30 March 2018

Why people can’t take invasive crayfish seriously

In compiling the news coverage and reactions to the Marmorkrebs genome sequence (which is still trickling in), I’ve noticed a common reaction. The story describes Marmorkrebs as an invasive, outlines the problem, and someone shows up in the comments saying something like, “Mmmm. Gumbo!” or “Get the melted butter ready,” or something like that.

Jokes like that show pretty clearly that people think invasive crayfish are a joke, and nothing to worry about. And as much as I love the Non Sequiter cartoon about Marmorkrebs, it also uses the problem for comedy.

“Eat them all” is not an attitude unique to North America:

This novel perspective on invasive species was perhaps most elegantly stated as we made small talk with a taxi driver in Wuhan. As we explained our research through an interpreter, the taxi driver smiled and asked, “Can they really be considered a problem if people eat them?”

This attitude is perhaps more understandable in China, given that “Chinese food” in China means “crayfish” more than General Tso’s chicken. Louisiana red swamp crayfish are the most popular restaurant dish, and that makes for a $22 billion (yes, with a “B”) market.

But there are at least two problems with the “We can eat them” attitude. First, people don’t understand that there are differences in commercial viability. Marmorkrebs are small compared to Louisiana red swamp crayfish, meaning that you are expending more effort for less meat. It’s like saying, “Hey, Asian carp are fish, we can eat fish, no problem,” without realizing that they’re bony, and not many people want to eat carp. (This may not be an insurmountable problem, though.)

Similarly, not everyone wants to eat crayfish. My understanding that in some places, suggesting that people eat crayfish goes over about as well as suggesting people in the United States eat cockroaches.

But the other problem is that while it sounds good in theory, there’s not a lot of evidence that introducing commercial harvest for invasives will get rid of the problem. Barbour and colleagues (2011) looked at the prospect of controlling lionfish by fishing them for food. They concluded:

(C)omplete eradication of lionfish through fishing is unlikely, and substantial reduction of adult abundance will require a long-term commitment and may be feasible only in small, localized areas where annual exploitation can be intense over multiple consecutive years.

A later paper (de Leon and colleagues, 2013) reached similar conclusions:

While removal efforts are effective at reducing the local number of lionfish, recruitment from unfished locations, such as those too deep for recreational diving and at dive sites that are difficult to access, will continuously offset the effects of removal efforts.

Still, some are continuing to investigate this for lionfish (Chapman et al. 2016).

Indeed, creating commerical fisheries for aquatic invasives probably increases the problems, since you now have incentives to perform even more introductions (Nuñez and colleagues, 2012; Pasko and Goldberg 2014), even through the track record is poor. Establishing commericial fisheries for crayfish was one of the main reason North American species were introduced in many European countries decades ago (e.g., Sweden), and they have since realized that they are causing far more problems than they made money.

If we are going to stop introductions of non-native crayfish, we are going to have to convince people that the problem is serious. Jokes about food show they aren’t there yet.


Barbour AB, Allen MS, Frazer TK, Sherman KD. 2011. Evaluating the potential efficacy of invasive lionfish (Pterois volitans) removals. PLOS ONE 6(5): e19666. https://doi.org/10.1371%2Fjournal.pone.0019666

Chapman JK, Anderson LG, Gough CLA, Harris AR. 2016. Working up an appetite for lionfish: A market-based approach to manage the invasion of Pterois volitans in Belize. Marine Policy 73: 256-262. http://www.sciencedirect.com/science/article/pii/S0308597X16304857

de León R, Vane K, Bertuol P, Chamberland VC, Simal F, Imms E, Vermeij MJA. 2013. Effectiveness of lionfish removal efforts in the southern Caribbean. Endangered Species Research 22(2): 175-182. http://www.int-res.com/abstracts/esr/v22/n2/p175-182/

Nuñez MA, Kuebbing S, Dimarco RD, Simberloff D. 2012. Invasive species: to eat or not to eat, that is the question. Conservation Letters 5(5): 334-341. https://doi.org/10.1111/j.1755-263X.2012.00250.x

Pasko S, Goldberg J. 2014. Review of harvest incentives to control invasive species. Management of Biological Invasions 5(3): 263–277. https://doi.org/10.3391/mbi.2014.5.3.10

Related posts

Marmorkrebs genome news round-up

External links

Louisiana crayfish: good, bad, and delicious
The economy of crayfish
Non Sequiter cartoon: Crayfish apocalypse
Eat The Enemy: The Delicious Solution To Menacing Asian Carp

Picture from here.

26 March 2018

The crayfish apocalypse

Of over a hundred news articles, blog posts, and other miscellaneous things I have seen on the Internet about Marmorkrebs since the genome paper came out, this Non Sequiter comic by Wiley may be my favourite of all of them. And that includes articles that quoted me or used my Marmrorkrebs picture.

Click here to read it.

Hat tip to James Murray.