We are currently catching Astacus leptodactylus in the Danube Delta and the Razim-Sinoie lagoonary area, but reading the mentioned article I was wondering if (and how many) specimens were with the respective disease?
p.s. Taking into account that we are eating that crayfish... I just hope that Aphanomyces astaci can harm only crayfish, not humans.
Article Invasive crayfish and crayfish plague on the move: First det...
It is possible that some A. leptodactylus are indeed infected (likely by a chronic infection without associated ass mortalities) in the region where you are sampling. However, the pathogen prevalence may substantially vary in space, so it can't be even guessed...
The infected individuals that look healthy are perfectly safe to eat - after all, populations of American crayfish are widely used for consumption in Europe, although lots of them are infected by this pathogen...
P.S. Visual inspection for the disease is unreliable. You may look for melanised spots but these are general immune response and are not necessarily associated with infection by A. astaci. Thus, some individuals with melanisation are actually uninfected, and the pathogen DNA may be detected also in animals where macroscopic melanisation is not apparent.
Adam Petrusek: "Visual inspection for the disease is unreliable."
That means that, actually, it is not really possible to establish based on visual observation if a crayfish is infected or not with A. astaci.
Adam Petrusek: "You may look for melanised spots but these are general immune response and are not necessarily associated with infection by A. astaci."
Aha, so the infected individuals have some darker (or even black) spots. I have not really noticed this kind of detail in case of the specimens collected in these years. Or may be they are (very) small spots?
p.s.
Adam Petrusek: "The infected individuals that look healthy are perfectly safe to eat - after all, populations of American crayfish are widely used for consumption in Europe, although lots of them are infected by this pathogen..."
Well, if the manager of a protected wetland will hear that:
1. the infected specimens can be detected ONLY with the use of quite COMPLICATED PROCEDURE,
2. the effect on the wild population is NOT REALLY KNOWN,
3. the disease is NOT HARMFUL (not even transmitted) to human population,
than the administration will no really be occupied with the issue of (in this case native) species with a disease caused by other (in this case alien) species.
Hi Adam! Do you have literature or any more information on Astacus leptodactylus being infected but not dying of the disease? I have only found few information on supposedly "surviving" native populations...
Something like this?
Kokko (H.), Koistinen (L.), Harlioğlu (M. M.), Makkonen (J.), Aydın (H.), Jussila (J.), 2012 - Recovering Turkish narrow clawed crayfish (Astacus leptodactylus) populations carry Aphanomyces astaci. IN: Knowledge and Management of Aquatic Ecosystems, vol. 404.
( http://dx.doi.org/10.1051/kmae/2012006 )
l.e. attached the pdf of the article on the Astacus population-recovery in Turkey...
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