DESTRUCTION OF IMMATURE FISH. 157 



it would seem to be hardly understood by the majority of well-in- 

 formed people who are not naturalists. 



The Royal Commissioners of 1863^ 1878, and 1883 have all come 

 to the conclusion that the destruction of very young fry by man is 

 so very small relatively to its prodigious destruction by other agen- 

 cies that it can make not the slightest difference to the total number 

 of fish that survive. In point of fact, however, very little is known 

 as to the numerical relation between fry killed by man and those 

 destroyed by other agencies, and until accui*ate estimates are made 

 in several localities, it is not possible to lay down a law on the subject. 



Minute flat-fishes are not found on the rocky shores of Plymouth 

 Sound, but there are several localities on the south coast where the 

 conditions are favorable to the life of young fishes ; such are Tor 

 Bay, Whitsand Bay, and Mevagissey Harbour, The want of a suit- 

 able steamboat has prevented the staff of the Marine Biological Asso- 

 ciation from making the long and numerous expeditions to distant 

 places necessary to the prosecution of this line of research, but with 

 the help of Mr. Matthias Dunn they have gained a good deal of 

 information about Mevagissey Harbour. Mr. Dunn sent some two 

 dozen young flat-fish, about as large as a man's thumbnail, to the 

 Laboratory in April, and since then Mr. Cunningham has visited 

 Mevagissey and received several consignments of young fish. His 

 experiences are given in his own words. 



" On May 15th I paid a visit to Mevagissey to see Mr. Dunn and 

 examine the young flat-fishes which he had informed me were to be 

 seen in large numbers in the harbour at low tide. The old harbour 

 of Mevagissey is almost completely empty of water at low spring tides 

 and it was in this condition when I was there ; the bottom consists 

 of soft mud or harder muddy sand, and in the inequalities of the sur- 

 face were left pools of water and running streamlets. In these were 

 myriads of young flat-fishes, most of them completely metamorphosed 

 and of a dark colour, but a few transparent and still having an eye 

 on each side of the head. Among them I found a few soles. The 

 little fish were in constant motion, rising to the surface of the water 

 and then going again to bottom and lying on or in the sand. They 

 could be caught without difficulty by the hand or with a cup or with 

 a muslin net. I found all except the soles were of one species, 

 namely, the flounder {Pleiironectes flesus) ; the individuals of this 

 species varied from 10 mm. to 18 mm. in length (three eighths to 

 three quarters of an inch). The young soles were scarce, I caught 

 only three specimens the day I was there, but Mr. Dunn sent me up 

 fifteen more the next day ; these were all about 14 mm. in length 

 (half an inch). 



" On May 31st Mr. Dunn sent up about a hundred more Pleuro- 



