112 Part Hi. — Seventeenth Annual Report 



temperature of 8 deg. C, according to Dannevig*, the plaice egg hatches 

 in 14| days, haddock in 13, cod in 13, whiting in 10, and flounder in 

 5 J days. 



If spawning were known to proceed in a regular curve without 

 spasmodic periods of activity, it might be comparatively easy to estimate 

 the probable number of eggs that had been spawned in the intervals 

 between the trips; but nevertheless I am inclined to the view that in 

 doubling the numbers of each species no serious over-estimate will be 

 made. Much, indeed, might be said in favour of a larger increase. So 

 far, however, this is a matter of opinion and not founded on exact data. 

 The totals, therefore, given at the bottom of the Table probably represent 

 the minima for each species during the eight months. 



Out of a total of 30,700 millions of eggs of thirty-two species 

 estimated to be present in the loch in 1898, 8,000 millions were the eggs 

 of cod and haddock. These were the eggs which appeared in greatest 

 profusion, although the eggs of the whiting and saithe were not far short 

 of that number. It may be worth while here to give the estimated totals 

 for the period. 



Estimated Number of 

 Eggspresentin Upper 

 Loch Fyne during the 

 seven trips — Feb.- 

 August 



Plaice. 



Cod and 

 Haddock. 



Whit in s, and 

 Saithe. 



Turbot. 



Mackerel. 



Lemon Sole. 



24] ,S00,000 



4,020,000,000 



3,281,000,000 



182,000,000 



178,000,000 



225,000,000 



Estimated Number of 

 Eggs in Upper Loch 

 Fyne during the First 

 Eight Months of 1898 



' 483,600,000 



8,040,000,000 



6,-362,000,000 



364,000,000 



356,000,000 



450,000,000 



As a basis of comparison with other areas, the number of eggs to each 

 square yard of water surface is given in Table XV. Henson and Apstein 

 estimate for the North Sea 92*5 eggs and fishes for each square metre. 

 My observations give for the period from March to July the average 

 number of eggs for each square yard of water surface at 25 '8 eggs. 



Comparison between the numbers of Ova and the volume of Copepoda, etc., 

 found on each Station. 



The meshes of the tow-nets were sufficiently small to retain a portion 

 of the plankton— viz., the Copepoda and Zoe'se. All the collections were 

 preserved and roughly measured in cubic centimetres. The Copepoda were 

 transferred to spirit, and when they had settled at the bottom of the vessel, 

 the volume was read off. With this method a certain quantity of spirit is 

 necessarily included in the volumes obtained; it is simply a rough and ready 

 means of comparison between stations and months. In order to give an 

 indication of the absolute quantity, the number of Copepods in a certain 

 volume — for example, '5 or lcc. — was from time to time counted. The 

 number of individuals in lcc. varied from month to month in accordance 

 with the kind of Copepods present. In certain collections large Copepods — 

 e.g., Calanus finmarcliicus — alone were present; in others the vast majority 

 were young forms, and in still other collections the large and small 

 Copepoda were mixed in various proportions. In order to satisfactorily 

 overcome this great diversity in the quality of the takes, Hensen's plankton 

 method, as the most accurate one, would require to be adopted ; but the 



Thirteenth Annual Report Fishery Board for Scotland, Part III., p. 149. 



