NOM TR NMFSCIRC-366

A UNITED STATES
DEPARTMENT OF
COMMERCE
PUBLICATION

T

NOAA Technical Report NMFS CIRC-366

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric *'*'"'n|nTriilTm" ±

National Marine Fisheries Service 1 MarinO DiOK>gKai Uboratory

LtBRAPy
MAY I t972

J

Key to Field Identification of
Anadromous Juvenile Salmonids in
the Pacific Northwest

ROBERT J. McCONNELL and GEORGE R. SNYDER

SEAHLE, WA.

January 1972

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315. Synopsis of biological data on the chum salmon,
Oncorhynchus keta (Walbaum) 1792. By Rich-
ard G. Bakkala. March 1970, iii + 89 pp., 15
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319. Bureau of Commercial Fisheries Great Lakes
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330. EASTROPAC Atlas: Vols. 4, 2. Catalog No.

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333. Recommended practices for vessel sanitation and
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336. The northern fur seal. By Ralph C. Baker, Ford
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342. Report of the Bureau of Commercial Fisheries
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NOAA Technical Report NMFS CIRC-366

Key to Field Identification of
Anadromous Juvenile Salmonids in
the Pacific Northwest

ROBERT J. McCONNELL and GEORGE R. SNYDER

SEATTLE, WA.
January 1972

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publication.

CONTENTS

Page
Introduction 1

Use of key 1

Key 1

Acknowledgments 5

Bibliography 5

Figures

1. A hypothetical salmonid showing external characteristics 2

2. Anal fins: (A) Trout, genus Salmo; (B) Pacific salmon, genus
Oncorhynchus. The two drawings show differences in structure and

fin ray count 2

3. Location of dentition in (A) the roof and (B) the floor of the mouth

of salmonid fishes 3

111

O E

Ifl C

Wi

C

.-3 D-

IV

Key to Field Identification of Anadromous Juvenile Salmonids

in the Pacific Northwest

By

ROBERT J. McCONNELL and GEORGE R. SNYDER

National Marine Fisheries Service

Northwest Fisheries Center

2725 Montlake Boulevard East

Seattle, Washington 98102

ABSTRACT

A key is jn-esented with descriptive illustrations to help in field identification
of live, juvenile salmonids in fresh waters of the Pacific Northwest. Other juve-
nile fish that may be mistakenly identified as salmonids are included.

INTRODUCTION

Species identification of live, anadromous
juvenile salmonids is frequently a problem to
the field biologist. The purpose of this key
is to list and illustrate the external character-
istics which will expedite field identification
of juvenile salmonids in the Pacific Northwest.

Five species of Pacific salmon (pink, chum,
sockeye, chinook, and coho) ; four species of
trout (cutthroat, brown, Dolly Varden, and
rainbow or steelhead) ; and otlier juvenile and
adult fish ' that may be mistaken for salmon or
trout in fresh water are described in this key.

USE OF KEY

The characteristics for identification are list-
ed in a series of alternative statements, some
of which are illustrated. To use the key, ex-
amine the first statement; if applicable, pro-
ceed to the next and continue to successive
statements until the species is identified. If
a statement is not applicable, ]iass to the alter-

' Especially adult smelt, family O.smeridae.

native characteristics indicated by numbers in
parentheses (numbers on the drawings corres-
pond to numbers of statements in the key).
Continue in this manner until the specimen is
identified. Some external characteristics are
positive separating features (marked with as-
terisk ) , whereas others are not. Therefore, two
or more statements should be considered before
final rejection. If a precise identification can-
not be made using the external characteristics
— and the fish can be sacrificed, a positive ident-
ification can usually be made from internal
features (marked with double asterisks). A
bibliography of keys that utilize more descrip-
tive internal characteristics is included in this
paper.

KEY

1. (47) Adipose fin and scales present.

(Fig. 1)

2. (48) Fleshy appendage at base of pelvic

fins present.

3. (49) Mouth large, reaching at least to

center of eye.

Family Salmonidae

Vomer

Tongue

Loterol Parr marks Dorsal

line

Adipose
fin

Coudol
fin

-■/

^sS----/

Moxiilory Pectoral Scales 1'^'^ Fleshy Anol

fin Pelvic appendage fin

fin

Figure 1. — A hypothetical salmonid showing external characteristics.

4. (17) Anal fin higher than long, with 8 to

12 developed rays (Fig. 2A)

5. (52) *Teeth on head and shaft of vomer.

(Fig. 3A)

LENG-rw^-^

Genus Salmo

Genus Oncorhynchus

Figure 2. — Anal fins: (A) Trout, genus Salmo; (B) Pacific salmon, genus Oncorhynchus. The two drawings
show differences in structure and fin ray count. (Note that the length of the anal fin is its overall basal length,
and its height is that distance from the origin of the fin to the tip of the anterior lobe. In counting fin rays, in-
clude only those which originate from the base and terminate at the outer margin of the fin or are half as long
as [or greater than] the longest ray.)

MAXILLARY
HEAD OF VOMER
-PALATINE —

SHAFT OF VOMER

MANDIBLE
TONGUE

HYOID BONE
GILL ARCH

'^ B

Figure 3. — Location of dentition in (A) the roof and (B) tlie floor of the mouth of salmonid fishes. (Presence or
absence of teeth on the vomer or tongue may be determined by use of the little finger or a blunt instrument. The
small hyoid teeth at the base of the tongue are located between the gill arches of the lower jaw and are difficult
to find.)

6. (18) Dorsal fin with large dark spots.

Trout
Genus Salmo

7. (53) Adipose fin not orange; no row of

pale round spots along lateral line.

8. (12) * Small hyoid teeth at base of tongue.

(Fig. 3B)

9. (13) Not more than five parr marks on

mid-dorsal ahead of dorsal fin.

10. (14) Maxillary reaching past posterior

margin of eye.

11. (15) Red or yellowish hyoid mark under

lower jaw. Tail usually black spotted.
Cutthroat trout
10 9 6 (Salmo clarki)

2 4

12. (8) *No teeth at base of tongue.

13. (9) Five to 10 parr marks along mid-dor-

sal ridge ahead of dorsal fin.

14. (10) Maxillary short, not reaching past

posterior margin of eye.

15. (11) No hyoid mark under lower jaw. Few

or no spots on tail.

IG. (20) Parr marks almost round.

Rainbow or

steelhead trout
(Salmo gairdneri)

'3 - 6 ,6

17. (4) Anal fin longer than high, with 13

or more developed rays. (Fig. 2B)

18. (6) Dorsal fin without large dark spots,

may be black tipped.

Pacific salmon
Genus Oncorhynchus

19. (20) No i)arr marks. Fry leave fresh

water while small — approximately
1.75 inches (45 mm) long.

Pink salmon
(0. gorhuscha)

20. (16) Parr marks present as vertical bars

or oval spots.

21. (30) Parr marks short, extending little,

if any, below lateral line.

22. (25) Gill rakers on first arch, 19 to 26.

** Pyloric caeca, 140 to 186.

23. (26) Parr marks faint. Sides below lat-

eral line iridescent green.

24. (27) Small when migrating from fresh

water, approximately 1..5 inches (40
mm) long.

Chum salmon

21,23 <°- '*>

2,5. (22) Gill rakers on first arch, 30 to 40.
**Pyloric caeca 60 to 115.

26. (23) Parr marks usually sharply defined.

Sides below lateral line silvery, not
iridescent green.

27. (24) Relatively large when migrating

from fresh water, approximately 3
to 5 inches (80 to 126 mm) long.

28. (31) Gill rakers long and slender, more

than 29 on first arch.

29. (32) Adipose fin clear, not pigmented.

Sockeye salmon
(0. verka)

30. (21)

31. (28)

32. (29)

33. (40)

34. (41)

35. (42)

36. (43)

37. (44)

38. (45)

39. (46)

Parr marks large, vertical bars cen-
tered by lateral line.
**Gill rakers short and thick, fewer
than 29 on first arch.
Adipose fin at least partially pig-
mented.

**Plyloric caeca more than 90.
Parr marks broader than interspaces.
Anterior rays of anal fin not dis-
tinctly longer than rest, not white
edged.

Anal fin not pigmented.
Black spots, when present, on both
lobes of caudal fin.
Adipose fin not completely mottled,
clear area at anterior base of fin.
Black gums along base of lower teeth.
Chinook salmon
(O. tshawytscha)

30,34

39.46

35,36

40. (33) **Plyloric caeca less than 80.

41. (34)^ Parr marks narrower than inter-

spaces.

42. (35) Anterior rays of anal fin elongated;

when depressed they extend to base
of last ray. (Fig. 2B)

43. (36) Anal fin pigmented between rays, re-

sulting in black banding.

44. (37) Black spots, when present, on upper

lobe of caudal.

45. (38) Adipose fin completely pigmented.

46. (36) Mouth gray to white.

Coho salmon
(0. kisutch)

42-43

47. (1) Adipose fin not present; scales pre-

sent or lacking.

Not Salmonidae

48. (2) No fleshy appendage at base of pelvic

fins.

Smelts

Family Osmeridae

49. (3) Mouth small, not reaching center of

eye; teeth weak or absent.

50. (51) Depressed dorsal fin, shorter than

head.

Whitefishes
Genus Coregonus

51. (50) Depressed dorsal fin, longer than

head.

Arctic grayling

( Thymallns a rcticus)

52. (5) **Teeth on head of vomer only.

Chars

Genus Salvelinus

Dolly Varden {S. malma)

53. (7) Adipose fin orange; row of distinct

pale round spots along lateral line.
Brown trout
(Salmo trutta)

ACKNOWLEDGMENTS

We especially thank Dr. Arthur D. Welander,
Professor of Fisheries, and Dr. Bruce S. Miller,
Research Biologist, College of Fisheries, Uni-
versity of Washington, Seattle, for their val-
uable suggestions. We also thank Galen H.
Maxfield, Fishery Biologist, and Dr. Alan J.
Beardsley, Fishery Biologist, both from the
NMFS Northwest Fisheries Center, Seattle.

BIBLIOGRAPHY

Alaska

MEEHAN, W. R., and J. S. VANIA.
1961. An external characteristic to dif-
ferentiate between king and silver salm-
on juveniles in Alaska. Alaska Dep.
Fish Game, Inf. Leafl. 1. 5 p. (Pro-
cessed.)

WILIMOVSKY, N. J.

1958. Provisional keys to the fishes of
Alaska. U.S. Fish Wildl. Serv., Fish.
Res. Lab., Juneau, Alaska. 113 p. (Pro-
cessed.)
California

SHAPOVALOV, LEO.

1947. Distinctive characters of the spe-
cies of anadromous trout and salmon
found in California. Calif. Fish Game
33: 185-190.
Canada

CARL, G. CLIFFORD, W. A. CLEMENS,
and C. C. LINDSEY.
1967. The fresh-water fishes of British
Columbia. B. C. Prov. Mus., Dep. Rec-
reation Conserv., Handb. 5. 192 p.
CLEMENS, W. A.

1935. The Pacific salmon in British Co-
lumbia waters. B. C, Rep. Comm. Fish.
1934: K103-K105.
CLEMENS, W. A., and G. V. WILBY.
1946. Fishes of the Pacific Coast of Can-
ada. Fish. Res. Board Can., Bull. 68.
368 p.
FOERSTER, R. E., and A. L. PRITCHARD.
1935. The identification of the young of
the five species of Pacific salmon, with
notes on the fresh-water phase of their
life-history. B. C, Rep. Comm. Fish.
1934: K106-K116.
SCOTT, W. B.

1958. A checklist of the freshwater fishes
of Canada and Alaska. R. Ont. Mus.,
Div. Zool. Palaeontol. 30 p.
Montana

WEISEL, G. F.

1957. Fish guide for intermountain Mon-
tana. Mont. State Univ. Press, Mis-
soula. 88 p.
Oregon

BOND, CARL E.

1961. Keys to Oregon fresh-water fishes.
Oreg. State Univ., Agric. Exp. Stn.,
Tech. Bull. 58. 42 p.
Pacific Northwest

BURGNER, R. L. (edited by William A.
Smoker) .
1955. Preliminary key for identification
of salmon fry, juveniles, and adults.
State of Wash., Dep. Fish. 8 p. (Pro-
cessed.)

GREGORY, R. W., P. E. FIELDS, R. W.
LICHTENHELD, and G. R. SNYDER.

1961. Using anal chromatophores for dis-
tinguishing between ciiinook and silver
salmon smelts in the Columbia River.
Coll. Fish., Univ. Wash., Seattle, Tech.
Rep. to U.S. Army Corps Eng. No. 51.
4 p. (Processed.)

ROUNSEFELL, G. A.

1962. Relationships among North Amer-
ican Salmonidae. U.S. Fish Wildl. Serv.,
Fish. Bull. 62: 235-270.

SCHULTZ, LEONARD P.

1936. Keys to the fishes of Washington,
Oregon and closely adjoining regions.
Univ. Wash., Publ". Biol. 2: 103-228.
Washington

CRAWFORD, DONALD R.

1925. Field characters identifying young
salmonid fishes in fresh waters of Wash-
ington. Univ. Wash., Publ. Fish. 1 (2) :
64-76.

GPO 999-498

MBL WHOI Library Serials

5 WHSE 00493

349. Use of abstracts and summaries as communica-
tion devices in technical articles. By F. Bruce
Sanford. February 1971, iii + 11 pp., 1 fig.

350. Research in fiscal year 1969 at the Bureau of
Commercial Fisheries Biological Laboratory,
Beaufort, N.C. By the Laboratory staff. No-
vember 1970, ii + 49 pp., 21 figs., 17 tables.

351. Bureau of Commercial Fisheries E.xploratory
Fishing and Gear Research Base, Pascagoula,
Mississippi, July 1, 1967 to June 30, 1969. By
Harvey R. BuUis, Jr., and John R. Thompson.
November 1970, iv + 29 pp., 29 fig.s., 1 table.

352. Upstream passage of anadromous fish through

navigation locks and use of the stream for spawn-
ing and nursery habitat, Cape Fear River N C
1962-66. By Paul R. Nichols and Darrell E.'
Louder. October 1970, iv + 12 pp., 9 figs. 4
tables.

356. Floating laboratory for study of aquatic organ-
isms and their environment. By George R.
Snyder, Theodore H. Blahm, and Robert J. Mc-
Connell. May 1971, iii + 16 pp., 11 figs'.

361. Regional and other related aspects of shellfish
consumption — some preliminary findings from
the 1969 Consumer Panel Survey. By Morton
M. Miller and Barrel A. Nash. June 1971, iv +
18 pp., 19 figs., 3 tables, 10 apps.

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