I was super stoked to see this #SignalCrayfish, Pacifasticus leniusculus, in the main stream of McCormick Forest Park today!
I've spent 100's of hours along this stream & this is the first I've seen our only #Native #Crayfish. An indicator species demonstrating the vitality of that forest/stream!
I've spent 100's of hours along this stream & this is the first I've seen our only #Native #Crayfish. An indicator species demonstrating the vitality of that forest/stream!
August 31, 2025 at 12:04 AM
I was super stoked to see this #SignalCrayfish, Pacifasticus leniusculus, in the main stream of McCormick Forest Park today!
I've spent 100's of hours along this stream & this is the first I've seen our only #Native #Crayfish. An indicator species demonstrating the vitality of that forest/stream!
I've spent 100's of hours along this stream & this is the first I've seen our only #Native #Crayfish. An indicator species demonstrating the vitality of that forest/stream!
🦞 Why remove #SignalCrayfish?
Introduced to the UK in the 1970s for farming, they escaped & spread rapidly. They carry #CrayfishPlague - deadly to native #WhiteClawedCrayfish.
Protecting our #biodiversity is why we act - take a look at our species action plan here: buff.ly/GKvWMjx
#Conservation
Introduced to the UK in the 1970s for farming, they escaped & spread rapidly. They carry #CrayfishPlague - deadly to native #WhiteClawedCrayfish.
Protecting our #biodiversity is why we act - take a look at our species action plan here: buff.ly/GKvWMjx
#Conservation
June 12, 2026 at 9:02 AM
🦞 Why remove #SignalCrayfish?
Introduced to the UK in the 1970s for farming, they escaped & spread rapidly. They carry #CrayfishPlague - deadly to native #WhiteClawedCrayfish.
Protecting our #biodiversity is why we act - take a look at our species action plan here: buff.ly/GKvWMjx
#Conservation
Introduced to the UK in the 1970s for farming, they escaped & spread rapidly. They carry #CrayfishPlague - deadly to native #WhiteClawedCrayfish.
Protecting our #biodiversity is why we act - take a look at our species action plan here: buff.ly/GKvWMjx
#Conservation
🦞 It’s #CrayfishSeason! 🦞
We’re back at Bulwell, #Nottinghamshire, trapping invasive #SignalCrayfish in two fishing ponds.
Early starts, baited traps, and careful checks help us manage their impact. Stay tuned for what happens next!
#Conservation #Biodiversity #Crayfish #InvasiveSpecies
We’re back at Bulwell, #Nottinghamshire, trapping invasive #SignalCrayfish in two fishing ponds.
Early starts, baited traps, and careful checks help us manage their impact. Stay tuned for what happens next!
#Conservation #Biodiversity #Crayfish #InvasiveSpecies
May 15, 2026 at 9:02 AM
🦞 It’s #CrayfishSeason! 🦞
We’re back at Bulwell, #Nottinghamshire, trapping invasive #SignalCrayfish in two fishing ponds.
Early starts, baited traps, and careful checks help us manage their impact. Stay tuned for what happens next!
#Conservation #Biodiversity #Crayfish #InvasiveSpecies
We’re back at Bulwell, #Nottinghamshire, trapping invasive #SignalCrayfish in two fishing ponds.
Early starts, baited traps, and careful checks help us manage their impact. Stay tuned for what happens next!
#Conservation #Biodiversity #Crayfish #InvasiveSpecies
🦞 Netting is another key method in our crayfish surveys! 🦞
We sweep pond edges and vegetation, turning stones to find hidden individuals. Unlike traps, nets help us catch smaller crayfish that can escape, ensuring more thorough removal.
#SignalCrayfish #Fieldwork #Conservation #InvasiveSpecies
We sweep pond edges and vegetation, turning stones to find hidden individuals. Unlike traps, nets help us catch smaller crayfish that can escape, ensuring more thorough removal.
#SignalCrayfish #Fieldwork #Conservation #InvasiveSpecies
June 5, 2026 at 9:03 AM
🦞 Netting is another key method in our crayfish surveys! 🦞
We sweep pond edges and vegetation, turning stones to find hidden individuals. Unlike traps, nets help us catch smaller crayfish that can escape, ensuring more thorough removal.
#SignalCrayfish #Fieldwork #Conservation #InvasiveSpecies
We sweep pond edges and vegetation, turning stones to find hidden individuals. Unlike traps, nets help us catch smaller crayfish that can escape, ensuring more thorough removal.
#SignalCrayfish #Fieldwork #Conservation #InvasiveSpecies
September 4, 2026 at 7:42 AM
Absolutely crawling with #invasive #nonnative Signal Crayfish in Culford Stream including one (lower right) that seemed to be diseased. Note the diagnostic red under claw of this angry one, to separate it from the native White-clawed.
#crayfish #chalkstream #signalcrayfish
3/5
#crayfish #chalkstream #signalcrayfish
3/5
December 11, 2024 at 7:09 PM
Absolutely crawling with #invasive #nonnative Signal Crayfish in Culford Stream including one (lower right) that seemed to be diseased. Note the diagnostic red under claw of this angry one, to separate it from the native White-clawed.
#crayfish #chalkstream #signalcrayfish
3/5
#crayfish #chalkstream #signalcrayfish
3/5
🦞So what happens after we collect Signal Crayfish? 🦞
Back at the table, we record trap locations, measure carapace length, and check for abnormalities like missing claws. We also note moulting stage: softer mid-sections mean active moulting!
#SignalCrayfish #Fieldwork #Conservation #InvasiveSpecies
Back at the table, we record trap locations, measure carapace length, and check for abnormalities like missing claws. We also note moulting stage: softer mid-sections mean active moulting!
#SignalCrayfish #Fieldwork #Conservation #InvasiveSpecies
May 29, 2026 at 9:01 AM
🦞So what happens after we collect Signal Crayfish? 🦞
Back at the table, we record trap locations, measure carapace length, and check for abnormalities like missing claws. We also note moulting stage: softer mid-sections mean active moulting!
#SignalCrayfish #Fieldwork #Conservation #InvasiveSpecies
Back at the table, we record trap locations, measure carapace length, and check for abnormalities like missing claws. We also note moulting stage: softer mid-sections mean active moulting!
#SignalCrayfish #Fieldwork #Conservation #InvasiveSpecies
A signal crayfish was recorded in the Ter at Sant Joan de les Abadesses on August 5, in the middle of town where the old bridge crosses the river. The following day three white-clawed crayfish were logged at the same point, a few metres…
#SignalCrayfish #WhiteClawedCrayfish #CrayfishPlague #RiuTer
#SignalCrayfish #WhiteClawedCrayfish #CrayfishPlague #RiuTer
Northeast Spain and Southern France Mediterranean forests — Speak for the Trees
www.speakforthetrees.com
September 4, 2026 at 11:12 PM
A signal crayfish was recorded in the Ter at Sant Joan de les Abadesses on August 5, in the middle of town where the old bridge crosses the river. The following day three white-clawed crayfish were logged at the same point, a few metres…
#SignalCrayfish #WhiteClawedCrayfish #CrayfishPlague #RiuTer
#SignalCrayfish #WhiteClawedCrayfish #CrayfishPlague #RiuTer
Rapurutto spreads via wet gear including swimsuits #crayfishplague #laketemperatures #signalcrayfish
Rapurutto spreads via wet gear including swimsuits
A warning from long-time crayfish researcher Japo Jussila says the deadly rapurutto fungus can travel between lakes on almost any damp equipment, including swimsuits and wetsuits. Jussila, based at the University of Eastern Finland, told Yle that Aphanomyces astaci spores latch onto wet materials…
www.dailynorthern.com
July 20, 2026 at 1:45 PM
Rapurutto spreads via wet gear including swimsuits #crayfishplague #laketemperatures #signalcrayfish
#SundayMotivation clocks just changed to #BST watching rerun of #SaturdayKitchen #RickStein sharing his method of humanely killing crabs before boiling, secret is immersion in very cold (ice) water #foodie #seafood would this work with #invasivespecies #SignalCrayfish ... probably
March 30, 2025 at 8:53 AM
#SundayMotivation clocks just changed to #BST watching rerun of #SaturdayKitchen #RickStein sharing his method of humanely killing crabs before boiling, secret is immersion in very cold (ice) water #foodie #seafood would this work with #invasivespecies #SignalCrayfish ... probably
Here are photos of an invasive American Signal Crayfish showing diagnostic white claw joints, rostrum sides parallel with small triangular apex, 2 post-orbital ridges & smooth shoulder.
Plus Minnows photobombing a #SignalCrayfish & a Pike.
#RiverLark #WestSuffolk @crayfish_uk
3/3
Plus Minnows photobombing a #SignalCrayfish & a Pike.
#RiverLark #WestSuffolk @crayfish_uk
3/3
December 13, 2024 at 9:18 PM
Here are photos of an invasive American Signal Crayfish showing diagnostic white claw joints, rostrum sides parallel with small triangular apex, 2 post-orbital ridges & smooth shoulder.
Plus Minnows photobombing a #SignalCrayfish & a Pike.
#RiverLark #WestSuffolk @crayfish_uk
3/3
Plus Minnows photobombing a #SignalCrayfish & a Pike.
#RiverLark #WestSuffolk @crayfish_uk
3/3
Incredible densities of Signal Crayfish upstream of Temple Bridge. New sport irritating them to see if they fight or flight; the first opted for flight...
#RiverLark #ChalkStream #CavenhamHeath #signalcrayfish #invasivespecies @Britnatureguide @theriverstrust @crayfish_uk
2/4
#RiverLark #ChalkStream #CavenhamHeath #signalcrayfish #invasivespecies @Britnatureguide @theriverstrust @crayfish_uk
2/4
December 13, 2024 at 6:44 PM
Incredible densities of Signal Crayfish upstream of Temple Bridge. New sport irritating them to see if they fight or flight; the first opted for flight...
#RiverLark #ChalkStream #CavenhamHeath #signalcrayfish #invasivespecies @Britnatureguide @theriverstrust @crayfish_uk
2/4
#RiverLark #ChalkStream #CavenhamHeath #signalcrayfish #invasivespecies @Britnatureguide @theriverstrust @crayfish_uk
2/4
Big beautiful Perch a foot long at Isleham Marina & an #Invasive #NonNative Signal Crayfish, amongst the Pike & Roach.
#RiverLark #Isleham #Cambridgeshire #Suffolk #Fens #Fenland #Chalkstreams #Perch #Pike #invasivespecies #signalcrayfish
3/4
#RiverLark #Isleham #Cambridgeshire #Suffolk #Fens #Fenland #Chalkstreams #Perch #Pike #invasivespecies #signalcrayfish
3/4
December 13, 2024 at 8:06 AM
Big beautiful Perch a foot long at Isleham Marina & an #Invasive #NonNative Signal Crayfish, amongst the Pike & Roach.
#RiverLark #Isleham #Cambridgeshire #Suffolk #Fens #Fenland #Chalkstreams #Perch #Pike #invasivespecies #signalcrayfish
3/4
#RiverLark #Isleham #Cambridgeshire #Suffolk #Fens #Fenland #Chalkstreams #Perch #Pike #invasivespecies #signalcrayfish
3/4
River Nar at Blackborough heavily infested with Signal Crayfish. Interesting how much they vary in colour - some with blue claws, some red.
#signalcrayfish #AlienInvasive #Invasive #NonNative #InvasiveSpecies #crustacean #RiverNar #Wormegay #Norfolk #chalkstreams #KingsLynn 2/7
#signalcrayfish #AlienInvasive #Invasive #NonNative #InvasiveSpecies #crustacean #RiverNar #Wormegay #Norfolk #chalkstreams #KingsLynn 2/7
December 11, 2024 at 5:33 AM
River Nar at Blackborough heavily infested with Signal Crayfish. Interesting how much they vary in colour - some with blue claws, some red.
#signalcrayfish #AlienInvasive #Invasive #NonNative #InvasiveSpecies #crustacean #RiverNar #Wormegay #Norfolk #chalkstreams #KingsLynn 2/7
#signalcrayfish #AlienInvasive #Invasive #NonNative #InvasiveSpecies #crustacean #RiverNar #Wormegay #Norfolk #chalkstreams #KingsLynn 2/7
River Lark absolutely infested with #nonnative #invasive #signalcrayfish (several dead). Assume they oust Bullheads from any suitable hidey hole, so I resent them even more.
Green Drake mayflies still on wing.
Blue-tailed Damselfly among the clouds of Banded Demoiselle.
4/8
Green Drake mayflies still on wing.
Blue-tailed Damselfly among the clouds of Banded Demoiselle.
4/8
December 11, 2024 at 2:08 AM
River Lark absolutely infested with #nonnative #invasive #signalcrayfish (several dead). Assume they oust Bullheads from any suitable hidey hole, so I resent them even more.
Green Drake mayflies still on wing.
Blue-tailed Damselfly among the clouds of Banded Demoiselle.
4/8
Green Drake mayflies still on wing.
Blue-tailed Damselfly among the clouds of Banded Demoiselle.
4/8
As part of our aims to improve water quality in the #RiverChess, we have sensors in the river at Rickmansworth, which have actually detected daily patterns of nocturnal activity from #SignalCrayfish through heightened turbidity levels (see tweet 1/4 for graph 📈).
3/4
3/4
February 26, 2025 at 6:31 PM
As part of our aims to improve water quality in the #RiverChess, we have sensors in the river at Rickmansworth, which have actually detected daily patterns of nocturnal activity from #SignalCrayfish through heightened turbidity levels (see tweet 1/4 for graph 📈).
3/4
3/4