OF THE GRIMSBY TRAWL FISHERY. 377 
these remains* having been expelled, nothing remains to distinguish 
a fish that has recovered from spawning from one which has never 
spawned?” Personally I do not think there are, for even though, as 
Cunningham observes, the ovary of a shotten fish may shrink to a very 
small size, it does not appear, in my own experience at all events, that 
it ever regains the appearance of immaturity or the close adhesion to 
the surrounding parts of the body. I must admit that the question 
is not absolutely judicially proved ; still I think the probabilities of 
the correctness of my own opinion are at least considerable, and, in 
putting forward the results of my inquiries, have little fear of their 
substantial accuracy being challenged by subsequent investigators, 
if only on the ground that the specimens on which my published 
results were based were examined either during the spawning season 
or within so short a period from it that traces of maturity, if they 
existed, could not fail to be detected. 
The variation already alluded to in the size at which fish of a 
species attain to sexual maturity, makes it imperative that any 
standard of maturity should be based, not on either of the extremes, 
but on whatever intermediate size appears to apply to the 
greater number of species. This point was most justly urged by 
Cunningham, in criticism of the method adopted in my own defini- 
tion of immature fish on the West Coast of Ireland; but, as I have 
already remarked, the paucity of material in that case seemed to render 
the minimum size the safest standard for provisional purposes. 
Having no lack of material in the North Sea work, I was able to 
adopt the better method, and the standards given below accordingly 
represent the sizes at which I believe most females spawn for the 
first time. 
The standard of secual maturity in North-Sea fish. 
Flat-fish : 
Turbot 18 inches 
Brill hoe Ps, 
Common sole ial 
Plaice iba 
Lemon sole | eh ae 
Common dab : : yo ae, 
Hahbut (provisional) . yO! Els, 
Round-fish. 
Cod : : . 20 inches 
Haddock i dale | es 
Whiting : : iy ee 
bP) 
* J.e. the remains of ripe eggs, 
