458 REI'OKT ON TRAWLING AND OTHER INVESTIGATIONS 



Table VII. shows that in the summer and autumn of 1901 there was 

 a great scarcity of small dabs as compared with the corresponding 

 season of 1902. The difference cannot be attributed to differences in 

 the combination of the stations, since Station III., which alone exhibits 

 a deficiency of dabs, is not represented in the averages for July and 

 August in either year. 



If we again use Mr. Holt's figures for 1895-8 as a test, we find that 

 in July the Busy Bee made an average catch of 29 dabs per hour, of 

 which 22 were small and 7 marketable. Thus the Oithoncis figures for 

 1901 may be taken as indicating an abnormal scarcity of dabs, especially 

 small dabs, in Start Bay ; while the figures for the spring and summer 

 of 1902 indicate the gradual resumption by the dabs of at least their 

 former abundance. 



As a matter of fact, during the investigations in 1895-8, the dabs 

 in Start Bay outnumbered the plaice in each season of the year; whereas 

 in 1901-2 the reverse was the case until the summer of 1902, when 

 three times as many dabs were taken as plaice. 



Table VIII., showing, for Start Bay, (1) the total proportion of Dahs to 

 Plaice, and (2) the jjroportion of Large Dahs (8 inches and upioards) 

 to Large Plaice (12 inches and upioards), for each quarter during the 

 two sets of investigations. The numhcr of Plaice has heen taken in 

 each case as 100. Total Dabs to Plaice. Large Dabs to Large Plaice. 



July to September 

 October to December 

 January to March 

 April to June 

 July to September, 1902 



These facts are shown in the accompanying table, in which the 

 relative abundance of large dabs and plaice is also compared for the 

 two periods. The size limits selected correspond roughly with the size 

 of maturity in the two species. It will be observed that in 1895-8 the 

 mature dabs outnumbered the mature plaice in Start Bay in each season 

 of the year, whereas in 1901-2 the reverse was the case, even during 

 the summer of 1902, when so many small dabs were taken. 



It appears permissible to conclude from these data that, whatever the 

 causes which had led to the scarcity of immature intermediate-sized 

 plaice in 1901, the previous abundance of dabs was reduced to a still 

 greater extent ; and that both species were recovering from this wave of 

 depression in the course of 1902. The previous scarcity of these fish 

 cannot therefore be attributed to the " fouling " of the ground from 

 lack of trawling, since under such circumstances the dab, as a mud- 

 loving species, would probably have suffered less than the plaice, and 



