When it comes to crayfish, crawdad, yabbis or whatever you want to call them, I could eat those little bugs by the bucket. I caught about 120 lbs. last year during the summer. They make for some fine eating with a cold beer and some fresh corn.
Here is a link to Trapper Arne's Crawfish website.
Trapper Arne's I've purchased about 2 dozen traps from this fellow a couple of seasons ago and have had wonderful success with them. I caught 48 in one trap after an overnight soak.
The "Trappy" and "Jackpot" both fold up nicely and could be packed if needed. The Trappy would be a bit more of a pain to get into a pack or bag. It's made of rigid plastic and the end funnels are separate pieces. The Jackpot collapses down into concentric rings and snaps together quickly.
I could see how this might fit into someone's survival gear. It's not The Deadliest Catch, but it's close.
No affiliation to Trapper Arne, beer, garlic butter, and crawfish other than I really like 3 of them on a hot summer evening.