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BULLETIN OF THE UNITED STATES FISH COMMISSION 1882. PAGE 103
CONNECTION OF ABUNDANCE OF MOSS AND OF BLACK FLIES
WITH ABUNDANCE OF TROUT.
It requires but very little imagination to connect the presence of moss
growth with the pleasures and convenience of man, so close are the
links of facts which join one circumstance with another.
In the unsettled wooded regions we find the torment of black flies and
mosquitoes, which oppress the inhabitants and render it difficult in the
newly-cleared land of Maine to summer young stock.
On the confines of the Arctic, regions they are mentioned by voyagers
as plagues of existence; and they are a serious drawback to the comfort
of the tourist who seeks in the Gulfof Bothnia to see the midnight sun.
Laestadius says that he will not affirm that they have ever devoured a
living man, but that many young cattle, such as lambs and calves, have
been worried out of their lives by them. All the people of Lapland declare
that young birds are killed by them, which is not improbable, says our author.
Wherever in Maine we find trout the most abundant, there we find the black
fly, the gnat, and the mosquito in overpowering abundance; and as the country
becomes settled these pests of man diminish and disappear; and, as angler-
sportsmen note with grief, there is a diminution of the fish, which they
ascribe usually to poaching, and to the destruction brought about by
the rod, the spear, or the seine; and in cases of late years have en-
deavored to check this disappearance through the hatching of ova and
the restocking of the waters.
These gentlemen, however commendable their intentions, have
overlooked the fact that there is a relation between the fish and
its food; and with the destruction of the moss of the forests
the breeding ground of the food insects is taken away, and
the food supply thereby diminished.
In the clearing of the land and the thinning of the forests are causes at work,
through the diminution of the insects which furnish the food to the trout, by the
destruction of the mosses, whereby the moisture essential for the development
of the insect ova is retained, which acts more disastrously on the fish than the
rod or the spear.
In proof of this we offer our own experience that insects. abound in greater
abundance in mossy woods than in second growth; that trout brooks which
flow through mossy woods are usually more prolific of trout than neighboring
brooks whose flow is throughcleared land or second growth; that artificially-
stocked ponds and streams in settled regions are never equal to the support
of as much trout-life as like streams in the backwoods of Maine; that fishing
cannot exterminate trout in the region of the black fly.
Let us illustrate by an opposite fact recorded by Williams in his History of Vermont.
In a pond formed by damming a small stream, to obtain water-power
for a saw-mill, 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 (trout) were
taken by the hands at pleasure, and swine caught them without diffi-
culty.
A single sweep of a small scoop net would bring up half a bushel;
carts were filled with them as fast as if picked up on dry land. The
increase in size of the trout was as remarkable as the multiplication of
their numbers.
We thus have indicated: Diminution of mossy woods; diminution of
insect-life, upon which the young prey almost entirely and adult fish
largely feed; diminution of fish. Could a more complete circumstantial
chain of evidence be required?
Thus the mosses have an importance in supporting that prolificacy of
life in the streams which exist in the far North; and the same pests
which torment the Indian serve him in one remove as food; the same
pests which trouble the frontiersman stock the, streams with abundant
life to serve him as food, and to attract the angler who employs him as
a guide.
As the mosses lose their supremacy the black fly disappears,
the mosquito diminishes in number, and our streams dwindle in size,
and even lose their flow in seasons of drought; and their capacity for
supporting trout-life is sadly diminished.
In overcoming the wilderness man is necessitated, through the infinite
correlations of nature, to destroy the natural sources of food, and
through art to sustain himself, less precariously, it is true, but with greater
toil, from the land.
He promotes vicissitudes of climate, and changed conditions which work to
him injury, in order to realize the immediate gains which he desires; but
is prone to overlook the causes of his acts, as nature acts through lit-
tles, which require thought to connect with their effects; and not the least
of her littles are the humble mosses which exist so abundantly where
coolness and moisture are to be found.
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