6 



Part III. — Twenty -second Annual Report 



fact that the actual trawling operations are carried on exactly as 

 they are in commercial fishing, opportunities are thus afforded for 

 certain observations of importance, as the proportion of the market- 

 able and unmarketable fishes which are caught, and the destruction 

 of immature fish on different grounds and at different seasons. 



Trawling Investigations. 



In the course of the year the results of 148 hauls of the large 

 otter-trawl were recorded, of which 101 were made in the Moray 

 Firth and 29 in Aberdeen Bay, making 130 in the closed waters ; 

 and in addition 18 drags were recorded in the waters offshore, the 

 aggregate thus being 148. In the Moray Firth the more important 

 areas were examined in February, March, April, June, October, 

 November, and December, and the grounds in Aberdeen Bay were 

 visited in the same months. The localities in the Moray Firth 

 which were most thoroughly examined were Burghead Bay and 

 the Dornoch Firth, as well as Smith Bank, the grounds off Lossie- 

 mouth, off the Suters of Cromarty, and the coast of Caithness. 



The total quantity of fish recorded in the course of the investi- 

 gations was large, viz., 180,515, of which 126,485 were of a kind 

 and size to be marketable, and 54,030 were found to be unmarket- 

 able, either because they were of inedible varieties, or too small to 

 be profitably sold. Those which belong to the former category are 

 comparatively not numerous, comprising mostly long rough dabs 

 and various odd kinds, but they may include large numbers of the 

 angler or monk fish and gurnards, though these are very often 

 brought to market. The great majority of the unmarketable 

 fishes belong to edible and saleable forms, and are simply rejected 

 because of their small size, such as small haddocks, whitings, plaice, 

 &c. In the hauls in the inshore waters the proportion of the 

 unmarketable fishes varied from 7'4 per cent, for cod to 78'2 per 

 cent, for gurnards among the round fishes, and from 0*5 per cent, 

 for brill to 89 per cent, for common dabs among the flat fishes. 

 The percentage of unmarketable plaice was relatively large, namely, 

 30 - 3, due to the fact that the fishing was to a large extent carried 

 on in shallow water. The proportion of the marketable and 

 unmarketable was found to vary very greatly according to the 

 depth of the water and the season. 



In the paper by Dr. Wemyss Fulton, the Scientific Superinten- 

 dent, on this subject, will be found described also the results of an 

 investigation on the proportion of the marketable fishes which are 

 immature — that is, which have not yet reached a size at which 

 reproduction takes place. The limit between the mature fishes 

 and the immature in respect to size is first dealt with, and it is 

 shown that in most cases it is not the average size of the generation 

 which first becomes mature that is the true dividing line, but 

 something under it, the precise point varying in different species 

 according to whether the reproductive stage is reached early or 

 late in the growth of the species. 



The proportion of the immature, whether regarded in terms of 

 weight or of size, of different species brought to market varies very 

 greatly according to the species. Among some flat-fishes, such as 



