In general, control of invasive species in any ecosystem is difficult as one must take into account how the invasive species interacts with the community, whether or not another organism has become dependent on the presence of the invasive species. However, the introduction of any non-specific poison into an ecosystem is never the proper method of removing any species from an ecosystem. This could possibly result in the removal of more than the target species. This would drastically affect the community structure present in the area. Even more so, if one of the species affected by the poison is a keystone species. The removal of a keystone species might cause a collapse in the structure and dynamics of the community. Thus the best choice in handling invasive species are methods which are specific only to the target species. This usually entail biological or mechanical methods as chemical methods are usually non-specific. Neither of these methods are easy. Mechanical methods require effort as this entails fishing of the target species until population levels drop. This is highly ineffective for large populations. Biological methods entail the introduction of a consumer or parasite or any organism which lowers the fitness of the target species. This however needs careful planning as the newly introduced species may eventually become invasive too.

You may be interested in this website as they describe the different methods of managing invasive species

http://eeweek.org/assets/EDN%20Lesson%20Plans/Invasive%20Species%20and%20ClimateKS.pdf

..is the poison species specific? And by the way what is the name of this poison?

Dear Sofia

The technique is controversial as it may also affect other non-target species living in the water. Further, the birds and other carnivores that would feed on the dead carcasses of the poisoned fished (or other organisms in the water) may either accumulate the poison in their tissues or may get negatively affected by it. However, as experts say that most of the native organisms may recover quickly/ or will be introduced once again into the lake system. It all depends on the concentration of the poison used, its residence time in the water, its chances of bioaccumulation along food chain (metabolic pathway), etc. I am sure that the local authorities will undertake elaborate studies to decide upon its introduction into the water bodies.

Best

Dola

Dear Sofia, is there a chance that you have a picture of secondary ecological succession in mind, where you wipe out all or most of the existing species, and perhaps new/ desired species are re-introduced to recolonize the habitat????

Well ! I don't think this is the best option. It will definitely going to harm the ecology of lake. I will suggest some non-hazardous, bio-remedial measures or some thing like which will slow down the fertility rate of silver fish or to introduce some species in the lake which feed on silver fishes. I think this will not harm the food web of the lake as well.

In my opinion poisoning the lake is not the best solution to the problem. The poison may affect the conditions of the lake and lead to the death of other species too if it does not target just the silver fish. Drastic changes to the feeding relationships within the community may also occur.

Hi Sofia! I think this is not a viable solution since there are numerous factors that have to be considered before introducing a poison into the lake. First of all, the poison must be assessed whether it is poisonous to the silver fish alone or it generally affects the entire ecosystem. Next thing to consider is what niche does the silver fish occupy in the ecosystem. Is it one of the keystone species? If it is, then their removal would cause a top-down effect on the ecosystem. Another factor to consider is the resistance and resilience of the ecosystem. Hypothetically speaking, if this poison were to wipe out all organisms, will the lake be resilient enough to recuperate from the damage caused? Moreover, will it able to proceed with secondary succession after?

These are some of the many factors that have to be considered before resorting to such a solution. I think the more appropriate solution would be to introduce a new species which specifically feeds on silver fish to prevent further damage to the ecosystem.

I think adding poison to a lake to wipe out a certain species is definitely not the best option, because even though that certain species is not a keystone species and its extinction from the lake would not affect much of the food web or trophic levels, adding poison change the different abiotic factors within the lake that sustains life to both the floral and faunal species to it. It would not only wipe out the silver fish but also put a damage on other species because poisoning is one kind of disturbance, which I think would be hard for an ecosystem to recover from, especially that it is brought by human interference.

Thank you all for your contributions.

In fact, poisoning water bodies may seem extreme, but experts say this is a necessary evil; if topmouth gudgeon spread throughout UK river systems it will be an ecological disaster for fisheries. Personally, I believe these actions should be carefully taken. Do ends really justify the means?

..i think the question should be, does the means really justify the end? i still think poisoning a water body to kill a species is unjustifiable particularly when nothing has been said about the nature of the poison, its toxico-kinetics, the risk factors to man and other species and much more is still unknown. I dont know how things are done in your country but i think the government or executors of this intended annihilation owes the good people of the country a written document showing the expected impact assessment.

I suggest targeting spawning grounds of these species and use a strategy that entails elimination of the eggs or larva of these species.

Just to add up, parasites of Topmouth Gudgeon consists of 84 species (Protozoa 40, Monogenea 10, Cestoda 3, Trematoda 16, Nematoda 3, Acanhocephala 6, Bivalvia 1, Crustacea 4, Hirudinea 1).

Here is an article, may be of your interest

http://link.springer.com/article/10.1134%2FS2075111712010079

In general, control of invasive species in any ecosystem is difficult as one must take into account how the invasive species interacts with the community, whether or not another organism has become dependent on the presence of the invasive species. However, the introduction of any non-specific poison into an ecosystem is never the proper method of removing any species from an ecosystem. This could possibly result in the removal of more than the target species. This would drastically affect the community structure present in the area. Even more so, if one of the species affected by the poison is a keystone species. The removal of a keystone species might cause a collapse in the structure and dynamics of the community. Thus the best choice in handling invasive species are methods which are specific only to the target species. This usually entail biological or mechanical methods as chemical methods are usually non-specific. Neither of these methods are easy. Mechanical methods require effort as this entails fishing of the target species until population levels drop. This is highly ineffective for large populations. Biological methods entail the introduction of a consumer or parasite or any organism which lowers the fitness of the target species. This however needs careful planning as the newly introduced species may eventually become invasive too.

You may be interested in this website as they describe the different methods of managing invasive species

http://eeweek.org/assets/EDN%20Lesson%20Plans/Invasive%20Species%20and%20ClimateKS.pdf

For me, the use of poison is not the best way to wipe out a certain species. Introducing poison can not only threaten the life of the silver fish but also other organisms. It can generally affect the whole river or lake. Other ways of removing invasive species as this may be studied.

One basic question here is regarding the specificity of the poison. If it targets only the silver fish, then maybe it's justifiable. But laboratory tests would hardly be able to predict how water dynamics and the trophic structure would influence the activity of that poison. If it is not at all species-specific, then I don't think it's justified at all. After all, we'd like to get rid of invasive species to save the ecosystem. Why do something that will harm the native species? Like the others said, maybe biological control with the fish's natural predator will be better, but that it nearly always a slippery slope that one should be very careful with.

Well said Ronald, two wrongs really don't make a right!

Don't you all think that the Environment Agency (the UK goverment body carrying out this eradication) would have thought about all these issues? On balence, if a handful of lakes are slightly "damaged" by this poison, as long as the invasive species is wiped out and does not get into the river systems (where eradication would be almost impossible), then it has to be the only viable option.

S.A.: "Lakes in the UK are to be poisoned"

with what?

...unless we know the poison of choice we cannot project the potential ecological damage.

So Sofia, does the poison have a name?

Topmouth gudgeon = Pseudorasbora parva. I was wondering what is this godzilla army that will invade and destroy the whole UK ;-)

We have P. parva in France and I've never heard that it eradicate salmonids. They don't even live together ! Plus, it's not that invasive. I've caught many invasive species by angling like hundreds of Lepomis gibbosus, Ameirus melas and Silurus glanis, but I've never caught any P. parva in my life.

I quote the end of the posted article:

"Last year 17 lakes at Clawford Vineyard Fishery in Devon were treated but its managers says business was affected. John Ray, 69, said: “All the frogs disappeared and fish stocks are only just starting to recover now.”"

The "piscicide" used is rotenone. Its use has been banned by E.U. ;-)

This so-called "piscicide" is in reality ectothermicide. That's why the frog disappeared. I believe that eliminating P. parva is not for salmonid protection but for fish farmer's business protection...

The article mentions that the poison is harmless to mammals and that invertebrates "will quickly recover", which, I interpret to mean "will be replaced by migration from unpoisoned sources", etc. I rarely see "harmless" used in this context as other than an LD50 number, etc...and rarely used regarding the collateral damage/ the impact on, say, what the mammals (And other non-target species) are supposed to eat while waiting for said "recovery", etc.

I know poisoning has been done in the past, in other bodies of water infested with invasive species, with varying results. The use of imported parasites/predators specific to the invasive species/not ("Supposed to") dangerous to native species, has been used as well, also with some unintended consequences.

I worry about species that may not have been discovered yet, being extinguished in the parva-caust, and other unforeseeable collateral damage that can occur when we invoke purposeful targeted mass extinction.

Hi Sofia, if we reflect as ecologists, this is not at all the right option.In fact, we should know the exact impact of the poison on the environment and all species that live there.

the best solution is to make the biological control against this invasive but then you really should know the main predator of this species in order, not to kill other species.

we can fish regularly, put the invasive fish out of water (can be fed to cats!) and quickly replace other species in the lake (just as the capture-recapture method). But this approach is very time consuming and expensive!

But to find a solution to invasive species is still difficult.

..do we need to say more to show how wrong this'poisonous option' really is? But i'm still interested in the name of the poison of choice, perhaps it we could draw out some important dimensions to this discussion.

Not at all. Using poison to eradicate invasive species from lake is never a good choice. What about the ecology and ecosystem of the lake? If eradication of invasive species is that easy then we might not have any invasive species in the nature by this time. To me biological methods should be used to control the invasive species because past experience tell us that it is not easy to eradicate invasive species from a water body as big as a lake.