SEA-FISHERIES LABORATORY. 163 



parts of our fish nurseries to shrimping. We desire to 

 know riot merely the statistics of the " catch," i.e., the 

 fish and shrimps in each haul, but also the relative 

 abundance of invertebrate (food) animals on closed and 

 open grounds, and full details as to their kinds and 

 abundance, their life-histories and changes throughout the 

 year, and their food, for comparison with that of- the 

 shrimps and fishes. 



Furthermore, we obviously require to have full infor- 

 mation in regard to the structure and habits of both the 

 shrimp and the fishes throughout their life-histories before 

 we can be sure that any alteration in relative numbers will 

 be permanent. We know a good deal about such matters 

 already, either in our own seas or in other parts of the 

 world. Professor J. S. Kingsley,* in America, has made 

 us acquainted with the development of the early stages of 

 the shrimp [Crangon vulgaris), and Dr. Ehrenbaum has 

 given us much information as to the structure and life- 

 history of the shrimp at Heligoland.! All that is a help, 

 but still there are many local details that must be worked 

 up on our own ground. We must know exactly where 

 and when the various stages occur, and in what abundance, 

 and in what association. 



Then turning to the little fishes, if we take the plaice 

 again as an example, Mr. -Johnstone has given, in the 

 appendix to our own Eeport for 1901 (No. X., p. 211), a 

 summary of what is known as to the development on our 

 coasts, and the habits and food at the various stages. If, 

 however, we take the young sole — a very valuable, and 

 frequently abundant, constituent of the fauna on the 

 shrimping grounds- — much less is known, and the exact 



* Bulletin of the Essex Institute, 1887 and 1889. 

 + Naturgeschiehte von Crangon vulgaris, 1890. 



