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What Works in Conservation 2015

 | 
William J. Sutherland
, 
Lynn V. Dicks
, 
Nancy Ockendon
, 
et al.

5. Some aspects of control of freshwater invasive species

5.2. Threat: Invasive crustaceans

Full text

5.2.1 Procambarus spp. crayfish

Based on the collated evidence, what is the current assessment of the effectiveness of interventions for controlling Procambarus spp. crayfish?

Likely to be beneficial

● Add chemicals to the water
● Sterilization of males
● Trapping and removal
● Trapping combined with encouragement of predators

Unknown effectiveness (limited evidence)

● Create barriers
● Food source removal

Unlikely to be beneficial

● Encouraging predators

No evidence found (no assessment)

● Draining the waterway
● Relocate vulnerable crayfish
● Remove the crayfish by electrofishing

Likely to be beneficial

Add chemicals to the water

1A replicated study in Italy found that natural pyrethrum at concentrations of 0.05 mg/l and above was effective at killing red swamp crayfish both in the laboratory and in a river. Assessment: likely to be beneficial (effectiveness 80%; certainty 50%; harms 0%).

Sterilization of males

2A replicated laboratory study in Italy found that exposing male red swamp crayfish to X-rays reduced their mating success. A review study from the UK found that pleopod removal in male red swamp crayfish was an effective form of sterilisation, reducing population size over three years. Assessment: likely to be beneficial (effectiveness 50%; certainty 40%; harms 0%).

Trapping and removal

3A controlled, replicated study from Italy found that food (tinned meat) was a more effective bait in trapping red swamp crayfis, than using pheromone treatments or no bait (control). A review study from the UK found that Procambarus spp. crayfish populations could be reduced in density but not eradicated by trapping. Baiting with food increased trapping success compared to trapping without bait. Assessment: likely to be beneficial (effectiveness 40%; certainty 60%; harms 0%).

Trapping combined with encouragement of predators

4A before-and-after study in Switzerland and a replicated, paired site study from Italy found that a combination of trapping and predation was more effective at reducing red swamp crayfish populations than predation alone. Assessment: likely to be beneficial (effectiveness 50%; certainty 50%; harms 0%).

Unknown effectiveness (limited evidence)

Create barriers

5A before-and-after study from Italy found that the use of concrete dams across a stream was effective at containing spread of the population upstream. A review from the UK found barriers were effective at halting or delaying movement of the red swamp crayfish. Assessment: unknown effectiveness (effectiveness 30%; certainty 30%; harms 0%).

Food source removal

6A replicated study in Japan found fewer red swamp crayfish in ponds containing less leaf litter. Assessment: unknown effectiveness (effectiveness 20%; certainty 30%; harms 0%).

Unlikely to be beneficial

Encouraging predators

7Two replicated, controlled studies in Italy found that eels fed on the red swamp crayfish and reduced population size. Assessment: unlikely to be beneficial (effectiveness 30%; certainty 60%; harms 0%).

No evidence found (no assessment)

8We have captured no evidence for the following interventions:

  • Draining the waterway
  • Relocate vulnerable crayfish
  • Remove the crayfish by electrofishing

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