I 



103 



Females. — Of 12 adult females, the condition of the ovaries was ascertained 

 in 11. None were full}" mature. Two were "nearly ripe," 1 caught in January 

 1914, off the coast of Aberdeen. 59 miles to the north and east ; the other, in 

 December 1912, 5 miles to the south and west. One was " spent " ; it was the 

 fish caught midway between Scotland and Norway in May 1913. The other 8 

 females were " immature," and none of them was taken within the limits of the 

 spawning season, 1 being caught at the end of May, 4 in June, 1 in July, and 2 

 in September. The position of recapture is known for 6 ; 2 had migrated some 

 distance north and east, 1 for 85 and the other for 44 miles ; 1 was caught to the 

 north and west ; 1 to the soutli and cast, and 2 to the south and west, short 

 distances. 



EXPERIMENT IV. 



l^thJunel^ll. 



Fifty-three fishes were marked and liberated in this experiment, 24 being males, 

 28 females, and 1 of undetermined sex. The sizes of the males ranged from 29 cm. 

 to 41 cm., and of the females from 26 cm. to 51 cm. The numbers liberated between 

 certain sizes in groups of 5-cm. are represented in the accompanying table, which 

 also shows the numbers recaptured in the same groups : — 



Eight of the males liberated (33 per cent.) were under adult size (33 cm ), and 

 22 of the females (78-6 per cent.) were also under adult size (38 cm.). 



All the fish marked and liberated were caught by the " Goldseeker " at Station 

 VI., Firth of Forth, at 3 p.m. on the 19th June ; they were marked and ki-jit in 

 tanks of water until 7.35 p.m., when they were liberated. 



The number recaptured was 41, or 77-3 per cent., viz. 20 males, or 83-3 per 

 cent, of the males liberated, 20 females, or 714 per cent, of the females hberated, 

 and the single fish of undetermined sex. 



Of the 20 recaptured males, 16 were of adult size on recapture, the sizes ranging 

 from 33-6 to 43-4 cm., and averaging 37*4 cm. ; they were at Mberty for from 1 to 

 757 days, the mean being 187 days ; the distances migrated ranged from 5 to 144 

 miles, and averaged 39-3 miles, and the mean rate was 2-1 miles per 10 days. The 

 4 immature males were at liberty for from 13 to 56 days, the average being 35 days ; 

 the distances travelled were 5 and 6 miles, the mean being 5-3 miles, and the mean 

 rate 1-9 miles. 



Only 6 of the females were of adult size on recapture ; they had been at liberty 

 for from 13 to 1821 days, the average being 595 days, their average size on liberation 

 was 37-2 cm., and on recapture 42-7 cm. ; the distances migrated ranged from 6 to 

 43 miles and averaged 18-2 miles, and the mean rate was -3 mile. 



Fourteen of the females were under adult size, the range being from 31-8 to 

 37 cm. and the average 34-3 cm. ; they had been at liberty for from 13 to 299 days, 

 the mean period being 82 days ; they migrated distances of from 5 to 45 miles, 

 the mean being 11-3 miles, and the mean rate 1'29 miles per 10 days. 



The fish whose sex was not determined, either on liberation or recapture, had 

 migrated north and east for 26 miles. 



The Extent and Direction of Migration. 



First Quarter. — One fish, a male, of 36 cm., was caught the next day after 

 liberation, 7i miles to the south and west. In July, the month following liberation, 

 13 fish were taken (32-5 per cent.), 5 males, or 25 per cent., and 8 females, or 421 



