The best way to catch crabs is not so different in the many beaches of the world where this crustacean makes it home. One thing most people are unaware of is that you do not attempt to catch crabs by hand. Their pinchers are sharp and strong. A result of them getting a hold of a finger is having it severed in many instances. If you do want to catch a crab by hand, use your foot instead. By stepping on their rear portion you can immobilize it and then pick it up without getting pinched by holding one of its rear most legs.
Another way of catching crabs is to go out where they live with a dip net. By seeking them out in shallow water you can locate them instead of waiting on them to find your bait and trap. Once you see a crab just scoop it up in your net. You can do this walking in the water or you can be in a boat that is also in shallow water. Remember the deeper the water, the slower your dip net will travel when you try to capture your dinner.
There are also those that use a combination of rod and reel and a dip net. With the bait on a hook it can be lowered into the water around where you think crabs live or might be traveling. This is generally in valleys or gorges under the water. When you catch a crab on your line, pull it up slowly. Remember this is not a fish that you will be able to fight. The crab is just holding on to the bait thinking it has its dinner. If you pull too fast, the crab will just let go and sink back to the bottom. When the crab is near the surface, use the dip net to get them out of the water. Once out of the water they will release the bait and the reason for the net.
Since the crabs have a great defense mechanism, the use of a trap is highly recommended. This way the crab will be in a confined space where they are more easily handled. With a crab cage lowered in the water with a buoy connected to it, you can sit back and relax until a crab decides it wants your bait as dinner. This can be off a pier or you can deploy the traps by boat.
Bait is the most important thing in attracting a hungry crab to your line or trap. The smellier the bait is the better, just like in catfishing. Old chicken, fish heads that are smelly are two that work great.
Just remember that most crabs catught off the Coast of America are blue crabs. All females must be released along with any crab whose shell is less than 4 inches wide. This is the law.