860 
SCANDINAVIAN FISHES. 
are regular lock-weirs, with sluices above and below, the 
former in two rows. The uppermost row (a) is merely 
a grating, which continually lets the water through, 
as well as the gates ( c ) at the lower end. The latter are 
let down only when the watertight gates in the second 
row at the upper end (b) are shut, the water now running 
out, but the fish being left behind. In the tinbyggnader 
large Salmon-traps ( tinor ) are set, which are lifted with 
a hoist when they are to be examined". The vralclius 
are, strictly speaking, large Jcar (see above, Salmon- 
pens), constructed beside a race. So manifold are these 
Fig. 217. A Salmon stair. After Day. 
contrivances that Sweden, to her cost, can boast of 
her wealth of devices for the taking of Salmon. 
In order to counterbalance the destruction wrought 
by these engines, and to extend the run of the Sal- 
mon by enabling them to surmount falls otherwise 
impassable, Salmon stairs are built. In these the force 
of the water is diminished by transverse walls pro- 
jecting alternately from the sides, and extending across 
more than half the width of the staircase but not 
reaching to the opposite side. The stairs may be erected 
beside a fall in many different modes, according to 
the nature of the locality; but care should be taken 
to avoid placing the lower opening of the stair in the 
same direction as the fall, and to turn it obliquely 
across the stream or, still better, straight against the 
current. 
The River Trout too — even those which pass 
their whole life in brooks and small streams — rove 
to the spawning-place. “In a valley not far from my 
native place,” says Brehm*, “there rise copious springs, 
which together form a brook that has power enough 
to drive a mill-wheel. This brook falls into the Roda 
and clears the water of the latter, which is sometimes 
rather thick. As long as can be remembered, Trout 
have lived here, but only for an extent of at most 
eight kilometres. Above and below this part of the 
brook they do not occur, as a general rule; and only 
during the spawning-season does it happen that they 
abandon their true home and rove to rocky parts of 
the Roda in quest of breeding-places, though they have 
equally good spots in their usual haunts.” The spawn- 
ing-dress of the River Trout sometimes includes a black 
coating on the forepart of the body, such as that we 
have above remarked in the Charrs. 
The longer marine Salmon remain in the rivers, 
the more tumid are their generative organs, and the 
darker their dress. Our figures show the appearance 
both of the true Salmon (Plate XXXVII, figs. 3 and 4) 
and the Sea Trout (Plate XXXIX, figs. 1 and 2) at the 
beginning of these alterations; but at the end of then 1 
wanderings, when the spawning-season commences, they 
have assumed quite a different colour, of much darker 
tone, as depicted by v. Wright in his figure (Plate 
XXXIX, fig. 3) of a female Sea Trout ( Oring ) in fresh- 
water dress. The belly of the males becomes entirely 
red. In old males of the true Salmon the margin of 
the caudal fin is also straightened, without a trace of 
indentation, or even, like the margin of the anal fin, 
convex. By a retrogression to the characters of youth, 
they are besides approximated to the Sea Trout in the 
characters relating to the least depth of the tail and 
the height of the anal fin, otherwise the most constant 
distinctions between the two varieties. 
In September the spawning-season begins. The 
old fish commence first. The young sometimes wait 
even till the following March. And among the latter 
a See Gisler, Vet.-Akad. Handl. 1752, tab. I. 
b Thierleben, 1. c., p. 227. 
