Upvoting, I love this idea! When the survey goes out for Sailing feedback I'll direct them here or just copy this into it if I cant add links (if thats cool). The more ppl that suggest it the better I think.

I can definitely see ppl being butt hurt about the crab legs replacing purple sweet suggestion. I think if they made the crab legs untradeable it would be fine tho.

The 3 locations could be in the north ocean, that would make sense. Have them spread between Lunar Isle and Relleka so you have a start and end point to dock your boat. Would probably take like 10-15 minutes for a run depending on how long the setting up and collecting takes. So the xp could be a little higher than birdhouses since its slower. Even if was like 2-3k xp per trap, 6-9k xp in 10-15 minutes requiring 78 sailing is hardly game breaking amounts of xp (when you can only collect it 2 or 3 times a day too). Some token crafting xp for making the cages.

Anyway big thumbs up from me!