146 



mean being 260 days; the distances migrated varied from 9 to 151-5 miles, tlie 

 average being 49"4 miles, and the mean rate of movement 1-9 miles per 10 days. 

 Six of the females were under the adult size, the average being 36*6 cm., as com- 

 pared with 35-9 cm. when hberated ; the average period of freedom was 93 days, 

 the mean distance travelled 36'5 miles, and the mean rate of movement per 10 days, 

 3-9 miles. 



The Extent and Direction of Migration. 



First Quarter. — In September, which is included in this quarter, 6 hsh were 

 recaptured, 1 male and 5 females, 1 of the females to the west, and all the others 

 to the south and west. The male, m>easuring 39'5-39'2 cm., was taken, after 6 

 days, 24 miles to the south-west ; 2 of the females were got, 3 days after hberation, 

 both 12 miles to the south-west, 1, measuring 40-39-8 cm., and the other, 40-39-4 

 cm. ; 2 were taken after 7 days, both to the south-west, 1, of 34-5-34-5 cm., at a 

 distance of 19 miles, and the other, of 39-5-38-6 cm., at a distance of 9 miles ; the 

 last female, which measured 37-37-1 cm., was got, after 16 days, to the east of the 

 Isle of May, at a distance of 30 miles to the westward. The rates of movement 

 of these fishes were considerable, in three cases amounting to 40 miles per 10 days, 

 or 4 miles per day. 



In October, 6 fish were recaptured, 2 males, 3 females, and 1 whose sex was 

 undetermined. One of the males, measuring 39-38-5 cm., and " nearly half-ripe," 

 was caught, after 22 days, ofi Fife Ness, at a distance of 28J miles to the west : 

 the other male, which measured 36-35-8 cm., and "immature," was recovered, 

 after 24 days, 13J miles to the south-west : 1 of the females, measuring 44*5-44 

 cm., and " nearly ripe," was caught, after 27 days, to the east of St. Abb's Head, 

 at a distance of 30 miles south-west of the station ; another female, of 40-41-2 

 cm., and " fully half-ripe," was caught, after 36 days, offshore, to the east of 

 Aberdeen, at a distance of 42 miles to the north and east ; the remaining female, 

 measuring 37-5-38-3 cm., and also " fully half -ripe," was recaptured, after 42 days, 

 off Tod Head, at a distance of 30 miles ; the fish, whose sex was unknown, was 

 taken, after 27 days, off Dunbar, a distance of 40 miles in a south-westerly direction. 



In November, 4 females were recaptured, but the position of capture of 1 was 

 not recorded. One, measuring 54-54*1 cm., and " nearly ripe," was got, after 59 

 days, near the Bell Rock, at a distance of 36 miles ; another, measuring 38-37-8 

 cm., and the condition of whose ovaries was not determined, was taken, after 63 

 days, to the south and east, off AVliitby, at a distance of 102 miles ; the other 

 female, whose size on recapture was 42-3 cm., was taken, after 74 days, off the Isle 

 of May, at a distance of 34 miles to the south and Avest ; this fish was originally 

 liberated between Elie and Fidra, on the 19th June 1911, and recovered by the 

 " Groldseeker " at Station VI., Firth of Forth, on the 11th September, when trawhng 

 for fish for this experiment ; it was then liberated on the 12th September, 40 miles 

 east of the Isle of May. 



In the first quarter, therefore, 16 of the plaice, or 26-2 per cent., were recap- 

 tured, namely, 3 males, 12 females, and 1 of unknown sex ; 9 had moved to the 

 south and west, 1 to the west, 3 to the north and west, and 1 each to the north- 

 east and south-east ; the position of 1 was not recorded. 



Second Quarter. — In December, 6 fishes were recaptured, 3 males and 3 females. 

 One of tlie males, which measured 35 cm. on liberation, was taken, after 83 days, 

 13 miles to the south-west ; another, measuring 35-34-8 cm., and "nearly ripe," 

 was taken, after 92 days, in the same locality, at a distance of 16 miles ; the third, 

 of 39-38-4 cm., and " nearly ripe," was caught, after 108 days, to the east of the 

 Isle of May, at a distance of 28 miles. One of the females, which measured 42 cm. 

 on liberation, was taken, after 83 days, to the east of the Isle of May, at a distance 

 of 24 miles ; another, of 38-5-38*1 cm., was recaptured, after 86 days, 17 miles to 

 the westward ; the remaining fish, which measured 36-36-6 cm., was taken, after 

 93 days, to the east of the Isle of May, at a distance of 24 miles. 



In January 1912, a female, which was 44-46 cm., and "nearly ripe," was 

 recovered, after 133 days, off Aberdeen, at a distance of 47 miles to the north 

 and east. 



In February, 7 of the marked plaice were got, 3 jnales and 4 females. One of 

 the males, which measured 36-37-6 cm., and the condition of whose testes was not 



