Bad News for Madagascar Crayfishes !!

[jwfetz]

A recent e-mail I received about the introduction of a self-reproducing crayfish getting released into the wild in Madagascar. This is NOT good news for the unique Madagascar crayfishes!

Many of you will have already heard the bad news that Procambarus, a North American crayfish genus, has invaded Madagascar. This is very bad news for native crayfish (Astacoides) and potentially for other aquatic biodiversity and even for rice farmers. The invader has been preliminarily identified as 'Marmorkrebs', a new species of Procambarus related to P. fallax by German taxonomist Chris Lukaup. I attach a paper in Nature and a Nature news article which describes a frightening feature of Marmorkrebs: it can reproduce by parthenogenesis (reproduces without the need of males). This makes it potentially extremely invasive. Mrs. Rasamy of the University of Tana has collected about 50 individuals, all of them females. She first found them 2 years ago in a swamp near Tana but says they are spreading fast and are now sold in markets all over town.

There are a number of reasons to be seriously concerned about the spread of Procambarus in Madagascar:

1) They may carry a fungal disease (Aphanomyces astaci) known as crayfish plague. North American species are immune but Astacoides are likely to suffer extremely high mortality. Where plague has been introduced to non-immune populations, local extinctions have followed.

2) Procambarus are voracious predators of tadpoles and aquatic invertebrates and may cause serious changes to aquatic ecosystems in general.

3) Where Procambarus has been introduced in rice growing areas (e.g. Spain and Portugal) they have become an important pest of rice fields, damaging banks and disrupting irrigation through burrowing and eating seedlings.

I think we need to carry out urgent surveys to establish how fast Procambarus is spreading. We need to look at how Procambarus is acting in the Madagascar rice farming context (is it causing problems to rice farmers? how great are these problems?). We also need to look and see if Madagascar populations of Procambarus are carriers of the plague.

Please forward this message to anyone you feel might be interested in
this issue.

[Chris]

This is indeed very bad news.....

I think it´s very important to keep an eye on the ongoing range expansion (including any vectors, like the food trade). Public education and prevention of any human mediated translocation may be of primary interest.
If I recall correctly most Astacoides species are native to headwater streams and rivers at higher altitudes. I doubt that Procambarus will rapidly spread upstream, thus from my perspective, the actual risk is that some specimens might be translocated by locals.