of the Fishery Board for Scotland. 



49 



may be due to the presence of a better food supply, a careful examina- 

 tion of the bottom fauna of the various grounds is being made with 

 the object of arriving at a quantitative estimate of the stocks of food 

 on different areas and their relation to the stock of fish. 



The introduction of the Danish seine-net or snurrevaad into 

 Scottish waters has given an added interest to the plaice investiga- 

 tions. Several trips were made by the fish measurers on the Board's 

 staff in boats using this type of net. In each case every fish 

 captured was measured, and out of a total of 3000 plaice the smallest 

 was 18 cm. (7 in.) while 75 per cent, were over 31*5 cm. (12 in.). It 

 is interesting to compare the results of fishing on the same grounds 

 with an otter trawl. The " Goldseeker," working at the same time 

 of year as the records were obtained from the vessels using the 

 snurrevaad, captured 8000 plaice, half of the total catch being 

 between 18 and 32 cm. (7 to 12-| in.), whereas the corresponding half 

 of the total catch of 3000 fish measured on the boats using the seine- 

 net was between 32 and 44 cm. (12-|- to 17 in.), a very marked differ- 

 ence in size. In each case 25 per cent, of the catch was smaller 

 and 25 per cent larger than the limits stated. 



Special investigations as to the effect on the stock of plaice of 

 this newly introduced method of fishing have been carried out by 

 the research vessel and will be continued. 



6. Lobsters and Crabs. 



The investigations into the lobster fisheries of the West Coast 

 continued throughout the year, and the motor boat " Enid " did useful 

 service in this connection. The difficulty experienced by many classes 

 of fishermen in making an adequate living by line or net has induced 

 an increasing number to take up the lobster pot as a means of 

 livelihood. In view of the fact that the necessity for legislation may 

 arise in the near future, as it has done in most other lobster fisheries, 

 the statistical information being gathered should prove invaluable to 

 the Board in arriving at any decision. In common with other 

 branches of fishery research, unless results from a series of years are 

 considered as a whole, most misleading deductions may be made, but 

 it is hoped that it will be possible to continue this work, which also 

 includes a general investigation into the life history of the lobster. 



The catches of crabs on the Scottish coasts vary very much from 

 year to year. Former experiments have shown that the crab may 

 wander long distances from one area to another, and it is desirable to 

 know the law which governs these movements, in what direction the 

 crabs are likely to travel, to what extent the crabs of one fishing- 

 region are likely to leave it, and how many will be expected to reach 

 another region. The number of crabs which, in the autumn, leave 

 the inshore waters where they have been living during the summer 

 seems to be very large, and only a small proportion of these are 

 subsequently captured by the fishermen. Some individuals return 

 again to their home waters, while a few may be found to have 

 travelled considerable distances. 



Further experiments have been initiated in which crabs have 

 been labelled and set free at different places on the East Coast of 

 Scotland, and many interesting recaptures have been made. As a 

 rule, the crabs which migrated more than 10 miles were found to the 



D 



