While looking up some other material, I happened to come across a surprising note on the IUCN page for Small-clawed Otter saying "Introduced: United Kingdom (Great Britain)". The reference for this was Jefferies, D.J. 1989. The Asian short clawed otter Amblonyx cinerea (Illiger) living wild in Britain. Otters (Earsham) 2(3): 21-25; and Jefferies, D.J. 1991. Another record of an Asian short-clawed otter living free in Oxford with notes on its implications. Journal of the Otter Trust 2(5): 9-12. This took me somewhat by surprise because to my recollection I had never heard of this before. I had a quick google and found the following article from 1996. Asian otters thrive in chilly Oxford river | The Independent Then I found a 2008 pdf entitled "The status of scarce non-native birds and mammals in England" with the following: And thus an interesting tale came to an end. Or do the Small-clawed Otters still live there, and the locals are assuming they are just Common Otters...?
An otter is an otter so its very probable that the asian could maintain some small pocket populations without detection by locals; remembering that most people can go their whole lives without seeing a live otter and that even most studies rely upon evidence of activity instead of actual live sightings. Many people have trouble telling a cheetah from a leopard so an asian from a native otter would be beyond most for a sighting in the wild; though I suspect most could readily see the differences if they were placed side by side. For me this highlights the problem with non-natives in todays world; we might identify them but unless they pose a threat or cause a serious problem they can go ignored without much attention and no drive to remove from the wild. Of course once a species is found to be highly invasive initial small populations can quickly expand to numbers which prove to be expensive to then remove
I'm surprised to read that the reintroduction of Lutra lutra might help to decrease the local mink population. We have populations of both (as well as various other small mammalian predators) living along one another where I live, and so far I haven't heard anything from the local biologists that could confirm this assumption. Will the Asian short clawed otter be part of a future [EU-despite the Brexit] list of potentially invasive species European zoos will not be allowed to keep?
It has not been assessed and it is not on the list of 95 species that are recommended to be addressed first, so unless the UK thinks it is a concern and does the risk assessment themselves to be proposed to the other member states I do not see it ending on the list.
I've heard this suggestion on many occasions, as it happens - mostly this is from anecdotal accounts, but there has been at least one study which has come to this conclusion. I don't have the book with me at present as I am not at home, but the Natural History Society of Northumberland did a study on the mammals, reptiles and amphibians found within Northumberland, Tyne and Wear, and County Durham some years ago and published a book containing the results. Within, I seem to recall the suggestion that recovering populations of L. lutra are displacing and decreasing the introduced mink population was discussed and given some credence by the figures published. When I get home I shall post the relevant information into this thread. On a more personal anecdotal level, I am told by older family members that the River Tees and River Skerne - both of which pass through Darlington - used to be particularly infested by American Mink in the 1980's and early 1990's. In the intervening time, both the European Otter *and* the Eurasian Water Vole have returned to these rivers, and the American Mink population is said to have fallen significantly. The return of the latter will certainly be due to the fall in mink populations; the question is whether the return of the former is the cause of the fall in mink populations. It is perhaps also pertinent to note that of the various mustelid species present as breeding wild populations in the United Kingdom I have still never seen an American Mink despite many years of looking for them throughout the north-east of England and the Scottish borders - yet have seen species which are allegedly harder to see such as Pine Marten, European Otter and European Badger with no difficulty. (In a digression from this point, but something of a return to the original thread topic, the book also contains a list of exotic species recorded within the region - and notes the brief existence of a small Smooth-Coated Otter population in County Durham! Again, when I get home I will post the relevant information into this thread)
this account notes a single escaped individual at Stanley in the 1960s: Escaped Mammals – The Natural History Society of Northumbria
That is actually the precise account I was thinking of - although my recollection had been (incorrectly) that a pair had been mentioned. It seems the entire book I mentioned earlier has now been uploaded to the NHSN website, so I can now quote the relevant passage from the American Mink account:
I'm not sure how reliable this one study can be taken as evidence, but it is still interesting: Impact of released Eurasian otters on a population of American mink: a test using an experimental approach - Conservation Evidence
