NORTH SEA INVESTIGATIONS. 133 



magnitude and importance. In September there were no herrings to be 

 caught at Lowestoft, and a large proportion of the boats were away- 

 fishing for these fish off the coast to the north of the Humber. Some 

 boats were catching mackerel at Lowestoft during this mouth. I several 

 times opened the stomach of mackerel to see what the food was, and 

 only twice found anything except a little white chyme. In both these 

 cases the tail and backbone of a fish were present, and belonged 

 apparently to a clupeoid : very probably they were feeding on sprats. I 

 saw no Copepods or other Crustaceans in any of the stomachs. Up to 

 the date of my departure from Lowestoft — October 22nd, the herrings, 

 though full, had not begun to spawn. 



III. Causes of the Observed Distribution of Fish in the 



North Sea. 



As my paper in the previous number indicates, my interest in these 

 investigations was chiefly excited by the fact that no satisfactory 

 explanation appeared to have been discovered for the remarkable 

 abundance of small plaice in the German Bight of the North Sea. 

 The explanation suggested, and held by many to be sufficient, was that 

 there was a current from west to east which carried floating or buoyant 

 objects towards the German shores, and that, therefore, the buoyant 

 eggs and larvae of the plaice were carried thither in great numbers. 

 Dr. Fulton* has recently made direct experiments on the course of the 

 drift, by putting floating bottles into the sea in the neighbourhood of 

 the Firth of Forth. In certain cases, out of groups of bottles put 

 overboard at the same spot, some were afterwards found on the English 

 Coast to the south, and others on the coast of Schleswig and the 

 Island of Heligoland. The course thus determined for the general 

 circulation would probably cause more of the plaice spawn, shed in the 

 North Sea, to be conveyed to the German and Danish Coasts than to 

 English. But the difficulty that perplexed me was that the peculiarity 

 of the German grounds seemed to consist not in the greater numbers of 

 plaice generally, but in the exclusive occurrence of small plaice at 

 distances from land at which, on the opposite English Coast, large 

 mature plaice seemed also to occur with the small. 



It is not certain that this difficulty exists ; if it does exist at all, it is 

 not to be explained by the suggestion that the plaice of the German 

 Bight are a smaller race. The smaller race, similar in the size at which 

 maturity is attained to the Channel plaice studied at Plymouth, exists 

 on the Dutch coast as far as the Texel, and extends to a distance of 

 50 miles from that coast. 



♦ Thirteenth Annual Report of the Scottish Fishery Board, 1895. 



