Distribution of Plaice Eggs — Shetland. 35 



standing the many observations made in these two months. Only on 

 one occasion, namely, on 28th February 1905, although attempts were 

 made in eight different years, were any plaice eggs (and then only 

 three) found in the Petersen Young Fish Trawl. It is not until March 

 that plaice eggs occur in any number in this locality. The highest 

 frequency observed was in March 1909 ; and it was not until towards 

 the latter part of the month that they appeared in any number. The 

 following are the totals obtained in this locality in March 1909. 



Number at different Developmental 

 Stages, 



a |3 y 5 



Station 46— 5th March ... 4 2 10 



Station VI. (West end)— 27th March 38 20 133 26 



Station VI. (East end)— 27th March 20 8 50 12 



Station v.— 26th March . .12 7 40 18 



One may conclude from the above data that a few plaice may spawn 

 towards the outer limit of the estuary late in March. The eggs 

 collected on the 26th and 27th of March 1909 at Stations V. and VI. 

 probably have had a similar origin, the percentages at the different 

 developmental stages being very much alike. 



On 24th March 1911 observations were made at Station VI. in 

 the difierent water layers, but only one egg in the " a " stage was got in 

 a bottom tow-net, whilst on the same date no eggs were found at Station 

 V. Other observations in this locality in the month of March have also 

 given equally poor results, but when any plaice eggs occur the fre- 

 quencies are generally higher at Station VI. than at Station V. 



The absence of eggs from the area in February, and the large number 

 in the later stages of development got in March, indicate that the 

 locality, although a late spawning one for a few plaice, receives eggs 

 from earlier spawning areas. 



Station 45 (56° 16' N. ; 2° 17' W.) and Stations VII I. and IX, 



Firth of Forth. 



These stations are situated outside the Firth of Forth area ; Station 

 45 lying about ten miles due east of May Island ; Stations VIII. and IX. 

 somewhat closer to that island, but a little to the south. 



On 22nd December 1904 one plaice egg in the " a " stage of develop- 

 ment was taken in a surface haul at Station 45. The record is a very 

 early one, especially when compared with the conditions at Station 46. 

 But on 31st January 1905, that is in the same spawning year, no plaice 

 eggs were found at Station 45, although horizontal hauls were taken at 

 the surface at depths of 5 metres, 10 metres, 20 metres, and at mid- 

 water and bottom. Very few plaice, if any, could have spawned in 

 this area before that date. One plaice egg was got in a bottom haul 

 with the Petersen Young Fish Trawl on 5th January 1905 a mile east 

 of the May Island. On 15th January 1906 only one egg, in a tow-net 

 ten metres below the surface, was got at Station 45, while 27 eggs all 

 in the earlier stages of development were taken in the different water 

 layers at Station IX. on 25th January 1911. 



Thus, although spawning may begin early in this area, the frequency 

 of plaice eggs in the plankton in January is very low. 



