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Salmon And Sea-trout








In many ways nature is apparently very wasteful, and in nothing is this
more marked than in the case of the salmon. Probably not more than one
egg in a thousand produces a fish which reaches the smolt stage, and a
still smaller proportion grows to the spawning stage. This great
mortality which occurs among the eggs and young fish when left to nature
may be very considerably reduced by artificial means, so that a very
fair proportion of the eggs deposited by the female fish will not only
be hatched out successfully, but the little fish will reach the smolt
stage safely and have a good chance of reaching the sea. How successful
artificial intervention may be has been proved over and over again in
the United States and in Canada. In the case of more than one river in
Canada, the artificial propagation and protection of salmon has resulted
in what is apparently the actual manufacture of a salmon river,
yielding an annual haul of fish far beyond anything known in Europe,
from a river which before yielded no salmon, or hardly any.

These operations, carried out by the State, were of course far beyond
anything which could be undertaken by the amateur, but I am sure that if
several riparian owners on a salmon river carried on artificial hatching
and rearing operations for several seasons, a marked increase in the
number of fish in the river would ensue. The objection of most people to
this course is that it is unfortunately only too apparent that they are
benefiting chiefly, not the rod fisherman, but the netsman at the mouth
of the river.

The different artificial means used to help nature in producing a good
head of salmon in a river vary chiefly in the amount of the help given
by each. It will suffice to say that the best is that which provides for
the protection and feeding of the young fish till it is ready to take
its first journey to the sea. The reason of this is obvious, as every
day passed in safety is a day gained, both in strength and in power of
self-preservation.

Though it is possible to purchase a certain number of salmon ova, this
is not at all a satisfactory way of obtaining them. To begin with, it is
impossible to get them in sufficient numbers to carry out operations on
a large enough scale. Salmon ova are also expensive; and it is no use
working with less than half a million in several stations if the river
is of any size. It is advisable that the ova should be obtained from the
fish. This may be done either by collecting the ova deposited by the
fish in the spawning beds or from the gravid females. The latter course
necessitates the ripe female and male fish being caught and artificially
spawned. As in nature, at best but a comparatively small percentage of
the ova are impregnated, and by artificial spawning over ninety per
cent. of them may be successfully hatched out, there can be but little
doubt as to which is the better way. It is difficult to make sure of
catching the fish just at the time they are ripe, so it is advisable to
impound them in a fenced-off portion of the river, where they may be got
at easily.

In the ripe female the ova flow out very readily, and but little
pressure is necessary. Hard pressure on the abdomen should never be
applied, as it is sure to injure the fish. A ripe female having been
obtained, from which the ova flow readily, the female is held over a
perfectly clean tin or earthenware dish--wet, but containing no
water--and the ova are caused to flow into it by gently but firmly
pressing the hand on the abdomen, and stroking it down towards the vent.
Milt from a ripe male fish is then allowed to run over the ova in the
dish, and is made to run well between them by tilting the dish about
from side to side. The ova will now adhere together, and some water
should be added. This water should be poured off and fresh added till
the superfluous milt is washed away, when the ova should be left in the
water till they separate, which will be in about twenty minutes or half
an hour.

The fertilized ova thus obtained may either be laid down in artificially
protected hatching beds, or may be transferred to a hatchery. The latter
proceeding, of course, requires a hatching house specially built and
arranged, and as this is outside the scope of the present work, I would
refer my readers to larger works upon the subject, such as _An Angler's
Paradise_, by J. J. Armistead. Of course, by using a hatchery a large
number of the eggs will be saved, ninety per cent. of them should hatch
out. This is, therefore, obviously the best way to proceed. A very much
larger number of eggs will, however, be hatched out in properly-chosen
artificial beds than would be the case if they were left to nature.

The necessary qualities of a good artificial bed are, a good supply of
clean water which is not liable if there is a spate to deposit sediment
on the eggs, protection from light, and protection from the many
creatures which prey upon the ova. The hatching beds may be so arranged
that the young fish may escape as soon as they like after hatching out,
but it is best to watch and protect them for at any rate the first few
weeks after they have begun to feed, and while continuing the feeding,
to allow those of the fish that wish to escape.

The rearing of young salmon and sea-trout is practically the same as
that of the common trout, except that they require more water. If kept
in rearing ponds they grow more quickly than they do when left to find
food for themselves. While young, the salmon is marked with transverse
bars of a darker colour than the rest of the body. During the time it
bears these marks it is known as a parr.[3] In about fifteen months it
loses these marks and becomes quite silvery, being now known as a smolt.
Shortly after assuming the smolt dress, the young salmon takes its
departure to the sea. In some cases the young salmon do not appear to go
down to the sea till over two years after being hatched out, but they
should always be set at liberty in March, April, or May in the year
following that in which they were hatched out, according to how far they
have developed the smolt or silver appearance.

[3] All the trouts go through this stage, which is distinguished by
"finger marks" upon the sides.

If spring water is obtainable, particularly if the water, as is usually
the case, is of an even temperature throughout the year, the troubles of
the fish culturist are considerably lessened. Without a building for the
hatching troughs it is almost impossible in many places to guard against
frost unless such a spring is available. Sediment may be avoided by
putting frames covered with flannel at the inlets to the hatching beds,
these will, if kept clean, prevent any sediment from coming into the
ponds, and will allow plenty of water to flow in. If hatching trays are
not used, the bottom of the artificial bed should be covered with clean
gravel.

The time which elapses from the impregnation of the eggs to their
hatching out varies according to the temperature of the water, a fairly
average time is about ninety days. The ova should be watched during this
time, and the dead ones removed. For a short time after they are
impregnated they are fairly hardy, but from then till shortly before
they hatch out the very slightest concussion will kill or seriously
injure them.

The management of sea-trout ova is similar to that of salmon, and the
ova are obtained in the same way. As in the case of the salmon it is
best to rear the little fish artificially, till they are ready to go
down to the sea; they will thus escape dangers likely to cause the loss
of about eighty per cent. of their number.

The same methods and the same precautions as advised in the chapters on
rearing trout should be adopted in the case of salmon and sea-trout as
far as is possible, and if this is done a very large percentage of the
ova should be successfully reared to the smolt stage.





Next: Coarse Fish

Previous: The Rearing Of The Rainbow Trout American Brook Trout And Char



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