How many different ways are there to say that culling invasive or unwanted species is rarely the best solution to manage a disrupted ecosystem? It looks like we have to keep coming up with new ways of saying it, because our hunting behavior itself is driving invasive lionfish into hiding.
Culling sharks is not going to make beaches safer, culling wolves only serves to completely disrupt their ecosystem, and culling badgers isn't actually helpful in stopping the spread of bovine tuberculosis.
At Conservation Magazine's Conservation This Week blog (disclosure: I am also a contributor to that blog) science writer Dave Levitan writes about the crazy ways in which attempting to cull the invasive Indo-Pacific lionfish from the Caribbean could actually be making things worse, according to a new study in PLoS ONE.
The study was fairly straightforward: the researchers compared lionfish behavior on 8 reefs that have been subject to culling for at least two years to the behavior of the fish on 8 reefs that had not been culled, all in the Bahamas. The culling was done with "non-projectile, three-prong paralyzer-tip pole spears." In other words, giant forks. Levitan writes:
The lionfish clearly did learn something about the huge creatures that lunge at them with tridents. On culled reefs, a lower proportion of the fish were active during the day, and they hid themselves much more carefully as well. The investigators assigned a "hiding score" to the fish based on certain behaviors: half of the lionfish on culled reefs achieved the highest such score, compared to only 19 percent of those on the unculled reef...
...This suggests, of course, that if a lionfish survives a cull (the culls achieved success rates ranging from 30 to 100 percent), it becomes more likely to survive the next one as well. It is, in a sense, a very rapid form of natural selection.
Given how strong a foothold lionfish already have in the Caribbean, the best we can probably do is probably to try and manage the population at sustainable levels, rather than trying to eradicate them completely. Which, to be fair, is no easy task.
Head on over to Conservation Magazine to learn more about what this means for dealing with invasive species.