It's nowhere near as hard as shrimping. Crabbing is harder than shrimping, but tonging for oysters is the hardest of all. Tonging involves a lot of upper body strength, and oystermen have REALLY nice arms.
People can catch crawfish in ditches, here, no sweat- but usually in a creek or bayou. Mostly they use nets or crawfish traps. They don't have to go out into the gulf like shrimpers. When my grandfather was young, he crabbed in the morning and shrimped at night. I admire him for his work ethic. He just stopped working last year, opening oysters (back breaking work) at the ripe old age of 83.
Useless knowledge- people who open oysters wear gloves with six fingers, there are two thumb holes on each glove. This is because the thumb wears out first, so instead of buying a whole new pair of gloves, you would just use the extra thumb hole. It is due to the way you have to hold the oyster to open it. We call it "opening oysters" here, but in other places people call it "shucking oysters".
When people go shrimping, they use trawl nets that are attached to a trawler, a board that kind of works like a dredge, so shrimpers catch all kinds of things in their nets, but not crawfish because they are not saltwater animals. They throw a lot of "trash" away- after the nets are pulled up and dumped, shrimpers keep the shrimp and edible fish. A lot of shrimpers will sell flounder or grouper right off the boat when they come in, or take them home to eat. Cast nets are weighted with lead weights, and are used to catch bait fish, porgies (which we call pogies). The pogies are used in crab traps.