6 Part ITT.—Twenty-third Annual Report 
food and other fishes on the grounds visited in different years and 
at different seasons, but observations are also made on the repro- 
duction of the fishes, their spawning, food, and on various other 
questions connected with their life-history and habits, and at the 
same time collections of the plankton, or floating organisms, are 
obtained, and experiments made with large-meshed and small- 
meshed nets. 
Although the employment of ccmmercial vessels in these 
investigations is associated with certain inseparable disadvantages, 
it is possible with the large ship, the efficient trawl, and the 
experienced trawlers on board, to make a much more thorough 
examination of the bays than was formerly the case. From the 
fact, moreover, that the trawling operations are carried on under 
the same conditions as in commercial fishing, opportunities are 
afforded for certain observations of importance, as the proportion 
of the marketable and unmarketable fishes which are caught, the 
relation between the sizes of the fishes captured and the dimensions 
of the meshes of the net, and the amount of destruction of 
immature fish that occurs on different grounds and at different 
seasons. 
For some years past, as mentioned in previous reports, by an 
arrangement with the Technical Education Committee of the 
County Council of Aberdeenshire, representative fishermen from 
various parts of the coast of that county have visited the Labora- 
tory and Hatchery in spring to receive demonstrations on various 
aspects of the life-history and habits of fishes, such as may be of 
interest and use to them in the course of their calling. The 
fishermen have been much interested in the instruction they 
received, and as it appeared to the Board advantageous to 
encourage the desire for such knowledge on their part they issued 
a circular to the other sea-board County Councils inviting them 
also to send fishermen if they thought proper so to do, to attend a 
similar series of demonstrations. This invitation was accepted by 
the County Council of Argyleshire, a number of fishermen from 
that shire subsequently visiting the Laboratory and Hatchery, and 
it is under consideration by some of the others. 
TRAWLING INVESTIGATIONS. 
In the course of the year the results of 91 hauls of the large 
otter-trawl in the closed waters were recorded, of which 75 were 
taken in the Moray Firth, 14 in Aberdeen Bay, and two in Sand- 
side Bay, on the north coast. The examination of the grounds was 
made in January, March, April, September, October, November, 
and December, the localities in the Moray Firth which were most 
thoroughly investigated being Burghead Bay and adjacent parts of 
the south coast, the Dornoch Firth, and the grounds off the coast 
of Caithness. Some hauls were also taken at Smith Bank and in 
the deeper portions of the Firth at the so-called “witch-grounds.” 
The aggregate number of fishes of all kinds caught in the 
recorded hauls was 63,525, and of these 44,538, or 70 per cent., 
were marketable, the other 18,987, or 30 per cent., being thrown 
