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Topic: Signal crayfish

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	Crayfish plague - Wikipedia, the free encyclopedia
		The signal crayfish is, although more resistant than Astacus, a carrier of the plague, and efforts to reintroduce the original European crayfish, has been quite unsuccessful because of subsequent large implantations of signal crayfish, most of them done on private initiative.
		Implantations of the signal crayfish was the reason for the spread of the disease to United Kingdom and Ireland.
		In Sweden the signal crayfish has also started to decline in significant numbers over the last years, and researchers now suspect that the signal crayfish may be less resistant to the plague than previously believed, possibly in combination with stress or another unknown disease.
	en.wikipedia.org /wiki/Crayfish_plague (491 words)

	Signal crayfish - Wikipedia, the free encyclopedia
		The signal crayfish, Pacifastacus leniusculus, is an American crayfish indigenous to the western United States.
		Due to the crayfish plague that ravaged European crayfish stocks and has almost exterminated the noble crayfish Astacus astacus, Swedish biologists searched for a crayfish that could replace the native European crayfish.
		Unfortunately, this crayfish has been carelessly introduced to various countries without considering the fact that it carries the crayfish plague, and thus causes the eventual extermination of native crayfish.
	en.wikipedia.org /wiki/Signal_crayfish (168 words)

	Signal crayfish (Site not responding. Last check: 2007-10-21)
		The North American signal crayfish, Pacifastacus leniusculus (Dana, 1852), was introduced to Sweden in 1969 after several years of experiments with transplantations to replace the noble crayfish (Astacus astacus Linnaeus, 1758), which had been decimated by a plague and in many places disappeared altogether.
		The crayfish plague, which is a fungal disease, arrived in the second half of the nineteenth century from America in Europe, where it destroyed large parts of the indigenous crayfish populations that lacked resistance to the new disease.
		Crayfish are omnivorous, which means they will eat anyything, and won't hesitate to eat dead individuals of the same species or even living ones that are still soft shortly after casting their calcareous outer skeleton.
	nrm.se /inenglish/.../signalcrayfish.4.4e32c81078a8d924980009498.html (581 words)

	Crayfish
		Crayfish bred in fish farms are fed with vegetables and fruits.
		Even though the stocks of native crayfish have since declined due to the crayfish plague, the revival and protecting of the stocks and import of signal crayfish stocks have ensured that crayfish can be enjoyed also in the future.
		The plague is caused by a parasitic fungus, Aphanomyces astaci.
	www.dlc.fi /~marianna/gourmet/crayfish.htm (1042 words)

	Crayfish Plague
		Crayfish are nocturnal and feed on all kinds of vegetation and animal food including snails, small fish, tadpoles, young insects and insect larvae and worms.
		Recent studies have shown that the crayfish plague is not indigenous to Europe, rather it was introduced by the incorporation of new species of crayfish from the Americas.
		It is feared that the crayfish plague is dangerous enough to cause the actual extinction to some of the five species of crayfish which are indigenous to Europe.Some of the native species of crayfish have already disappeared from areas in which they used to inhabit.
	www.american.edu /TED/crayfish.htm (4419 words)

	Spring Rivers: Spring Creek Culvert Replacement
		The Shasta crayfish population in Spring Creek is located upstream of the four culverts at the Spring Creek Road crossing.
		In addition to re-creating an effective barrier to signal crayfish, all signal crayfish upstream of the Spring Creek Road crossing had to be eradicated to achieve the overall project goal, which is to maintain an allopatric population of Shasta crayfish in upper Spring Creek.
		Most signal crayfish that escaped upstream of the road crossing during construction were removed when the cofferdams were removed.
	www.springrivers.com /spring_creek.asp (601 words)

	SocietyGuardian.co.uk \| Society Guardian \| The aliens have arrived
		Ironically, the signal was imported into Europe to replace the native noble because it was thought to be immune from the plague.
		In England, the signal crayfish was deliberately introduced by crayfish farmers in the 1970s, and by the 1980s the native white-clawed crayfish was being affected.
		They have caught 3,091 signals in a 250-metre long stretch of the Stour, and as netting accounts for only a third or less of the total, they have been tackling a total signal population of perhaps 10,000 crayfish in 250 metres of narrow river.
	society.guardian.co.uk /societyguardian/story/0,7843,769967,00.html (1014 words)

	SNH - Display Bulletin (Site not responding. Last check: 2007-10-21)
		Crayfish are not native to Scotland, although two populations of white-clawed crayfish, native to southern Britain, are known to have been transported to two Scottish locations at least 50 years ago.
		Signal crayfish arrived in England as part of a drive to farm crayfish commercially during the 1970s.
		Accidental escapes of signal crayfish, together with deliberate introductions, have led to known populations of these animals being found in the River Dee in Kirkcudbrightshire and the River Clyde but small numbers of them have been reported from other areas as well.
	www.snh.org.uk /scripts-snh/nw-displ.asp?ID=1084 (786 words)

	Crayfish
		The White-clawed Crayfish is widespread in the British Isles but absent from Scotland, west Wales, and SW England, and it is generally tends to be confined to hard alkaline waters.
		Crayfish feed on animal and vegetable matter, usually at night, and they are eaten in turn by a range of fish, eels, birds and mammals, including rats, otters and mink.
		Crayfish are master escape artists and this is reflected in the rigid code of practice regarding transportation.
	www.wbrc.org.uk /WorcRecd/Vol1Iss2/crayFish.htm (1423 words)

	BBC NEWS \| UK \| England \| Tyne/Wear \| Crayfish war rages in North rivers
		Environmentalists say the northern stronghold of native British crayfish, in the rivers Wansbeck and Aln, could be under threat from the spread of the aggressive signal crayfish, from the United States.
		Agency conservation officer, Anne Lewis, said: "At the moment, the signal crayfish seem to be present in the Derwent in low numbers, but it is essential that we take every step to prevent their spread.
		Signal crayfish already dominate in the south and east of the UK.
	news.bbc.co.uk /2/low/uk_news/england/tyne/wear/3277443.stm (334 words)

	Angling News
		Signal crayfish carry the fungal disease 'crayfish plague' to which native species have no immunity and any remaining native crayfish downstream of the outbreak are unlikely to survive.
		The deadly crayfish plague is responsible for wiping out native crayfish populations in large parts of the country.
		Signal crayfish dominate in the south and east of the country.
	www.anglingnews.net /rep_detail.asp?ID=3751 (610 words)

	Crayfish Survey (Site not responding. Last check: 2007-10-21)
		The signal crayfish was originally introduced into England in the mid-1970s, in an attempt to develop a stock of crayfish immune to crayfish plague Aphanomyces astaci, but with the same culinary characteristics of the European noble crayfish.
		The signal crayfish poses another threat to the white-clawed crayfish, as they are also more successful when competing for food and habitat.
		The aim of Crayfish Survey 2000 is to establish the status and distribution of both the native white-clawed crayfish, and non-native crayfish within the county of Worcestershire.
	www.wbrc.org.uk /WorcRecd/Issue8/crayfish.htm (483 words)

	BBC - British Isles - A User's Guide To Natural History
		The invasion of signal crayfish has been detrimental to the native white-clawed crayfish (Austropotamobius pallipes, Lereboullet 1858), whose population was already threatened in the British Isles by habitat alteration and pollution.
		Signal crayfish have similar habitat requirements to white-clawed crayfish, which means that when signals invade, the two species often compete for the same space.
		Studies of the reproductive biology of the signals showed that the females produce a chemical, known as a pheromone, to attract male signal crayfish.
	www.open2.net /naturalhistory/invaders/wanted/crayfish.html (517 words)

	Defra, UK - Fisheries - Salmon and freshwater fisheries - Crayfish
		In Britain one of the biggest threats to the native crayfish is the presence of introduced non-native species, particularly the signal crayfish (Pacifastacus leniusculus).
		The signal crayfish is quite capable of walking overland in its search for a home, it will rapidly colonise freshwater sites and can not only competitively exclude our native crayfish, but it also carries a fungal disease, the crayfish plague, to which the native crayfish has no defence.
		Signal crayfish however, under the Crayfish Order 1996 may be kept in certain areas of the country without a licence (details can be found in the table below).
	www.defra.gov.uk /fish/freshwater/crayfish.htm (1359 words)

	Crayfish Traps, Crayfish Trap, Catching crawfish and crayfish with Trapper Arne's crayfish traps (Site not responding. Last check: 2007-10-21)
		The signal crayfish is resistant to this fungal pest, so many crayfish served in Sweden nowadays are of the signal variety.
		After the crayfish pest arrived in Scandinavia around 1907, the crayfish lovers there have been on the prowl for varieties that are less susceptible to the pest than their native species.
		The Sacramento River is full of the variety called the signal crayfish, a variety that has been exported to Sweden to start a new stand after the native crayfish was hit by the devastating crayfish pest.
	www.trapperarne.com /wherelive.htm (1573 words)

	crayfish (Site not responding. Last check: 2007-10-21)
		The much larger North American Signal Crayfish (Pacifastacus leniusculus), which have been farmed in Britain since the 1970's are believed to be the carriers and the source of 'Crayfish Plague', a virulent disease caused by the fungus Aphanomyces astaci.
		Signal Crayfish, being much larger and more aggressive than the White Clawed Crayfish, have been able to spread rapidly throughout the UK, spreading with them the Crayfish Plague and causing the decline in populations of White Clawed Crayfish.
		The crayfish is nocturnal and omnivorous, feeding on a wide range of freshwater macrophytes (small plants), macroinvertebrates (small insects) and detritus (organic debris), it is also cannibalistic, feeding on recently moulted individuals.
	www.edenriverstrust.org.uk /Crayfish.htm (448 words)

	Coarse fishing articles at Fish South West
		The Signal Crayfish, introduced into the UK in 1970 have become an unwelcome and destructive invader of the rivers, canals and lakes in the South West.
		Signal crayfish have had a major impact on our own native crayfish species, the white clawed crayfish.
		Large Signal Crayfish eat smaller ones and as trapping tends to catch the larger crayfish, more smaller ones survive increasing the population and causing more damage to the environment.
	www.fishsouthwest.co.uk /articles5.htm (534 words)

	B&BC BAP - White-clawed Crayfish Species Action Plan
		Signal crayfish are known to transmit Crayfish plague, a disease caused by the fungus Aphanomyces astaci to native populations but do not themselves suffer from it.
		The relationship between crayfish farming and the decline of native crayfish was investigated and confirmed though a contract with Nottingham University and the Nature Conservancy Council.
		Research is needed on the ecology, distribution, population trends and conservation of the native crayfish, and the impact of introduced crayfish on both the native crayfish and freshwater ecosystems.
	www.wildlifetrust.org.uk /urbanwt/ecorecord/bap/html/crayfish.htm (1209 words)

	Limnology at the University of Lund.Crayfish, Stable Isotopes and Organic Pollutants
		We are a group working with the ecology of freshwater crayfish, with particular emphasis on the interactions within the benthic communities and the structuring effects of crayfish on the benthic ecosystems and on the resulting influence on the dynamics of pollutants in these ecosystems.
		The signal crayfish is an exotic species (introduced from North America in the late 1960s), that may have negative effects on the distribution of the native crayfish by transferring the fungus causing the crayfish plague (Aphanomyces astaci), and by competitive exclusion.
		Despite a large human consumption of crayfish captured (ca 1000 tons) and imported to Sweden for consumption (ca 2500 tons, mainly Procambarus clarkii farmed in Louisiana, Spain and China), the bioaccumulation of pollutants in crayfish is not known.
	www.limnol.lu.se /limnologen/grupp_sida.asp?id=4 (980 words)

	Spring Rivers: Crayfish Barrier Flume Study (Site not responding. Last check: 2007-10-21)
		The invasion of non-native crayfish species, particularly signal crayfish, is the single greatest threat to the continued existence of the federally and state-listed endangered Shasta crayfish (Pacifastacus fortis).
		Barriers to the upstream migration of signal crayfish need to be installed at several sites to protect the remaining allopatric Shasta crayfish populations.
		The Crayfish Barrier Flume Study, which is to develop and test crayfish barrier designs in controlled flume studies, is a first priority recovery task in the Shasta crayfish Recovery Plan, which was published by the United States Fish and Wildlife Service in August 1998.
	www.springrivers.com /crayfish_barrier.asp (229 words)

	CALIFORNIA'S PLANTS AND ANIMALS
		Unlike other crayfish, this crayfish is primarily herbivorous, feeding upon the periphyton (composed of benthic algae and diatoms, flocculent organic detritus, and small benthic invertebrates) which forms a surface film upon volcanic rock substrates.
		The Shasta crayfish is limited to the mid sections of the Pit River drainage, primarily the Fall River and Hat Creek drainages in Shasta County.
		Competition with and predation by signal crayfish, an invasive nonnative species, is one factor contributing to the Shasta crayfish's decline.
	www.dfg.ca.gov /hcpb/cgi-bin/read_one.asp?specy=invertebrates&idNum=2 (783 words)

	Abstracts
		Results indicate that signal crayfish significantly reduce prey densities and that impacts are significantly higher at high crayfish densities.
		In particular, signal crayfish have been identified as the primary cause of the decline of an endangered endemic crayfish.
		The distribution of crayfish in streams and mark-recapture data thus suggest that crayfish mainly spread downstream from a point of colonization and are restricted in their movement to adjacent upstream sections by the presence of both natural and artificial obstructions.
	www.des.ucdavis.edu /research/sihlab/profiles/abstracts.htm (2074 words)

	Swedes in danger of loving crayfish delicacy to de - AsianFanatics Forum
		But as the crayfish fishing season draws to a close in Swedish lakes and the breeding season gets underway, researchers are expressing concerns that stocks may once again be under threat from a deadly plague that could be spreading out of control.
		Crayfish mature in late summer, making an annual return to the table which is widely celebrated with a crayfish party, or "kraeftskiva".
		Signal crayfish were chosen because their taste is similar to that of the noble crayfish and because they were believed to be resistant to the plague.
	asianfanatics.net /forum/index.php?showtopic=49085 (756 words)

	South Downs VIC - White Clawed Crayfish
		Populations of native crayfish have been dramatically affected in the South by the introduction of the crayfish plague carried by the non-native Signal Crayfish.
		Crayfish have many enemies including birds, trout, pike, eels, rats, mink, otters and the greatest of all, man. Habitat destruction and pollution may have also contributed to the species decline.
		The Environment Agency is currently monitoring the status of both native white clawed and signal crayfish populations.
	www.vic.org.uk /edu/subfs/crayfish.html (414 words)

	Freshwater Crayfish
		Breeding populations of the signal crayfish and two other non-native species have become established in the wild in the UK and, as well as threatening the white-clawed crayfish with plague, compete with it for food and habitat.
		The spores of the fungus that causes 'Crayfish Plague' are usually transmitted to the white-clawed species via non-native crayfish and, therefore, it is important to safeguard against the introduction, accidental or otherwise, of other crayfish species in the vicinity of white-clawed populations.
		White-clawed crayfish are known to be sensitive to water pollution, particularly by pesticides and organic pollution/enrichment.
	www.lbap.org.uk /bap/species/crayfish.htm (1010 words)

	Scotland on Sunday - Sport - Other Sport - Rise in American crayfish is bad signal for Scottish rivers (Site not responding. Last check: 2007-10-21)
		In Scotland we have no indigenous crayfish but signal crayfish, which grow to over 20cm, are omnivores and can prey on small fish and fish eggs.
		Signal crayfish become less active and move around less during the winter.
		Evidence of signal crayfish should be reported immediately to any of the above organisations or a relevant angling association.
	scotlandonsunday.scotsman.com /othersport.cfm?id=1419962004 (780 words)

	Edinburgh Evening News - Sport - Other Sport - Advancing crayfish signal grave danger (Site not responding. Last check: 2007-10-21)
		The cause for such worry is the introduction of the American signal crayfish which not only eats the eggs of trout and salmon but will attack smaller juvenile fish, driving them from their habitat.
		Signal crayfish can grow to more than seven inches in length and once in a river system it is near impossible to get rid of them.
		Signal crayfish can move over land and it would not take much for them to cross the wet headlands into the Tweed system.
	edinburghnews.scotsman.com /othersport.cfm?id=151412004 (571 words)

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