154 DESTRUCTION OP IMMATURE FISH. 



titles of such fish were destroyed it might be conceivable that great 

 damage is being done to sea fisheries, for young fish of all kinds 

 have a great many enemies to contend with, and it is quite possible 

 that man, by employing more numerous and more powerful engines 

 for their destruction, might so diminish the number of breeding fish 

 as to cause the young brood to be unable to cope with the numerous 

 destructive agencies which beset them on their road to maturity. 

 However this may be, and the case admits of much argument on 

 both sides, the first question is whether such immature fish are in 

 fact destroyed in vast numbers. It is just for this reason that a 

 precise meaning should be attached to the expression " immature 

 fish." An arbitrary standard of size is no criterion of the imma- 

 turity of different species of fish ; a turbot of ten inches length may 

 be immature when a plaice or sole of the same length is filled with 

 ripe ova, and there are some species of fish commonly used for food 

 which seldom exceed ten inches in length, and in such cases many 

 adult, that is to say, sexually mature specimens, fall below the arbi- 

 trary standard and are classed as " immature " or sometimes '' under- 

 sized " fish. In making inquiries on this subject it is necessary 

 that, by comparison of very many specimens, a minimum of size 

 should be determined for the adults of each species of fish, so that 

 it can be affirmed with tolerable certainty in each case that every fish 

 below a certain size is really immature. Obvious as this may seem, 

 it is necessary to insist upon it, for hitherto size and not sexual 

 maturity has been the test of observei's ; and even Prof. Mcintosh's 

 report, admirable in all other respects, leaves one in complete doubt 

 as to whether the fish classed by him as immature were really sexu- 

 ally iuimature or merely undersized fish. It must be remembered, 

 however, that the Professor had a very limited time in which to 

 carry out his investigations, and that it would require long observa- 

 tion and experience to obtain the necessary data for determining at 

 what average size different species of fish may be expected to come 

 to maturity. 



The importance of precision in definition will readily be under- 

 stood after examination of Prof. McIntosh^s report. In ninety-three 

 hauls of the trawl 81,854 fish were taken, of which 11,613 — a large 

 proportion numerically — were classed as immature fish. But of 

 these no less than 2956 were long rough dabs {Eippoglossoides 

 limandoides) , 6314 were common dabs {Fleuronectes limanda), and 

 1072 were combined common and long rough dabs. These two 

 species of flat-fish are often small, never exceeding thirteen inches 

 in length, and generally they are much smaller. It is probable that 

 a large proportion of those taken by Prof. Mcintosh were really 

 mature, but small or undersized fish. But in any case the number 



