Fish have so many enemies that were it not for the millions of embryo
or spawn deposited by the female, the breed of Salmon and Trout (to say
nothing of other species) would long since have become extinct. Eels,
fish, birds, water rats, toads, frogs, and last but not least, the
water beetle,[8] prey upon the ova, spawn and young fry; floods also
sweep away and leave on banks, or rocks, a considerable quantity of
spawn, which of course comes to nothing. Escaping the above perils and
causalities, and arrived at maturity, they become the prey and food of
the otter and heron, king's fisher, gull, &c., who emulate man in their
destructive propensities. The larger fish also prey upon the smaller.
Luckily otters are not so numerous in any English river as they used to
be. Night lines, shackle, rake and flood nets, and other devices not at
all creditable to those who use them, and to which I shall not further
allude, make terrible havoc amongst fish, and mar and spoil the fair
and honest angler's sport, but in most rivers and brooks of Trouting
celebrity, such practices are greatly on the wane. Proprietors will not
sanction such wholesale destruction; and now almost universally adopts
measures for the detection and punishment of such depredators.
[8] The water beetle is chiefly instrumental in conveying the
spawn of various kinds of fish to waters, where such species
had previously been unknown.