— 21 — APPENDIX B: HEINCKE 



shall content ourselves here, with stating the most obvious of the positive results of the 

 experiments and with making a few appropriate and, it appears to us, simple and certain 

 conclusions. 



The greatest quantities of these 3215 marked plaice, viz. 2004 specimens or 63 "/o, 

 were set out in only two regions, namely, in the neighbourhood of Heligoland (20 sea-miles 

 round) and in the neighbourhood of Horns Reef. Of 1320 plaice set out at Heligoland, 

 183 were recaught; no less than 168 at Heligoland itself, within 1 to 443 days of replac- 

 ing them in the water, and only 15 in other parts of the North Sea. Of the 689 plaice 

 set out at Horns Reef, 90 in all were retaken, 83 at Horns Reef, therefore near to where 

 they were set out, within 1 to 184 days and only 7 in other parts of the North Sea. 



Of the 15 plaice set out at Heligoland, but retaken elsewhere, 10 did not leave the 

 German Bight (i. e. Borkum — Tail of Dogger Bank — Horns Reef) ; the interval between 

 the setting out and recapture varied from 68 to 354 days; the places of recapture lay in 

 all directions. Of the 5 others, which had migrated out of thisi region only one was retaken to 

 the north, namely, on the Little Fisher Bank after 472 days; the other 4 had gone to the 

 west and south-west, one in 116 days as far as Puzzle Hole (c. 145 s. m.), the second in 

 313 days, as far as the eastern edge of the Brown Ridges (c. 180 s. m.), the third in 125 

 days, to off Scheveningen (c. 200 s. m.), the fourth lastly, in 281 days to off the mouth of 

 the Maas (c. 210 s. m.). 



Of the 7 plaice set out at Horns Reef, but not recaught there, none were retaken 

 over 120 s. m. from where they were put into the water; 4 had gone to the south, 2 in 

 28 and 29 days as far as Norderney (88 s. m.) ; 3 to the north , 1 in 43 days as far as 

 Lökken in the Skager Rak (c. 120 s. m.). 



Concerning the plaice set out in other parts of the North Sea than at Heligoland 

 and Horns Reef, some of those retaken are especially remarkable, namely, 7 put out on the 

 Great Fisher Bank at the end of September 1903. With the exception of one, which had 

 gone easterly as far as Holmen's Ground (c. 85 s. m.) in 104 days, all had wandered to 

 the south, one for example in 138 days to the Oyster Bank (c. 170 s. m.), another in 214 

 days to Graadyb (c. 195 s. m.) 



The noteworthy results of these experiments seem to us the following: 



(1) The great majority of all the plaice marked were retaken within 

 the same narrow region in which they were set out. Of all those set out in 

 the German Bight, only a few, about 3 to é^/o, were recaught beyond the boniidaries of 

 this region, and most of these had gone to the south, west and south-west along the 

 German and Dutch coasts. It cannot as yet be concluded, therefore, that the great mass 

 of plaice, especially of the still immature, in the German part of the North Sea, make 

 relatively extensive migrations yearly, over 50 to 100 s. m. and more in one direction. 

 The critical value of this conclusion is frankly not very great, as yet. We do not know, 

 for example, whether the plaice set out at Heligoland , and recaught there only after a 

 large number of days, have not in the interval wandered some distance away and returned; 

 we must remember also, that the probability of retaking the plaice marked, is greater where 

 and when the fishery is greater, and smaller when the plaice wander far and distribute 

 themselves in all directions. It is quite possible, therefore, that relatively many more 

 plaice have in reality wandered far beyond the region investigated, than the experiment 

 allows one to suppose. 



