of the. Fishery Board for Scotland. 
243 
IL — THE COMPAKATIVE FECUNDITY OF SEA-FISHES. By 
Dr T. Wemyss Fulton, F.E.S.E., Secretary for Scientific 
Investigations. 
Introductory. 
In last year's Report * I gave, without discussion, the results of an 
investigation into the proportional numbers and sizes of the sexes among 
sea-fishes, and pointed out the surprising variation among even closely- 
allied forms. The present paper may be considered as a supplementary 
contribution along the same line of inquiry into the propagation of marine 
food-fishes. Besides its biological bearing, the question of the comparative 
fecundity of the food-fishes is closely related to arguments often used in 
regard to proposals for restriction in certain fisheries or in fisheries 
generally. 
Leeuwenhoek and some other early naturalists investigated the number 
of ova produced by a few species of fishes, especially the cod, but no 
extensive research seems to have been made until towards the latter part 
of last century, when Bloch on the Continent and Harmer in this country 
devoted considerable attention to the subject. Harmer's paper, which 
was published in the Philosophical Transactions in 1768, embodies, so far 
as I can ascertain, the most extensive and thorough inquiry into the 
fecundity of fishes hitherto made. He determined the fecundity of 44 
specimens belonging to eleven species, five of which were fresh water 
forms and six marine (cod, herring, mackerel, smelt, flounder, and 
common sole). Further, the portions of the ovaries used for calculation 
were relatively large — varying from 19 to 57 grains among the sea-fish 
examined — and there is evidence that great care and thoroughness were 
exercised. Bloch's observations on the subject are scattered through his 
great work on Ichtyologie^\ and also indicate much care ; but the propor- 
tion of the roe used is not given. Later, Blanch ere, Thompson, Buck- 
land, Earll, and others have determined the number of eggs produced in 
a number of individuals of a few species. Earll, in America, very care- 
fully determined the fecundity of the cod, pollack, and haddock. 
Buckland made observations on the fecundity of the brill, cod, conger, 
herring, lamprey (136,800), lumpsucker, mackerel, plaice, smelt, sole, and 
turbot; but, in the few cases in which it is given, the part of the ovaries 
used was very small, and there is evidence in at least some cases that 
Buckland's observations on this subject were not always exact. Cunning- 
ham has recently made an investigation into the fecundity of the conger. | 
In the course of the present investigation, the results of which are given 
in the following pages, the fecundity of 112 fishes belonging to 39 marine 
species, comprising most of the food fishes, was determined. In addition, 
above 100 other specimens were examined, and the proportional weight of 
the ovaries to the rest of the fish ascertained ; but in most of these cases 
so many of the eggs were minute or microscopic that enumeration, 
although sometimes attempted, was not completed. Considerably over 
400,000 eggs w^ere individually enumerated. The mode adopted was as 
follows : — The length and gross weight of the fish and the weight of the 
ovaries were ascertained (the weight of the ovarian membrane being in 
most cases separately determined, but in a few instances calculated from 
* Eighth Annual Report of the Fishery Board for Scotland, Part HI. p. 348, 1890. 
Ichtyologie ou histoire naturelle ginirale et particulUre des poissons, 1785. 
X Journal of the Marine Biological Association of the United Kingdmn, vol. ii. 
No. 1, p. 16, 1891 
