17 



In contrast to the females the males remain altogether in the 

 place of liberation, only moving out and in during the annual 

 migration already stated, and to a very limited extent along the 

 coast. Two, Nos. 136 and 323, were caught, liberated again, and 

 recaptured a second time in the Beadnell district, and similar results 

 have been reported in former years. 



While the males then remain in the district, and we have records 

 of them having done so for two years, a certain proportion of the 

 females migrate to a variable, sometimes to a considerable, distance 

 to the north. I have shown in previous reports from actual observa- 

 tions and from marking experiments that spawning and ecdysis are 

 not annual in the older crabs. Still every time the female crab 

 becomes ripe the migration presumably takes place. The question 

 is, does it always take place in the same direction ? 



I have been speaking of the crabs of the Northumberland 

 coast, a number of the females of which scatter themselves along 

 the eastern coast of Scotland. Where do they go after the next 

 ecdysis, or rather when the ripening of the ova is taking place ? Do 

 these crabs replace females which previously occupied the Scottish 

 region ? Where do the latter migrate to ? 



In 1897-8 * Williamson marked and liberated at Dunbar a large 

 number of crabs, but of these only one, a female, indicated a similar 

 migration to that which has been described for Northumberland. 

 This one migrated between September 25th and April 26th, 7 months ; 

 to St. Andrew's Bay (18 miles). Even this solitary example is 

 interesting, as it shows that at all events there is a tendency for 

 the females on the south side of the Forth to migrate northwards. 



Some years ago a number of crabs were marked on the York- 

 shire coast, and some of the females were recaptured at different 

 places on the coast of Northumberland. 



It is evident, therefore, that the northward migration of the 

 females applies not only to Northumberland but to the districts 

 on either side of Northumberland. 



Our experiments led to Mr. Donnison,| on behalf of the Eastern 

 Committee, marking and liberating over a thousand crabs on the 

 coasts of Norfolk and Lincolnshire. The results were very similar 

 to those obtained b}^ Williamson. None of the crabs made any 



* 18th Ann. Rep. Fish. Bd. for Scotland, 

 t Eastern Sea Fish. Dist. Itep. on crab Investigations. 1912, Ibid., Inspector's Rep. 



