RAPPORTS. XIV: MASTERMAN — 14 — 



Several important points in the sole fishery are brought out from the statistics of 

 value. The value of this species is so high that in Holland the sole fishery is equal in 

 value to that of the plaice. 



Special Statistics. 



An important memorandum upon special statistics has recently appeared (2a). It deals with 

 certain special returns of selected English trawlers fishing from Grimsby, which differ chiefly 

 from the general statistics in that they give the number of hours during which fishing 

 took place, rendering it possible to determine the ratio (K 2 ) or catch per hour's fishing 

 and the locus and catch of each haul. The operations of these trawlers covered the 

 middle portion of the North Sea which the author divides for statistical purposes into six 

 regions sub-divided into twenty-three areas, indicated by letters of the alphabet. It is 

 regrettable that the system of statistical areas as adopted by the International Council was 

 not employed or some other system which is strictly comparable with it. In a very general 

 way, the areas may be compared as follows: — 



By some such rough comparison as this it is possible to draw certain deductions in 

 connection with the relative values of catch per diem (K x ) and catch per hour's fishing 

 (K 2 ) as was urged in the First Report on Pleuronectidae. This matter will be referred 

 to later. 



The data include particulars of over 13,000 hauls, with 49,000 hours' fishing, during 

 the years 1904 — 7 inclusive, and supplementary data for over a thousand hauls in 1908. 



The seasonal and annual fluctuations of certain species of fish, including four pleuro- 

 nectids, are shown by variations in the average catch per 10 hours' fishing for each area 

 and each month. 



There are four species of Pleuronectidae considered in this paper, plaice and soles, 

 turbot and brill. Tho landings are further sub-divided into three trade-categories, large, 

 medium and small for the plaice and soles, and into large and small for turbot. Owing 

 to this, some very interesting comparisons have been drawn in the distribution of the 

 large and small fish and in some cases the fluctuations of the two trade categories were 

 found to differ appreciably. An example of this occurs in area M where the group "large" 

 in both turbot and soles begins to dissappear immediately after the height of the spawning 

 season while the "small" fish become still more abundant throughout the summer. 



