10 



Fishery Board for Scotland. 



average date of the first appearance of the plankton eggs may be 

 approximated. 



Beginning of Spawning Season in Dornoch Firth. 



Month. 



November 



December 



January . 

 February 

 March 



Note. — + indicates occurrence of eggs in plankton. 

 — observations made, no eggs found. 

 . no observations made. 



This table shows clearly that plaice begin to spawn before the last 

 days in December or dming the first days of January, and in ex- 

 ceptional years spawning has begun late in November or very early in 

 December. It is clear that season 1908-1909 was a very early one. 



It is possible to approximate fairly closely to the date of first 

 spawning of this species by an examination of the degree of develop- 

 ment of the reproductive organs of the adults within the area. It has 

 to be added, however, that it is doubtful whether adults which are 

 approaching maturity remain in the immediate locality to spawn. 

 Dr. Fulton (1905) records spawning plaice from the Moray Firth 

 towards the end of December 1903, a fact which fits the early records 

 of the " Goldseeker." On the East Coast of Scotland the reproductive 

 organs of adult plaice show the earliest signs of the approaching 

 spawning season of those species which have pelagic eggs. Males are 

 usually earlier than females. In November 1913 three males were 

 found quite ripe, and motile spermatozoa were demonstrated by ex- 

 amination under the microscope. The following are the records : — 



Dornoch Firth, 17th November 1913 — Two ripe males, each 37 cms. 

 long. 



Station II., Firth of Forth, 25th November 1913 — One ripe male, 

 37 cms. long. 



The record from East of the May Island (56° 16' N. ; 2° 17' W.) consists 

 of one egg obtained on the 22nd December 1904. This area has been 

 visited very regularly in December, but as the frequency is always 

 comparatively low even at the height of the spawning season, it is very 

 difficult to say whether this area is actually as early as the Dornoch Firth. 



The only other positive record made for this month was at Station 

 29 (57° 57' N. ; 3° 20' W.) on 20th December 1904. The two eggs 

 found had already been some time spawned as the embryos had reached 

 the "y" stage, so that one must conclude from this evidence thatspawn- 

 inghad begun in the Moray Firth area in 1904 some time before this date. 



As continuous records for each locality over such a wide area are 

 not available, the elucidation of the quantitative distribution of the 

 newly spawned eggs is all the more difficult. Each locality, no doubt, 

 has its own peculiarity in regard to the range of time and maximal 



