Looking for hope

When I went to the International Association for Astacology meeting last year, the first couple of days were largely concerned with crayfish as invasive species. The phrase that kept kept popping into my head was, “horror show.”

A new review article taps into that concern, asking flat out, “Is there a hope?” in the title. Note the use of the singular. Things are so bad, we are just looking for one hope.

Marmorkrebs make a brief cameo appearance in the paper:

Today, it is extremely easy to buy, via aquarium trade fairs and internet sales, NICS for ornamental use, as shown in the case of both the marbled crayfish (Nonnis Marzano et al. 2009; Peay 2009), a North American species recently identified as a parthenogenetic form of Procambarus fallax (Martin et al. 2010), and the Australian red-claw crayfish C. quadricarinatus in the UK (Peay 2009).

This is in section discussing the prospects for preventing invasive crayfish from becoming established. The laws are inconsistent and many proposed policies have never been implemented.

The bulk of the paper focuses on prospects for managing crayfish that have been already been introduced (with a convenient summary in Table 1). One of the surprises is that control by predators is more promising than I would have expected. For instance, eels have some attractive features – they don’t breed in fresh waters, so may not establish new populations, and they can get into crayfish burrows. Eels may not eat enough crayfish to keep the populations down, however.

The section on “Autocidal methods” shows, without the authors intending to do so, why Marmorkrebs could be such a challenge as an introduced species. These control techniques are based around “swamping” a population with sterile males, or using sex pheremones. But the common factor in both is sex... which Marmorkrebs don’t bother with. So a suite of promising management tools for other crayfish are highly unlikely to make a scratch in an introduced Marmorkrebs population.

In the end, the authors do see hope, but I think their last sentence is telling, because they find hope in the exotic crayfish situation not just in the science, but in science and education. This endeavour is not going to work is non-professionals (hobbyists, anglers, etc.) getting involved.

Reference

Gherardi F, Aquiloni L, Diéguez-Uribeondo J, Tricarico E. 2011. Managing invasive crayfish: is there a hope? Aquatic Sciences 73(2): 185-200. DOI: 10.1007/s00027-011-0181-z

Photo by Gregory Moine on Flickr; used under a Creative Commons license.