110 



Part II I. Seventeenth Annual Report 



During March the number of eggs of all species, when reduced to a 

 quarter-mile tow, was 2913. If, then, we multiply this number by the 

 coefficient, we should get approximately the total number of eggs in the 

 loch at that time. In allowing for the loss of the contents of two of the 

 nets, the factor has to be increased by one-thirteenth. 



Thus the approximate number of eggs in Upper Loch Fyne at the 

 time of the March trip = 2913 x (708,872 + 54,528) = 2913 x 

 763,400 = 2,223,784,000 eggs of all species. 



The total number of eggs of each species, obtained by filtering the 

 standard volume of water, is multiplied by the factor, and the approxi- 

 mate number of eggs of the species present in the loch at the time is 

 obtained, This is done for each month, and the results are given in 

 Table XY. In this case the eggs of cod and haddock are grouped, as 

 likewise are whiting and saithe. 



Table XV. —Estimated Xumbers of the Eggs of Certain Species 

 Present in Upper Loch Fyne at the Periods of Examination. 



[The numbers denote millions.] 





Plaice. 



CJod and Haddock. 



Whiting and Saithe. 



.5 

 3 



o 

 o 

 Ph 



Dragonet. 



Turbot. 



Witch. 



Flounder. 



,0 

 eS 

 P 



pq 



1 



o 



cS 



Lemon Sole. 



Other Species. 



Grand Total. 



Average Number of 

 Eggs' to 1 Sq. Y,n<! 

 Water Surface. 











•8 





















1 



•009 



February, . 





6 



31 



40 



1-2 



















79 



•6 



March, 



41 



603 



231 



156 



22 



9 





246 



122 



6?6 







172 



2228 



18-9 



April, 



178 



2161 



1491 



333 



51 



7 





765 



317 



238 







192 



5734 



48-9 



May, . 



20 



961 



674 



91 



70 



14 



12 



285 



175 



29 







340 



2671 



22*7 



June, 



2 



266 



824 



183 



190 



121 



809 



73 



202 



38 



34 



135 



793 



3670 



31-3 



July, 





17 



23 



55 



43 



28 



64 



1 



113 



4 



144 



85 



316 



893 



7-6 



August, 





3 



7 



4 



21 



3 



26 





14 







5 



7 



91 



•7 



Total, . 



241 



4017 



3281 



862 



398 



182 



911 



1370 



943 



935 



178 



225 



1820 



15,367 



•• 



The quantitative estimation of plankton has been carried to a high 

 degree of accuracy by Hensen. An adaptation of the vertical net invented 

 by him he found to be applicable to the estimation of pelagic ova in the 

 [North Sea. 



In Upper Loch Fyne vertical hauls with the net described on 

 page 80 were made at four stations, but they w T ere unfortunately found 

 to be too few in number to give reliable results. 



In Loch Fyne, which is a comparatively small area, the eggs are not by 

 any means equally distributed through its waters. Four vertical hauls were 

 therefore too few upon which to base any approximately accurate calcula- 

 tion. When the work was begun the difficulty caused by the diversity in 

 richness of the water at different points was not foreseen, and was not even 

 expected. Owing, then, to the vertical hauls being so few in number, a 

 single haul on a comparatively rich station introduces, in estimating the 

 total number of eggs, a serious error which only a very large number of 

 hauls would eliminate. The distance between Stations IY. and Y. is a 



