Black basses (Micropterus spp) are enigmatic North American sportfishes that support the most economically valuable freshwater sport fishery in the United States and serve as keystone predators within aquatic ecosystems.
Investigating Blotchy Bass Syndrome in Black Basses (Micropterus spp)
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By Eastern Ecological Science Center
December 30, 2024
USGS is studying the spread and effects of “blotchy bass syndrome” on black basses (Micropterus spp). USGS and state agencies have partnered with citizen scientists and recreational organizations to create a continent-wide biosurveillance network to monitor the syndrome.
What is the issue?
Anglers have long noticed dark spots on some of the largemouth bass (Micropterus salmoides) and smallmouth bass (Micropterus dolomieu) they encounter when fishing, but only recently was the appearance of these spots linked to newly-described adomaviruses and given the name “blotchy bass syndrome.” Although the dark spots appear to cause no apparent harm, the relatedness to cancer-causing viruses causes some concern about the potential effects that blotchy bass syndrome may have on bass health and populations.
What is at stake?
Host-specific adomaviruses are causing dark spots to appear across multiple black basses. Fish exhibiting blotchy bass syndrome may spread adomaviruses among other bass and the syndrome may lead to population declines, which is a concern for the bass sportfishing industry. Declines in bass populations could affect recreational anglers, as well as others who want bass to thrive and have an interest in the health and safety of these fish.
What is our approach?
USGS is working with citizen scientists to help identify hotspots and areas of increased viral spread. Working with partners, an online tracker has been developed that uses citizen scientist photos to create a map of viral hotspots, allowing researchers to track the spread of the virus. Data collected by citizen scientists may also support virologists in similar applications where highly visible conditions can be tracked using new techniques and technologies.
What are the benefits?
Studying the adomaviruses that cause blotchy bass syndrome provides insight into how these viruses affect their hosts, and whether these viruses share the same tumor-causing properties as other similar viruses. Tracking how these adomaviruses spread will allow USGS and partners determine how blotchy bass syndrome hotspots are created and may provide information into how other similar viruses may spread.
Sources/Usage: Public Domain. View Media Details
States and provinces with suspected cases of blotchy bass syndrome identified from photos submitted by anglers during March 2022 - February 2023. A total of 5,534 photos of black bass from 36 states and provinces were submitted to the Anglers Atlas MyCatch application (left; blue icons). Of these, 362 (6.5% of submissions) photos of bass from 26 states and provinces showed dark spots, which are clinical signs of blotchy bass syndrome (right; red icons). Circle size denotes relative number of photo submissions, with larger circles indicating that more photos were submitted by anglers in that state or province. Gray icons (B) denote the 10 states and provinces where none of the photos submitted showed clinical signs of blotchy bass syndrome. As of December 2024, data used in these figures are not publicly available from West Virginia University. For more information, contact Pat Mazik, Unit Leader of the West Virginia Cooperative Fish and Wildlife Research Unit.
2022 Blotchy Bass Syndrome Biosurveillance Project
Blotchy bass syndrome (BBS) is the presence of hyperpigmentation (melanosis) on the external surface of black basses. This condition has received increased attention from anglers and resource managers in recent years and is a popular topic of discussion and reporting on angling websites and blogging platforms. Advances in discovery and diagnostic capabilities using “next generation sequencing”...
Blotchy Bass Syndrome
Black basses (Micropterus spp) are enigmatic North American sportfishes that support the most economically valuable freshwater sport fishery in the United States and serve as keystone predators within aquatic ecosystems.
Blotchy Swab
A dermal swab being used on a Largemouth Bass at a Bass Pro Shops retail store with a presumptive case of blotchy bass syndrome. We can see the transfer of pigmented epidermal tissue to the swab changing its color. The collected swabs can be used to isolate DNA and RNA which can be used to identify pathogens including those associated with hyperpigmentation.
A dermal swab being used on a Largemouth Bass at a Bass Pro Shops retail store with a presumptive case of blotchy bass syndrome. We can see the transfer of pigmented epidermal tissue to the swab changing its color. The collected swabs can be used to isolate DNA and RNA which can be used to identify pathogens including those associated with hyperpigmentation.
C. Raines Blotchy Bass Swab
Clay Raines, a USGS scientist, performing a dermal swab on a Largemouth Bass at a Bass Pro Shops retail store with a presumptive case of blotchy bass syndrome. The collected swabs can be used to isolate DNA and RNA which can be used to identify pathogens including those associated with hyperpigmentation.
Clay Raines, a USGS scientist, performing a dermal swab on a Largemouth Bass at a Bass Pro Shops retail store with a presumptive case of blotchy bass syndrome. The collected swabs can be used to isolate DNA and RNA which can be used to identify pathogens including those associated with hyperpigmentation.
USGS is studying the spread and effects of “blotchy bass syndrome” on black basses (Micropterus spp). USGS and state agencies have partnered with citizen scientists and recreational organizations to create a continent-wide biosurveillance network to monitor the syndrome.
What is the issue?
Anglers have long noticed dark spots on some of the largemouth bass (Micropterus salmoides) and smallmouth bass (Micropterus dolomieu) they encounter when fishing, but only recently was the appearance of these spots linked to newly-described adomaviruses and given the name “blotchy bass syndrome.” Although the dark spots appear to cause no apparent harm, the relatedness to cancer-causing viruses causes some concern about the potential effects that blotchy bass syndrome may have on bass health and populations.
What is at stake?
Host-specific adomaviruses are causing dark spots to appear across multiple black basses. Fish exhibiting blotchy bass syndrome may spread adomaviruses among other bass and the syndrome may lead to population declines, which is a concern for the bass sportfishing industry. Declines in bass populations could affect recreational anglers, as well as others who want bass to thrive and have an interest in the health and safety of these fish.
What is our approach?
USGS is working with citizen scientists to help identify hotspots and areas of increased viral spread. Working with partners, an online tracker has been developed that uses citizen scientist photos to create a map of viral hotspots, allowing researchers to track the spread of the virus. Data collected by citizen scientists may also support virologists in similar applications where highly visible conditions can be tracked using new techniques and technologies.
What are the benefits?
Studying the adomaviruses that cause blotchy bass syndrome provides insight into how these viruses affect their hosts, and whether these viruses share the same tumor-causing properties as other similar viruses. Tracking how these adomaviruses spread will allow USGS and partners determine how blotchy bass syndrome hotspots are created and may provide information into how other similar viruses may spread.
Sources/Usage: Public Domain. View Media Details
States and provinces with suspected cases of blotchy bass syndrome identified from photos submitted by anglers during March 2022 - February 2023. A total of 5,534 photos of black bass from 36 states and provinces were submitted to the Anglers Atlas MyCatch application (left; blue icons). Of these, 362 (6.5% of submissions) photos of bass from 26 states and provinces showed dark spots, which are clinical signs of blotchy bass syndrome (right; red icons). Circle size denotes relative number of photo submissions, with larger circles indicating that more photos were submitted by anglers in that state or province. Gray icons (B) denote the 10 states and provinces where none of the photos submitted showed clinical signs of blotchy bass syndrome. As of December 2024, data used in these figures are not publicly available from West Virginia University. For more information, contact Pat Mazik, Unit Leader of the West Virginia Cooperative Fish and Wildlife Research Unit.
2022 Blotchy Bass Syndrome Biosurveillance Project
Blotchy bass syndrome (BBS) is the presence of hyperpigmentation (melanosis) on the external surface of black basses. This condition has received increased attention from anglers and resource managers in recent years and is a popular topic of discussion and reporting on angling websites and blogging platforms. Advances in discovery and diagnostic capabilities using “next generation sequencing”...
Blotchy Bass Syndrome
Black basses (Micropterus spp) are enigmatic North American sportfishes that support the most economically valuable freshwater sport fishery in the United States and serve as keystone predators within aquatic ecosystems.
Black basses (Micropterus spp) are enigmatic North American sportfishes that support the most economically valuable freshwater sport fishery in the United States and serve as keystone predators within aquatic ecosystems.
Blotchy Swab
A dermal swab being used on a Largemouth Bass at a Bass Pro Shops retail store with a presumptive case of blotchy bass syndrome. We can see the transfer of pigmented epidermal tissue to the swab changing its color. The collected swabs can be used to isolate DNA and RNA which can be used to identify pathogens including those associated with hyperpigmentation.
A dermal swab being used on a Largemouth Bass at a Bass Pro Shops retail store with a presumptive case of blotchy bass syndrome. We can see the transfer of pigmented epidermal tissue to the swab changing its color. The collected swabs can be used to isolate DNA and RNA which can be used to identify pathogens including those associated with hyperpigmentation.
C. Raines Blotchy Bass Swab
Clay Raines, a USGS scientist, performing a dermal swab on a Largemouth Bass at a Bass Pro Shops retail store with a presumptive case of blotchy bass syndrome. The collected swabs can be used to isolate DNA and RNA which can be used to identify pathogens including those associated with hyperpigmentation.
Clay Raines, a USGS scientist, performing a dermal swab on a Largemouth Bass at a Bass Pro Shops retail store with a presumptive case of blotchy bass syndrome. The collected swabs can be used to isolate DNA and RNA which can be used to identify pathogens including those associated with hyperpigmentation.