Chinese mitten crab, Eriocheir sinensis. (Photo: EriocheirSinensis1/CC BY-SA 3.0)

Salmon and trout could be threatened by invasive crab

UNITED KINGDOM
Friday, September 26, 2014, 23:50 (GMT + 9)

Salmon and trout stocks in the north and north-east of Scotland could be under threat from the invasion of the Chinese mitten crab (Eriocheir sinensis), which has reached Glasgow’s River Clyde, Scotland, for the first time.

The Clyde River Foundation discovered a single specimen as the first evidence this invasive species, which has already spread across many of England’s waterways, -- including the Thames and as far north as the Tyne -- and has now crossed north of the border, explained scientists from the University of London.

According to Dr. David Morritt, from the School of Biological Sciences at Royal Holloway, "the occurrence of these Chinese mitten crabs in a Scottish river could have a devastating impact on the famous salmon and trout fishing rivers should they manage to reach parts of the catchments where these fish spawn."

For his part Alan Wells, policy and planning director for the Association of Salmon Fishery Boards (ASFB), has also warned about this threat.

“Given the propensity of the Chinese mitten crab to colonise new river systems, including by crawling over land, this is potentially an additional threat to our native freshwater fish populations that needs to be taken very seriously,” Wells told The Press and Journal.

Concern has been raised among researchers from the Natural History Museum, who explained that as well as outcompeting other marine life, this invasive crab species causes erosion by damaging riverbanks and impacts infrastructure such as dykes when they burrow into them.

As part of mitigating measures, the International Maritime Organisation (IMO) has set out standards for the control and management of ships’ ballast water and sediments, in an effort to control the transport of species to non-native waters.

Besides, Wells considered that as is the case with other non-native invasive species, anglers and other users of the freshwater environment need to pay particular attention to bio-security including the thorough disinfection of fishing gear and other equipment when moving from catchment to catchment.

The Chinese mitten crab, named after the furry mats covering its claws, is native to East Asia but is now found across NE Europe and the US.

Experts consider that it is not clear yet whether the crab was deliberately released or has naturally colonised the river, and the foundation is appealing for sightings of further specimens.
 

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