Breeds of British Salmon.
Having on a former occasion advanced some reasons for discrediting the
theory that fish hatched from the ova of autumn-running salmon _must_
immigrate or run inland in autumn; and that, similarly, the progeny of
spring salmon _must_ regularly return to the rivers in spring, in
obedience to inherited proclivities, we may now be permitted to give
additional reasons, not less weighty perhaps, for our disbelief. The
gist of our previous argument in controverting the theory in question
was that since the strength of the migration of grilse—and
fish-culturists and competent observers have conclusively proved that
grilse are the adolescents of spring and of autumn salmon alike—is
always evident in summer, this fact alone completely knocks on the head
every iota of what has been advanced to prove the existence of two
different breeds of British salmon, each inheriting an instinct for
ascending the rivers at a particular time, irrespective of age, sex, or
condition. This theory of transmitted instinct to obey a seasonal duty
may at first sight appear plausible enough to some, but those who give
credence to it cannot, we fear, do so from ascertained facts. Why, for
instance, as already remarked, the ascent of the grilse in summer should
alone be sufficient to demolish such a theory, since, when making their
first ascent, and while yet adolescents, they are not obeying, as is
perfectly clear, an inherited instinct for ascending during what may be
called the “parental ascending season.”
From personal observation and a mass of reliable data, we have the
strongest reasons for believing that the spring salmon of the Scottish
rivers—not the winter salmon, which, as a rule, are older and larger—are
the most vigorous and active fish of all; that the grilse are the young
of spring, summer, and autumn salmon alike, ascending at a time when the
temperature of the fresh water suits them, for though scarcely less
active, they are less vigorous and certainly more sensitive than the
spring salmon; and that the autumn salmon, generally, are fish that have
already been inland as spawners, and from not going back to the sea till
late in spring or early in summer, are therefore later in reascending
the rivers than they were in ascending them on the previous occasion,
not returning from the feeding grounds till autumn, when they are heavy
with spawn, and consequently unable to remain long in the fresh water
without injury to themselves.
Mr. J. A. Harvie-Brown, F.Z.S., foremost and most versatile of
authorities upon the salmon, entirely agrees with what we have stated.
“The spring fish,” he says, “are vigorous younger fish and reach highest
up the rivers, and can stay longer in the fresh water without hurt to
themselves. The autumn fish are older, larger fish: and many begin to go
out of condition before they leave the brackish, as they are less able
to stay long in the fresh.”
In his book on “The Salmon,” the late Mr. Russell, of the _Scotsman_,
argues “that the facts are at the least equally compatible with, and
indeed entirely suitable to, the theory that the fish coming up all the
year are the adults of various ages, and that those rushing up in a body
in summer are the young of the same species. What are those clean salmon
that run up the rivers in late winter or early spring? Where have they
been in the preceding months? What do they want now? They cannot be
wanting to spawn, for there is no spawning for at least six months to
come. They cannot have spawned early in the preceding or rather present
spawning season, gone down, recovered, and returned, for numerous
experiments show that the period of return is about three months, and it
is only about three months since the earliest fish had begun to spawn in
the rivers which these are now ascending. They must have passed the
autumn or earlier winter in the sea. Then they must have passed the
winter without breeding.”
Briefly put, the views we hold concerning the whole matter (as regards
long-seasoned rivers) are: That the early running salmon are fish that
have not spawned in the immediately preceding season (the great
majority, which are small fish, females preponderating, have passed
their girlshood in the sea); that the late spring and early summer
salmon, for the most part, are fish that have not been gravid in the
preceding spawning season; that the salmon appearing later in the
summer, say from June, represent the first-descended of the previous
season’s spawners returning again to the rivers; that the grilse that
arrive inshore in summer seeking the fresh water are the breeding
portion of the stock of grilse for the year, as proved by their ova and
milt, and that the autumn salmon, the great majority of which are large
fish, are those that spawned latest in the previous season, or, as
kelts, were exceptionally late in getting back to the sea.
What we have stated and emphasised above is expressly intended to show
how untenable is the theory that spring and autumn salmon (or, as we
should call them, if we are to speak accurately, spring-run and
autumn-run salmon) are distinct and separate breeds.
We now come to give other strong reasons for discrediting the notion,
theory or hypothesis, that there are different breeds of salmon in the
Scottish rivers. Accordingly it is advisable to be specific, necessary
to select certain rivers and state the facts. Our choice is the Don and
the North Esk. Now as regards these rivers, what are the facts? First,
that early every year thousands of salmon are netted at their mouths and
in their tideways, and many thousands more above their tideways; second,
that owing to the severe river netting _plus_ the fixed obstructions
which no fish can pass as long as the water has a low temperature, not a
score, perhaps not half-a-dozen, pairs of so-called “spring fish”
survive, and eventually reach the upper strath or glen sections. These
are strictly facts, facts that cannot be disputed, facts that the
Fishery Board for Scotland may conveniently verify. Now we should like
to ask, is it at all likely that the many thousands of salmon that are
netted in these rivers in spring are _exclusively_ the progeny of three,
six, or even a dozen pairs of spring-run salmon? We answer that it is
not likely. We go farther and say it is impossible. But some one will
query: Are there not in ten spawning salmon more thousands of potential
salmon than the thousands that are caught annually in spring by the rods
and nets conjointly? Quite true—say fifty thousand in a dozen fish of 8
or 9 lb. each (a good average weight in spring). But then the crucial
question must be asked? What percentage, reckoning all the risks from
frost, drought, spates, and so forth, hatches out? And what proportion,
considering the scarcity of their food at recurrent periods, and all the
perils and all the enemies to which they are exposed during the years of
their growth in sea and river, survives to reach the adult stage? Let us
suppose that 5 per cent. of the whole hatched ova—and this is a liberal
estimate—advances through all the stages—parr, smolt, and grilse—till
the adult fish is reached. On this calculation the mature progeny,
resulting from a dozen pairs of spring salmon, would number two thousand
five hundred.
No, we cannot accept the theory that spring salmon are a different breed
from autumn salmon; nor can we agree with the dictum that they are to be
preferred for hatchery purposes. No fish-culturist who has devoted
himself with eminent success to the breeding of salmon, would ever dream
of preferring the spawn of fish that have been ten or eleven months in
the fresh water, to the spawn of fish that have been in the rivers only
two. Numerous experiments have proved that of the ova of spring salmon
about 75, and of the ova of autumn salmon about 95 per cent. is the
average that hatches out and reaches the parr stage; and that as a
particularly high percentage, 98 is more common in the latter than 78 in
the former case. How, then, can it be contended that spring salmon are
to be preferred for their ova? In conclusion, the whole argument may be
clinched in a single sentence thus: If from twelve pairs of spring
salmon, the maximum number of “escapes” in Don and North Esk annually,
there survive to reach maturity a progeny of two thousand five hundred,
are we not warranted in assuming that the grand result from the ova of
the many thousands of fine large fish that ascend these rivers in autumn
and early winter would be millions on millions of salmon, or more than
the pools could comfortably hold? Enough! Enough! Informed opinion is
against the theory of different breeds of British salmon with different
inherited migratory instincts.