G4 



and the spent fish and the migrations which result from the call 

 of maturity is again prominent. 



The " Goldseoker " experiments as well as the earlier 

 " Garland " experiments in Scottish waters have been analysed 

 by Fulton.* They evidence a general contranatant migration. 

 Our results illustrate the relatively static condition of the immature, 

 the summer inshore migrants. The deeper waters just outside 

 the depths of the Northumberland experiments are shown by the 

 Scottish results to contribute still more intensively to the con- 

 tranatant spawning migrants. They indicate also that with 

 increase in size the large immature plaice migrate inshore for 

 winter, and usually denatantlv. They may remain inshore from 

 December to May, and still tending to move southwards, returning 

 northwards and offshore later in the summer. The winter 

 maximum in modorate depths is thus contributed to by migrants 

 from the shore and by larger migrants from offshore. In still 

 deejier water the spawning migrants are more numerously repre- 

 sented amongst the large sizes marked, and the non-spawning 

 migrants arc winter inshore migrants for the most part. 



We gather from these experiments, viewed as a whole, that 

 the young plaice after their denatant pelagic journey are gathered 

 together on a recruiting ground, actively moving inshore to the 

 shore region or in that direction. They retreat to the region 

 beyond tide marks in winter. They remain in relatively the same 

 region during the ensuing summer or migrate inshore (Group 1). 

 Next winter they move oufc into still deeper water, and migrate 

 inshore in summer (Group II.). This seasonal migration is repeated 

 in the case of Group III., but the incidence of the inshore appear- 

 ance is somewhat later. Group IV. do not appear until late in 

 summer, and spend the winter in shallower depths. This is 

 almost precisely the migratory sequence of the gadoids. The 

 spawning migration, as we have seen, is a contranatant one, and 

 after spawning the seasonal migrations are resumed. The plaice 

 then become inshore denatant migrants, and are found frequently 

 far to the south in the region of the eastern North Sea. 



* 1913, 5th Rep. Fish, and Hydrogr. Invest., Fish Bd. for Scotland, 1919, Sci. Invest. 

 No. 1, Fish. Bd. for Scotland. 



