Non-native species are plants and animals that are not native to our area. Some, like brook trout, come from east of the Continental Divide. Others, like spotted knapweed or whirling disease, come from as far away as Europe or Asia. Non-natives often have advantages over native species because insects, diseases, and animals that would normally control them are absent. And many non-natives, whether they are fish or plants, thrive in areas that have been degraded or disturbed by human activities; all the more reason to take care of streams and riparian areas. Explore the impacts of non-natives on the Jocko River by clicking through the slides using the slide-navigation buttons () below.
Brook Trout
Hybrids
Hybridization
One of the major threats brook trout pose is that they can hybridize with bull trout. Most but not all bull trout x brook trout hybrids are sterile. Hybridization threatens bull trout in several ways:
(1) There is a wasted reproductive effort on the part of already-threatened bull trout populations;
(2) There is a mixing of genetic material between the two species, potentially resulting in a loss of bull trout genes; and
(3) There is the potential introduction of a highly competitive hybrid population.
Competition
Brook trout compete with native trout for food, space, and other resources. Brook trout have a reproductive advantage over bull trout. They reproduce earlier and at a higher rate and so can supplant them. The two species compete for food, and brook trout appear to be more aggressive. Young brook trout also have signifi-cantly higher growth rates than young bull trout. Brook trout have an especially strong advantage over bull trout at warmer water temperatures. So global warming and the loss of riparian habitat will help non-native brook trout at the expense of native bull trout.
Brook trout also outcompete juvenile westslope cutthroat trout for food. Experience shows that once brook trout dominate a stream, cutthroat trout never regain it.
Rainbow Trout
Hybridization
Hybrids
Rainbow trout pose one of the greatest threats to native westslope cutthroat trout because both spawn in the spring and can interbreed or hybridize.
Hybrid trout may be perfectly good fish for angling, but because they carry non-native trout genes, they are a threat to the genetically pure native westslopes. If the problem is not corrected, rainbows and cut-throat-rainbow hybrids will continue mixing with the native westslopes, and the west-slope cutthroat trout population will eventually be lost.
Hybrid characteristics include slashes and rose-colored ventral region (WCT traits) and profuse spotting and a hint of a red mid-lateral band (rainbow traits).
Competition
Rainbow trout and brook trout are considered the most significant competitors with native westslope cutthroat trout and native bull trout, even to the extent of wiping out westslope cutthroat trout populations in some areas. Rainbows compete for food and habitat with both bulls and cutthroats and, when it comes to westslope cutthroat trout, they also compete for mates.
Water temperature plays a central role in how much competition there is between bull trout and rainbow trout. Higher water temperatures may not completely exclude bull trout, but they may well shift the competitive advantage toward rainbow and brook trout.
Brown Trout
Competition and Predation
Brown trout impact both bull trout and westslope cutthroat trout. In some Rocky Mountain streams, brown trout have caused bull trout populations to decline. Elsewhere, they have even contributed to their extirpation (local extinction). That's because brown trout occupy the same niche as bull trout and achieve a similar size. Both eat fish, so they compete for food. They also compete for space and spawning habitats. Brown trout can also prey on young bull trout.
Brown trout prey on westslope cutthroat trout too, and competition between the two is believed to have caused the displacement of some westslope cutthroat trout populations. This has most often occurred in conjunction with habitat degradation, which has made waters more suitable for introduced fish like brown trout. Higher water temperatures, especially, shift the competitive advantage towards brown trout.
Whirling Disease
A Non-Native that Kills
Whirling disease is a parasitic infection caused by a non-native, microscopic organism called Myxobolus cerebralis. Myxobolus cerebralis (abbreviated hereafter as Mc) infiltrates the head and spinal cartilage of fingerling trout like westslope cutthroat, rainbow, and brown, causing spinal deformities and decreased abilities for feed. Once in the fish, it multiplies rapidly, and because it affects the fingerling’s organ of equilibrium, it often causes it to swim erratically and in a whirling pattern.
In severe cases, the fish dies, and when an infected fish dies, millions of tiny, nearly indestructible Mc spores (each about the size of a red blood cell) are released to the water where they can survive in this “dormant” form for 20 to 30 years. They fall on to the bottom of the stream and are covered by sediments.
Eventually, many of the spores are ingested by Tubifex worms that live in the sediments (tubifex worms are sometimes called sludge worms). Inside the worm, the spore changes and is then released in a highly infective form, called the Triactinomyxon (TAM). TAMs are free-floating in the water until they infect trout, beginning the cycle over again. Rainbow and cutthroat trout are the most vulnerable to whirling disease, but it can infect all salmonid species.
What does an infected fish look like? Typical signs of whirling disease include a darkened tail, twisted spine and deformed head (shortened, twisted jaw). Young fish may also swim erratically (whirl). However, other diseases and even genetic conditions can cause these signs as well. If you see fish with these signs in an area where whirling disease has not been reported, you should contact the Tribes’ Fisheries Program or if you are off the Reservation, the state fisheries agency—in Montana, Montana Fish, Wildlife & Parks.
1. The TAMS
This is the TAM stage of Myxobolus cerebralis. TAMs are a free-floating form of the parasite released by the tubifex worms. They float in the water until they infect trout fry.
2. The Spores (called Myxospores)
Myxobolus cerebralis spores enter stream sediments when infected trout die and decay. Each fish can release many thousands to millions of the parasite spores into the water. Each spore is virtually indestructible -- it can live in a stream (or former stream) for 20 - 30 years through freezing temperatures and drought.
3. Infected Trout Fry or Fingerlings
The parasite penetrates the head and spinal cartilage of fingerling trout. There, it multiplies rapidly, deforms the body, and affects the organ of equilibrium, which causes the fish to swim erratically in a whirling pattern. Feeding and avoiding predators becomes difficult. In severe infections, the disease causes high rates of mortality in young fish. Those that do survive until their cartilage hardens to bone can live a normal life span, but they are marred by skeletal deformities and that reduces reproduction, although fish can reproduce without passing on the parasite to their offspring.
4. Tubifex Worms
Eventually a spore will be ingested by its alternate host, a tiny, common aquatic worm known as Tubifex tubifex. In the worm, the spores change into the highly infectious stage of Myxobolus cerebralis, the TAM stage that infects trout fry.
What Can We Do To Prevent the Spread of Whirling Disease?
Stocking or natural movement of live, infected fish is the primary route by which whirling disease is spread. However, there are other ways that the parasite can be spread, including by birds and humans – particularly boaters and anglers.
But is there anything anglers and boaters can do to help prevent further spread? Absolutely! Anglers, boaters, and others can make a difference. Distribution of the parasite is expanding rapidly in some areas, so you should assume its presence if you don’t know otherwise. Recommended precautions that will help prevent not only the spread of whirling disease, but also other disease-causing organisms and aquatic pests include:
1. Never transport live fish from one water body to another. (This is illegal under Tribal and state regulations.)
2. Do not use trout, whitefish, or salmon parts as cut bait.
3. Dispose of fish entrails and skeletal parts properly. Never discard fish parts in or near streams or rivers. Because an infected fish may harbor tens of thousands of myxospores, simply disposing of infected fish parts in a clean drainage could provide enough spores to start an infection. Do not discard fish parts in a kitchen disposal. Whirling disease myxospores can survive most wastewater treatment systems. Instead, discard in dry waste that would go to a landfill.
4. Rinse all mud and debris from equipment and wading gear, and drain water from boats before leaving an infected drainage. This is good practice for preventing transfer of other aquatic hitchhikers as well.
Non-Native Plants
Reed canarygrass, introduced as early as the 1880s, has probably had a greater effect on native plants than any other weed. It was typically seeded on wet pastures to improve hay and forage yields. But it’s aggressive and spreads prolifically, and it can rapidly colonize a range of moisture conditions, forming large monocultures and almost totally precluding the establishment of woody vegetation.
Non-native species are plants and animals that are not native to our area. Some, like brook trout, come from east of the Continental Divide. Others, like spotted knapweed or whirling disease, come from as far away as Europe or Asia. Non-natives often have advantages over native species because insects, diseases, and animals that would normally control them are absent. And many non-natives, whether they are fish or plants, thrive in areas that have been degraded or disturbed by human activities; all the more reason to take care of streams and riparian areas. Explore the impacts of non-natives on the Jocko River by clicking through the slides using the slide-navigation buttons () below.
Brook Trout
Hybrids
Hybridization
One of the major threats brook trout pose is that they can hybridize with bull trout. Most but not all bull trout x brook trout hybrids are sterile. Hybridization threatens bull trout in several ways:
(1) There is a wasted reproductive effort on the part of already-threatened bull trout populations;
(2) There is a mixing of genetic material between the two species, potentially resulting in a loss of bull trout genes; and
(3) There is the potential introduction of a highly competitive hybrid population.
Competition
Brook trout compete with native trout for food, space, and other resources. Brook trout have a reproductive advantage over bull trout. They reproduce earlier and at a higher rate and so can supplant them. The two species compete for food, and brook trout appear to be more aggressive. Young brook trout also have signifi-cantly higher growth rates than young bull trout. Brook trout have an especially strong advantage over bull trout at warmer water temperatures. So global warming and the loss of riparian habitat will help non-native brook trout at the expense of native bull trout.
Brook trout also outcompete juvenile westslope cutthroat trout for food. Experience shows that once brook trout dominate a stream, cutthroat trout never regain it.
Rainbow Trout
Hybridization
Hybrids
Rainbow trout pose one of the greatest threats to native westslope cutthroat trout because both spawn in the spring and can interbreed or hybridize.
Hybrid trout may be perfectly good fish for angling, but because they carry non-native trout genes, they are a threat to the genetically pure native westslopes. If the problem is not corrected, rainbows and cut-throat-rainbow hybrids will continue mixing with the native westslopes, and the west-slope cutthroat trout population will eventually be lost.
Hybrid characteristics include slashes and rose-colored ventral region (WCT traits) and profuse spotting and a hint of a red mid-lateral band (rainbow traits).
Competition
Rainbow trout and brook trout are considered the most significant competitors with native westslope cutthroat trout and native bull trout, even to the extent of wiping out westslope cutthroat trout populations in some areas. Rainbows compete for food and habitat with both bulls and cutthroats and, when it comes to westslope cutthroat trout, they also compete for mates.
Water temperature plays a central role in how much competition there is between bull trout and rainbow trout. Higher water temperatures may not completely exclude bull trout, but they may well shift the competitive advantage toward rainbow and brook trout.
Brown Trout
Competition and Predation
Brown trout impact both bull trout and westslope cutthroat trout. In some Rocky Mountain streams, brown trout have caused bull trout populations to decline. Elsewhere, they have even contributed to their extirpation (local extinction). That's because brown trout occupy the same niche as bull trout and achieve a similar size. Both eat fish, so they compete for food. They also compete for space and spawning habitats. Brown trout can also prey on young bull trout.
Brown trout prey on westslope cutthroat trout too, and competition between the two is believed to have caused the displacement of some westslope cutthroat trout populations. This has most often occurred in conjunction with habitat degradation, which has made waters more suitable for introduced fish like brown trout. Higher water temperatures, especially, shift the competitive advantage towards brown trout.
Whirling Disease
A Non-Native that Kills
Whirling disease is a parasitic infection caused by a non-native, microscopic organism called Myxobolus cerebralis. Myxobolus cerebralis (abbreviated hereafter as Mc) infiltrates the head and spinal cartilage of fingerling trout like westslope cutthroat, rainbow, and brown, causing spinal deformities and decreased abilities for feed. Once in the fish, it multiplies rapidly, and because it affects the fingerling’s organ of equilibrium, it often causes it to swim erratically and in a whirling pattern.
In severe cases, the fish dies, and when an infected fish dies, millions of tiny, nearly indestructible Mc spores (each about the size of a red blood cell) are released to the water where they can survive in this “dormant” form for 20 to 30 years. They fall on to the bottom of the stream and are covered by sediments.
Eventually, many of the spores are ingested by Tubifex worms that live in the sediments (tubifex worms are sometimes called sludge worms). Inside the worm, the spore changes and is then released in a highly infective form, called the Triactinomyxon (TAM). TAMs are free-floating in the water until they infect trout, beginning the cycle over again. Rainbow and cutthroat trout are the most vulnerable to whirling disease, but it can infect all salmonid species.
What does an infected fish look like? Typical signs of whirling disease include a darkened tail, twisted spine and deformed head (shortened, twisted jaw). Young fish may also swim erratically (whirl). However, other diseases and even genetic conditions can cause these signs as well. If you see fish with these signs in an area where whirling disease has not been reported, you should contact the Tribes’ Fisheries Program or if you are off the Reservation, the state fisheries agency—in Montana, Montana Fish, Wildlife & Parks.
1. The TAMS
This is the TAM stage of Myxobolus cerebralis. TAMs are a free-floating form of the parasite released by the tubifex worms. They float in the water until they infect trout fry.
2. The Spores (called Myxospores)
Myxobolus cerebralis spores enter stream sediments when infected trout die and decay. Each fish can release many thousands to millions of the parasite spores into the water. Each spore is virtually indestructible -- it can live in a stream (or former stream) for 20 - 30 years through freezing temperatures and drought.
3. Infected Trout Fry or Fingerlings
The parasite penetrates the head and spinal cartilage of fingerling trout. There, it multiplies rapidly, deforms the body, and affects the organ of equilibrium, which causes the fish to swim erratically in a whirling pattern. Feeding and avoiding predators becomes difficult. In severe infections, the disease causes high rates of mortality in young fish. Those that do survive until their cartilage hardens to bone can live a normal life span, but they are marred by skeletal deformities and that reduces reproduction, although fish can reproduce without passing on the parasite to their offspring.
4. Tubifex Worms
Eventually a spore will be ingested by its alternate host, a tiny, common aquatic worm known as Tubifex tubifex. In the worm, the spores change into the highly infectious stage of Myxobolus cerebralis, the TAM stage that infects trout fry.
What Can We Do To Prevent the Spread of Whirling Disease?
Stocking or natural movement of live, infected fish is the primary route by which whirling disease is spread. However, there are other ways that the parasite can be spread, including by birds and humans – particularly boaters and anglers.
But is there anything anglers and boaters can do to help prevent further spread? Absolutely! Anglers, boaters, and others can make a difference. Distribution of the parasite is expanding rapidly in some areas, so you should assume its presence if you don’t know otherwise. Recommended precautions that will help prevent not only the spread of whirling disease, but also other disease-causing organisms and aquatic pests include:
1. Never transport live fish from one water body to another. (This is illegal under Tribal and state regulations.)
2. Do not use trout, whitefish, or salmon parts as cut bait.
3. Dispose of fish entrails and skeletal parts properly. Never discard fish parts in or near streams or rivers. Because an infected fish may harbor tens of thousands of myxospores, simply disposing of infected fish parts in a clean drainage could provide enough spores to start an infection. Do not discard fish parts in a kitchen disposal. Whirling disease myxospores can survive most wastewater treatment systems. Instead, discard in dry waste that would go to a landfill.
4. Rinse all mud and debris from equipment and wading gear, and drain water from boats before leaving an infected drainage. This is good practice for preventing transfer of other aquatic hitchhikers as well.
Non-Native Plants
All the plants listed in the image at right are weeds that grow along the Jocko. Depending on the plant and/or its location, infestations of noxious and non-native weed species (hereafter referred to as weed species) have many ecological consequences, including altering hydrologic cycles, increasing erosion, displacing desirable native vegetation, and reducing forage and cover for wildlife. In particular, weeds are highly competitive with native plant species for resources like water, nutrients, and light, and their presence can hinder or prevent the restoration of native plant communities.
Reed canarygrass, introduced as early as the 1880s, has probably had a greater effect on native plants than any other weed. It was typically seeded on wet pastures to improve hay and forage yields. But it’s aggressive and spreads prolifically, and it can rapidly colonize a range of moisture conditions, forming large monocultures and almost totally precluding the establishment of woody vegetation.
Non-native species are plants and animals that are not native to our area. Some, like brook trout, come from east of the Continental Divide. Others, like spotted knapweed or whirling disease, come from as far away as Europe or Asia. Non-natives often have advantages over native species because insects, diseases, and animals that would normally control them are absent. And many non-natives, whether they are fish or plants, thrive in areas that have been degraded or disturbed by human activities; all the more reason to take care of streams and riparian areas. Explore the impacts of non-natives on the Jocko River by clicking through the slides using the slide-navigation buttons () below.
Brook Trout
Hybrids
Hybridization
One of the major threats brook trout pose is that they can hybridize with bull trout. Most but not all bull trout x brook trout hybrids are sterile. Hybridization threatens bull trout in several ways:
(1) There is a wasted reproductive effort on the part of already-threatened bull trout populations;
(2) There is a mixing of genetic material between the two species, potentially resulting in a loss of bull trout genes; and
(3) There is the potential introduction of a highly competitive hybrid population.
Competition
Brook trout compete with native trout for food, space, and other resources. Brook trout have a reproductive advantage over bull trout. They reproduce earlier and at a higher rate and so can supplant them. The two species compete for food, and brook trout appear to be more aggressive. Young brook trout also have signifi-cantly higher growth rates than young bull trout. Brook trout have an especially strong advantage over bull trout at warmer water temperatures. So global warming and the loss of riparian habitat will help non-native brook trout at the expense of native bull trout.
Brook trout also outcompete juvenile westslope cutthroat trout for food. Experience shows that once brook trout dominate a stream, cutthroat trout never regain it.
Rainbow Trout
Hybridization
Hybrids
Rainbow trout pose one of the greatest threats to native westslope cutthroat trout because both spawn in the spring and can interbreed or hybridize.
Hybrid trout may be perfectly good fish for angling, but because they carry non-native trout genes, they are a threat to the genetically pure native westslopes. If the problem is not corrected, rainbows and cut-throat-rainbow hybrids will continue mixing with the native westslopes, and the west-slope cutthroat trout population will eventually be lost.
Hybrid characteristics include slashes and rose-colored ventral region (WCT traits) and profuse spotting and a hint of a red mid-lateral band (rainbow traits).
Competition
Rainbow trout and brook trout are considered the most significant competitors with native westslope cutthroat trout and native bull trout, even to the extent of wiping out westslope cutthroat trout populations in some areas. Rainbows compete for food and habitat with both bulls and cutthroats and, when it comes to westslope cutthroat trout, they also compete for mates.
Water temperature plays a central role in how much competition there is between bull trout and rainbow trout. Higher water temperatures may not completely exclude bull trout, but they may well shift the competitive advantage toward rainbow and brook trout.
Brown Trout
Competition and Predation
Brown trout impact both bull trout and westslope cutthroat trout. In some Rocky Mountain streams, brown trout have caused bull trout populations to decline. Elsewhere, they have even contributed to their extirpation (local extinction). That's because brown trout occupy the same niche as bull trout and achieve a similar size. Both eat fish, so they compete for food. They also compete for space and spawning habitats. Brown trout can also prey on young bull trout.
Brown trout prey on westslope cutthroat trout too, and competition between the two is believed to have caused the displacement of some westslope cutthroat trout populations. This has most often occurred in conjunction with habitat degradation, which has made waters more suitable for introduced fish like brown trout. Higher water temperatures, especially, shift the competitive advantage towards brown trout.
Whirling Disease
A Non-Native that Kills
Whirling disease is a parasitic infection caused by a non-native, microscopic organism called Myxobolus cerebralis. Myxobolus cerebralis (abbreviated hereafter as Mc) infiltrates the head and spinal cartilage of fingerling trout like westslope cutthroat, rainbow, and brown, causing spinal deformities and decreased abilities for feed. Once in the fish, it multiplies rapidly, and because it affects the fingerling’s organ of equilibrium, it often causes it to swim erratically and in a whirling pattern.
In severe cases, the fish dies, and when an infected fish dies, millions of tiny, nearly indestructible Mc spores (each about the size of a red blood cell) are released to the water where they can survive in this “dormant” form for 20 to 30 years. They fall on to the bottom of the stream and are covered by sediments.
Eventually, many of the spores are ingested by Tubifex worms that live in the sediments (tubifex worms are sometimes called sludge worms). Inside the worm, the spore changes and is then released in a highly infective form, called the Triactinomyxon (TAM). TAMs are free-floating in the water until they infect trout, beginning the cycle over again. Rainbow and cutthroat trout are the most vulnerable to whirling disease, but it can infect all salmonid species.
What does an infected fish look like? Typical signs of whirling disease include a darkened tail, twisted spine and deformed head (shortened, twisted jaw). Young fish may also swim erratically (whirl). However, other diseases and even genetic conditions can cause these signs as well. If you see fish with these signs in an area where whirling disease has not been reported, you should contact the Tribes’ Fisheries Program or if you are off the Reservation, the state fisheries agency—in Montana, Montana Fish, Wildlife & Parks.
1. The TAMS
This is the TAM stage of Myxobolus cerebralis. TAMs are a free-floating form of the parasite released by the tubifex worms. They float in the water until they infect trout fry.
2. The Spores (called Myxospores)
Myxobolus cerebralis spores enter stream sediments when infected trout die and decay. Each fish can release many thousands to millions of the parasite spores into the water. Each spore is virtually indestructible -- it can live in a stream (or former stream) for 20 - 30 years through freezing temperatures and drought.
3. Infected Trout Fry or Fingerlings
The parasite penetrates the head and spinal cartilage of fingerling trout. There, it multiplies rapidly, deforms the body, and affects the organ of equilibrium, which causes the fish to swim erratically in a whirling pattern. Feeding and avoiding predators becomes difficult. In severe infections, the disease causes high rates of mortality in young fish. Those that do survive until their cartilage hardens to bone can live a normal life span, but they are marred by skeletal deformities and that reduces reproduction, although fish can reproduce without passing on the parasite to their offspring.
4. Tubifex Worms
Eventually a spore will be ingested by its alternate host, a tiny, common aquatic worm known as Tubifex tubifex. In the worm, the spores change into the highly infectious stage of Myxobolus cerebralis, the TAM stage that infects trout fry.
What Can We Do To Prevent the Spread of Whirling Disease?
Stocking or natural movement of live, infected fish is the primary route by which whirling disease is spread. However, there are other ways that the parasite can be spread, including by birds and humans – particularly boaters and anglers.
But is there anything anglers and boaters can do to help prevent further spread? Absolutely! Anglers, boaters, and others can make a difference. Distribution of the parasite is expanding rapidly in some areas, so you should assume its presence if you don’t know otherwise. Recommended precautions that will help prevent not only the spread of whirling disease, but also other disease-causing organisms and aquatic pests include:
1. Never transport live fish from one water body to another. (This is illegal under Tribal and state regulations.)
2. Do not use trout, whitefish, or salmon parts as cut bait.
3. Dispose of fish entrails and skeletal parts properly. Never discard fish parts in or near streams or rivers. Because an infected fish may harbor tens of thousands of myxospores, simply disposing of infected fish parts in a clean drainage could provide enough spores to start an infection. Do not discard fish parts in a kitchen disposal. Whirling disease myxospores can survive most wastewater treatment systems. Instead, discard in dry waste that would go to a landfill.
4. Rinse all mud and debris from equipment and wading gear, and drain water from boats before leaving an infected drainage. This is good practice for preventing transfer of other aquatic hitchhikers as well.
Non-Native Plants
All the plants listed in the image at right are weeds that grow along the Jocko. Depending on the plant and/or its location, infestations of noxious and non-native weed species (hereafter referred to as weed species) have many ecological consequences, including altering hydrologic cycles, increasing erosion, displacing desirable native vegetation, and reducing forage and cover for wildlife. In particular, weeds are highly competitive with native plant species for resources like water, nutrients, and light, and their presence can hinder or prevent the restoration of native plant communities.
Reed canarygrass, introduced as early as the 1880s, has probably had a greater effect on native plants than any other weed. It was typically seeded on wet pastures to improve hay and forage yields. But it’s aggressive and spreads prolifically, and it can rapidly colonize a range of moisture conditions, forming large monocultures and almost totally precluding the establishment of woody vegetation.
