of the Fishery Board for Scotland. 



XV 



of this year (1917) than for a considerable period, the season's total 

 up to 19th March amounting to 8,493 crans, as against 491 crans in 

 the corresponding period last year. 



Fluctuations in the herring fishery, especially in fjords or arms 

 of the sea, are not infrequent on the coasts of other countries, and 

 have been attributed to a variety of causes. In Lochfyne a series of 

 temperature observations are made at different levels, and collections 

 of the floating food secured, and it is proposed to continue these 

 investigations until the herrings return to the Loch in their former 

 abundance, so that comparison may be instituted between the 

 observations taken in the period of scarcity and those taken in the 

 period of abundance. 



Fishery Investigations in the North Sea. 



Traivling and Other Investigations. 



The reduced staff have been kept busily engaged in working at 

 the collections of various kinds, which were obtained in previous years, 

 and also in dealing with the records of the observations and the 

 statistics obtained. Among these may be mentioned the marking 

 experiments on the plaice, in connection with the study of the 

 migration and growth of that fish. A Report on this subject dealing 

 with the marking experiments in the years 1910-1913 is nearing 

 completion. 



Other work on which the scientific staff have been engaged, and 

 in regard to which Reports have either been completed, or are in 

 course of preparation, includes the following: — The influence of 

 herring-trawling on the fish supply; the life of the herring in 

 captivity ; the determination of the age and growth of the herring 

 and of the lemon sole from a study of the markings on the scales ; 

 the diseases of fishes ; the life-history of the angler {Lophius pis- 

 catorius) ; and the distribution of the pelagic eggs, and of the larval 

 and post-larval stages of the food fishes. 



Hydrographical Investigations. 



The whole routine of our hydrographical work. (including sea- 

 temperature observations and the collection of water-samples by 

 passenger captains) is of necessity suspended, with the exception of 

 a few observations which continue to be made at lighthouses and 

 certain other coastal stations. But, on the other hand, considerable 

 progress has been made in the tabulation and study of observations 

 recorded in previous years. 



For example, the whole available stock of temperature-observa- 

 tions has been collated, and the results printed in a paper by Pro- 

 fessor D'Arcy W. Thompson, " On the Surface Temperature of the 

 North Sea, and of the North Atlantic." In this paper are set forth 

 charts (for the twelve months) of the mean monthly sea-temperatures 

 around the British Isles, as well as charts of the mean annual sea- 

 temperature, the mean annual range of temperature, the mean 

 maxima and minima, and other related phenomena. Some further 



