Need a live bait shrimp net

Just get a cast net. Way more versatile. When the shad are running on the banks, you can pick up a bucket full in two or three casts for bait. You're not going to do that with a trawl and you don't have the added equipment, expense, and strain on your motor that you would pulling a trawl.

Never tried to keep the things alive, though. I imagine they're like any other crustacean:
-cool water
-clean water
-don't change the salinity from the water you caught them in (don't drop them immediately into a livewell filled with fresh water and leave the intakes closed if you're going to fish at a distance from where you caught them, ESPECIALLY if there are any rivers emptying in the area)
-keep the water aerated
-keep your filthy hands out of the water. Use a dip net.
-remove dead IMMEDIATELY, as they'll kill the others

Basically, do what Deadliest Catch does to keep their crab alive.

Oh yeah. Don't forget to empty the livewell when you get home. You just THOUGHT selling a boat was hard.

Here's something one of my uncles use to do to catch live shrimp. He's take a can of dog food and tie a string around it with enough line to let the can sink to the bottom.

He'd puncture the can in several places and toss the can out in the water and wait a bit, then start tossing his cast net to catch live shrimp to use for bait to catch specks and reds. Worked like a charm most of the time.

Gus' tackle in Slidell used to sell 8-10 foot test trawls, we had a lot of fun with that.

Caught enough to eat and fish with.