The Spawning Areas of Sand-Kels in the North Sea. vi 
of the North Sea, between the Pentland Firth and Sumburgh Head. 
In this area the larve are present in the plankton in countless 
thousands in the month of March—in fact, they are the predominant 
young fish captured. Yet not a single example of this species was 
found in this area in any of the January or February collections, 
although numerous observations were made during these months 
throughout a series of years in the vicinity of the Fair Isle. In this 
area of greatest density, on the average over 100 examples were got 
in vertical hauls with a cheese-cloth net having a mouth of one 
metre diameter; and horizontal hauls of one half-hour duration 
with a similar net gave an average of 173, 3683, and 5523 
respectively for surface, middle, and bottom layers. | On one 
occasion as many as 19,860 individuals were captured near the 
bottom in a single horizontal haul of half an hour’s duration. 
These are figures which are not approached by any of the numerous 
observations made in other parts of the Northern North Sea, and at 
this time of year. Although there is, of course, considerable 
variation in the numbers captured in different localities in this 
neighbourhood, yet taken in the aggregate the figures go to prove 
that without doubt there is here an area with a very great 
abundance of sand-eels. The localities referred to, so far as the 
observations go at present, include the Fair Isle grounds, the east 
of Orkney, and the Pentland Skerries, as well as the Pentland Firth 
from beyond Dunnet Head to Noss Head and Sinclair Bay. At the 
most westerly of these localities even as early as the 8th of the 
month, the frequency was found to be high, for over 2000 newly- 
hatched sand-eels (none exceeding 7.5 mm.) were obtained in one 
half-hour in a bottom tow-net, whilst 558 were got near the surface. 
Now experience gained in the capture of these larve in March 
proves that they are without doubt more numerous in the deeper 
layers, for the surface hauls, as in the example just quoted, are 
invariably the least productive. The frequency in the Pentland 
Firth itself may be estimated from the fact that on the average 2360 
examples were taken in a series of surface hauls. Similarly, to the 
east of Orkney 7310, 6024, and 30 are the respective numbers for 
bottom, mid-water, and surface hauls, while the corresponding 
figures for Noss Head are 4256, 13,360, and 186, and for Sinclair 
Bay 3024, 3191, and 8. These figures are typical of the results 
obtained in this area. 
An examination of figures got from hauls taken in the Moray 
Firth is highly instructive, as a glance at the following table will 
prove :— 
