Whirling Disease (Myxobolus cerebralis) and Idaho Fisheries

1
Whirling Disease (Myxobolus cerebralis)andIdaho
Fisheries

• Keith Johnson
• Retd Supervisor, IDFG Fish Health Program
• Eagle Fish Health Laboratory
• Eagle, Idaho

2
(No Transcript)
3
myxospores
4
(No Transcript)
5
DOCUMENTED INTRODUCTIONS OF M. cerebralis-POSITIVE
TROUT INTO IDAHO WATERS.
1986. Palouse area farm pond. Rainbow trout
from northeast Oregon.
1985-87. Lost River Trout Farm. Rainbow trout
from California.
1993 2004 Canyon Spring Trout Farm. Rainbow
trout from Utah.
1966-75. Nevada Div. Wildlife. Rainbow trout
from Truckee National Hatchery stocked into
streams that cross the state border.
Have apparently not lead to established
infection.
6
Susceptibility of Salmonid Species To M.
cerebralis
7
(No Transcript)
8
Dynamic Relationship of Host/Parasite/Environment
HOST
Presence, No Disease M. cerebralis spores rare,
no disease signs, host population resilient Ex
S.F. Snake R, S.F. Boise R, M.F. Salmon R
PARASITE
ENVIRONMENT
Disease, No Impact Prevalence and intensity of
infection high, disease signs occasional, host
population resilient Ex Big Wood R, upper
Salmon R, Lemhi R
HOST
ENVIRONMENT
PARASITE
Negative Population Impact Spores and pathology
abundant, disease signs common, host population
is parasite limited Ex Big Lost R, Little Lost
R, Pahsimeroi R
9
Idaho Department of Fish and Game Hatcheries
Pahsimeroi
Sawtooth
10
Figure 1. Prevalence and intensity of M.
cerebralis infection of sentinel rainbow trout
exposed for ten days to the Salmon River water
supply of Sawtooth Hatchery, Feb, 2000-Jan, 2001.

.
139
10
22
109
144
88
2
15
7
6

50
54
4
4
53

23
24
5
4
22
5
7

5
Prevalence () 0 0 20 95 88 80
95 85 55 19 13 5 Degrees C 2.6
3.6 6.1 7.2 11.2 14.1 13.0 11.4 7.1 3.3 2.9 3.2 Hy
drograph (CFS) 110 110 250 1570 2190 470 341 30
4 258 180 123 118
11
Figure 2. Prevalence and intensity of M.
cerebralis infection of sentinel rainbow trout
exposed for ten days to the river water supply of
Pahsimeroi Hatchery, Feb, 2000- Jan, 2001.
140

43
18
143
1 139
56
102
19
23
52
127
52
15


194
15

17
53
26

46
266

4
4
5
2


4
21


25

58
28

7
25
7
8

6


3
68
3


Prevalence () 67 85 100
100 90 100 100 80
100 86 91 80 Degrees C 5.0
6.4 9.2 10.3 12.0
13.1 13.5 11.9
9.3 5.8 3.2 3.4 Hydrograph 329
327 300 135 133 109
175 175 284 300 311 321
12
Effect of delaying exposure of Chinook juveniles
to river water at Sawtooth and Pahsimeroi
hatcheries on detection of M. cerebralis at
pre-release sampling the following spring.
Exposure Date
13
Detection of M. cerebralis from Chinook and
steelhead adults at Upper Salmon River trap
locations. Return years 1987-2006.
Return Years
14
UPPER SALMON R
15
Distribution of Myxobolus cerebralis within the
Salmon River during the migration period of 2001
for juvenile anadromous salmonids Wade
Cavender JAAH 2003
16
Snake River
10
9
7
8
NF Salmon River
5
6
4
Lemhi R.
3
Pahsimeroi R.
2
EF Salmon
1
17
April
Snake River
NF Salmon River
OFH
15
?
100
Lemhi R.
100
PFH
?
Pahsimeroi R.
0
STFH
?
EF Salmon
60
18
May
Snake River
15
NF Salmon River
OFH
100
?
20
100
Lemhi R.
90
PFH
?
Pahsimeroi R.
100
STFH
?
EF Salmon
100
19
Myxobolus cerebralis Observations in Natural
Steelhead and Chinook for the Period 1987 2006
Organized by IDFG Regions
REGION STEELHEAD CHINOOK
Clearwater 0/301
0/428 Southwest 0/57
0/493 Salmon
22/192 (11.5) 262/2066 (12.7)
20
Implications of Tributary Reconnection to
Establishing Myxobolus cerebralis in the Lemhi
River Drainage, Idaho Keith Johnson and Tom
Curet Eagle Fish Health Laboratory and Salmon
Region Idaho Department of Fish and Game
21
Lemhi Exposure I June 03
Positive
Negative
22
Lemhi Exposure II Oct03
100
Hayden Cr
Positive
Negative
23
Reconnection of Lemhi River Tributaries Would
not expand the existing range of the parasite
since it is already present, regardless of
tributary connection status Basin Creek may be
the origin of infectivity in the Hayden Creek
drainage but ponds a source also
24
Does M. cerebralis limit natural Trout production
in the Teton River ? Martin Koenig Utah State
University Application of the UofI
epidemiological model of Anlauf, Colvin, Moffitt
25
Teton I exposure (Aug,03) prevalence and
intensity (x000) of M. cerebralis infection
Teton River
?
Flow
Teton Creek
Fox Creek
Trail Creek
Teton R.
26
Anemic challenges in the first Teton River
exposure indicate a low probability that M.
cerebralis infections could limit natural
production of salmonids.
27
Teton II exposure (July,04) prevalence and
intensity (x000) of M. cerebralis infection
100 (40)
Teton River
?
Flow
Teton Creek
(16)
(69)
50 (2)
(23)
Unnamed Creek
(39)
(18)
(39)
Fox Creek
(41)
Teton R.
Trail Creek
28
Implications from Teton River Trials

• Exposures made in 2004 resulted in higher
  prevalence and intensity of M. cerebralis
  infection than in 2003, annual variation in
  exposure must be considered
• Habitat differences throughout study area varied
  only slightly
• Population declines were apparent in Yellowstone
  cutthroat, not rainbow trout even though both
  species are highly susceptible
• Tubifex habitat characteristics and
  susceptibility lineages are needed
• Unnamed Creek may provide fry a refuge from
  intense challenge

29
Application of Risk Assessment to Whirling
Disease in Idaho

• Introduction
• Isolation of new waters, prevent movement
• Establishment Amplification
• Need an understanding of what environmental
  mechanisms operate to limit parasite numbers
• Persistence
• Need to demonstrate the probability that M.
  cerebralis will not persist and in what time
  period, the incentive for painful change

30
Persistence of M. cerebralisWill the infection
fade into the sunset?

• Modin (1998) reported infections decreased to
  below detectable limits when positive rearing
  facilities in California were closed in 3 of 22
  waters over a 32-year period
• Cache de Poudre River (Colorado Division of
  Wildlife) infections were no longer detectable
  two years after an earthen rearing pond ceased
  rearing trout (Nehring, 2003)
• Hayspur Hatchery (IDFG) switched to well water
  in 1993 and we can no longer detect the parasite
• These examples show the parasite may not persist
  in certain waters
• and support enforcement of IDFGs role in
  private pond management

31
PROBABLE INFLUENCE OF IRRIGATION WATER DIVERSION
ON Myxobolus cerebralis-INFECTIVITY AT HAYSPUR
HATCHERY AND IN LOVING CREEK, A TRIBUTARY TO
SILVER CREEK IN SOUTH CENTRAL IDAHO
32
Bellevue
N
W
E
S
Gannett
Big Wood River
Loving Creek
Hayspur Hatchery
Silver Creek
Stalker Creek
5 km
33
HISTORY OF HAYSPUR HATCHERY

• Built 1906.
• Peak annual production of 1 million rainbow trout
  fingerling and 350,000 rainbow catchables.
• Myxobolus spores first detected from adult fish
  in the brood pond in 1988 confirmed M.
  cerebralis in 1989.
• Reconstruction began in 1989.
• All use of surface water for production ceased in
  1995.

34
SENTINEL EXPOSURE DATES SENTINEL EXPOSURE DATES SENTINEL EXPOSURE DATES SENTINEL EXPOSURE DATES SENTINEL EXPOSURE DATES SENTINEL EXPOSURE DATES SENTINEL EXPOSURE DATES
  4/03 6/03 9/03 3/04 5/04 6/04 10/04
HATCHERY INTAKE X X X X      
BROOD POND X X X X      
GAVER LAGOON X X X X      
RAILROAD TRESTLE X X X X X X X
KILPATRICK BRIDGE X X X X X X X
IRRIGATION CANAL   X       X  
BIG WOOD RIVER       X X   X
EXPOSURE SITES
35
Bellevue
N
W
E
S
Big Wood River
3 exposures 64/112 fish (57)
Irrigation Canal
2 exposures 80/81 fish (99)
Hayspur Hatchery sites
Intake
4 exposures 0/133 fish
Brood Pond
Gannett
Big Wood River
4 exposures 0/101 fish
Loving Creek
Railroad Trestle
Hayspur Hatchery
7 exposures 0/197 fish
Gaver Lagoon
4 exposures 0/122 fish
Silver Creek
Kilpatrick Bridge
5 km
Stalker Creek
7 exposures 0/217 fish
36
Bellevue
N
2006
W
E
Heavy snowpack extended runoff
S
Irrigation Canal
1 exposure 47/47 fish (100)
Intake
2 exposures 0/88 fish
Gannett
Big Wood River
Loving Creek
Railroad Trestle
Loving Creek Diversion
Hayspur Hatchery
2 exposures 1/84 fish
2 exposures 0/75 fish
Silver Creek
Kilpatrick Bridge
5 km
Stalker Creek
2 exposures 0/86 fish
37
Conclusions from the Hayspur Hatchery
Exposures M. cerebralis detections at Hayspur
H. during the 88-93 period was sporadic and low
in prevalence (lt2) Parasite did not become
established in Silver Creek Irrigation water
from Big Wood River canals was the likely source
of infection during 1988 to 1993 but even
adjacent spring creeks have not become infected
So.parasite was introduced but did not
persist Implications for private pond permitting
process, we may not have to live with this
parasite in all cases
38
Management Solutions

• Resistant strains of Hofer rainbow trout
• CDOW, UC Davis, U Munich teaming on
  applications.
• 1. Resistance is inherited from both parents and
  operates early in parasite migration
• 2. Lower spore counts, fewer signs, and lower
  histology scores characterize infections in Hofer
  RBT
• 3. Hofer x wild RBT stocks being evaluated in
  CO UT
• Not stocking positive trout is common to sites
  where M. cerebralis does not persist
• Land use also has a role in persistence

39
CDOW Resistant Trout Research (Schisler,07)

• Growth in hatchery for Hofer RBT was superior
• compared to CDOW hatchery strains
• Evaluations of spore counts after planting showed
  reduction by 10-100 fold
• Return-to-creel was 15 higher
• Utah DWR is conducting similar trials
• Commercial trout suppliers in Co and CA have
  Hofer RBT to stock

40
So now I get to speculate on why whirling disease
does not cause levels of impact in Idaho as
reported in MT and CO.

• Habitats within the shaded area in which
  population impacts are suspected are all
• Volcanic tuft soils, easily eroded
• Abundant groundwater, stable water
  temperature
• Eutrophic, highly productive
• High level of grazing impacts
• Low gradient river bottoms
• Tubifex habitat and lineages
• are important to examine

41
Shaded drainages have aquatic habitats conducive
to amplification Pahsimeroi, Lemhi, Big Little
Lost, Birch Creek, and Teton R on
a bad year
?
Drainages outside of the shaded area are basaltic
and granitic origin, lack amplification after
parasite was introduced
42
PLANS FOR THE FUTURE

• Expand knowledge on distribution and epidemiology
  of M. cerebralis Upper Salmon River and role of
  carcasses
• Cooperate with ISDA and industry to reduce WD
  range and intensity through Invasive Species
  legislation
• Administer private pond stocking to reduce risk
  of parasite spread
• Monitor Hofer RBT resistance research and explore
  application for Idaho
• Educate regional biologists, conservation
  officers and anglers about whirling disease

43

Thanks to Idaho Power Company for this 12 M
investment!