44 . 



A similar southerly migration of the dabs of the Forth school 

 was evidenced in the earUer Scottish experiments.* Those recap- 

 tured in February were 12 to 37 miles south of the place of libera- 

 tion ; one returned in April was 3 miles and another in Juty 4 miles 

 from the place of Uberation. An interesting exception was an 

 example which was recaptured 12 miles north of St. Andrews in 

 February. It is not proposed, however, to suggest obvious 

 ex^^lanations of this case until further evidence is available (p. 51). 



The Scottish experiments mdicated also that the dabs migrated 

 either from St. Andrews across the Firth of Forth to the south side 

 or mto the Firth on the north side, and also that the Forth dabs 

 migrate from the Firth eastwards along the south side. It is thus 

 evident, as was suggested in the preceding section, that the Forth 

 school of dabs spHts into two streams of immigration and emigra- 

 tion, one entermg the Firth and the other crossing it. 



The few records we have pomt therefore also to a " homing " 

 tendenc}". The dabs of the Forth school and of the Northumberland 

 school belong to a race which has the habit of the southern race of 

 plaice. Whether the habits change still further north there is no 

 evidence yet to say. So far as we know then the dabs of the greater 

 part of the North Sea may be said to belong to a southern race. 



5. — The Probable Oeigin of the Migrations. 



The foregoing considerations have led to the conclusion that 

 the plaice of the North Sea belong to two races, a northern and a 

 southern, each of which is again resolved into schools. The schools 

 have probably originated in association with as many spawning 

 grounds. On the east coast of England and Scotland the wintering 

 area of the schools of the northern race is to the north of the inshore 

 summer grounds. At the southern end of the east coast the schools 

 of the southern race have their wintering areas to the south of the 

 inshore summer grounds. On the continental aspect of the North 

 Sea the schools of the same race have their winter quarters to the 

 west of the feeding grounds. Each school consists of young and 

 immature plaice for the most part which migrate each season 

 between the winter and the summer grounds, and which appear to 

 have a strong tendency to remain in the school to which they 

 belong. On reaching maturity, however, they migrate in the 



* Fulton, loc.lcit. 



