LEMON SOLES 147 



Fluctuations in the Catch 

 At this point a digression is indicated. The catch of lemon 

 soles landed on the east coast by steam trawlers from the 

 North Sea has risen steadily from 1,037 tons in 1909 to 1,280 tons 

 in 1913. This is an extremely short period to regard as a cycle, 

 and the curve may indicate only that the lemon-sole grounds 

 were more intensively exploited, but from Table VIII of the 

 Annual Sea Fisheries Beport for 1913 it appears that the lemon 

 sole is the only steam-trawl fish of which the catch. steadily grew 

 in this manner. The writer would inquire whether there are 

 grounds for believing that the lemon-sole population of the 

 North Sea was, in the five years before the war, really growing. 

 Whether the fact that the lemon-sole statistics for this period 

 give an upward curve quite distinct from the curve of every other 

 species of fish can be connected with the fact that its diet in 

 the earhest larval stage differs from the diet of its congeners, 

 soles and plaice and dabs ? Are lemon soles less subject to 

 infant mortahty than other fish ? Is this because its baby food 

 is a more stable quantity on its nursery grounds than that of 

 other fishes ? Is it because it does not (hke its larger-mouthed 

 cousins) require any food other than the contents of its yolk-sac? 



Further Development 

 It will be noted that none of the Plymouth specimens this 

 year had taken to the bottom, and none, of course, had turned 

 into flat fishes. They were swimming at the surface ' edge up ' 

 even when they were 19 millimetres^ (over three-fifths of an 

 inch) in length. Petersen has obtained in November a specimen 

 1-6 inches long, which was actually at the bottom in the Ska- 

 gerrak. Meek tells us that the fish begins to turn over on to its 

 right side and swim as a flat fish not before it is about 1 inch 

 long ; even the early hatched larvae do not go to the bottom 

 till late in the year, and they always go to the bottom in fairly 

 deep water. The fish hatched late in summer pass the first 

 winter drifting at the surface. Some of the young fish float 

 down the coast of Scotland with the current, and have been 

 found in the Humber by Holt in October and November at 

 2J-3| inches. These fish were beheved to have been hatched in 

 the previous year. Williamson in 1893 drew up a complete table 

 of sizes of lemon soles from (9-7 millimetres) 0-3 inch to 10 inches 

 long, and concluded that in the North Sea the fish took several 

 years to reach the latter size. 



^ i. e. in length. Plaice turn into flat fish when they are 



about 45 days old and about {— ) 15 mm. long [see p. 36]. Lemon 



soles float longer than plaice at the surface, i. e. they have what is called 

 a longer ' pelagic existence '. 



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