Synopsis of Biological Data on the Chum Salmon, Oncorhynchus keta

Figure 1.--The chum salmon, Oncorhynchus keta (Walb urn). (Photo r h counesy tlonal Fi h rman)
Generic
Oncorhynchus Suckley, 1861 (1862: 313)
Genotype:
Salmo scouleri (Richardson)
The generic name is derived from Greek
Onkos (hook) and rhynchos (snout).
The generic concept used here is that <strong>of</strong>
Jordan and Evermann (1896):
"Body elongate, subfusiform, or compressed.
Mouth wide; the maxillary long,
lanceolate, usually extending beyond the
eye; jaws with moderate teeth, which become
in the adult male enormously enlarged
in front. Vomer long and narrow,
flat, with a series <strong>of</strong> teeth both on the
head and the shaft, the latter series comparatively
short and weak; palatines with
a series <strong>of</strong> teeth; tongue with a marginal
series on each side; teeth on vomer and
tongue <strong>of</strong>ten lost with age; no teeth on the
hyoid bone. Branchiostegals more or less
increased in number. Scales moderate or
sma 11. Dorsal fin moderate; anal fin
comparatively elongate, <strong>of</strong> 14 to 20 rays.
Pyloric appendages in increased number.
Gill rakers rather numerous. Ova large.
Sexual peculiarities very strongly developed;
the snout in the adult males in summer
and fall greatly distorted; the premaxillaries
prolonged, hooking over the
lower jaw, which in turn is greatly elongate
and somewhat hooked at tip; the teeth
on these bones also greatly enlarged. The
body becomes deep and compressed; a
fleshy hump is developed before the dor­
&al fin, and the scales <strong>of</strong> the back become
embedded in the flesh; the flesh, which is
red and rich in spring, becomes dry and
poor. Salmon, mostly <strong>of</strong> large size, ascending
the rivers tributary to the North
2
Pac 1 fl c in
pawnmg m th
Sp ciflC
orth Amenca and ASi ,
fall. "
The type sp Clm n 1 Salmo keta <strong>of</strong> 'albaum
(1792: 72) from the Kamchatka Rw r. The
orlgmal escnption, a Cited by 0 ada (1960)
lS:
S lmo keta VEL KA YKO W ALBA
D. 14. P. 15. v. 11. A. 1
" Caput breve, obtu urn. Corpu lmmac ­
ulatum. Ca a Lunata. Caro alba.
Squamae argenteae. Dorsum viri escens .
Capitur copiose in flumlninbu Kamtschatkae.
"Salmo keta VEL KA YKO, Krascheinnikow,
l.c. pag. 181. Salmonem Tarkam
magnitudine aliquatenus superat: Caput
oblongum, planum. Rostrum resimum.
Dentes, post quam aliquam in in flumine
moratus est, caronis slrniles fuint. Lingua
acuta. C a ud a parum bifurca. Dorsum
atro-viride, latera & abdomen similiter
colorata ac alEs selmonibus sed absque
maculis. "
Species diagnosis according to Clemens and
Wilby (1946):
"Body elongate, somewhat compressed;
caudal peduncle slender. Head conical;
mouth terminal; teeth conical, strongly
developed, becoming fang-like in mature
males; branchiostegals, 10 to 16; rakers
on first gill arch, 19 to 26, short, stout,
smooth, widely spaced. Fins: dorsal (1),
10 to 13; adipose, small, slender, fleshy;
anal, 13 to 17; pelvic, abdominal, each
with fleshy appendage at base; caudal,
e rna r gina t e. Lateral line: slightly decurved,
then straight. Scales: cycloid; in
first row above lateral line, 130 to 153;