Giant Spider Crabs (Leptomithrax gaimardii)
Each year we are lucky enough to be graced with an awesome underwater sight. The annual Giant Spider Crab march. If you have never witnessed it, think of an underwater moving hill of spider crabs, and when i say hill i mean thousands and thousands of crabs as far as you can see!
In about June each year thousands and thousand of spider crabs have been coming into the shallows to mate and moult. When i first started to dive it was mid to late March and Rye pier was the venue, the last few years it has been early June and Blairgowrie pier has played host.
What do they do, why do they come and where do they go? Other than to mate and moult, we dont know.
This leads into a debate that has only this year raised it's head. Fishing.
This year for reasons no one knows hundreds of people flocked to the pier to fish and catch the spider crabs. By law they can do this, 30 crabs is the bag limit i believe.
I went for a dive yesterday and where i would usually expect to see a carpet of moulted shells there were barely any at all. Speaking with regular swimmers and divers they report that the fishermen (fisher people for the politically correct) have taken hundreds of thousands over the last few weeks.
What impact does this have? Well without more information on what the crabs do and why they come into sore we can give it our best guess. My worst case scenario is that we have fished out a species during its annual breeding march. We have cut them off before they have mated and cut the cycle of life.
Could this single season of fishing have almost wiped out the bay's Spider crabs?
The Blairgowrie spider crab march is not the only swarm (whats a group of crabs called?) of crabs in the bay, but it is the only one that we have been viewing with any regularity.
A solution that i like is something similar to lobster fishing. A ban on fishing during the mating season. Fisheries can simply ban the fishing of the crabs during March and June, giving them a chance to come in, do what they do and go back to deeper waters.
Food for thought, and discussions happily accepted.
p.s if you havnt seen the spider crab march, keep your ears to the ground around late March early June next year, grab your extra thick wet suit and snorkel and make your way to Blairgowrie. It is something you absolutely must see
