50 



disappear from the Irish Sea fishing grounds, and there is always 

 much speculation among fishermen as to where they go. There 

 is little doubt that they " dawk " — that is, bury themselves in 

 the sand in the channels offshore and among the sand-banks. 

 Here they remain during the period of the year when the 

 temperature is at or little above its minimum value, and when 

 food has become scarcer than usual. Noting all these facts 

 as to the seasonal nature of the plaice fishery, and comparing 

 them with the results of the marking experiments — to be stated 

 on pp. 110-132 of this report — we have little difficulty in 

 making a general picture of the migrations of plaice in the 

 Irish Sea regions (see p. 130). 



The Migratory Fishes. 



It will be noticed haddock are mentioned in the tables on 

 pp. 46-7, though if a similar series of experiments were to 

 be made at the present time this fish would be much scarcer — 

 and it might not be represented at all in some of the aieas. A 

 number of species are migratory ones, entering the region we 

 are considering and then moving away again. Some of these 

 species come back every year with a certain amount of 

 regularity and others only return after a more or less prolonged 

 period. Although we are dealing mainly with the plaice in 

 this report it may be useful to say a few words about these 

 migratory species. 



Hake. 



Specimens of hake may be obtained now and then from 

 most parts of the Irish Sea, but the fish is only (relatively) 

 abundant to the west and south of the Isle of Man in the autumn 

 months (usually July, August, and September). It migrates 

 up from St. George's Channel, in the South, with the rising 

 temperature of the sea and moves southwards again when 

 the temperature falls. The fishery is, however, not a very 

 important one. 



