38 



CONTENTS— co«</n?te(^. 



PART II— cotilimied. ^^^^ 



Migrations of the plaice ... ... ... ... ... ••• 108 



Plaice-marking experiments, p. 110; Age and the migration 

 paths, p. 126. 



General remarks on the migration experiments 130 



Growth-rate of marked plaice, p. 131. 



PART III: The Pre-War and Post-War Plaice Fisheries ... 133 



Fluctuations in the Plaice fisheries in the North Sea, English Channel 



and Irish Sea ... ... ... ... ... ... ••• 133 



Fluctuations in Lancashire Fisheries, p. 136 ; Fluctua- 

 tions in the Mersey fishery, 1908-1920, p. 139 ; Table 

 XVI, length frequencies on the Mersey grounds, 1908- 

 1920, p. 140 ; Fluctuations in Liveii^ool Bay, 1909-1913, 1920, 

 p. 143; The Northern plaice grounds, 1920-21, p. 145; 

 Table XVII, length frequencies on the Northern grounds, 

 1920-21, -p. 146 ; Proportions of the age-groups in various 

 years, p. 148 ; Table XVIII, length-frequencies for Age-group 

 III, p. 148 ; Table XIX, length-frequencies for Age-groups II 

 and III, p. 157 ; Composition of the plaice stock as I'egards 

 groups, p. 150. 



Causes of the fluctuations ... ... ... ... ... ... 152 



Table XX, length-frequencies of plaice caught in the shrimp 

 trawl-net, Mersey grounds, 1908-1920, p. 154. 



The post-war fisheries, 1920 ... ... ... ... ... ... 155 



Tables XXI to XXVII, length-frequencies of plaice caught on the 

 various grounds in the year 1920, p. 156. 



The effect of the war restrictions on the fisheries ... ... ... 164 



PART IV: Practical Administrative Questions 167 



The rate of exploitation ... ... ... ... ... ... 168 



The impoverishment of a fishing region ... ... ... ... 170 



Has there been impoverishment of the Irish Sea plaice fisheries ? 

 p. 170 ; Is there an accumulated stock ? Does increased fishing 

 tend to make the plaice run smaller, p. 172 ; Did a stock of 

 plaice accumulate in the Irish Sea during the war years, p. 173. 



The possible effects of legislative restrictions ... ... ... 174 



The protection of the spawning grounds, p. 174 ; The question 

 of size-limits, p. 175 ; Effect of latter on smacks, p. 175 ; Effect 

 on the steam-trawlers, p. 175 ; Possible effects on the fisheries 

 of a size-limit, p. 176 ; The theory of restrictions, p. 178. 



Cultivation ... ... ... ... ... ... ... ... 179 



