SEA-FISHERIES LABORATORY. 161 



would be manifestly unfair to the shrimping industry to 

 impose restrictions, and possibly interfere with the liveli- 

 hood of so many fishermen, before making those further 

 investigations that are practicable, and are most likely 

 to throw much light upon the matter. . 



We may take the probable effect of such restrictions 

 upon shrimping as have been suggested as an instance that 

 will show the problems that confront us, and the kind of 

 information we want. It is interesting to speculate upon 

 what would be the resulting effect upon the fish and 

 shrimp populations if shrimping were either stopped 

 or restricted to certain months on particular grounds. 

 The number of immature fishes would probably increase, 

 at least for a time — possibly permanently — and this 

 might be expected to lead to an increase in the market- 

 able fishes on the off-shore grounds a year or two later. 

 The great numbers of young fish at present destroyed 

 would be preserved, and, no doubt, the number of shrimps 

 would also increase considerably. Interesting questions 

 would then arise as to whether the fish and shrimps would 

 be competitors for the same food, and whether there 

 would be enough for both in their increased numbers. 

 Taking the plaice as an example of the young fish, we 

 know that when very young it feeds mainly on Copepoda 

 — we have found their stomachs crowded with Jonesiella 

 hycence and other allied forms. But, after the meta- 

 morphosis, the young fishes from, say, 1^ to 4 inches in 

 length, feed largely upon worms such as Nereis and 

 Pectinaria, upon small Crustaceans such as Mysis and the 

 Amphipoda, and even upon small shrimps. Later on, the 

 fish adopts its proper adult food, which is Mollusca 

 (mainly small cockles, mussels and allied bivalves). 



Shrimps, we know, are general feeders fusing small 

 Molhiscs and other animals, and also Algse) and 



