44 Fishery Board for Scotland. 



obtained from the line of stations east of Tarbet Ness, and is seen in 

 lesser degree in the line east from the May Island. 



Although spawning begins very early in the Dornoch Firth, the other 

 coastal areas in the Moray Firth are later. Thus spawning is late at 

 Noss Head. 



At Shetland spawning begins almost two months later than in the 

 Dornoch Firth. 



Even within the Firth of Forth area plaice are later in spawning 

 than east of the May Island. 



" There are also marked differences with regard to the intensity of 

 spawning over this wide area." 



The most favoured spawning areas lie well within the Moray Firth. 

 There is a gradual fall in the intensity of spawning from north to south 

 along the East Coast of Scotland. The frequency is low in the area to 

 the east of Orkney and at the Fair Isle. The intensity of spawning 

 within the narrow belt at Shetland falls very far short of that in the 

 Moray Firth. 



In the central region of the Northern North Sea, in depths of over 

 fifty fathoms, plaice do not spawn. Adverse conditions for spawning 

 extend southwards through the " Gut," and prevail even over that 

 shallower area east of the Firth of Forth between 0° and 2° E. longitude. 



The analyses of the distribution of the spawning places may be 

 carried much further. The observations made have again and again 

 shown that plaice eggs are not uniformly distributed even within a 

 comparatively restricted area. In other words, the spawning of plaice 

 is distinctly localised ; there are localities of higher and of lower density. 



Within the Moray Firth area the localities most favoured by spawn- 

 ing plaice within the years under review were the following : 



It has been found that every year plaice spawn in number in the 

 vicinity of Tarbet Ness. There are, however, slight variations from 

 year to year in the exact position of the most favoured places, for 

 sometimes it lies within the Dornoch Firth and sometimes it is further 

 off-shore. The frequency of spawning falls rapidly in an easterly direc- 

 tion. Plaice in considerable number frequent the neighbourhood of 

 Lossiemouth and Burghead for the pm'pose of spawning. There is a 

 fall in the intensity of spawning in an easterly direction from Lossie- 

 mouth along the Moray Firth Coast. Noss Head is also a locality where 

 plaice spawn in number, but the frequency is very much less than at 

 Tarbet Ness. The intensity of spawning between Dornoch Firth and 

 Noss Head is much lower than at either of these localities. There is a 

 spawning area in the neighbourhood of Bosey's Bank, and although 

 spawning plaice are few in number their occurrence here is exceptional. 



To conclude — plaice spawning is localised. It is true that each of 

 the favoured localities has not been visited regularly, but the obser- 

 vations are otherwise so extensive that it is all but certain that these 

 specialised localities are unique, and show but slight variations from 

 year to year. Since these spawning localities are not fortuitous they 

 must be intimately correlated with conditions which are advantageous 

 to the species. The selecting of the spawning area determines more 

 immediately the fate of the newly hatched larvse and later the distri- 

 bution of the very young forms. 



AVhile pelagic plaice eggs at the different stages of development, 

 even with the larva ready to hatch, are exceedingly numerous, the 



