236 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



statistics show, I think, that dabs have become much 

 more numerous, with regard to plaice, on the Blackpool 

 ground (which is closed against trawling) than on the 

 Mersey ground (which is open to trawling). This 

 suggests that closing the former ground has favoured the 

 dabs much more than the plaice. In what precise way, 

 it is difficult to conjecture. 



It is always very difficult to forecast what may be 

 the result of interference with natural conditions with 

 regard to marine animals. Thus, according to the cockle 

 fishermen of Morecambe Bay, cockles are not so abundant 

 in many places as they used to be, because of their 

 destruction by sea-birds, which have increased greatly ou 

 account of the operation of the Sea Birds Preservation 

 Acts. Then the Inspectors of Salmon Fisheries for 

 England and Wales pointed out* the positively injurious 

 effects of fish culture in American fresh waters. The 

 introduction of the fry of a fresh-water fish — the black 

 bass (Micropterus dolomieu) — not only led to the practical 

 destruction of the trout in the streams into which this 

 fish had been introduced, but by-and-bye the bass them- 

 selves became dwarfed, and nearly valueless as game 

 fishes. 



Too much reliance can, of course, be placed on the 

 statistics quoted above, but it is evident that the conclu- 

 sion which I have suggested may be as reasonable as any 

 that may be deduced from the facts. 



i. Occasional Scarcity of Shrimps on Blackpool Closed 

 Ground. 



On June 10th, 1904, several hauls were made on the 



above ground, with the object of getting some shrimps 



for bacteriological analysis. Usually there is no difficulty 



* See their Annual Reports for 1897 and 1898, pp. 14-15 and 6-9 

 respectively. 



