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Invasive Xenopus in Washington State

21 July 2023

The lush and leafy suburbs of Washington are invaded

Unlike the dry canyons of San Diego, Washington State is a very green place with endless forests of trees, and plenty of water cursing through creeks out to the sea. In 2015, the first records of African clawed frogs started coming in from a stormwater pond in Bothell, WA. Two boys were fishing and saw an unusual looking frog moving in the water. The same year, in another stormwater pond in Lacey, WA more Xenopus  were found. The two invasions appear unrelated other than a change in the legislation at the time that advised people that anyone keeping these (and other) potentially invasive animals as pets would require a special permit and meet biosecurity conditions. The result seems to be that the animals were dumped and the invasion started. By 2019, another site (Issaquah, WA) to the south of Bothell was found to be teaming with Xenopus. Another invasion, or animals travelling through creeks and lakes? 

  I've been in contact with the good people of DFW Washington State since the start and we have had many email exchanges and discussions about how best to tackle these invasions. However, the area is full of stormwater ponds and creeks that connect them, so appears ripe for continued invasion. 

I was given lots of help in Washington by Reed Ojala-Barbour (Jen and Al) who came to show me all the sites. Max Lambert was also hugely helpful, traffic delays aside, we had a successful day out in Issaquah. Other helpers in Lacey were Megan Friesen and Mark from Saint Martin’s University (Lacey) who kindly allowed me to use their lab space.  

One of the really special treats for me was to see Xenopus laevis in the same traps as Ambystoma gracilis. These two species would never naturally meet, but have some interesting similarities.

Further Reading: 

Anderson, D., Cervantez, O., Bucciarelli, G.M., Lambert, M.R., Friesen, M.R., 2024. Feral frogs, native newts, and chemical cues: identifying threats from and management opportunities for invasive African Clawed Frogs in Washington state. PeerJ 12, e17307.
Ojala-Barbour, R., Visser, R., Quinn, T., Lambert, M., 2021. African Clawed Frog (Xenopus laevis) Risk Assessment, Strategic Plan, and Past Management for Washington State Department of Fish and Wildlife. Washington State Department of Fish and Wildlife, Olympia.
  Frogs  Lab  Xenopus
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