Today I used a large plastic bottle with the neck cutoff, then inverted and stapled back into place, to make a shrimp trap for the Bloody Mary shrimp in my 60 gallon office tank.
In total I trapped 296 shrimp, of which 17 were culled. I bagged 50 to bring home for my new 55 gallon tank, and the remaining 229 were returned to the tank.
I certainly did not trap all the shrimp in the tank, particularly the mothers with eggs and the smallest juveniles seemed less adventurous and eager to enter the trap. In fact I did not trap a single berried female though I spotted quite a few in the tank.
On the other hand, I did manage to cull the shrimp I had specifically noticed in the tank and wanted removed. Of the 17 culls 1 would have passed for a Blue Dream, 2 could nearly have though they had a few red spots, 4 were a very dark, nearly black blue, 3 were an equally dark red, 2 were outright dark chocolate, and the remaining 5 were red but with very little color.
Overall I was pleased with the results which seemed to justify my estimates of 500+ shrimp in the tank, as well as the overall quality of the Bloody Mary line, with 5.7% of the shrimp culled. This being my first culling I have no real baseline, but would be interested to know what other people with experience have seen.