06-01-2011, 07:34 PM
Just because the DNR stocked a few carp in the 1880s (I thought the rest were privately introduced, but I wouldn't be surprised if the government encouraged stocking them until about the 1970s) doesn't make it justified. The carp may not consume native species but they do:
1. eat from the base of the food chain
2. Destroy spawning beds
3. Destroy water quality
Number three is the one that scares me the most. When I say "water quality" I mean to say that they contribute to stratifying phosphorus by kicking up sediment. They destroy ecosystems. This isn't to say they're the reason a eutrophic lake goes into overdrive; we also have to consider fertilizers and damming.
But the problem occurs when we compound the factors; damming slows water currents. Coupled with an algae bloom, oxygen will be depleted. The system will go from a eutrophic body of water to a hypereutrophic body of water. During this period only a few species will survive; namely, bullheads and carp, and maybe channel catfish.
It seems far fetched, but it happens a lot in Illinois:
1. River is dammed; oxygenation is impeded
2. A dry season- people overcompensate with fertilizers
*2. farmers' fertilizers run off into river
3. Algae bloom further depletes oxygen
4. Cold winter with heavy snows freezes water, further depleting oxygen
5. Spring thaw
When spring thaw arrives, what's left are nothing but carp. They flood into the river system. The original body of water, meantime, will reach its max population density... with carp. Native fish populations can't fit back into the ecosystem. Whether or not they compete directly with carp doesn't actually matter. The system becomes so imbalanced that it can't support more fish. This happened in a lake near me- even the carp stopped breeding temporarily. The native fish are tiny; with carp at the base of the food chain, the forage species are dwindling. Carp also make the water so muddy that bass have difficulty spawning.
And I am never in support of planned aclimatization/ species introduction. I am against stocking non-native salmonoids in the Great lakes, introducing flatheads to the Potomac and rivers in the Carolinas, nor do I support spreading bass beyond their natural ecosystems.
Carp are especially concerning because they don't even belong on the North American continent. They decrease water visibility by kicking up mud and many top-tier gamefish like walleye and various esox have evolved to thrive in clear water.
If you don't agree with me, I suggest you read reports of flathead introduction Minnesota lakes as a method to control carp populations. Bearing in mind that flathead are apex predators, it should becof little surprise that they reduced carp populations by 90% in some cases. What may surprise you is that the quality of native game fish spiked drastically; as carp declined, native fish grew larger. You can attribute this to flathead controlling gamefish species- but that doesn't account for bass and Muskies growing larger and healthier. Especially when a survey of the flatheads' stomach contents showed that they preyed almost entirely on young carp.
If this doesn't convince you that carp negatively effect gamefish populations, check out the reports of all the lakes where flathead weren't introduced and carp persisted. A few years after carp are introduced, the native fish species, including bass and crappie, are negatively impacted.
At the very least, take the carp home and bury them in your garden for a natural fertilizer. This helps reduce carp numbers and fertilizer use.
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1. eat from the base of the food chain
2. Destroy spawning beds
3. Destroy water quality
Number three is the one that scares me the most. When I say "water quality" I mean to say that they contribute to stratifying phosphorus by kicking up sediment. They destroy ecosystems. This isn't to say they're the reason a eutrophic lake goes into overdrive; we also have to consider fertilizers and damming.
But the problem occurs when we compound the factors; damming slows water currents. Coupled with an algae bloom, oxygen will be depleted. The system will go from a eutrophic body of water to a hypereutrophic body of water. During this period only a few species will survive; namely, bullheads and carp, and maybe channel catfish.
It seems far fetched, but it happens a lot in Illinois:
1. River is dammed; oxygenation is impeded
2. A dry season- people overcompensate with fertilizers
*2. farmers' fertilizers run off into river
3. Algae bloom further depletes oxygen
4. Cold winter with heavy snows freezes water, further depleting oxygen
5. Spring thaw
When spring thaw arrives, what's left are nothing but carp. They flood into the river system. The original body of water, meantime, will reach its max population density... with carp. Native fish populations can't fit back into the ecosystem. Whether or not they compete directly with carp doesn't actually matter. The system becomes so imbalanced that it can't support more fish. This happened in a lake near me- even the carp stopped breeding temporarily. The native fish are tiny; with carp at the base of the food chain, the forage species are dwindling. Carp also make the water so muddy that bass have difficulty spawning.
And I am never in support of planned aclimatization/ species introduction. I am against stocking non-native salmonoids in the Great lakes, introducing flatheads to the Potomac and rivers in the Carolinas, nor do I support spreading bass beyond their natural ecosystems.
Carp are especially concerning because they don't even belong on the North American continent. They decrease water visibility by kicking up mud and many top-tier gamefish like walleye and various esox have evolved to thrive in clear water.
If you don't agree with me, I suggest you read reports of flathead introduction Minnesota lakes as a method to control carp populations. Bearing in mind that flathead are apex predators, it should becof little surprise that they reduced carp populations by 90% in some cases. What may surprise you is that the quality of native game fish spiked drastically; as carp declined, native fish grew larger. You can attribute this to flathead controlling gamefish species- but that doesn't account for bass and Muskies growing larger and healthier. Especially when a survey of the flatheads' stomach contents showed that they preyed almost entirely on young carp.
If this doesn't convince you that carp negatively effect gamefish populations, check out the reports of all the lakes where flathead weren't introduced and carp persisted. A few years after carp are introduced, the native fish species, including bass and crappie, are negatively impacted.
At the very least, take the carp home and bury them in your garden for a natural fertilizer. This helps reduce carp numbers and fertilizer use.
[signature]