13 



THE MIGRATIONS OF CRABS. 



By ALEXANDER MEEK. 



During the years 1902-05, 781 crabs were marked and liberated 

 at various places along the coast of Northumberland, principally at 

 Beadnell. Reference to the accounts of the experiments in the 

 reports for the years mentioned will show that the results were 

 remarkably consistent. The crabs were marked in the autumn, 

 those used being " white " crabs or crabs which were becoming 

 hard after a recent ecdysis. The label used throughout has been 

 the same, viz., a brass label bearing the letter N and a number, and 

 fastened to one of the chelae by copper wire. It was found that a 

 proportion of the females migrated in a northerly direction along 

 the coast, reaching for the most part the Firth of Forth, and some 

 of them the coasts of Forfarshire and Kincardineshire. The males 

 did not exhibit any tendency to migrate, although in one or two 

 cases they were free for two years. There is, as is well known, 

 an annual winter migration from the coast, and it is during this 

 migration that many at least of the females which are about to 

 spawn migrate northwards. 



As will be seen from the accounts of these earlier experiments, 

 most of the crabs were marked and liberated by my late and much 

 regretted friend, John Douglas, Beadnell. I thought it desirable 

 in view of the proposed protection of the crab during the season of 

 casting or ecdysis, to repeat the experiment on a larger scale., and 

 I asked Mr. Douglas to mark and liberate 500. This he did between 

 the dates October 7th and December 7th, 1912, marking some 400 

 females and 100 males, — see the accompanying table. 



Up to June 30th, 1913, 110 have been recovered, or 22 per cent. 

 Of these 28 were females or presumably females, which had migrated 

 into Scottish waters ; the remainder consisted of 22 males and 59 

 females which had remained in the Beadnell district or had migrated 

 only a short distance, and a female which appeared to have migrated 

 southwards, — see below. 



