45 



On the 30th of May we were agaiii at the same spot in the western Baltic 

 as on the 6th and 17th. Immediately afterwards we went northwards with the 

 »Sallingsund« and investigated the coudition of the plaice yonng in the Skager 

 Rak and northern Kattegat on the Ist and 2iid of June. 



By this means we agaiu had proof of the great advance in development, 

 which the plaice young in the northern Danish waters show over those in the 

 western Baltic. 



On May 30th I note in my journal: 



J). 30 — 5 — 04. To-day we again took many pelagic pUiice yonng lo the west of Skjold- 

 nfe.s. Tliey were taken in inlermediaie haul.s wiLh the young-fi.sh trawl and were all symmetricai. 

 In a yertical haul witli the pelagic net we got 84 eggs, none of which were plaice. 



In Søby Bay we were successfnl this time in our search for the young plaice. Wilb 

 the "bobinet" net we took in ca. 1 foot of water 1 metamorjihosed plnice young in which the eye 

 had just corapleted the migration. In deeper water with the "half-moon" nel towed behind the 

 boat we caught 2 jihiire young. Of these one was strongly pigmented on the right side, the eye 

 had jusl completed its migration. In the other the left eye was on the ridge, and there was but 

 little difference in the pigmentation of the two sides. They swam in a slanting position when 

 put into a basin. 



The plaice yoiwg at Ærø were tims at the end of May at a similar develop- 

 mental stage to those of the northern Kattegat at the end of April. In the northern 

 Kattegat development was therefore a whole mouth in advance, and when we 

 took them there in the first days of June they had with a single exception com- 

 pleted metamorphosis. 



D, 1—6—08. Skaw light-ship in S., 60 fm. (Tab. 1, Skager Rak). Young-fish trawl in 

 inlermediate lavers — 40 fm., 40 minutes: no plaice young, many young of other species, e. g. 

 long-rough dab, dab, a few flounder. Young-fish trawl on blocka on the botiom, 20 minutes : a 

 few fish young, no plaice. Young-fish trawl on bottom, 15 minutes: many adult fishes, 4 bottom- 

 stages of long-rougli dab. 



We thus did not find the ]ilaice young again in the Skager Rak, where 

 they were so numerons on April 28th. 



We then searched the coast in Aalbæk Bay with the shove-uet. No plaice 

 young were taken, but the coast was exposed to storms and the action of waves 

 and therefore little suited as an abode for the young plaice (see "Biol. Stat. Beret- 

 ning XII", p. 6: "Yngelens Udbredning ved Kysterne"). 



We then went out to deeper water: 



D. 1—6—04. Off Aalbæk, 2—4 fm., sandy bottom. Young-fish trawl on the bottom, 

 2 hauls of 10 and 15 minutes: 11 plaice young, 12—18 mm. These were all metamorphosed 

 except one, which however was asyiumetrical 



Next dav we found to the north of Frederikshavn's harbour a numerous 

 stock of metamorphosed plaice, 1 — 2 cm., which must have wandered in since 

 April 27th, as we the found but one though we searched two hours (see above). 



On May 30th when we left the western Baltic the movement of the meta- 

 morphosed young to the coast had just begun. In June we again paid a visit 

 there in order to follow the fate of the young plaice. The day's investigations 

 read as follows in the journal: 



D. 13 — 6 — 04. In deep water W. of Skjoldnæs we took today a pdagic plaice young 

 in an intermediate haul with the young-fish trawl; it was symmetricai. 



In Søby Bay we took ^plaice of the O group, l'/a, IVj, l'/j. S'/s cm. in the "bobinet" net. 



In deeper water of ca. 1 fm. we made a haul \\ith the "half moon" net and got two 

 plaice of the O group, 1, IV2 cm. 



