Distribution of Plaice Eggs — Burghead Bay. 25 



these years do not correspond with those in which plaice eggs were 

 found in December in the Dornoch Firth. Indirect evidence led to 

 the conclusion that plaice were spawning in the Dornoch Firth early in 

 December 1907, and the negative results from Burghead in the same 

 year may be due to later spawning in that area. 



On 23rd January 1908 observations were made in this area in the 

 shallow water, in the intermediate depths, and in the deep gully. 



Burghead — Plaice Eggs (vertical distribution). 



Plaice eggs are here most numerous apparently in the neighbourhood 

 of the intermediate depths. 



The frequencies, however, fall very far short of those obtained in 

 the Dornoch Firth in the same month. 



The percentages of eggs in the different stages of development ob- 

 tained from the three observations are in such close agreement as to 

 indicate they have all had the same origin. 



Depth. Percentages at Developmental Stages. 



14 Metres . . 87-8 2-44 9-76 



23 „ . . 87-0 7-0 6-00 



56 „ . . 77-85 1013 1202 



The high frequency of the eggs in the first stages of development 

 suggests that plaice were then spawning in number in the locality. 



The deeper the water the greater is the admixture in the collections 

 of eggs of other species, the percentage of plaice eggs in the total catch 

 from the shallow water outwards being 95'06, 8r35, and 80'61 re- 

 spectively. 



On 10th January 1912 no plaice eggs were taken in the plankton 

 nets, although two days previously they were found in small numbers in 

 the Dornoch Firth. Spawning had begun somewhat earlier than this 

 date in the Dornoch Firth, so that the absence of place from the plank- 

 ton in Burghead is probably due either to the lateness of the spawning 

 season or to the small number of plaice in the area. 



No direct comparison can be made between the January and 

 February collections from this locality, as the February ones were 

 taken in the years 1906 and 1910, and no observations were made in 

 the month of January in those years. On 26th February 1906 fom'teen 

 eggs were taken in a haul of one half-hour's duration at the surface. 

 On 3rd February 1910 there were only six eggs in the surface haul from 

 the offshore ground,where the depth is 50 metres,and none in the sm-face 

 haul from the shallower water about 15 metres deep. These February 

 records are very poor, and in somewhat striking contrast to the com- 

 paratively rich hauls of January 1908. But the February 1906 col- 

 lections from the Dornoch Firth were very rich in plaice eggs. These 



