290 



EXPERIMENT X. 



llth November 1913. 



In this experiment, 100 plaice were marked and liberated at 58° 10' N. ; 3° 2' W., 

 viz. 51 males and 49 females. The males measured from 23*5 to 46 cm., and 1 3 were 

 under adult size ; the females ranged from 25 to 55 cm., and 14 were under adult 

 size on liberation. 



The numbers liberated and recaptured, arranged in 5-cm. groups, were as 



follows : — 



cm. cm. cm. cm. cm. cm. 



25-30-5 31-35-5 36-40 5 41-45-5 46-50-5 51-55-5 Total. 



F. Lib. .. 7 4 14 12 9 3 49 



F. E«cap. ..13 8 2 2 2 18 



M. Lib. .. 9* 6 18 17 1 — 51 



M. Recap. . . — 1 6 9 _ _ 16 



* One at 23-5 cm. 



The fish used in this experiment were taken by the " Goldseeker " in Burghead 

 Bay, on the sa^ne day as they were Uberated. 



The number recaptured was 34, or 34 per cent. — a very small proportion — 

 viz. 16 males (31-4 per cent.) and 18 females (36-7 per cent.). All the males recap- 

 tured were of adult size, measuring from 38-8 to 44 cm., and averaging 41-4 cm., as 

 compared with a range of from 32-5 to 43 5 cm. and a mean of 41 -2 cm. on hbera- 

 tion ; thev were at hberty for from 87 to 822 days, the Uican being 186 days ; they 

 migrated distances of from 3| to 28| miles, the mean being 18-3 miles, and the 

 average rate "9 mile. Of the females, 14 w^ere of aduk size, measuring from 38 to 

 55-2 cm., the average being 44*1 cm., as against a ranee of from. 35-5 to 55 cm., and 

 an average of 43 cm. on Uberation ; they were at hberty for from 89 to 695 days, 

 the average being 217 days : they travelled distances of from 4 to 277 miles, Ihe 

 mean being 60-4 miles, and the average late 2-8 miles. 



The Extent and Direction of Migration. 



First Quarter. — Only 1 fish was recaptured in this quarter, a male, which was 

 taken in January 1914, 4| miles to the north and west. 



Second Quarter — ^ight males and 3 females were taken in February, but the 

 place of capture of 1 male was unknown. Of the other 7, 6 were found to the 

 south and west, 1 at 11 miles, and 5 near Tarbet Ness, at the entrance to the 

 Dornoch Firth, at distances of 24, 26, and 27 miles ; the remaining male was 

 captured farther to the north, south-east of Berriedale Ness, at a distance of 

 11 miles ; the 3 females were all taken to the south and west, 2 to the east of Tarbet 

 Ness, at distances of 21 and 29 miles, and 1 at Burghead, at a distance of 28 miles. 



Four males and 4 females were taken in March ; the place of capture of 1 of 

 the males was unknown ; 2 were taken to the south and west, at Burghead, and 

 near Tarbet Ness, distances of 28 and 25 miles ; the remaining male was taken 

 on Smith Bank, 3| miles to the south and east ; 2 of the females were recaptured 

 to the south and west, at Burghead, distances of 29 and .34 miles ; 1 was taken 

 4 miles to the north and west, and 1, 6^ miles to the north and east. 



Three females were recaptured in April, 1, 5 miles to the north and west 1 

 27 miles to the south and west, off Tarbet Ness, and 1, 16 miles soutli of Sule Skerry, 

 off the north coast, 76 miles to the north and westwards. 



In this quarter, 22 of the marked plaice, or 64-7 per cent., were recaptured, 

 the place being known for 20 (58-8 per cent.), and of those, 14, or 70 per cent, were 

 taken to the south and west, at an average distance of 26 miles, in the mean direction 

 S. 63° W., 3 to the north and west, 2 to the north and east, and 1 to the south and 

 east. 



Third Quarter. — Three females were taken in May, all to the northwards, 1 

 close to Noss Head, 19 miles to the north and east, 1 at the Pentland Skerries, 

 37 miles to the north and east, and the third on the west coast of Scotland, 7 miles 

 W.S.W.of Dubh Artach (Lat. 56° 3' N. ; Long. 6° 47' W.), a distance of 277 miles, 



