The mystery of the swimming crabs

Ok, so this wasn't him - but I didn't have my GoPro with. Pity, cos would have a cool shot of him sunning himself on Anne's board!

Gotto love the fog. Perfect timing saw it keep the fun glassy waves out of view from everyone driving to work or varsity yesterday morning. Once it burnt off at about 08h30 there were a few hip high peelers rolling through. Just a lekker morning to be in the water.

Paddling out I spotted what looked like 2 fish tales frommeling on the surface. Couldn't work out what it was so paddled over to have a closer look. Turned out it was actually a swimming crab, and it was his two pincers that I'd mistaken for fins. He hung about for the rest of our surf, with Anne letting him chill out on her board between waves.

Turns out there's a bunch of these lil critters in the bay, and here's why:
“HUNDREDS of mysterious Smith’s swimming crabs, have beached themselves at Cape Recife, apparently trying to escape from severe “upwelling” (cold water) in the bay.

Algoa Bay is host each summer to classic examples of upwelling, which follows on strong and prolonged onshore winds that fold the waves back upon themselves and draw up icy water from the lower depths, wildlife and environment society conservation officer Morgan Griffiths explained. Reports indicate the crabs have been washing up for over a week on Recife’s beacon beach, which runs along the northern side of the cape. But by Monday, the piles of pink and orange carcasses had grown still further.

A very high tide came up in the early hours of yesterday morning and by mid-morning it had retreated taking most of the crab remains with it. The birds had torn into the remaining specimens but there were still dozens of claws and shells left behind at the high-water mark.

Libby Sharwood, co-director of the SA Marine Rehabilitation and Education Centre at Cape Centre, said the crabs seemed to be Smith’s swimming crabs as opposed to rock or shore crabs.
“The species have very large nippers and a very distinct flipper-like pair of claws at the back

“We also had an earlier report from a fisherman in a canoe of masses of them shoaling on the surface, off-shore.”
 Attempts were made to help some back into the sea but they simply beached themselves again, she said.
 “The gulls were dik gevreet and we saw a heron on the rocks that was also presumably eating them.”

Smith’s swimming crabs live out at sea, where they are eaten by tuna. Records note that they were first described by science in False Bay in 1838 but then not seen again until 1978, when enormous numbers appeared. This sequence happened again in 1983 and 1993.”

By Guy Rodgers, Herald 18 Feb 2011