192 
Part III. — Eighth Annual Report 
The application of the term Immature. 
In the first place one must be clear as to what is meant by the term 
* immature. 5 It is generally restricted to small fish and fry, and to edible 
fish which are too small to be saleable. This idea is erroneous. There 
are two aspects in which the question has been considered; the 
biological aspect, in relation to the reproduction of the fish, and the 
economic aspect in relation to whether the fish are saleable or unsaleable 
as food. These aspects have been often confounded and confused. But 
it is very desirable to keep them clearly defined ; for many adult indi- 
viduals of several of the edible fishes, such as dabs, are practically 
unsaleable, while many immature specimens of other kinds are eminently 
saleable, e.g. t turbot, brill, plaice, cod, ifcc. It is better to restrict the 
application of the term immature" to what it means literally, viz., a fish 
which has never developed ripe milt or roe — which has never exercised 
the function of reproduction. The term ' undersized ' might be applied 
to immature fish below a certain size. For instance, cod between one 
inch and twenty inches are immature ; but no one, probably, will advo2ate 
that the sale of all cod under twenty inches should be prohibited, although 
some, like the government of George the First, might advocate the pro- 
hibition of their sale when under, say, twelve inches. In that case, cod 
under twelve inches would be 4 undersized.' 
The distinction between different species of Fish. 
Another point is the necessity, when discussing the desirability of 
interference with the capture or sale of immature fish, of carefully dis- 
tinguishing between one kind of fish and another. Neglect of this truth 
has led to many strange conclusions. There is no doubt that certain food- 
fishes can suffer enormous destruction of their young by man, without the 
number of adults taken being sensibly diminished. Millions of immature 
herrings are captured annually by bag-nets and cotton surface drift-nets, 
without the catch of adults in succeeding years being much, if at all, 
reduced. Millions of immature cod are also annually captured around our 
coasts, and their capture is not apparently followed by detrimental 
results. It is different with certain flat-fish, such as turbot, brill, sole, and 
plaice. It is generally acknowledged that the admitted falling off in the 
number of these fish is due largely to the destruction of their young. 
Mere fecundity per se has nothing to do with it — although it is 
an argument which has been frequently used by Royal Commissioners 
and others. The female herring produces an average number of about 
20,000 to 30,000 eggs only, and the cod about 3,000,000. The turbot 
produces about 10,000,000 ; the sole about 200,000 and the plaice 
about 150,000. Yet the herring can suffer, as we have seen, 
enormous destruction of its young. The cardinal principle which should 
guide action in this matter is the relative abundance of the adults. The 
rarer a species the more liable it is to extinction. If any food-fish is proved 
to be diminishing in numbers for a period of years, and if the average size 
of the fish captured is also diminishing, then that fish requires protection ; 
it is an indication that the adults are being fished out and the non-producing 
young drawn upon. If it is shown that immature individuals are destroyed 
in large numbers, their destruction should, if possible, and as far as possible, 
be prevented. Several fisheries have gone through these stages of diminu- 
tion in the numbers of adults, and general diminution in size ; notably the 
lobster fisheries, especially in Canada, Newfoundland, Norway, and to 
some extent in Scotland. 
