162 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



scavengers, and will subsist largely on dead material. 

 Consequently, if there should be any scarcity of food, I 

 do not doubt that they might, to some extent, compete 

 with the little fish by eating the worms and smaller 

 Crustacea, but it is improbable that there would be 

 any such scarcity. We may put great trust in the 

 recuperative powers of the invertebrate fauna of the sea- 

 bottom. Even in the spots where fishes are most crowded, 

 we bring up plenty of invertebrate food material in the 

 dredge and trawl ; and, moreover, if there were any 

 scarcity of food the star-fishes and crabs, which are so 

 abundant on these grounds, would move away. 



A greater danger might be brought about by the 

 increased numbers of shrimps and young fishes attracting 

 many skates, rays and other larger predaceous fishes 

 to the ground. In fact, the disturbance of the fauna 

 might be very wide spread. Some forms of invertebrata 

 might be either favoured or the reverse by the changed 

 conditions, and then that change in the food might re-aot 

 upon the fish population. For example, if the smaller 

 crabs which are usually present in enormous profusion on 

 the shrimping grounds, found conditions uncongenial and 

 migrated to other banks and channels, the Gadoid fishes, 

 which feed largely upon such crabs, might in their turn 

 be affected. 



The chief enemies of shrimps in our district (see our 

 Report for 1894) are skates and rays, whiting, gurnard, 

 and the larger Gadoid fishes. The latter are not abundant 

 on the shrimping grounds, but skates and rays seem to 

 have increased on the Blackpool closed ground, possibly 

 as a result of the more abundant feeding upon that 

 sanctuary. A careful detailed comparison of this closed 

 area with the open grounds on both sides of it might give 

 information as to effects to be expected by closing other 



