Although there is a lot of information about Carassius species, I could not found any methodological guideline nor successful practice of controlling invasive Carassius species in the lakes. Can any one suggest something or indicate relevant literature?
I am interesting in C. gibelio. However I think if one can control C. auratus, then gibel carp can be controlled also in similar ways
Yes, I mean killing. Although no specific researches has been done, in some lakes I have evidence that gibel carp is out competing other cyprinids which results significant fall of lake productivity. If this will be true (after some investigation) then the question will be removing all the gibels, or maintaining them in low abundance
Dear Elias, thank you for providing interesting links (but I could not open first one).
According to Georgian legislation rough intervention in any freshwater ecosystem is strictly forbidden. At the same time however the same legislation charges leaseholders to remove entirely or reduce at least 80% of Carassius carp from the lake. There is no any guideline or suggestion of how one can do this. We are asked to help the leaseholders in performing their obligations.
Another interesting thing is that recently our Ministry of Nature Protection initialized a project to update national biodiversity strategy and action plan which includes also chapters for improving or modernize legislative bases. We are also included in this process.
This is the current state.
In fact the aim is to reduce the Carassius species and if possible remove it entirely. It appeared in Georgia 30 years ago. From one lake near Black Sea there were old data about existence of Carassius carassius with low abundance, but it is not there any more. Instead there is Carassius gibelio with enormously high density and the same is in almost all lakes in Georgia. No data exists about the effects on the other native species and we are going to gain such data. In parallel I am trying to work out the strategy control that species which then would be offered to the government to be supported.
Introduction of conspecifics that will breed with an produce non- viable offspring or sterile offsprings is an option or the introduction of a natural predator like the pike fish or large-mouth bass fish.
Proper evaluations must be made to foresee potential negative sides of this intervention to the lake ecosystem, and of course all interventions must be guided by the native (national) laws on alien species.
Hi Dana:
First of all, i think its important to note that this suggested intervention is not an immediate process, but a gradual but more natural approach to solving this problem, and more importantly is subject to research.
Although i don't have references directly reporting such successes, but i've in times past come across literature on the incidence of hybridization among some fish species (including cichlids) and the inference was that a number of species have conspecifics (ecological neighbors) in nature which are not their species but look like their species and hybridizing with these species result in hybrids which are often sterile.
The good part of hybridization is that it produces offspring which are most times better adapted to the environment than the parent species leading to a natural selection of the hardier breed. This means that with a hardier breed the original species (fertile population) are more likely to be out-survived thus resulting in a reduction in their population.
it is also important to note that in nature conspecifics are unlikely to be avoided by the fertile population especially if the prevalent reproductive cues are visual cues, thus creating a near-equal probability of being mated with.
Dear Dana, i strongly agree with the uncertainties and complexities that you have highlighted by my suggestions, but i think i have another idea that might be cheaper, cost effective and easily research-able on a short term to confirm its feasibility and effectiveness on a larger scale.
I strongly believe that information from reproductive cues of this species can be harnessed to solve this problem if the parameters i anticipate really align.
First of all i believe that the prevalent reproductive cue i.e visual, sound or chemical should be investigated.
An introduction of this cue downstream of the lake or at a suitable location of the lake can cause a large or mass aggregation of these fish species towards the source of the cue, and this will allow for a mass evacuation of these species by some means.
The principle of this proposal is that sound and chemical cues are documented as cues that allow for high mating accuracy, meaning that these cues have a lower likelihood of overlapping across species, thus when they are introduced, its accuracy of attracting only the species of interest is ensured.
" do you think that building and running this model is possible?"
Yes, this is possible to do and I think I can easily cope with. The Idea is truly interesting which at least is very good research subject. However it must be noted that this species reproduces ginogenetically and hence is not depended much on the fertilization. Since either con-specific or other cyprinids can still produce sperms Carassius species will produce fertile offspring (although I am not sure if sterility means that sperms will not able to stimulate eggs). Anyway there must be some published data on this subject and I will check it
Hi dear friends,
I think control of Carasius carp in lake is so hard. in lakes we cant do anything.
Unfortunately Carasius carp is omnivores, eurytherm, resistant to environmental conditions and sometimes has a parthenogenesis reproduction system.
anyway, now we are working on biology, diet and reproduction study of northern Pick in Zrebar lake in the west of Iran. The food preference of northern Pick is Carasius carp and I think in closed lakes it can be helpful. but we should to know the northern Pick is strong predator of fish and is a very big treat for endemic fish.
Developed commercial fisheries well control the abundance of Carassius auratus complex in southern Russia. However, for this control to be established, it was necessary to organize the production of fish products from it and the marketing of these products. In addition, almost every year there is a mass mortality of Carassius auratus complex. Probably from viral diseases. However, viral diseases of the Carassius auratus complex are not studied in Russia.
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