of the Fishery Board for Scotland. 



125 



The migration offshore in August and September cannot, however, be 

 explained by reference to temperature. At the end of August last 

 year, at which time the soft crabs were probably making their way sea- 

 wards, the temperature of the inshore water was still higher than that 

 of the deep water, and on September 25th the temperature at 10 fathoms 

 was only -3 of a degree less than that at 25 fathoms. Moreover, small 

 soft crabs are to be found between tide-marks on the beach all through 

 the winter {vide Table IV.). It is not at all likely that the adult 

 soft crabs would be inconvenienced by cold when the small crabs are not 

 affected by it. The migration of the soft crab may with some reason be 

 attributed to the necessity for food. Immediately after casting the crab 

 feeds ravenously, and it is therefore not unlikely the shore waters may 

 not offer them a sufficient food supply. It is not improbable that the 

 inshore migration may also be due to a search for food. Both migrations 

 appear to be shared by male crabs which are not about to cast. The 

 offshore ground upon which the crabs are found in winter appears from 

 the chart to consist of sand, with stony patches here and there, while 

 further to sea the bottom is of mud. About 600,000 crabs are taken 

 each year at Dunbar, and although the length of the fishing ground is 

 considerable, probably 14 miles, its breadth will not exceed about 4 

 miles. The amount of food which these crabs consume must be great 

 indeed. The crab fishing consists in simply setting a barrier of creels 

 in front of, or in the midst of, the migrating crabs, and as the crabs 

 move along the creels keep pace with them. 



Mr. Hutchison, Dunbar, has informed me that certain fisher- 

 men at Skateraw had been accustomed to bring the soft crabs which 

 they caught in deep water during winter to the shore in order to set 

 them at liberty in shallow water. They did so with the view of stocking 

 the shore waters for the summer fishing. It is very doubtful if 

 any of these transported crabs remained inshore ; they probably 

 immediately moved right off to deep water, just as did the labelled soft 

 crabs put away in September, October, and November. 



There is evidence that long-continued frosty weather tends to diminish 

 the catch of crabs ; the cold is said to make the crabs " hole up." 

 Similar evidence was given before Buckland. 



Migration Experiments at Berwick-on-Tweed and Beadnell, 

 Northumberland. 



By the courteous permission of the Northumberland Sea Fisheries 

 Committee, their fishery officer, Mr. Buglass, labelled 100 crabs and set 

 them free off Berwick-on-Tweed in February and May 1898. The 

 majority were undersized, and none were recovered. 



Mr. Douglas, Beadnell, also kindly labelled 100 crabs, and of these 5 

 were recaptured. 



Date of 

 Liberation. 



Place. 



Date of 

 Recapture. 



Place. 



Direction of 

 Migration. 



1898. 



1. March 1 



2. Feb. 26 



3. „ 21 



4. March 8 



5. Feb. 25 



At the Haven. 



4 miles offshore, 

 26 fathoms. 



4 miles offshore, 

 26 fathoms. 



4| miles offshore. 



March 22 

 May 31 

 June 3 

 „ 17 

 July 9 



Off N. Sunder- 

 land, 8 fms. 



Close inshore, 4 

 fathoms. 



Close to rocks, 4 

 fathoms. 



Close to rocks, 3 

 fathoms. 



1£ miles shoreward. 

 N.E. 



4 miles shoreward. 



?> »> 

 4J „ 



These five crabs are valuable additions to the material supplied by the 

 Dunbar specimens, illustrating, as they so well do, the shoreward 

 migration in spring and summer. The first crab fills a gap which exists 

 in the Dunbar list, since at Dunbar no crab was recaptured in March. 



