87 



73*7 per rent., of the males were recaptured, and 43, or 72*9 per cent, of the females. 

 Of the males recaptured, 12 belonged to the smaller group and Ifi to the larger. 

 Among the females recaptured, 11 belonged to the first group (31-35"5 cm.) ; 20 

 belonged to the next group ; 11 to the group measuring from 41-45" 5 cm. ; and the 

 female over 51 cm. on liberation was also recaptured. All the males recaptured 

 were of adult size (33 cm. or over), and the particulars in regard to them are as 

 follows : — They had been at liberty for periods varying from 8 to no less than 

 1892 days, the average being 254'3 days. Their average size on liberation was 

 36" 5 cm. and on recapture 38" 2 cm. The position of recapture of 26 of the fishes 

 was ascertained, and the distances migrated varied from 3*5 to 215 iniles, the mean 

 distance being 76" 4 miles, and the mean rate 3*9 miles per 10 days. Of the females, 

 35 were of adult size on recapture ; they had been at liberty for from 10 to 1566 

 days, the average being 375 days ; their average size on liberation was 39' 6 cm. 

 and on recapture 43*6 cm. ; the distances migrated (in the 33 cases in which it was 

 ascertained) varied from 3*5 to 184 miles, the average distance being 64*8 miles, 

 and the average rate of travel 1*78 miles per 10 days. The other 8 females were 

 under adult size on recapture, the mean size being (in the 5 cases ascertained) 

 35*1 cm., both on liberation and on recapture ; the periods of freedom varied from 

 3 to 462 days, the average being 95" 7 days ; the distances travelled (ascertained 

 in 7 cases) was from 2 to 58 miles, the mean distance being 16*8 miles, and the 

 mean rate of travel 3'9 miles per 10 da}'TS. 



The Extent and Direction op Migration. 



First Quarter. — Of the 98 fishes liberated, 9 were recaptured in the following 

 month, December 1910, viz. 4 males and 5 females. Four had migrated short 

 distances of from 2 to 7 miles ; 3 of these were immature females, and 1 was a 

 male. Of the other 5, 2 had moved 13 miles, 1, an adult female, which was " almost 

 ripe," to the south-east of the Isle of May, the other, an adult male, also " almost 

 ripe," to the north-east of the island. Another male, described as "immature," 

 but measuring 38 cm. when liberated, was taken 15 miles away, to the north-east 

 of St. Abb's Head. Of the remaining 2, a female had travelled 56 miles north-east, 

 and was taken off Aberdeen only 10 days after liberation ; it was " nearly ripe." 

 The other, a male, described as "three-quarters mature," had also gone north-east, 

 and was taken at a distance of 76 miles, off Peterhead, after 20 days. 



In January 1911 — after about two months' freedom — 11 of the marked plaice 

 were recaptured, viz. 5 males and 6 females. One of the males (33"3 cm.), described 

 as " quite immature," was caught 5 miles distant, and another, 13 miles, to the 

 south-east of the Isle of May. Of the others, 7 (both males and females) had 

 moved to the north-east, and were taken at distances ranging from 19 to 113 miles, 

 mostly off the coast of Aberdeen ; but 1, a female 39 cm. in length, and " nearly 

 ripe," off Banff, in the Moray Firth. Most of these fish were approaching maturity. 

 Of the 2 remaining, 1 was caught 16 miles to the south-east, off St. Abb's Head, 

 and was " immature " ; the other, a male, described as " maturing," was taken 

 to the north-west, south-east of Montrose, 26 miles distant. 



Six were recaptured in February, 4 males and 2 females, all to the noith-east 

 — 4 off the coast of Aberdeen, and 2 in the Moray Firth, off Banff, the distances 

 travelled ranging from 36 to 113 miles. All these fish were described as "almost 

 ripe," or " spawning," except 1 male which was " immature," but as it was 35 cm. 

 long, it may in reality have been " spent." 



Thus in the first 3 months, December 1910 and January and February 1911, 

 26 fishes were recaptured (or 36*6 per cent, of the total number recaptured). 

 Thirteen were males and 13 were females (or respectively 46-4 per cent, of the 

 total males, and 30-2 per cent, of the total females recaptured). Some of the 

 fishes had moved considerable distances, over 100 miles, and as the table shows 

 (and the chart indicates in a striking manner) the largest number had moved north 

 and east along the coast. Fifteen (or 57*7 per cent, of those taken in this quarter) 

 had migrated for an average distance of 62 miles N. 19° E. at rates varying from 

 3-8 to no less than 56 miles per 10 days, the mean rate being 14-2 miles. Three 

 (or 11*5 per cent.) had moved in the mean direction N. 49° W. for from 2 to 26 miles, 

 the average being 13 miles and the average rate 5-8 miles per 10 days. Four 



