Why do fishes materially increase in size, previous to the approach of the spawning season?

Because they may be the better enabled to undergo the fatigues and fastings by which spawning is accompanied. The muscles then acquire size and strength, especially those connected with the tail, the principal organ of progressive motion, so that the body behind appears plump and round. A great deal of fat is deposited between the muscles, but especially on the belly, the flesh of which is, at this time, of considerable thickness.

Why does this fatness decrease, as the spawn advances to maturity?

Because the fat is withdrawn for its nourishment; the belly becomes little else than skin, and while the deluded epicure, upon seeing the large roe, imagines that his fish is in the best condition, it has actually reached the very maximum of worthlessness. When the business of spawning is over, the leanness of the fish then becomes apparent, and the extraordinary muscular exertion which it has undergone, is marked by the leanness of its head and the lankness of its tail.

Why do fishes deposit the spawn towards the margin of a river, etc.?

Because in the shallow water the numerous small animals reside, which constitute the most suitable food for the tender fry.

Again, the cod and haddock, the mackarel and herring, annually leave the deeper and less accessible parts of the ocean, the region of the zoophytic tribe, part VIII. E and deposit their spawn within that zone of marine vegetation which fringes our coasts, extending from near the high-water mark of neap- tides, to a short distance beyond the low-water mark of spring-tides. Amidst the shelter in this region, afforded by the groves of arborescent fuci, the young fish were wont, in comfort, to spend their infancy; but since these plants have been so frequently cut down to procure materials for the manufacture of kelp, and the requisite protection withdrawn, the fisheries have suffered in consequence.

Why are fishes caught by baits?

Because they are deceived by analogy, considering the identity as perfect, when there are only a few points of resemblance. - Fleming.

We may observe, that the well-known voraciousness of fishes, the eagerness with which they seize a metal button, or any glittering object - the whole art of artificial bait and fly-fishing, all seem to point out the organ of sight, as the principal instrument by which they discover their food.

Why do anglers maintain that fly-fishing is not a species of cruelty?

Because the hook is usually fixed in the cartilaginous part of the mouth, where there are no nerves; and a proof that the sufferings of a hooked fish cannot be great, is found in the circumstance, that though a trout has been hooked and played for some minutes, he will often, after his escape with the artificial fly in his mouth, take the natural fly, and feed as if nothing had happened; having, apparently, learnt from the experiment, that the artificial fly is not the proper food. Pikes have been caught with four or five hooks in their mouths - and tackle which they had broken only a few minutes before. - Sir H. Davy, in " Salmonia, or Days on Fly-fishing."