I am developing a system for managing invasive crayfish that will allow dam removal without allowing the spread of the crayfish. This will hopefully enable more obstructions to be removed without adversely affecting the biodiversity of the river. What would really help my cause at the moment is a detailed analysis of where a dam was removed even though there are invasive crayfish present. What was the Fauch et al (2009) model, what was the trade off process and how was it arrived at.
Many thanks
Hello Stuart; You might look into a river in Washington State, USA. It is called the Elhwa River. It had a dam that obstructed the salmon run for many years. That dam was removed a few years ago. It might have invasive crayfish in it. Best regards, Jim Des Lauriers.
There are other examples from the Pacific Northwest in the USA. The Conduit Dam in Washington State was removed a decade ago. It is part of the larger Columbia River system, which has both native and invasive crayfish. Many of the watersheds in the Northeastern USA where dam removal is quite active have invasive crayfish species.
American Rivers has a number of "dam busting" projects here in the Southeast. Their Dam Removal database is here: https://www.americanrivers.org/conservation-resource/american-rivers-dam-removal-database-now-available-public/
The map is here:
https://www.americanrivers.org/threats-solutions/restoring-damaged-rivers/dam-removal-map/
SC DNr identifies Red Swamp Crayfish as invasive, although its introduction is more closely related to aquaculture than dam busting: http://www.dnr.sc.gov/invasiveweeds/aisfiles/SCAISplan.pdf
and
https://www.nps.gov/rlc/ogbfrec/crayfish-research-at-congaree-national-park.htm
WHile native species have been inventoried (somewhat), it's not actually especially clear if or where introduced species are outcompeting natives:
http://www.dnr.sc.gov/fish/fwfi/files/idanddistributioncrayfishesSC.pdf
Thus, a comparion of distribution of non-natives to the dam removal maps and datasets would probably be productive.
Contacting people from the World Fish Migration Foundation might be a good beginning since they are involved in several ongoing projects relevant in this context (https://www.worldfishmigrationfoundation.com/projects; e.g. the AMBER project). Even some cases from UK, Spain and France are provided (https://amber.international/case-studies/). These countries have several invasive crayfish species, so these or other cases might be relevant.
This probably depends on dam and landscape/climatic context, and invasive species. To my opinion dams do not stop the invasion, at least downstream. Also upsream invasion may be slower when dam exists but this is just a metter of time when birds, otters or humans will accidentally or intentionally displace crafish from lower section to the upper. In Polish Carpathians two major reservoirs contain crayfish invader - O. limosus. In one of them crayfish does not penetrate upper reaches (probably due to lowe temperatures) in the other case they are seen usptream but does not exceed artiffisial bariers. But in the latter case it is hard to say wether they do not climb higher due to barriers itself or due to suboptimal conditions. All in all, I would say that when only optimal conditions are available, invader will invade even when there is a dam, on the other, when conditions are suboptimal invasion will probably not appear. In lowlands and lower uplands in smaller dam reservoirs in Poland O. limosus is always present downstream the dam when present also in the reservoir, but sometimes it is rare or absent upstream, even when it is common in reservoir and downstream. Thus, dam removing should be benefficial to river anyway.
- Badges
- Science topic
- Similar topics
- Publishing