44 



Nineteen of the 24 males recaptured were of adult size on recapture, the sizes 

 ranging from 33'3 to 43*8 cm., the mean being 38'6 cm., as compared with 29 to 

 39 cm., with a mean of 33'9 cm., on liberation ; the periods of freedom varied 

 from 121 to 1306 days, the average being 453 days ; the distances migrated varied 

 from 4 to 212 miles, with a mean of 93' 1 miles, and the average rate of movement, 

 per 10 days, was 2 miles. 



Five of the males were under adult size, the average being 32*2 cm., compared 

 with 31'4 cm. on liberation ; the mean period of freedom was 148 days, and the 

 distances migrated were from 4 to 28 miles, the average being 15*6 miles, and 

 the mean rate of travel, per 10 days, Tl miles. 



Of the 29 females, 22 were of adult size on recapture, the sizes ranging from 

 40"1 to 51"9 cm., the mean being 44*3 cm., while on liberation the sizes were from 

 31*5 to 49"5 cm., the average being 38"1 cm. ; the average period of freedom was 

 395 days, the range being 14 to 1148 days, and the distances migrated varied 

 from 11 to 161 miles, the mean being 68*2 miles, and the mean rate of movement 

 1*7 miles per 10 days. 



Seven of the females were under adult size, the average size being 34*1 cm., 

 as compared with 34*2 cm., on liberation ; the periods of freedom averaged 59 

 days, and the distances migrated, 12J miles, i-anging from 3 to 59"5 miles ; the mean 

 rate of movement, per 10 days, was 2"1 miles. 



The Extent and Direction op Migration. 



First Quarter. — Only 1 of the marked plaice was recaptured in February, viz. 

 a female, which measured 44-44 cm., and was caught after 14 days 18 miles to the 

 north and east, " spent." 



In March 1911, 9 were recaptured, 2 males, 6 females, and 1 of unknown sex. 

 Five of these, viz. 2 males and 3 of the females, were taken within the Firth of 

 Forth, at distances of from 3 to 5 miles, in from 22 to 41 days, all towards the 

 north shore of the Firth. All these fish were under the adult size, and the repro- 

 ductive organs were " immature," in the 4 cases in which the condition was known. 

 Three of the other females were found to the north and east, outside the Firth ; 

 1, of 39'5-39-6 cm., 28 miles distant, north-east of the Bell Rock ; it was 

 " spent " ; another, of 49"5-50"2 cm., was taken ofE the coast of Aberdeen, at a 

 distance of 62 miles, after 50 days, " spawning " ; the third was also taken near 

 Aberdeen, at a distance of 59 miles, after 45 days ; it measured 33-32*1 cm., and 

 was " immature." The remaining fish was of undistinguished sex, and had gone 

 to the south and east ; it was captured, after 51 days, 32 miles off Longstone Light, 

 at a distance of 78 miles, and was " partly spent." 



In April, 4 of the marked plaice were recaptured, 1 male and 3 females. The 

 3 females were all taken A^athin the Firth of Forth, 1 off Kirkcaldy, at a distance 

 of 11 miles, after 63 days ; it measured 37*5 cm. on liberation, but the size on re- 

 capture was not ascertained, nor the condition of the reproductive organ. Another, 

 under adult size, was found on Station VI., where it was originally caught, at a 

 distance of 4 miles, after 76 days. The third, of 36-5 cm., and thus under adult 

 size, was taken in Largo Bay, 4| miles distant, after 55 days. The male had moved 

 out of the Firth, and was taken to the east of the Isle of May, at a distance of 24 

 miles, after 79 days ; it measured 31-31*9 cm., and was " immature." 



In the first quarter, then (the month of February included), 14 of the marked 

 plaice, or 25*4 per cent., were recaptured ; 8 (57"1 per cent.) had moved north and 

 east for an average distance of 26 miles (4 of them into the Firth of Forth) ; 4 

 (28*6 per cent.) had moved north and west, an average distance of 6*2 miles (all 

 within the Firth of Forth) ; and 2 had moved to the south and east for an average 

 distance of 51 miles. Eight of the 14 fiish had remained within the Firth of Forth, 

 or 57" 1 per cent., and 2 of them were recaptured at Station VI., where they had 

 been originally caught. Of the 6 fish which left the Firth of Forth, 4 went to the 

 north and east for distances of from 18 to 59 miles ; 1 travelled east and a little 

 south for 24 miles, and another south and east for 78 miles. 



Second Quarter. — Only 1 of the marked plaice was caught in May 1911 ; it was 

 of undistinguished sex, measuring 33"5-34-5 cm., and was recaptured within the 

 Firth of Forth, near Methil, 7^ miles distant, after 99 days. 



