Prevalence of Bacterial Kidney Disease in Natural vs. Hatchery-Reared Adult Chinook Salmon Spawned in a Hatchery and in

Nature

Timothy L. Hoffnagle, Sally Gee, Glenda O'Connor, and Richard W. Carmichael

Oregon Department of Fish and Wildlife

Bacterial Kidney Disease• Caused by Renibacterium salmoninarum

• Slow growing bacterium• Causes chronic, systemic infection• Transmitted both horizontally and vertically

• Can be a major health problem in hatcheries, particularly captive broodstock programs

• Antibiotics are used to prevent and treat BKD outbreaks

• ELISA is the standard diagnostic method and is commonly used to cull fish to reduce vertical transmission

• Concern that hatchery salmon may spread disease to natural salmon

Objectives

Examine Chinook salmon for bacterial kidney disease and compare results among:

• Origins• Hatchery vs. Natural

• Spawning locations• Hatchery vs. Streams

• Hatchery Programs• Captive vs. Conventional

Broodstock• Management

• Wilderness vs. Supplemented streams

• Populations• Catherine Creek• Grande Ronde River• Imnaha River• Lookingglass Creek• Lostine River• Minam River• Wenaha River

Objectives

Look for trends that may indicate a change in BKD prevalence:

• Populations• Catherine Creek• Grande Ronde River• Imnaha River• Lookingglass Creek• Lostine River• Minam River - hatchery strays• Wenaha River - hatchery strays

Northeast Oregon Streams

Grande Ronde

Riv

er

Snake

Imna

ha

CatherineCreek

RiverCreek

Wenaha

Riv

er

River

Min

am

Riv

er

Lookingglass

Methods

Hatchery Sampling• Samples collected from freshly killed salmon

immediately after being spawned.• Samples kept cool until being frozen at the end of

the day.

Methods

Spawning Ground Survey Sampling• Samples collected from intact carcasses.• Samples stored in backpack until end of survey,

kept on ice for transport until frozen.

Methods

Enzyme-linked Immunosorbent Assay (ELISA)• Measures amount of R. salmoninarum antigen in

the sample. • Indicates present or past infection by R.

salmoninarum.

Can Samples Collected on Spawning Ground Surveys be Analyzed?

O’Connor, G. and T. L. Hoffnagle. 2007. Use of ELISA to monitor bacterial kidney disease in naturally spawning Chinook salmon. Diseases Of Aquatic Organisms 77:137-142.

P < 0.0001r2 = 0.925slope = 0.946

Spawning ground surveysimulation samples

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Nor

mal

ELI

SA p

repa

ratio

n sa

mpl

es

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Hatchery vs. Natural Adults

Stream

Mea

n EL

ISA

OD

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

Hatchery-reared adultsHatchery straysNatural adults

CatherineCreek

GrandeRondeRiver

LostineRiver

MinamRiver

WenahaRiver

LookingglassCreek

All GrandeRonde Basin

ImnahaRiver

*

*

*

Mean ELISA OD, 2004-2008M

ean

ELIS

A O

D

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

GrandeRondeRiver

Looking-glassCreek

LostineRiver

MinamRiver

WenahaRiver

ImnahaRiver

cd

a

b

d

a

bc

bcd

CatherineCreek

Mean ELISA OD ComparisonsM

ean

ELIS

A O

D

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

Hatchery

NaturalLFH

SGS

Supplemen

ted

Wildern

ess

Captiv

e

Conventio

nal

P<0.0001

P=0.5757

P=0.1540

P<0.0001

ELISA OD Categories

River

Perc

ent

0

20

40

60

80

100

WenahaRiver

CatherineCreek

Looking-glassCreek

GrandeRondeRiver

MinamRiver

LostineRiver

All GrandeRonde Basin

ImnahaRiver

ELISA CategoriesHigh: > 0.8Moderate: 0.2 - 0.799Low: <0.2

Grande Ronde River

Year2001 2002 2003 2004 2005 2006 2007 2008

Mea

n EL

ISA

OD

0.00

0.05

0.10

0.15

0.20

0.25

HatcheryNatural

Lookingglass Creek

Year2004 2005 2006 2007 2008

Mea

n EL

ISA

OD

0.0

0.1

0.2

0.3

0.4

0.5

HatcheryNatural

Lostine River

Year1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Mea

n EL

ISA

OD

0.0

0.1

0.2

0.3

0.4

HatcheryNatural

Minam River

Year2001 2002 2003 2004 2005 2006 2007 2008

Mea

n EL

ISA

OD

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Hatchery (strays)Natural

Wenaha River

Year2004 2005 2006 2007 2008

Mea

n EL

ISA

OD

0.0

0.2

0.4

0.6

0.8

1.0

Hatchery (strays - 1 fish, 2004)Natural

Imnaha River

Year1992 1994 1996 1998 2000 2002 2004 2006 2008

Mea

n EL

ISA

OD

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

HatcheryNatural

Conclusions• BKD is not prevalent in northeast Oregon

Chinook salmon• ELISA can be run on kidneys collected from

intact carcasses on spawning ground surveys• Naturally spawning salmon had higher ELISA

OD levels than those spawned in the hatchery• However, comparisons between hatchery and SGS samples are

confounded by the use of antibiotics in the hatchery• No difference in ELISA ODs between hatchery

vs. natural salmon• Supplemented streams may have less BKD than

wilderness streams.• No trends in BKD prevalence

Acknowledgements• ODFW La Grande Fish Health Lab• Spawning ground surveyors from ODFW,

CTUIR, NPT, USFWS and USFS• Lower Snake River Compensation Plan