This is a strange but true story. I had asked a fisherman to take me to an uninhabited mangrove island just off the coast of Ecuador / Columbia. it was a small Island (perimeter of ~2km). His son came along. The son has this long branch / switch that was about 8ft long and he would "whip" the crabs before they could run / burrow into the hole.

I suspect the more traditional way is to dig them out with a slender shovel.

Thank you! I will give it a try but there seem to be a lot of holes without crabs!

Dear Robbie,

I am not familiar with the Bermudan crab fauna, but as far as I know you have the northern-most mangroves in the Western Atlantic. So I presume your mangrove fauna will be somewhat impoverished, and Ucides cordatus may in fact  be "missing".

I know that besides Goniopsis cruentata, which can be easily recognized by its conspicuous red color, you also have Cardisoma guanhumi in Bermuda.   Cardisoma is a huge burrower crab, but definitely very rare in mangrove areas and more commonly associated to land than to wetlands.

I think that no answers from your colleagues will be better than a good spade or traps with fishing baits :-) so you can have the suspect itself in your own hands!

Dear Paulo,

Thanks for your response. Yes we do have scattered populations of C. guanhumi. along the supra-tidal margin of our remaining mangroves. I was thinking of  using  a trap as away to avoid a lot of digging but not  really sure of a design. Any ideas?

Fisherfolk from Paranagua Bay (S Brazil), where I work, use special traps for blue crabs called "puças" (you may have a look at them at Google images or at https://www.youtube.com/watch?v=ppVOx5bPxNg for a video. I think these artifacts may work in mangrove areas during ebb tides if your "suspect crabs" are carnivore or carrion-feeders. Please have also a look at the attached image.  Local fishermen from Paranagua' also use an illegal artifact made up by coiled plastic mesh with fish as bait, called "lacinhos" in Portuguese. They will surely work for Ucides or related crabs.

Paulo,

I am hoping my crabs are herbivores, busy stuffing leaves in their burrows. But they may be scavengers too. I will come up with a creative trapping solution.

Muito obrigado!

Hi,

good luck with the crab hunt, it can be a very humiliating experience, some of these critters are very hard to get. My five cents, try loosely draping some fine meshed fishing net around the burrow where you saw the crab wetn in and fix it with a stake. Works on Ucides, they get tangled when trying to leave the burrow. If you feel brave, the other method to catch Ucides is to use a glove made of cloth that goes allt he way up your arm (cheap and anybody with a sewing machine can do it), lie down and put your arm in  to catch the crab. This is how Ucides is caught in North Brazil, but its a good idea to get a good grip on the crap and avoid getting pinched.

Waidmannsheil!

Volker

Thanks, Volker. Though forbidden by environmental laws, the technique based on the fine meshed fishing net is widely used in Brazil (people call it lacinho). I am pretty sure it will work in Robbie's case. In fact, Brazilian fish-folk DO NOT use a glove to catch Ucides :-) They do it with their naked hands... Anyway I have never tried to learn the technique :-)

Hi,

I worked in Pará in the late nineties, in Braganca, back then they did use gloves and I strongly recommend it for Robbie! I learned the technique but the crab fishermen still beat me by about 5:1 after 1 year, could never have made a living crab fishing...

Cheers

Volker

Chinnamani and Volker,

Many thanks for your suggestions. I hope I can report success later this summer and that I still have all my fingers...

Best regards,

Robbie

Hi Robbie  I suggest  to use the glass trap!  one simple glass tin with a little piece of meat in the bottom. You burry the glass tin just near the den and if you will lucky ... the crab don't escape from the glass!

Best regards   

Gianluigi

Thank you, Gianluigi.  I  just have to get back to the traps  before the tide comes in! But it might work well and I will give it a try.

Best regards,

Robbie

For a recent survey of a burrowing crayfish in New York, we used burrowing crayfish net (BCN) traps (Welch and Eversole 2006). Each BCN was constructed of 20 cm x 150 cm section of old avian mist nets. The netting was folded over until it was approximately 20 x 20 cm and tied in the middle with a 1/2 meter length of string. The BCNs were deployed by inserting the net into the entrance of a hole and securing the other end of the string to the wire survey flag. The BCN trap was left overnight and checked the following day. The crayfish was entangled but alive in the netting, so we needed carefully remove the netting.  We could then return the crayfish to the same burrow. 

As in many other countries, ‘crab pots’ or ‘crab traps’, are widely used in India for trapping mud crabs. In Bangladesh, the crab pot (boon) is a common mud crab

fishing gear (Khan and Alam,1992) and in Myanmar, the use of cylindrical bamboo crab pots has been reported (Win et al., 1992). Similarly in Sri Lanka, baited crab pot is most common (Jayamanne, 1992), while in the Philippines, crab pot locally known as, ‘bubo’ is considered as an efficient mud crab fishing gear (Ladra and Mondragon, 1992). An elongated oval shaped crab pot, known as ‘wadong’ or ‘bubu’) are in use in Indonesia (Cholik and Hanafi, 1992) and rectangular or round crab pots in Queensland (Lee, 1992) for harvesting crabs. Crab pots that are used in Chilika lake , India are commonly designed as square or rectangular box with single non-return valve for easy entrance but difficult exit. The crab pots are made of bamboo strips of about 0.63 cm width separated from each other by about 2.5 cm. The single opening (valve) normally measures 15-25 cm x 5-10 cm. The opening of the non-return valve is surrounded by a conical structure made of bamboo splits, projected inside the trap.

In India, at few places on the west coast, fishermen use a loop type of trap, which is attached with a metal / wooden rod, anchored in the mud. success in this trap for mud skippers is high with almost 90% catch per effort. You may also try it for crabs. The only care to be taken is that the attached rod must be well anchored in mud.

Thanks you for the suggestions, Betsy, Rajeeb and Dishant. I will think about these idea when constructing my traps later this summer.

Best regards,

Robbie

Dear Researcher

All have suggested different methods. I will give left over method, which has to be operated manually. A bait attached to twine or thin wire has to be lowered in to burrow and crab grab the bait with chelates. The person holds the bait will sense it  and then slowly pull out the bait. The crab will come out along with bait. A scoop net is used to trap the crab when it is come out from the burrow. This is very old method which was operated by traditional  fisherman for their subsistence.