APPENDIX H: GARSTANG — 6 — 



2. Summer migrations 



A few words as to the metliod by wMch the migration charts have been constructed will 

 probably lead to an easier comprehension of the results there displayed. Particulars have been 

 forwarded to me by the members of the Committee as to the exact locality of capture of each 

 fish as reported by the fishermen. For each experiment the positions of recapture were first 

 separately indicated upon large charts, the date of recapture and size of the fish beiug repre- 

 sented at each spot. In the case of large experiments, e. g., Da 2, 3 and 5, it was then possible 

 to draw a contour line around all the positions of recapture in each successive month. The 

 successive positions of these monthly contour-lines give a correct representation of the directions 

 in which the fish gradually spread themselves as the season advanced. In other cases the 

 general direction of migration could be shown by drawing a contour liue representing the entire 

 range of migration during the summer period, e. g., E 4 and 6. Adjacent experiments, the 

 results of which were substantially the same, have been amalgamated in the reduced charts 

 now published. In other cases the number of recoveries did not permit of the adoption of the 

 contour method. In these cases (e.g.. Da 15, D 13) the positions of liberation have been 

 indicated on the chart, as well as the separate positions of recapture, the latter being connected 

 with the point of liberation by a line. It is of course impossible to state how far the lines 

 drawn upon the chart approximate to the real lines along whicli the fish migrated. The number 

 of the experiments carried out by the Danish investigators in the Skager Eak, in conjunction 

 with the restricted area of the experiments, has rendered it impossible without causing confusion 

 to distinguish the exact range of the inshore migrations corresponding to the different experi- 

 ments. On this account a single contour line has been drawn around the positions of recapture 

 during April, May and June in the case of the Danish experiments 7, 8, 9, 10, 16 and 17. 

 The positions of recapture after the month of June have been separately indicated for each 

 experiment, and connected with the point of liberation in each case. With this explanation I 

 hope that the charts will be easily intelligible. 



The Swedish experiments in the Kattegat, strictly speaking, do not represent the normal 

 migrations in that area, since the fish were caught west of Skageu and transplanted to the 

 thi-ee positions around the island of Orust indicated upon the chart. The number of recoveries 

 is too small to permit of any generalisations. 



In the Skager Eak the plaice from the Danish experiments were recovered during May 

 and June within the coastal waters with one exception. The general tendency of migration 

 during this period was westwards and southwards. Several of the fish from experiments 9 and 

 10 (6 on the chart) wandered as far south as the entrance to the Lim Fjord. One was caught 

 iu June near the northern boundary of the Horn Ueef Grounds. This fish, as in many similar 

 cases, was one of the largest recovered from this experiment, the length on liberation having 

 been 33 cm. During the later summer months the fish from these experiments were mostly 

 recovered in the offshore waters, and showed a general tendency toward the Holmen Grounds. 

 An eastward tendency was shown during the spring months by the fish marked offshore in 

 experiments 11 and 6 (2 and 4 on the chart) and one small fish from experiment 7 (5 on the 

 chart) was recovered in November in the Aalbek Bight east of Skagen. 



West of Jutland the general tendency was directly westwards or north-westwards towards 



