135 



place where it was originally captured ; the sixth, 40-5-41-4 cm., was taken in 

 April 1913, after 119 days, off the coast of Aberdeen, 49 miles to the north and east ; 

 t}ie seventh, measuring 32-41-5 cm., was caught in March 1915, after -816 days, 

 but the place of recapture in this case was not ascertained ; the eighth fish, measur- 

 ing 32-5-40-5 cm., was taken in April 1914 after 502 days, only 15 miles distant, 

 north and west; the ninth fish, 32-38-7 cm., was got in May 1914, after 534 days, 

 7 miles to the north and east ; a tenth fish, measuring 33-39-3 cm., was taken in 

 December 1913, after 376 days, 10 miles directly east. 



EXPERIMENT X. 



26th March 1913. 



In this experiment, 100 fishes were marked and Hberated, of which 35 were 

 males, 64 females, and 1 whose sex was not ascertained. The sizes of the males 

 ranged from 32 to 41-5 cm., and of the females from 32 to 42*5 cm. The numbers 

 liberated and recaptured are shown in the adjoining table, arranged in groups of 

 5 cm. : — 



The fish were caught at the usual place, namely. Station VI., Firth of Forth 

 (off St. Monans), and were hberated, after five hours' retention in the tanks on 

 board. 



The number recaptured was 64, or 64 per cent., namely, 24 males, or 68-6 per 

 cent., and 40 females, or 62-5 per cent. 



Of the 24 males, 22 were of adult size on recapture, and 2 immature. The adults 

 were at Uberty for periods varying from 14 to 912 days, the average being 296 days ; 

 their sizes on hberation varied from 32 to 41-5 cm., the average being 34-9 cm., 

 and on recapture from 33-4 to 43-6 cm., with an average of 38*3 cm. ; they had 

 migrated distances of from 2 to 215 miles, the mean being 60-6 miles, and the 

 mean rate of movement 2 miles per 10 days. The 2 immature males were taken 

 at distances of 15 and 25 miles, after 14 and 12 days respectively. 



Of the 40 females, 28 were of adult size on recapture ; they measured from 32 

 to 41-5 cm. on hberation, the average size being 36-7 cm., and on recapture from 

 38 to 48-6 cm., the mean being 42-8 cm. ; they were free for periods from 77 to 

 911 days, the average being 359 days ; they had nugrated distances of from 6 to 

 112 miles, the mean being 32-5 miles, and the mean rate of travel -9 mile in 10 days. 

 The 12 immature females had been at hberty for periods ranging from 9 to 203 days, 

 the average being 90 days ; the average size on hberation was 33-9 cm., and on 

 recapture 35-9 cm. ; they had migrated distances of from 5 to 44| miles, the mean 

 distance being 15-25 miles, and the mean rate of travel, per 10 days, 1-7 miles. 



The Extent and Direction op Migration. 



First Quarter.— In the month after hberation, April 1913, 5 of the fish, 3 males 

 and 2 females, were recaptured, all immature. The 2 females had moved directly 

 west for distances of 12 miles, and were caught 9 days after hberation. The 3 

 males were recaptured after 12 and 14 days, at distances of from 15 to 29i miles 

 to the north and west, 1, measuring 34 cm., being taken in the Firth of Forth, 

 near Station VI. 



In May, only 2 fishes were recaptured, both females ; 1 was taken 11 miles to 

 the north-east, and the other 12 miles directly west ; both were under adult size. 



Six were recaptured in June, 3 males and 3 females. One male had moved 

 directly west for 4J miles, 1 to the south-west for 2 miles, and the third north-east 



