3O FISHES AND FISHERIES OF THE IRISH SEA. 



upon larval Crustacea. Up to the age of about a month, the little fish is perfectly 

 symmetrical ; then that remarkable rotation of the head sets in, which results in both 

 eyes coming to lie upon the coloured side of the animal. The complete metamorphosis 

 takes about two weeks, and the little animal is then 13 mm. in length. The fish, now 

 flattened and coloured like the adult, rests upon the left side, and feeds chiefly upon 

 Copepoda. A somewhat rare Copepod, called yotiesiella hycence, which was not known 

 until Mr. I. C. Thompson found and described it from our district, is apparently a 

 favourite food of young plaice at this period, since we frequently find it in their 

 stomachs. When a size larger again, say from 3 cm. to 7 or 8 cm., the animal feeds 

 upon small worms and upon the feebler Crustacea, such as My sis. Later on again, and 

 during the remainder of its life, the plaice feeds mainly on Lamellibranch Mollusca, such 

 as Mactra and Donax. From the time of its metamorphosis onwards the plaice is a 

 bottom-living fish, feeding on the ground, in which it frequently lies partially buried. It 

 has small powers of migration, and in such a district as the Irish Sea is all its life 

 exposed to man and liable to be captured. In its early youth it is harried by the 

 shrimpers of all kinds along the shores, and in the estuaries, when it gets a little 

 larger but is still immature, it is the object of an extensive fishery on the coast by 

 means of stake nets, and on the in-shore grounds by trawlers ; finally, in the open 

 sea, it is one of the chief sources of revenue to the deep-sea trawler. In this 

 constant liability to be captured, it contrasts markedly with migratory fish, such as 

 the herring and mackerel, and even with fish such as the cod, which at times pass 

 beyond our local fishing operations. Hence the danger of over-fishing leading to a 

 serious decrease of such an important food-fish as the plaice in British waters. 



Our Lancashire statistics, taken over the last 10 years, although in many respects not 

 so continuous and complete as we should desire, give us many valuable items of information in 

 regard to the distribution and abundance of young and old fishes at different seasons. The 

 following extracts as to the plaice are of interest. They are all from hauls with the shrimp 

 trawl : 



June 2ist, 1893 ... ... Heysham ... ... 510 plaice, about ii inches long. 



August nth, 1892 ... ,, ... ... 1,200 ,, ,, 2 ,, 



,, ,, ... ,, ... ... I,IOO ., ,, 2 ,, 



July roth, 1893 ,, 1,200 ,, ,, 3 ,, 



July nth, 1894 ... ,, -..3,980 ,, ,, 3 ,, 



August yth, 1894 ,, ...3,760 ,, ,, 3! ,, 



September 27th, 1895 ... Ulverstone Ch. ... 1,877 3 



October 1 5th, 1895 ,, 9544 T 3 



October 23rd, 1894 ... Heysham ... ...4,000 ,, ,, 4 ,, 



November gth, 1894 ... ,, ... ...3,000 ,, ,, 4 ,, 



December 4th, 1894 ... ,, ... ...3,000 ,, ,, 5 ,, 



That gives an idea of the range in size of the little fish in the coastal "nurseries," 

 where the minute plaice, which has just completed its metamorphosis, usually appears in May, 

 and from which it gradually moves out into deeper water about the end of autumn. These 

 times are, of course, liable to some variation, from year to year, according to the season and 

 state of the weather. Then larger, but still immature fish, say from 5 to 11 or 12 inches in 

 length, are found a little further out along the banks, such as just outside the Blackpool 

 ground, and outside the Liverpool Bar, in depths of about 10 fathoms. Larger mature 



