Download 2004-05 New

F-80-R-6, Michigan
Study 230728
New Study: 2004-05
Name of Study: Effects of Piscirickettsia infection on the muskellunge population of Lake St. Clair.
A. Problem: Historically, Lake St. Clair has supported an economically and socially important
sport fishery for smallmouth bass, muskellunge, walleye, and yellow perch. Muskellunge
abundance tripled during the 1980s and 1990s as water clarity increased, and macrophyte
densities and spatial coverage increased (MacLennan 2003). Muskellunge anglers across North
America rank the Lake St. Clair muskellunge fishery as one of the most productive on the
continent. The muskellunge population in Lake St. Clair is completely self-sustaining, thus any
threat to the continued successful recruitment of muskellunge in the lake is a serious concern for
fisheries managers.
In 2002, muskellunge exhibiting external lesions were collected by the Michigan Department of
Natural Resources (MDNR) from the Anchor Bay area of Lake St. Clair. The lesions were in the
form of raised, reddish granulomatous-like sores that varied in diameter from 3 mm to 2 cm.
Laboratory analysis at Michigan State University revealed the presence of Gram-negative,
intracellular bacterium that occurred as rings or curved rods. The organism grew only in cultured
cell lines, with a tendency to grow better in the Chinook salmon embryo cell line, CHSE-214.
Based on its morphological and cultural criteria, the organism found in abundance in muskellunge
skin lesions and internal organs was determined to be a Piscirickettsia-like sp.
Identification of this bacterial infection in Lake St. Clair muskellunge raised numerous questions
regarding the implications. Fisheries managers need the answers to questions such as:
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How widespread is the disease in the lake’s muskellunge population?
Is the infection rate increasing?
What are the losses associated with this infection?
What could be the source of the infection?
What are the measures to be undertaken to control the infection and prevent its spread?
Are other fish species affected?
Do parasites play a role in the infection?
Can the disease be transmitted vertically?
Muskellunge anglers want to know the answers to questions such as:
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Do catch-and-release tournaments or tournament practices play a role in the spread of
the disease?
Will the infection affect the abundance of muskellunge in the lake?
Fish disease specialists have additional questions such as:
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Is this a new species?
What is its pathology?
How is this organism genetically related to P. salmonis?
B. Objective(s): The objectives of this study are (1) to determine the infection rate in Lake St. Clair
muskellunge and whether the rate varies spatially or temporally, (2) to determine if other fish
species in the St. Clair System are infected by the bacteria, particularly migratory salmonids, (3)
to identify the impacts of the organism on the health of individual muskellunge, and (4) to
determine if the disease can be vertically transmitted.
C. Justification: Approximately 4.5 million people live within a one-hour drive of Lake St. Clair.
Jamsen (1985) reported that nearly 22% of all Michigan Great Lakes sport fishing effort in 1981
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was spent on Lake St. Clair. In 1983 and 1984, the annual estimated fishing effort on Lake St.
Clair averaged 1.9 million angler hours (Haas et al 1985). An on-site creel survey in 2002
produced an estimated angler effort of 1.3 million angler hours (254,275 angler days) between
March and October (MDNR, unpublished data, Charlevoix Research Station). The economic
impact of the 2002 open water Lake St. Clair fishery was estimated at $82 million (254,275
angler days X $323 per angler day, US Dept. of Interior, 2001). Approximately 20% of the
fishing effort on Lake St. Clair targets muskellunge.
Piscirickettsia salmonis was the first "rickettsia-like" bacteria to be recognized as a pathogenic
agent of fish. P. salmonis infects a wide range of salmonid fish species causing a systemic
infection associated with high mortalities in Chile, Norway, Ireland, and Canada (west and east).
This organism, however, has never been reported in any non-salmonid fish species. Similar
agents, known as Piscirickettsia-like organisms, have been found associated with mortalities in
diverse fish species, including white seabass, black seabass, tilapia, blue-eyed plecostomus, and
dragonet. Three of these infections were reported from North America. This type of organism,
however, has not previously been reported from wild fish, muskellunge, or Great Lakes fish
populations. Since Piscirickettsia and Piscirickettsia-like organisms have been consistently
associated with severe mortalities in affected fish populations, the disease represents a threat to
the muskellunge fishery in Lake St. Clair.
Lake St. Clair is part of a shallow connecting waterway, centrally located in the Laurentian Great
Lakes. Fish passage through the St. Clair system is not impeded by anthropogenic or natural
barriers. Walleye (Haas et al 1988), lake sturgeon (Thomas and Haas 2003), and coldwater
salmonine species (unpublished MDNR creel survey data, Charlevoix Research Station),
including lake whitefish, chinook salmon, rainbow trout, brown trout, and lake trout (Salvelinus
namaycush) move freely between the connecting waters and the adjoining Great Lakes (Huron
and Erie). Salmonid tagging studies have documented a mixture of fish originating from stocking
sites all around the lake, is present in the St. Clair River and southern Lake Huron in early spring
(J. Johnson, MDNR Alpena Research Station, personal communication). These movement
patterns suggest that migrating salmonids could potentially be exposed to the infectious bacteria
in Lake St. Clair during the winter/spring, then migrate back into southern Lake Huron,
potentially spreading the bacteria to locations dispersed widely around the lake.
D. Expected Results and Benefits: Results from this study will provide basic information
regarding a newly identified bacterial infection in Lake St. Clair muskellunge. This basic
information will be critical in understanding the implications of the infection on the muskellunge
population and the socially and economically important fishery that it supports. In addition, by
sampling all trophic levels of the Lake St. Clair food web, the extent of the bacterial infection in
the ecosystem will also be assessed. Ultimately, this study will provide the informational basis
for determining what, if any, management steps are needed to appropriately respond to the
presence of the infection in the muskellunge population of Lake St. Clair.
E. Background: Limited assessment data exist to gauge the current status of the Lake St. Clair
muskellunge population. Data from creel surveys, angler diaries, charter boat reports, and the
Michigan Master Angler program all suggest that fishing success and interest for muskellunge
has been consistently high in recent years. On-site creel survey in 2002 produced annual fishing
effort estimates of 1,368,564 angler hours between March and October (Thomas and Haas 2003).
Estimated muskellunge harvest was 154 fish, but fewer than 5% of all muskellunge caught are
harvested due to an exceedingly strong catch and release practice by muskellunge anglers on the
lake. An on-water creel survey by the OMNR in August 2000 indicated a large shift in angler
effort from primarily walleye in the 1980s to muskellunge, smallmouth bass, and yellow perch
(Don MacLennan, personal communication, Wheatley, ONT). Meanwhile, charter boat catch
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rates for "other species", primarily smallmouth bass and great lakes muskellunge have increased
greatly since the early 1990s. Entries in Michigan's Master Angler Program indicated that
muskellunge angling on Lake St. Clair has expanded dramatically over the last decade.
Muskellunge catch rates recorded by an angler diary program supported jointly by the OMNR
and MDNR more than doubled between 1986 and 1995 (MacLennan 1996). The muskellunge
fishery draws anglers from the local area as well as from across the continent. Numerous charterfishing businesses specialize in muskellunge trips. Countless individual anglers fish exclusively
for muskellunge while the season is open. A large bi-national angling club is dedicated to the
sport of muskellunge fishing on Lake St. Clair. Most Lake St. Clair muskellunge anglers espouse
a strict catch-and-release ethic. From a human health standpoint, the catch-and-release ethic is
beneficial, since the Michigan Department of Community Health has issued a “no consumption”
advisory for muskellunge from Lake St. Clair due to elevated levels of mercury contamination.
No anecdotal evidence of increased muskellunge mortality has been apparent in recent years.
Small numbers of dead muskellunge have been observed and reported each year by anglers on
Lake St. Clair. This is not surprising considering the level of fishing effort directed at
muskellunge and the high degree of catch-and-release fishing for the species. Some post-release
mortality would be expected. Muskellunge anglers have not reported any perceived increases in
the incidence of dead muskellunge observed during the fishing season. Similarly, anglers have
not reported or complained about the red sores or lesions typical of the Piscirickettsia infection.
Increased angler reports of silver lamprey attachment and wounds on muskellunge (and other
species) have been noted by MDNR biologists in recent years.
Haas (1978), Bryant and Smith (1988), and MacLennan (1996) have reported on previous studies
of muskellunge in Lake St. Clair. These papers documented movement patterns within the lake,
effects of increased minimum size limits, and impacts of increased water clarity and aquatic plant
distribution in the lake. Haas (1978) and Bryant and Smith (1988) both reported evidence, based
on tagging studies, that at least two distinct groups of muskellunge inhabit the lake. One group
spawned in Anchor Bay at the north end of the lake, and dispersed southward to inhabit the entire
western side of the lake. Another group resided and apparently spawned in the southeastern
(Ontario) waters of the lake.
Michigan DNR Federal Aid Study 488 investigated the fish community of the lake from 1996 to
2002. These surveys revealed that the forage fish community of Lake St. Clair has been
dominated by native species, despite the colonization of the system by several exotic species.
Adult predator populations were not well sampled due to gear bias, but were monitored through
catch rates for anglers participating in the angler diary program. Muskellunge catch rates
improved through the late 1990s and remained high through 2001. Adult muskellunge
assessment is captured under a new job added to Study 488 in 2002. In fact, the fish infected
with Piscirickettsia were caught in trap nets set in Anchor Bay under Job 9 of Study 488.
Lake St. Clair has been colonized by a series of aquatic nuisance species over the past 20 years.
Spiny waterflea, white perch, zebra mussel, round goby, and tubenose goby have all established
populations in the St. Clair system. It is unclear if the sudden appearance of the Piscirickettsia
bacteria in Lake St. Clair represents yet another exotic species introduction.
During the spring of 2002, prior to isolation of Piscirickettsia bacteria from Lake St. Clair
muskellunge, eggs from Lake St. Clair muskellunge were collected, fertilized, and transferred to
Wisconsin. Progeny from those gametes were reared to fingerling size in Wisconsin DNR ponds
during summer of 2002. In fall 2002, those fingerlings were marked and stocked into the waters
of Green Bay, Lake Michigan.
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During spring 2003, an unusually high number of dead large muskellunge were reported by
anglers and boaters, as well as by people working and recreating along the Detroit River.
Anectodal information suggests that the level of mortality observed was far higher than any
normal winter or spring mortality event. Reports of the dead fish began in early April and
continued through late May. Other fish species were not included in the reports. Decomposition
was well underway for most of the dead muskellunge reported, thus it had not been possible to
collect tissue samples for bacterial analysis as of late May. Based on personal accounts from
reliable contacts frequenting the Detroit River, MDNR biologists suspect that 500 or more dead
adult muskellunge had passed through the Detroit River during April and May 2003.
The St. Clair System connects Lake Huron and Lake Erie via the St. Clair River, Lake St. Clair,
and the Detroit River. The watershed of the St. Clair System (Figure 2 and 3) encompasses
17,669 km2 (6,832 mi²) of which 7,223 km² (2,789 mi²) is in Michigan and 10,446 km² (4,033
mi²) is in Ontario (OMNR Provincial Geomatics Service Centre). The St. Clair System includes
the St. Clair and Detroit River watersheds, along with the Lake St. Clair watershed.
F. Procedure: This study will focus on 4 primary objectives: (1) to determine the infection rate in
Lake St. Clair muskellunge and whether the rate varies spatially or temporally, (2) to determine if
other fish species in the St. Clair System are infected by the bacteria, particularly migratory
salmonids, (3) to identify the impacts of the organism on the health of individual muskellunge,
and (4) to determine if the disease can be vertically transmitted. We will document spatial and
temporal infection rates by sampling muskellunge during spring, summer, and fall from
geographically dispersed areas of Lake St. Clair during 2004 (completed and funded with license
revenues), 2005, and 2006. Objective 1 will also be investigated by collecting data on visible
marks observed by volunteer muskellunge anglers through an angler diary program. We will
determine if other fish species in the St. Clair system are infected by the bacteria through
collection and sampling of other predator, planktivore, and benthivore species. Some will be
collected during fieldwork funded under other federal aid studies. Salmonids will be targeted and
collected with spring, night electrofishing. We will investigate the impacts of the organism on
the health of individual muskellunge in two ways. We will tag adult muskellunge with visible
lesions and monitor recaptures of those fish by anglers and in assessment gear over the 2 years of
the study. In addition, the physical and physiological conditions of infected and uninfected
muskellunge will be compared. Finally, we will determine if the disease can be vertically
transmitted by collecting gametes from fish bearing external lesions. Eggs will be fertilized and
incubated to hatching. Fry will be pond reared. Eggs, fry, and fingerlings samples will be
analyzed for presence of the bacteria.
Laboratory procedures: Collected fish will be thoroughly examined. Blood will be collected and
plasma separated. Blood films will be stained with Giemsa. Squash preparations will be made
from the lesions, skin, and gills and examined microscopically for the presence of tissue
alterations and external parasites. Samples from skin lesions and internal organs will be
homogenized and inoculated on CHSE-214 for Piscirickettsia isolation. The infected cells will
be followed for the appearance of cytopathic effects. DNA will be isolated from skin and internal
organ samples and will be tested for the presence of Piscirickettsia using primers specific to
Piscirickettsia-intergenic spacer region of the ribosomal RNA gene. Obtained amplicons will be
sequenced and parsimonial analysis performed to determine the phylogeny of the isolated
bacteria. Representative samples will also be subjected to transmission electron microscopy
analysis for the visualization of the agent. The possibility of vertical transmission will be
investigated using gonadal products. Prior to analysis, eggs will be rinsed several times using
sterile fish saline. The rinsing fluid will then be collected to determine if bacteria are present on
the outer shell of the eggs. Rinsed eggs will then be disinfected, and isolation will be attempted
F-80-R-6, Study 230728 - 5
using internal egg contents. Isolation and identification of Piscirickettsia-like organisms will
follow those detailed in Fryer et al. (1990); Fryer & Lannan (1992), and Fryer & House (2000).
Job 1. Collect muskellunge samples from Anchor Bay. Fish will be collected with survey gear
including trap nets and trawls. A maximum number of 60 fish will be sought. Up to 25
macroparasites found attached to muskellunge, particularly silver lamprey and argulus,
will also be sampled.
Job 2. Collect other species of fish and macroparasites during spring, summer, and fall.
Samples will be collected with survey gear, including trap nets, trawls, and electrofishing
boat. During spring, summer, and fall, a target number of ten walleye, smallmouth bass,
rock bass, northern pike, and yellow perch, for a total of 150 fish, will be sought for
bacterial analysis. Up to 75 individuals of available salmonid species will be collected
with electrofishing equipment from the St. Clair River during spring and fall (total of 150
individuals). A total maximum of 300 non-muskellunge fish samples will be sampled for
bacterial infection. In addition, up to 50 silver lamprey and 50 argulus will also be
collected for laboratory analysis.
Job 3. Collect gametes, fertilize eggs, incubate and hatch eggs, culture fry to fingerling size, and
collect samples from all stages for bacterial analysis. Sexually mature muskellunge will be
captured with trap nets in Anchor Bay during May. Eggs from 1 muskellunge bearing
external lesions and 1 muskellunge without external lesions will be fertilized with sperm
from muskellunge without external lesions. Fertilized eggs will be transported to Wolf
Lake for hatching. Fry will be returned to Lake St. Clair Fisheries Research Station and
reared in two small ponds located at the station. Fingerlings will be captured during
summer and fall with seines. If available, samples of 75 eggs, 75 fry, and 50 fingerlings
will be collected for bacterial analysis.
Job 4. Analyze samples of muskellunge eggs, fry, fingerlings, and adults for bacterial infection
(see laboratory procedures above). Adults of other fish species will also be analyzed for
bacterial infection. Macroparasites, including silver lamprey and parasitic copepods, will
be analyzed as well.
Job 5. Collect data on rate of external marks on Lake St. Clair muskellunge from volunteer
muskellunge anglers with muskellunge diary program. Each spring cooperating anglers
will be provided with muskellunge diaries in which to record the presence or absence of
external lesions for each muskellunge caught during the fishing season. In October, the
diaries will be recovered by the MDNR and data recorded. Completed diaries will be
returned to cooperators along with new diaries by the following spring. Cooperators will
be encouraged to continue their participation in the diary program through certificates of
appreciation, annual gratuities (such as program hats and crests or fishing lures), as well
as individual fishing data summaries.
Job 6. Prepare annual performance report.
Job 7. Prepare final report.
Job 8. Publish report through the Fisheries Division's editing and finishing process for Research
and Technical reports.
F-80-R-6, Study 230728 - 6
G. Schedule:
Year
2004-05
Work Planned
Job 1.
Job 2.
Job 3.
Job 4.
Job 5.
Job 6.
Collect muskellunge with assessment gear and volunteer anglers.
Collect other species of fish and macroparasites.
Collect muskellunge gametes, hatch fry, rear fingerlings, and collect samples of
all stages for bacterial analysis.
Analyze fish and macroparasite samples for bacterial infection.
Collect data on rate of external lesions on muskellunge with diary program.
Prepare annual performance and other reports.
2005-06
Job 1.
Job 2.
Job 4.
Job 5.
Job 6.
Collect muskellunge with assessment gear and volunteer anglers.
Collect other species of fish and macroparasites.
Analyze fish and macroparasite samples for bacterial infection.
Collect data on rate of external lesions on muskellunge with diary program.
Prepare annual performance and other reports.
2006-07
Job 7.
Prepare final report.
2007-08
Job 8.
Publish report through the Fisheries Division's editing and finishing process for
Research and Technical reports.
H. Geographical Locations: Lake St. Clair; Lake St. Clair Fisheries Research Station, Harrison
Township, Michigan; Aquatic Animal Health Laboratory, Michigan State University, East
Lansing, Michigan.
I. Personnel: Michael V. Thomas, Fisheries Research Biologist; Robert C. Haas, Biologist In
Charge; Jack Hodge, Boat Captain; Roy Beasley, Assistant Boat Captain; Ken Koster, Fisheries
Research Technician; Jeremy Maronowski, Fisheries Assistant; Pat Fouchey, Secretary, Lake St.
Clair Research Station; Dr. Mohamed Faisal, Professor of Aquatic Animal Medicine and the
state’s fish pathologist, Ms. Katrina Mueller (PhD student0, and Mr. John Hnath, Michigan State
University; Research Administrative personnel, and contract editor.
F-80-R-6, Study 230728 - 7
Literature Cited:
Bryant, W. C., and K. D. Smith. 1988. The status of the muskellunge in Lake St. Clair, Michigan,
1978-86. Michigan Department of Natural Resources, Fisheries Research Report 1955, Lansing.
Fryer, J.L., House, M.L. 2000. Piscirickettsiosis. In: OIE Diagnostic Manual for Aquatic Animal
Diseases, 3rd Edition. Pages 112-116.
Fryer, J.L., Lannan, C.N. 1992. Isolation of a rickettsia from diseased salmonids. In: Kimura, T.
(ed.) Salmonid Diseases. Hokkaido University Press, Hakodate, pp. 151-157.
Fryer, J.L., Lannan, C.N., Garcès, L.H., Larenas, J.J., Smith, P.A. 1990. Isolation of a rickettsialeslike organism from diseased coho salmon Oncorhynchus kisutch in Chile. Fish Pathol.
25(2):107-114.
Haas, R. C. 1978. The muskellunge of Lake St. Clair.
Publication 11:334-339.
American Fisheries Society Special
Haas, R. C., M. C. Fabrizio, and T. N. Todd. 1988. Identification, movement, growth, mortality, and
exploitation of walleye stocks in Lake St. Clair and the western basin of Lake Erie. Michigan
Department of Natural Resources, Fisheries Research Report 1954, Lansing.
Haas, R. C., W. C. Bryant, K. D. Smith, and A. J. Nuhfer. 1985. Movement and harvest of fish in
Lake St. Clair, St. Clair River, and Detroit River. Michigan Department of Natural Resources,
Final Report, Winter Navigation Study, U. S. Army Corps of Engineers.
Jamsen, G. C. 1985. Michigan's 1981 and 1982 sport fishery. Michigan Department of Natural
Resources, Fisheries Technical Report 85-4, Ann Arbor.
MacLennan, D. S. 1996. Changes in the muskellunge fishery and population of Lake St. Clair after
an increase in the minimum size limit. P19-27. In S.J. Kerr and C. H. Olver, [eds.]. Proceedings
of the “Managing Muskies in the ‘90s” Workshop. Ontario Ministry of Natural Resources and
Muskies Canada Inc. Kemptville, Ontario.
MacLennan, D. S., R. C. Haas, M. V. Thomas. 2003. Lake St. Clair: A Case History of Change
1970-1999. SCOL-2 manuscript (in preparation).
Thomas, M. V., and R. C. Haas. 2003. Status of the fisheries in Michigan waters of Lake Erie and
Lake St. Clair, 2002. Michigan Department of Natural Resources, Mt. Clemens.
United States Department of the Interior, Fish and Wildlife Service and United States Department of
Commerce, Bureau of Census. 2001. 2001 National survey of fishing, hunting, and wildlifeassociated recreation. United States Governmental Printing Office, Washington.