DESTRUCTION OF FISH. 
115 
ingly tlie feebler species, and even the spawn and young of its 
own. The enormous destruction of the pike, the trout family, 
and other ravenous fish, as well as of the fishing birds, the seal, 
and the otter, by man, would naturally have occasioned a great 
increase in the weaker and more defenceless fish on which they 
feed, had he not been as hostile to them also as to their perse¬ 
cutors. We have little evidence that any fish employed as 
human food has naturally multiplied in modern times, while 
all the more valuable tribes have been immensely reduced in 
numbers.* This reduction must have affected the more vora¬ 
cious species not used as food by man, and accordingly the 
shark, and other fish of similar habits, though not objects of 
systematic pursuit, are now comparatively rare in many waters 
where they formerly abounded. The result is, that man has 
greatly reduced the numbers of all larger marine animals, 
and consequently indirectly favored the multiplication of the 
smaller aquatic organisms which entered into their nutriment. 
This change in the relations of the organic and inorganic 
matter of the sea must have exercised an influence on the lat¬ 
ter. What that influence has been, we cannot say, still less 
* Among the unexpected results of human action, the destruction or 
multiplication of fish, as well as of other animals, is a not unfrequent oc¬ 
currence. I shall have occasion to mention on a following page the exter¬ 
mination of the fish in a Swedish river by a flood occasioned by the sudden 
discharge of the waters of a pond. Williams, in his History of Vermont , 
i, p. 149, quoted in Thompson’s Natural History of Vermont , p. 142, 
records a case of the increase of trout from an opposite cause. In a pond 
formed by damming a small stream to obtain water power for a sawmill, 
and covering one thousand acres of primitive forest, the increased supply 
of food brought within reach of the fish multiplied them to that degree, 
that, at the head of the pond, where, in the spring, they crowded together 
in the brook which supplied it, they were taken by the hands at pleasure, 
and swine caught them without difficulty. A single sweep of a small 
scoopnet would bring up half a bushel, carts were filled with them as fast 
as if picked up on dry land, and in the fishing season they were commonly 
sold at a shilling (eightpence halfpenny, or about seventeen cents) a bushel. 
The increase in the size of the trout was as remarkable as the multipli¬ 
cation of their numbers. 
