RAPPORTS. XIII C 4 : MASTERMAN 



6 - 



is based, not upon the distribution of "large" plaice, but upon the records by the fisher- 

 men of the presence of spawning fish. The size categories were found to be unreliable 

 in these daily trawlers, in which sorting is not so definite as on the steam trawlers. 



It will also be possible to employ these data in the way indicated last year, i. e. for 

 the interpretation of the more extensive general statistics. From them, it should be possible 

 to determine, for each area, the average number of hours' fishing in one day's absence 

 from port and thus to weight the returns for each area accordingly. 



B. Ichthyometric. 



Length frequencies. 



The length- and weight-frequencies of plaice in the North Sea are dealt with in 

 Vol. Ill of the Research Work of the English Board of Agriculture and Fisheries. The 

 statistics are treated specially from the point of view of the plaice problem and, accord- 

 ing to the procedure adopted in last year's report, it is proposed to leave detailed 

 consideration of these data to the Editor upon the Plaice and its problems, and only to 

 allude to points of general interest. Amongst these, it is to be noted that the figures 

 clearly indicate that the distribution of plaice according to size appears in the North Sea 

 to be closely related to distance from the inshore nursery, and to have only an indirect 

 relation to length, in so far as this corresponds with distance from shore. The composi- 

 tion of the catches from the Dogger (B i) and the deep water in the centre of the Fle- 

 mish Bight (C3) illustrates this fact very well, and confirms the similar conclusions ar- 

 rived at from study of the age-groups, (a) "The Dogger Bank, though shallower than 

 the surrounding areas, partakes of the nature of the deeper areas, as it is further from 

 the nursery grounds of young plaice than its isobathic areas, (b) C3, which, though 

 a deeper area than its neighbours, partakes of a nature of a shallower area as regards 

 the plaice fisheries, since it is nearer to the nursery grounds than its isobathic 

 areas". As regards the annual fluctuations in the plaice fishery, the figures may be 

 compared with those derived from the three selected vessels in the Report of Lee above 

 noticed. 



As regards the beam trawl fishery of the Southern Bight, sailing out of Ramsgate 

 and Lowestoft, the following figures may be quoted: — 



