Mass of dead crabs (1 Viewer)

[Jaff]

I was in Redcar last thursday and on the beach there must have been covered with thousands of dead crabs washed up on shore amongst the seaweed, most having been already devoured so I'm assuming they must have all been dead before the birds had at them.

What would cause such a mass death of these crabs? They all looked reddy brown in colour with the black tips to the pincers making me think they were all Edible crabs.

 

[etudiant]

Hard to think of anything that would kill crabs other than an anoxic event.
If the water has too much nutrient in it, from sewage or farm runoff, the biological processes of decay may create a dead zone where oxygen levels drop below the minima for sustaining life. Here in the US we have created at least 2 such zones, about 60,000 square miles of the Gulf of Mexico around the mouth of the Mississippi and a smaller one south of Miami.
Perhaps Britain is emulating the US example? I sure hope not, but your discovery is troublesome.

 

[Bowlander]

There was a big kill of crabs in Morrcambe bay when gulls switched to feeding on them en masse.

They are definitely dead and not the shells left over from when they 'peel'?

 

[Jaff]

There were a lot of shells but also lots of body parts and some whole ones. I don't think there is a Sewage outlet anywhere around Redcar as it is a popular sea front despite the heavy industry nearby with the ICI and Steelworks. Also as I said it looked exclusively like they were all the same species. Oddly there weren't that any gulls eating the leftovers, maybe they'd had their fill? The odd crow and waders were finishing off what was left. I should've taken a wide shot of the scene but didn't think of it. There seemed a lot in the little stretch I was on so I assumed it might have been the same all along the beach but that might not have been the case so the notion of thousands may be an exaggeration. I suppose it's just one of those things.