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Part III. — Eighth Annual Rcpwt 
IX. — THE PROPORTIONAL NUMBERS AND SIZES OF THE 
SEXES AMONG SEA FISHES. By Dr T. Wemyss Fulton, 
Secretary for Scientific Investigations. 
In carrying on the inquiries as to the spawning of the food-fishes, it 
was necessary to measure each individual fish obtained, to determine the 
sex and the condition of the reproductive organ. During the past two 
years there has, therefore, accumulated a mass of data as to the numerical 
proportions and the relative sizes of the males and females of the various 
species. It is from these data that I have written this paper. The 
information obtained has a special scientific value ; and it will also help 
us to understand many points in relation to the generation of fishes which 
are at present obscure. • 
With the exception of statistics relating to man and certain of the 
domestic animals, there is very little accurate information as to the 
proportion of the sexes among different species, especially those living in 
a state of nature. Our knowledge of the proportional numbers of males 
and females among fishes has hitherto been confined to fresh water forms, 
and even that is imperfect and scanty. This paper embodies the most 
extensive and detailed investigation which has been made on the subject ; 
and one of the most surprising results is the differences which obtain 
between closely allied species. 
The total number of fish of all kinds examined was 12,666. Of this 
number 3858 were males, and 8808 females, showing a general ratio of 
228 females to 100 males. The results regarding 21 species are detailed 
in the accompanying table. The fish include all sizes — from the smallest 
sexually differentiated to large adults. 
I. Proportional Numbers. 
1. Flat-fish. 
The number examined was 8209 ; 2075 were males, and 6134 females, 
or a ratio of 295 females to 100 males. In all cases but two the females 
exceed the males in number, but in very different proportions. One 
exception is the flounder (Pleuronectes flesus) in which the males 
preponderate ; the ratio of females to males being 84 to 100.* 
The brill (Rhombus laevis) is perhaps also an exception ; but the small 
number examined makes it uncertain. The relative preponderance of 
females over males among the other flat-fish varies very much. There is 
generally one male to about two or three females. The ratio is low in 
plaice (Pleuronectes platessa), 138 females to 100 males ; and remarkably 
high among long rough dabs (Hippoglossoides limandoides), 842 females 
to 100 males, or nearly seventeen females to every two males. The ratio 
is large also among lemon soles (Pleuronectes microcephalus), 297 females 
to 100 males, and common dabs (Pleuronectes limanda), 295 females to 
100 males. Among turbot there are about two females to each male. 
*The ratios which are given in the table, except when the numbers are small, may 
be relied upon as indicating with great accuracy the proportions, both of number 
and size, existing between the two sexes. The ratios were calculated on four or 
five occasions during two years, as the records accumulated, and now, on making 
the final calculations for the whole period, I have been impressed with the general 
equality of the averages derived from even comparatively small numbers. Where 
the numbers were large (plaice, haddock, &c.) the averages at the successive computa- 
tions rarely required the alteration of the first decimal. 
