1 86 NORTH SEA FISHERS AND FIGHTERS 



each of these species were determined for each area. 

 The comparative distribution of each species was 

 estimated, and investigation was made of the spawning 

 periods and regions. The final results gave a striking 

 contrast in the seasonal and geographical distribution of 

 the round and flat fishes. Plaice, soles, turbot, and brill 

 were found in their greatest numbers on the eastern 

 grounds and in the adjacent areas. Cod and haddock 

 were very scarce in these areas, but these species seemed 

 to be very abundant on the Dogger and on the grounds 

 north and north-east of it, where the prime fish are very 

 rarely found and plaice are comparatively scarce. The 

 round fish appeared on the inshore and southern grounds 

 in the autumn and winter only, when the flat fish are 

 present in very small numbers, and they are almost 

 completely absent from these grounds in the late spring 

 and summer, when soles and turbot are numerous. The 

 yearly fluctuations varied, but, on the whole, showed a 

 decline throughout the period for most of the species. 

 These fluctuations in some areas were complementary 

 to those in others. Compared with records of catches 

 of fish taken ten and twenty-five years before these, they 

 showed a very considerable diminution. 



The travels and movements of marked fishes and 

 other marine animals have been in many cases accurately 

 recorded, and some surprising results have been achieved. 

 A large marked plaice was found to have travelled 136 

 miles from the point of liberation to the spot where it 

 was caught, and many other instances of long journeys 

 are recorded. In the southern part of the North Sea 

 a definite southward migration of large plaice in the 

 winter months was demonstrated. The fish congregated 



