of the Fishery Board for Scotland. 



123 



4|j- inches, and one small hard female 3§ inches across. Not a single 

 soft crab was obtained. The probability is that the soft crabs had not 

 yet migrated, but the large hard females captured on this ocoasion had 

 done so ; since there is little doubt but that the berried females come 

 inshore, and the eggs hatch there in summer, July being probably the 

 principal month. By the middle of September (13th) 1899, the soft 

 crabs were got in great numbers in 25 fathoms. The migration of the 

 soft crabs appeared, then, to have begun last year (1899) between the 

 middle of August and the middle of September. The experiment 

 described above gives some ground for the conclusion also that the large 

 females which had lately been berried, and which are not about to cast, 

 migrate soon after the hatching of the eggs. From the labelling 

 experiments some little evidence is thrown upon the migration of the 

 large hard males. A number of large male crabs were labelled and set 

 free at the mouth of the harbour in June. On July 14th one of these, 

 No. 19, Table X., was got close to the harbour; in September another, 

 No. 20, was taken in a creel 2 miles N.E. in 22 fathoms, and in October 

 two more were captured ; one, No. 21, 2 miles N.E. in 22 fathoms, and 

 the other, No. 22, 1| miles E. by S. in 18 fathoms. A large hard 

 male crab, set free at the harbour in July, was found in December, 3 

 miles N. E. in 22 fathoms. We may probably conclude, then, that these 

 large males had not begun to migrate in J uly, and by September they 

 had done so. The migration seaward of hard and soft crabs then 

 probably occurs during August and September. The statistics which 

 were kept during the last four months of last year of the hard and soft 

 crabs captured daily point to a migration of crabs less than 4| inches 

 across the back taking place a little later than that of the gauge crabs. 

 In Table XII. it is seen that up till September 29th, although there 

 were a great number of soft gauge crabs, there was none under 4| inches. 

 After that date the number of small crabs increased rapidly. 



The inshore migration appears to begin usually in February. In 

 February and March the creels are still shot in deep water, and also 

 sometimes in shallow water. In these months the men begin to shift 

 the creels in, but up to the end of March 1898 some of the boats were 

 still fishing in 18 fathoms, while others were working in 8 fathoms in 

 February. The inshore migration appears to be more irregular than its 

 seaward counterpart. By April and May the crabs are usually close 

 inshore. In May 1898, however, the men had to shift their creels to 

 about a mile offshore, where there is a depth of about 1 4 fathoms, owing 

 to the scarcity of the crabs inshore. It is very evident that the inshore 

 migration is subject to considerable fluctuations. It moreover seems to 

 be very gradual, thus differing from the seaward migration, which is 

 apparently very rapid. Thus, three crabs which were set free at the 

 harbour on Saturday, September 23rd, were captured on the following- 

 Monday, September 25th — one at 2 miles, the other two at 2| miles 

 N.E. of Dunbar. The creels had been shot on Saturday and remained 

 in the water till Monday. The crabs had thus travelled 2 J miles in 

 two clays. The time taken to the journey was possibly less. The 

 inshore migration has a very important effect on the crab fishery, for 

 during April and May the concentration of the crabs in the shallow 

 water of necessity restricts the fishing area, and intensifies the fishing- 

 capacity of the creel. At this time of the year the largest number of 

 creels is employed, certain boats having as many as 200, while 

 no boat will have less than 100. There are probably at least 

 3000 creels shot each day during these months. The catch is at this 

 time the greatest. By June the takes diminish rapidly. While 

 this fact may be in part due to the crabs retiring to cast, it is 



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