Student Article

The practice of trapping American signal crayfish to protect the native white-clawed crayfish in UK waters has long been promoted by environmentalists and celebrity chefs. However, a recent study published in the Journal of Applied Ecology suggests that this approach may not only be ineffective but could also be doing more harm than good.

Most crayfish are too small to catch

Researchers from UCL and King’s College London conducted extensive trials and found that only a very small percentage of crayfish were large enough to be trapped, with most individuals being too small to catch. The study revealed that this meant populations of invasive signal crayfish could continue to reproduce unchecked, undermining the trapping efforts.

Trapping might spread more harm

What’s more concerning is that trapping could unintentionally spread the invasive species to new habitats and may increase the likelihood of spreading crayfish plague, a fungal pathogen that is fatal to native European crayfish. The white-clawed crayfish, already at risk of extinction, is particularly vulnerable to this disease.

What scientists recommend instead

The researchers strongly recommend ending the practice of recreational trapping and focusing efforts on improving aquatic biosecurity. The UK’s “Check Clean Dry” campaign, which educates water users about how non-native species can be transferred between bodies of water, should be a priority. Additionally, long-term strategies for controlling invasive species like the American crayfish should involve more targeted, science-driven approaches to managing their spread.

With invasive species causing widespread damage to ecosystems and fisheries, more effective management strategies are urgently needed. This new research offers critical insights that could help shift the focus from ineffective trapping to more sustainable methods of conservation.

© Mark Rowe / Our Media