292 



1914, 34 miles to the south and west, near Burghead, 1 in April 1914, 27^ miles 

 to the south and west, in the Dornoch Firth, another in May 1914, taken at Dubh 

 Artach, on the west coast of Scotland, at a distance of 277 miles, and the fourth 

 in October 1915, 34 miles to the south and west, near Burghead. A female, 

 measuring 40-40-8 cm., was taken in March 1914, 6i miles to the north and east, 

 and was " immature." 



Experiments 15 Miles E. | N. op Tarbet Ness, Moray Firth. 



On three occasions, marked plaice were liberated at a position 15 miles E. i N. 

 of Tarbet Ness (57° 58' N. ; 3° 21' W.), the depth of water being 21 fathoms. 



EXPERIMENT I. 



Uth March 1911. 



The first experiment was made on 14!h March 1911, when 50 marked plaice 

 were liberated. They comprised 21 maks, varying from 17 to 32-5 cm. in length, 

 all being under adult size, and 29 females, of from 22 to 53-5 cm., of which 24 were 

 under adult size. 



The fish used in this experiment were taken in the Dornoch Firth on the same 

 day. 



The number recaptured was 19, or 38 per cent., namely 9 males (42-9 per cent.) 

 and 10 females (34-5 per cent.). Six of the males were of adult size, averaging 

 37-35 cm. ; they had been at liberty for an average period of 475 days, and had 

 migrated from 13 to 116 miles, the mean being 42-5 miles. Three of the males 

 were under adult size on recapture, averaging 27-2 cm., and being at Uberty for a 

 mean period of 39-6 days, having travelled a mean distance of 17-6 miles. Three 

 of the females were of adult size, averaging 44-5 cm. ; they were free for an average 

 period of 522 days, and had travelled a mean distance of 77-6 miles. Seven of the 

 females were under adult size, averaging 32-9 cm. ; they were at liberty for a mean 

 period of 154 days, and had moved an average distance of 18-2 miles. 



The Extent and Direction of Migration. 



First Quarter. — Three males and 4 females were taken in April 1911, 2 of the 

 males off Embo Point, at 18 and 19 miles distant, and the third off Tarbet Ness, 15 

 miles to the south and west ; 1 of the females was found in the Dornoch Fii'th, 

 18 miles to the north and west ; another 2 miles off Golspie, also 18 miles to the 

 north and west ; the third off Burghead, 7| miles to the south and west : and the 

 fourth east of Clyth Ness, 27 miles to the north and east. 



Thus, 7, or 36-8 per cent., were taken in the first quarter, 4 to the north and 

 west, 2 to the south and west, and 1 to the north and east. 



Second Quarter. — In this period, only 1 fish was recaptured, a male, caught in 

 August off Embo Point, 20 miles to the north and west. 



Third Quarter. — One was taken in November, a female, at an unspecified 

 locaUty in the Moray Firth. 



