Dead Dolphin ashore May 2016

Dead Dolphin ashore May 2016

Saturday, 1 January 2011

Winter crab deaths

Last Winter we experienced the mass death of Velvet swimmer crabs on the Thanet foreshore. Such a site of thousands of dead crabs did lead to many theories, some bizarre and others feasible. However, the one I subscribe to is the one that Velvet swimmer crabs die in a sudden drop in water temperature around our coastline because Thanet inshore waters are the Northern point of their migratory cycle. The Velvet Swimmer crab thrive in warmer waters and the winter deaths are part of their life and death cycle. To make this point the TDC sponsored Thanet Coast Project has asked its wardens to report any winter crab deaths so they can build up data on the subject.
This morning I carried out my first survey of the New Year on Ramsgate main sands and for the first time this winter I came across substantial numbers of dead swimmer crabs. In fact I estimated something in the region of 1500 to 2000 dead velvet swimmer crabs on the strandline by the East Pier Ramsgate. They had been dead for well over a week as the bodies were breaking up and compared to last year the size of the majority of the crabs were smaller measuring less than 60mm across the carapace.
Apart from the dead velvet swimmer crabs, I found one dead female lobster around 200mm in length and a small number of edible crabs. I counted 70 mermaids purses and a large number of dogfish egg sacs probably around 200 to 250, in both cases they were empty. So it does look as if we are in for another good breeding year for both the Thornback Ray and Lesser Spotted Dogfish.

One of the advantages of being a coastal warden is that TDC do provide us with excellent identification sheets. So armed with this library of information I can positively report that I observed 25 turnstones foraging the strandline taking advantage of the winter kill.

7 comments:

ascu75 aka Don said...

You do a good job Tony and it is one of the positive things TDC do. I love your reports and updates.

FionaS said...

Great news about the thornbacks and turnstones. Happy New Year and keep up the good work.

Tony2 said...

Hi Tony, Happy New Year. We have a similar situation at Westbrook. However this is similar to last year, it started with traces in December then bang in January we had the major incident. Will keep an eye on the situation and if it happens again we can vistit the theories again.
Keep up the good work.

Tony Beachcomber said...

Tony2, Happy New Year,
It was interesting that the vast majority were 60mm or less across the carapace. Also it is a known fact the smaller crabs are not very good at burrowing because the back legs act a paddle to enable them to swim make effective burrowing difficult.

Tony Beachcomber said...

Happy new year Don & Fiona S.

Tony2 said...

Hi Tony
Press have been on this morning. A large number found in Palm Bay.
Keep an eye out I suspect we could have more if we get some more cold weather.
Tony2

Tony Beachcomber said...

Tony, at present my Ramsgate surveys are reliant on the wind, as long as it is between N and SE it is game on.
I expect the oyster and razors at Epple Bay have taken a similar hammering.
When the wind is back in SW I going see what impact there has been on the mitten crab in Pegwel Bay.