259 



20 females (46*5 per cent.), and 1 of unknown sex (11-1 per cent.). Nineteen of the 

 males were of adult size on recapture, ranging from 33 to 45-5 cm., and avera<jin» 

 38-9 cm., as compared wath a range of from 30 to 42-5 cm., and a mean of 35-8 cm., 

 on liberation ;' they were free for periods of from 45 to 1117 days, the mean being 

 384 days ; they migrated distaiices of from 9 to 96 miles, the mean being 34 "5 

 miles, and the average rate of movement, -85 mile. Three were under the adult 

 size, averaging 31-8 cm., as compared with 31-7 cm. on liberation ; they were at 

 liberty for an average period of 135 days, and travelled from 15 to 54 miles, the 

 mean being 37 miles, and the average rate 2.7 miles. Sixteen of the females were 

 of adult size on recapture, averaging 42-8 cm., and ranging from 38-7 to 47-5 cm., 

 as compared with a mean of 36"1 mn., and a range of from 28 to 44 cm. oii liberation ; 

 they were at hberty for from 291 to 923 days, the mean being 661 days ; they 

 travelled from 17 to 217 miles, the average being 73-9 miles, and the mean rate, I'l 

 miles. Four were under adult size, averging 31 cm., as against 31.4 cm. on Ubera- 

 tion ; they were free for a mean period of 109 days, and moved from 27 to 205 miles, 

 the average being 79-5 miles, and the mean rate 7-3 miles. So far as the port of 

 landing is recorded, 11 were landed at Aberdeen, 6 each at London and Grimsby, 5 

 each at Hull and Hamburg, 4 at Cuxbaven, 2 at Altona, 2 at North Shields, and 1 at 

 Ymuiden. 



The Extent and Direction op Migration. 



First Quarter. — Three males were recaptured in August, all to the south and 

 east, at distances of 27, 37, and 54 miles respectively. 



In September, 2 males were taken, also to the south and east, at 11 and 15 miles. 

 These were the only marked plaice caught in this quarter (11-6 per cent.), all to the 

 south and east. 



Second Quarter. — Three males, 2 females, and 1 of unknown sex were taken in 

 October, the 2 females, 1 of the males, and the fish whose sex was not determined 

 to the south and east, the male at 29 miles, and the female at 27 and 36 miles. The 

 fish of unknown sex was taken 25 miles W./N. f N. of Hanstholm, Denmark, at the 

 mouth of the Skagerak, the apparent rate of movement being 17-25 miles per 10 

 days. A male was caught 12 miles to the south and west, and another 34 miles 

 to the north and west. 



Four males and 2 females were taken in November, but the position of capture 

 of 1 of the males was not recorded. The females and 1 male were taken to the 

 south and east, the male at a distance of 59 miles, and 1 of the females at 50 miles ; 

 the other female was found 20 miles west of List, in the northern part of the island 

 of Sylt, Germany (54° 56' N. ; 7° 49' E.), at a distance of 205 miles, the mean rate of 

 movement having been 17*5 miles ; a male was recaptured 19 miles to the north 

 and east, and another 19 miles to the north and west. 



None was taken in December, so that the total recovered in the second quarter 

 was 12, or 27-9 per cent., but the position of 1 was unknown. Of the remaining 

 11 (25-6 per cent.), 7 (63-6 per cent.) were got to the south and east, at an average 

 distance of 78 miles in the mean direction S. 37° E. ; 2 (18-2 per cent.) were found 

 to the north and west, and 1 each to the north and east, and south and west. 



Third Quarter.— ^o plaice were recaptured during this period. 



Fourth Quarter. — In April 1912, a female v/as taken 136 miles to the south and 

 east, off Jutland Bank, and in May 2 males, 1, 42 miles to the south and east, and 

 the otlier at an unknown locahtv. 



Two females were recovered in June, both to the north and west, 1 at 17 miles 

 and the other at 25 miles. 



Five were found in this quarter, or 11-6 per cent., but the position of 1 was 

 unknown ; 2 were taken to the north and west, and 2 to the south and east. 



In the 12 months immediately following the Uberation of the fish, 22, or 51-2 

 per cent., were recaptured, the positions of 2 being unknown ; of the remainder 

 (46-5 per cent.), 14 (70 per cent.) were got to the south and east, 4 to the noit li and 

 west, and 1 each to the north and east, and south and west. 



Of the others, 5 were taken in the remainder of 1912, 11 in 1913, and 5 in 1914. 



In Jidy 1912, a male was taken 17 miles to the north and west. In October, 

 a male was caught 20 miles to the north and west, and a female 217 miles in the 

 same direction, 30 miles north-east of Sumburgh Head, Shetland. In November, a 



