176 



The fish used in this experiment were trawled by the " Goldseeker " in Aberdeen 

 Bay on the 10th June, and were hbe rated at the station the same evening, between 

 9.45 and 10.40 p.m. 



The number recaptured was 201, or 59-8 per cent., namely, 94 males (63-1 per 

 cent.) and 107 females (60-4 per cent.). 



Of the males, 73 were of adult size on recapture, ranging from 33 to 44*4 cm., 

 and averaging 36-7 cm., as compared with a range of from 24-5 to 39 cm., and an 

 average of 33-5 cm., on liberation ; they were at Uberty for from 4 to 1398 days, 

 the mean being 283 days ; they migrated distances of from 4 to 199 miles, the 

 average being 36"6 miles, and the mean rate 1*3 miles per 10 days. Twenty-one 

 were under the adult size on recovery, namely, from 26-7 to 32 "9 cm., the mean 

 being 30-6 cm., as compared with a range of 26-5 to 32-5 cm., and a mean of 29-1 

 cm. on liberation. They were at liberty for from 4 to 272 days, the average being 

 95 days ; they migrated distances of from 4 to 52 miles, the mean being 21*8 miles, 

 and the mean rate 2 '3 miles. 



Fifty-one of the females were of adult size on recapture, ranging from 38*2 to 

 57"6 cm., and averaging 41-8 cm., as compared with a range of from 25-5 to 56 cm., 

 and an average of .34'8 cm. on hberation ; their peiiods of freedom varied from 7 

 to 1447 days, the mean being 447 days ; they moved distances of from 1^ to 126 

 miles, the average being 30-5 miles, and the mean rate "7 mile. Fifty-six were under 

 the adult size, ranging from 28"5 to 37"7 cm., and averaging 34 cm., as compared with 

 a range of from 24*5 to 36-5 cm., and a mean of 31*6 cm. on liberation ; they were at 

 liberty for from 2 to 636 days, the mean being 180 days ; they travelled journeys of 

 fron. 3 to 114 miles, the average being 27' 1 miles, and the mean rate, per 10 days, 

 V5 miles. 



The Extent and Direction of Migration. 



Owing to the number of marked plaice recaptured, this experiment is of special 

 value. The chart, on which are presoited all rhe lines between the position of 

 liberation and of recapture of each fish, shows that the niajority ji.oved to the 

 north-west and the south-west, towards the coast, but a considerable number went 

 farther north, several to the Orkney Isles, and 1 to the west coast. On the other 

 hand, only 1 fish was recaptured to the south of the Firth of Forth, or Lat. 56° N. 



First Quarter. — Thirteen of the marked plaice were recaptured in June, viz. 

 5 males and 8 females. One of the males was caught after 20 days at the place of 

 liberation ; 2 were found to the north and west at distances of 15 and 22 miles ; 1 

 to the north at 10 miles distant ; and 1 to the south and west at a distance of 5^ 

 miles. Two of the females had moved to the north and west for distances of 9 

 and 15 miles respectively ; 4 were found to the north and east at distances of from 

 10 to 45 miles, the latter being offshore, east of Rattray Point ; 1 was caught 4 

 miles to the south and west ; and another 6 miles to the south and east. 



Twenty were recovered in July, 9 males and 11 females. Five of the males were 

 taken to the south and west, at distances of fron 10 to 16 n.iles ; 2 were got to the 

 south and east, at 9 and 11 miles distant ; 1 was found 11 miles to the north and 

 west ; and 1, 4 miles to the north and east, after 38 days. Five of the females 

 were taken to the south and west, at distances of from 12 to 34 miles ; 1, directly 

 west, at 21 miles distant ; 3 to the north and west, at distances of from 12 to 34^^- 

 miles ; and 2 to the south and east, at 8 and 21 miles distant. 



Nine were recovered in August, 6 males and 3 females. Three of the males were 

 found to the south and west, at distances of from 7 to 31 miles ; 2 to the north and 

 east, 4 and 23| miles away ; and 1, 12| miles to the north and west. One of the 

 females was got 3 miles to the south and west, 1, 9 miles to the north and west, 

 and 1, 8^ miles to the south and east. 



In this quarter, the total number recaptured was 42, or 20-9 per cent. ; 10 

 (24-4 per cent.) had moved an average distance of 16 miles in a mean direction N. 

 53° W., the average rate of movement being 15-5 miles per 10 days ; 8 (19-5 per 

 cent.) had gone an average distance of 15 miles in the mean direction N. 30° E., 

 the average rate of movement being 21-9 miles per 10 days ; 16 (39 per cent.) 

 migrated a mean distance of 14 miles S. 55° W., the average rate of movement being 

 3-9 miles ; 6 (14-6 per cent.) went an average distance of 10-6 miles in the mean 

 direction S. 44° E., at the average rate of 4-6 miles ; 1 fish moved 21 miles directly west. 



