Species Profile - Heterosporis sutherlandae

Heterosporis sutherlandae

Common Name: A microsporidian parasite

Synonyms and Other Names:

Skip Sommerfeldt (WI DNR) Copyright Info

Identification: Heterosporis sutherlandae is a parasite that occurs within the skeletal muscle cells of fish, where it creates thick sporophorocysts in which spores develop. Either 8 or 16 spores grow inside vesicles found inside the sporophorocysts. Macrospores contain an isofilar polar tube in three coils, while microspores exhibit the same apparatus with only one coil. Muscle tissue turns opaque and cloudy in affected fish, appearing granular and unappetizing for anglers (Lom et al. 2000; Sutherland et al. 2000; Lom 2002; Sutherland 2002; Sutherland et al. 2002; Sutherland et al. 2004).

Size: Sporophorocysts are up to 200 µm in diameter and spores are around 7-10 µm across (cf. Lom et al. 2000).

Native Range: Heterosporosis sutherlandae is believed to be native to Europe and Asia (EPA 2008), as other Heterosporis species have been reported from Japanese eel (Anguilla japonica) in Japan and Taiwan, cultured freshwater angelfish (Pterophyllum scalare) in France, cultured betta (Betta splendens) from Thailand, cultured ornamental cichlids and loricarid catfish in Germany, Eurasian perch (Perca fluviatilus), Egyptian mouthbreeder cichlid (Pseudocrelinabrus multicolor), and bristlenose catfish (Ancistrus cirrhosus) (Joh et al. 2007, Lom et al. 1989, Lom et al. 1993, Lom et al. 2000, Michel et al.1989). However, Phelps et al (2015) found it to be a novel species genetically distinct from the known Asian and European species that have been sequenced. Thus, it remains possible the North American Heterosporis sutherlandae is native to the Great Lakes, where it previously had not reached sufficient intensities to produce clinical signs (IDNR 2005, Sutherland 2002).

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This map only depicts Great Lakes introductions. Click here for Great Lakes region collection information

Great Lakes Nonindigenous Occurrences: Heterosporis sp. was first isolated in the Great Lakes region from yellow perch (Perca flavescens) in Catfish Lake, Wisconsin in 2000 (Sutherland et al. 2004). This parasite has been reported from 26 bodies of water in Minnesota, 16 in Wisconsin, 2 in Michigan, and 1 in Ontario (Phelps et al 2015).

Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Heterosporis sutherlandae are found here.

State/Province	First Observed	Last Observed	Total HUCs with observations†	HUCs with observations†
NY	2000	2000	1	Lake Ontario
WI	2008	2008	1	Brule

Table last updated 2/21/2025

† Populations may not be currently present.

Ecology: Heterosporis sutherlandae has been isolated from Yellow perch (Perca flavescens), Walleye (Sander vitreus), Cisco (Coregonus artedi), Northern pike (Esox lucius), Burbot (Lota lota), Mottled sculpin (Cottus bairdi), Slimy sculpin (C. cognatus), and Pumpkinseed (Lepomis gibbosus). Laboratory trials suggest Rainbow trout (Oncorhynchus mykiss), Brook trout (Salvelinus fontinalis), Coho salmon (Oncorhynchus kisutch), Brown trout (Salmo trutta), Channel catfish (Ictalurus punctatus), Largemouth bass (Micropterus salmoides), Fathead minnow (Pimephales promelas), Bluegill (Lepomis macrochirus), White sucker (Catostomus commersonii) and Koi (Cyprinus carpio koi) are also susceptible (Phelps et al 2015). To date, only Yellow perch (Perca flavescens) have exhibited outward lesions from the disease. The trout and minnow species are highly susceptible to infection, while the bass and salmon are marginally susceptible and experience much less muscle damage if infected at all (Sutherland 2002, Sutherland et al. 2004). Up to 80-90% of host fish skeletal muscle can be infected with sporophorocysts (IDNR 2005).

Host fish likely ingest Heterosporis sutherlandae spores directly from the water column or by scavenging carcasses of infected fish. Transovarial transmission might also be possible. Spores can remain infective in water for up to two months at 21°C and up to a year at 4°C (IDNR 2005, Sutherland 2002, Sutherland et al. 2004). There are no intermediate hosts known at present. While cormorants have been proposed as a potential mechanical vector for spores, experiments have shown this to be unlikely (Quinnell et al. 2006) as Heterosporis is not passed through the digestive tract of cormorants (GLFHC 2006).

Means of Introduction: Unknown. However, the infection can spread by transportation in water in live wells, bait buckets, and the bilges of boats (Sutherland et al. 2000). Infection could spread via the movement of susceptible bait fish species between water bodies. The discard of infected aquarium fish is another potential vector (Lom et al. 1989; Lom et al. 1993).

Status: Heterosporis sutherlandae is considered established in Michigan, Minnesota, Wisconsin, and Ontario.

Great Lakes Impacts:

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental Socioeconomic Beneficial

Heterosporis sutherlandae has a high environmental impact in the Great Lakes.

Yellow perch is the only species in which impacts have been realized (GLFHC 2012, IDNR 2005, Sutherland 2002, Sutherland et al. 2004). Prevalence of this parasite in Great Lakes yellow perch can range between 5% and 30%, with the majority of infections at 20% (Sutherland 2002). However, because of the wide range of Great Lakes native species susceptible to infection this species is assessed as having a high environmental impact in this region.

Declines to the Great Lakes Yellow perch stocks are believed to stress predator-prey relationships. There is no evidence to show this parasite causes fish mortality directly, but the destruction of muscle in infected fish increases susceptibility to predation (Goodwin 2008, Sutherland 2002).

Laboratory-based infections of Heterosporis sutherlandae have been observed in many additional Great Lakes native species (GLFHC 2012, IDNR 2005, Sutherland 2002, Sutherland et al. 2004).

There is little or no evidence to support that Heterosporis sutherlandae has significant socio-economic impacts in the Great Lakes.

Lake Ontario commercial fisheries are concerned about the economic impacts of Heterosporis sutherlandae as infected fish suffer a significant loss of muscle tissue and are not marketable (IDNR 2005, Sutherland 2002). Sutherland (2002) has also expressed concern that the presence of Heterosporis sutherlandae in Lake Michigan may significantly impede the recovery of depressed Yellow perch stocks, which have experienced population declines in Lake Michigan over the past decade. Economic impacts to the Lake Erie Yellow perch fisheries could be realized if this parasite becomes established there.

Laboratory-based infections of Heterosporis sp. have been observed in commercially valuable Great Lakes native and non-native species . Economic impacts to wild and cultured populations could be realized if natural infections are observed.

There is little or no evidence to support that Heterosporis sutherlandae has significant beneficial effects in the Great Lakes.

While there have been no field observations of biological control of nonnative species in the Great Lakes, Common carp (Cyprinus carpio) and Goldfish (Carassius auratus) appear to be highly susceptible to infection by Heterosporis sp. based on laboratory experiments (Sutherland 2002, Sutherland et al. 2004).

Management:

Regulations (pertaining to the Great Lakes)

The Great Lakes Fish Health Committee lists Heterosporis sp. as a restricted pathogen. Percids, esocids, and centrarchids are to be screened for the presence of this parasite. In the event of a detection in wild populations, surveillance programs should be initiated to determine the geographic distribution and reasonable means should be employed to prevent spread. If detected in a hatchery, biosecurity should be enhanced to limit spread.

Heterosporis sp. has been listed as a reportable pathogen or a disease of concern in many states including Illinois, Maine, Michigan, Minnesota, Utah, and Wisconsin (Phelps et al 2015).

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control
Biological
There are no known biological control methods for this species.

Physical
Effective physical control methods include complete desiccation of holding tanks and equipment for 24 hours, freezing at -20°C for 24 hours, and culling (GLFHC 2012, Sutherland 2006).

Chemical
Immersion of gear in a 2200 ppm bleach (3 cups of bleach per 5-6 gallons of water) solution for 5 minutes will destroy the parasite (GLFHC, IDNR 2005, Sutherland 2006).

Other
Infected fish or fish parts should not be discarded back into the water body.

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

Remarks: While recognized as nonindigenous, Great Lakes populations of this species were identified only as Heterosporis sp. prior to 2015, when Phelps et al used molecular techniques to identify the species.

References (click for full reference list)

Other Resources:

Great Lakes Waterlife

Author: Kipp, R.M., A.K.Bogdanoff, A. Fusaro and R. Sturtevant.

Contributing Agencies:

Revision Date: 9/13/2019

Citation for this information:
Kipp, R.M., A.K.Bogdanoff, A. Fusaro and R. Sturtevant., 2025, Heterosporis sutherlandae: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/GreatLakes/FactSheet.aspx?Species_ID=2661, Revision Date: 9/13/2019, Access Date: 2/21/2025

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.