My mother is crazy about fishing. Her favorite activity in the world is tooling around the Great Lakes in her boat and landing muskie or smallmouth bass. She’s the kind of fish crazy that watches televised sport fishing for fun, so when she started telling me about Asian carp, I didn’t pay enough attention at first.
These harmless looking fish were introduced by southern fish farmers in the 1970s because they cleaned tanks and ponds without devouring the stock fish. They soon entered the Mississippi river and started to reproduce at a rapid rate, overtaking many native species, polluting water, jumping dams, and taking advantage of floods to further expand. Millions have been spent to keep the carp out of the Great Lakes region, including investment in an elaborate electrical grid that is supposed to shock the fish before they can enter Lake Michigan. Unfortunately, the grid isn’t working as well as anticipated.
This story is being played out globally, and there are few good solutions. The toxic cane toad is proliferating in Australia, giant African land snails are spreading throughout Asia, and my mom’s favorite smallmouth bass is extending its fins everywhere like a mighty fishy plague. Teams of armed police haunt New Orleans waterways at night to pick off giant rats that undermine valuable Gulf Coast ecosystems.
This is what makes CRISPR gene editing so seductive.
CRISPR is basically a cheap and easy word processor for the genome, allowing you to cut and paste, altering DNA. Scientists can use this handy-dandy gene software to modify the genome of invasive species, such as our friend the carp, and alter it so that it’s offspring cannot reliably reproduce. The altered fish are released to spread that sad little DNA strand. Sounds like an easy solution to our piscine problem, no?
No.
In many scientific quarters the idea was short lived. In this global climate there is no way to make sure that the altered fish aren’t reintroduced back into their native habitat…with devastating results. Entire populations could be rewritten, meaning no rainbow trout, no eastern grey squirrels, no American bullfrog, no red-eared sliders, and no smallmouth bass for my mom to catch. The damage caused by a little splicing and dicing of animal genomes could be catastrophic, but that has not stopped several countries with ambitious anti-invasive species plans from courting CRISPR use. New Zealand is over-run with invaders that are driving its gentle little kiwi into extinction. The country has already lost a quarter of it’s unique bird population, and it wants to eradicate the intruders by 2050.
Their desperation is understandable, but it is clear a global consensus must be reached on CRISPR use, because what affects New Zealand wildlife will quickly affect wildlife worldwide. Some alterations to mosquitos, ticks, and other disease carriers may be possible, since they are only being modified to be less likely to transmit malaria and lyme, but there is currently no way to genetically remove Asian carp from one locale without risking the entire species.
The miracle of CRISPR is that it is so cheap and easy. The danger of CRISPR is also that it is cheap and easy. We haven’t been able to come to a global consensus on climate change, let alone issues surrounding gene editing. The technology is already out in the world, and we can only hope that its users consider global ecosystems, and not just the fish in their own backyard. Rachel Young
