95 



The 17 adult females were at liberty for from 38 to 721 daj's, the average 

 being 311 days ; the mean size on liberation was 37"5 cm., and on recapture 42*7 

 cm. ; they moved distances of from 4 to 74 miles, the mean being 28-8 miles, and 

 the mean rate '9 miles per 10 days. The 5 immature females were at liberty 

 for from 42 to 360 days, the mean being 236 days ; the average size on liberation 

 was 31" 3 cm., and on recapture 35*3 cm. ; they migrated distances of from 18 to 

 49 miles, the mean being 28*4 miles, and the mean rate 1*2 miles. 



The Extent and Direction op Migration. 



First Quarter. — In the month after liberation, April 1911, only 3 fish (2 

 males and 1 female) were recaptured. The female and one of the males were taken 

 5 miles to the south and west ; the other male had moved westwards to the coast 

 of Fife (to the same locality where it was originally captured) ; it was a small fish 

 (29-5 cm. in length), and had made the 23 miles at an average rate per 10 davs of 

 20-9 miles. 



In May, 4 were recaptured (2 males and 2 females), but the position of 

 recapture of 1 of the males was not ascertained. The other male and 1 of 

 the females had moved 6 and 4 miles respectively to the south and west ; the other 

 female, measuring 34 cm. on liberation, had gone westwards into the Firth of Forth, 

 to the coast of Fifeshire, and was taken near Elie, 31 miles distant, the average 

 rate of travel being 7' 4 miles. 



Two were taken in June (a male and a female) ; the latter was recaptured, 

 after 72 days, 8| miles to the north-east, and the male, after 78 days, 15 miles to the 

 north-west, near the Bell Kock. 



Thus 9 of the total recaptures, or 25" 7 per cent., were made in the first 

 quarter, and particulars in regard to 8 were ascertained. Four, or 50 per cent., 

 moved distances of from 4 to 6 miles to the south and west ; 3, or 37.5 per cent., 

 moved north and west (2 of them into the Firth of Forth) for distances of from 

 15 to 31 miles, the average distance being 23 nules : and 1, 12"5 per cent., had 

 gone 8i miles to the north-east. 



The feature of this quarter is the relatively small migration, and the predomin- 

 ance towards the coast, south-west and north-west. The condition of the repro- 

 ductive organs was ascertained for 2 of the males and 4 of the females ; thev 

 were all " immature." On hberation, 2 of the males were of adult size, measuring 

 33'5 and 34 cm. ; 2 of the females were also of adult size, measuring 38 cm. and 

 44*5 cm. respectively. All the others were under adult size. 



Second Quarter. — Six fishes (2 males and 4 females) were recaptured in July, 

 August, and September, i.e. 17-2 per cent, of the total recaptured. The position 

 of recapture of 1 was not ascertained ; of the others, 3 (or 60 per cent.), viz. 2 

 males and 1 female, had migrated to the south and west, for distances of from 

 4 to 12 miles ; 1 female was taken 18 miles to the north and west, near the Bell 

 Rock, and the remaining female 5 miles north and east of the station. All the 

 fish were, naturally, for the season " immature." On hberation, all except 2 females 

 were of adult size, and on recapture 1 of these females had grown to adult size, 

 the other measuring 37*1 cm. ; the latter had moved the greatest distance of all, 

 viz. 18 miles. The same feature is thus shown in the second quarter as in the 

 first, the relatively small distance migrated, the absence practically of any 

 recaptures to the northwards of the station, and the predominance to the south 

 and west. 



Third Quarter. — Only a single fish was recaptured in this quarter, a inale, which 

 was taken on 6th October, 6 miles to the south and west, and which is described as 

 " nearly ripe." 



Fourth Quarter. — In January, February, and March 1912, 12 of the marked plaice 

 (or 34'3 per cent, of the total) were recaptured, the position of capture being ascer- 

 tained for 11 of them. One was caught in January, 5 in February, and 6 in March. 

 Three were males and 9 were females. The migration of these fishes presents 

 contrast to those of the previous months, both in direction and distance. Only 

 1 was recaptured to the south and west, a small female, which measured 31 cm. 

 on liberation and 33-5 cm. on recapture and was taken at Embleton Bay, North- 

 umberland, a distance of 49 miles, on 15th March 1912, after 360 days, the rate 

 of movement being 1*4 miles per 10 days ; it was " immature." 



