234 



Females. — The condition of the ovaries was ascertained in 10 of the 12 females 

 recaptured. One was "spawning" ; it was taken in April 1911, to the east of 

 the Orlaieys, 35 miles to the south and west ; 1, taken in November, 6 miles to 

 the north and west, was " nearly ripe," and 2 were described as " spent " ; 1 

 recaptured in Apiil 1911, east of the Orkneys, 36 miles to the south and west, 

 and the other on the north coast, off Whiten Head, 105 miles to the westwards 



EXPERIMENT V. 



mhAfrill^U. 



In this experiment, 70 plaice, 33 males and 37 females, were liberated at the 

 same place as before, 59° 20' N. ; 1° 3' W., on the 11th April 1911. The males 

 ranged in size from 24-5 to 39 cm., and 25 were under adalt size on liberation ; 

 the females measured from 25 to 67 cm., and 20 were under adult size when liberated. 



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

 follows : — 



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



2.5-305 31-3.5-5 3fi-40-5 41-4.5-5 4G-50-5 51-555 Total. 

 F. Lib. . . 13 6 4 3 6 4 37t 



F. Recap. . . 1 3 3 3 5 4 20t 



M. Lib. . . 22* 9 2 — — — 33 



M. Recap. . . 3 7 1 — — — 11 



* Two at 24-5 cm. t One at 67 cm. 



The fish used were taken by the " Goldseeker " in the Dornoch Firth, Moray 

 Firth, on the 8th April, in the forenoon. The fish were placed in tubs of running 

 sea water, and the vessel proceeded to visit certain hydrographic stations ; owing 

 to bad weather it had to return to the Dornocli Firth on the 9th April, where it 

 lay until the evening of the 10th. TJie fish were liberated about 11 a.m. on the 

 11th, and although they had been in the tubs for 3 days, and the weather was 

 very rough, only 1 marked plaice died in the tubs. 



The number recaptured was 31, or 44'3 per cent., namely, 11 males, or 33-3 

 per cent,, and 20 females, or 54*1 per cent. Ten of the males were of adult size 

 on recapture, ranging from 34'8 to 47*5 cm., and averaging 39'3 cm., as compared 

 with a range of from 26 to 36 cm., and an average of 32-5 cm., on Hberation : they 

 were at Uberty for from 126 to 1349 days, the mean being 430 days ; they migrated 

 distances of from 13 to 113 miles, the mean being 67-6 miles, and the mean rate of 

 movement 1*5 miles. Seventeen of the females were of adult size, averaging 

 50-8 cm., and ranging from 39-7 to 68 cm., as compared with a range of from 31 

 to 67 cm., and an average of 46-6 cm. on liberation ; they were at liberty for from 

 79 to 1023 days, the mean being 304 days ; they migrated distances of from 6 

 to 188 miles, the mean being 45'4 miles, and the mean rate 1*5 miles. 



The Extent and Direotion of Migration. 



First Quarter. — None was taken in April or May, and only 1. a female, in June ; 

 it was caught east of the Orkneys, 33 miles to the south and we.st. 



Second Quarter. — One male and 5 females were recaptured in July, the male 

 16 miles to the north and west, and 4 of the females to the iiortli and west, at 11, 

 12, 13, and 13 miles ; the remaining female was taken Jiear Rattrav Head, 97 

 miles to the south and west. 



Two males and a female were taken in August, the female 10 miles to the 

 north and west ; 1 of the males off Kinnaird Head, 90 miles to the south and 

 west, and the other 8 miles south-east of Baltasound Light, at the north of the 

 Shetlands, 79 miles to the north and east. 



A male and a female were taken in September, the male 13 miles, and the 

 female 12 miles to the north and west. 



