Nautisk-meteorologisk Aarbog" for 1904. 

 If we take note of the observations made at the lightship of Schultz's Grund, which 

 lies in the southern Kattegat at the boundary to the Great Belt, we find that from 

 tlie 16th to the 24th of June a strong, westerly wiud was biowing, rising to a storm 

 in the later days. From the 17th to the 28t]i the curreut was flowing easterly 

 almost continuously, which meant that the Kattegat current was flowing down into 

 the Great Belt. The salinity on the surface rose from 14.7 "/(,„ on the 16th to 

 21.2 "/oo 0° the 28th. 



As mentioned in my extract from the journal a great quantity of jelly- 

 fishes was found in tlie salt water. Numerous Cyanea cap. were seen near the 

 surface everywhere in the Great Belt and further down in the Fehmarn Belt; deeper 

 down Bolina was found, at some piaces in such great numbers that we could take 

 a netful of them in a 10 minutes haul with the young-fish trawl. These jelly- 

 fishes come with the current from the uorth. We had not seen them in the Great 

 Belt before the June storms, at auy rate uo Bolina and not so manj' nor so large 

 Cyanea cap. The whiting young followed with the jelly-fislies. At the stations 

 where we took the whiting young in the Great Belt on the 20t!i and 28th of June, 

 there were many jelly-fishes (see the journal extract given above for the 20th and 

 28th — 6). 



