Australia To Use GM To Control Carp
mskfisher writes "Yahoo! News is running an AFP story on Australia's efforts to control the carp population using a 'male-only' gene. The gene will prevent the carp, considered a pest in Australia, from producing female offspring. The carp has wiped out some 90% of the native south Australian fish population, namely perch and bass. They do not, however, mention any ways of controlling the spread of this gene in the wild, besides the obvious death of any affected population."
The gene does not cause infertility, just maleness. So it can spread. Which is in fact what they want; They can't very well introduce the gene into all of the fish out there (if they could, they would have just killed them all) so what they want to do is introduce this gene, then as it spreads, gradually the proportion of males in the population will increase. When you have all males, then the population dies. There are, of course, problems with this approach. One is the potential for accidental spread, both to other populations of carp outside Australia, and to other species.* Another is that the females who are left are likely to produce more surviving offspring (population limits in fish are not usually from the number of eggs produced). Another is that it will take a while to have huge effects, during which time mutations might arise that block this mechanism and allow female development. Such a mutation would spread rapidly (it would be highly favored by selection once the population got far off 50-50) so you would be back a square one. Biocontrol of introduced species is notoriously bad, particularly in Australia. See Cane Toads. We are exceptionally bad at foreseeing all of the downstream consequences of such manipulations of the ecosystem. A cool idea, and some great work by the scientists, but lets hope that they think long and hard before releasing these fish into the wild. *do you really think that all those extra male carp will ignore the chance for some kinky inter-species romance? It just takes one...
Most exciting phrase in science: not "Eureka!" but "Hmm... That's funny..." -Asimov (abridged for \. limits)