Well I am a happy camper. I headed out into my local lake after midnight and anchored no more than 200 yards from my home, and waited for the tide to turn. I then turned on my headlamp, and began scooping prawns out as they floated past on their way out to the ocean. Being a first ever go, it took me a while before I could reduce the percentage able to jump clear of my net, but I finished up with about half a kilogram (local laws mandate a handheld net for amateurs).
I am confident that next time I could get 2-3kgs, with better lighting to light up their "headlights" to give me earlier warning, plus more effective use of the net (plus, more importantly, getting there earlier so nobody else anchored further uptide!)