if ur after thesze shrimp and are in the area, take a trip to Manly Dam.
u gotta wait for the water to be down as at the moment the level is too high and it is harder to catch these lil guys.
just scoop anywhere underneath rocks or in the plants in the water and i am sure, like i have experienced personally u will catch them in the thousands. lol
only prob is take an air pump cause trust me, after 3 hours of catching these guys (collectin enough of these guys to feed to my oscars and cichlids,) u dont want to be like me and get home to have a bucket full of dead shrimp.
lol
hope this helps
-Baz
P.s. dunno how legal this is too as it is in a Nat. Park, but u often see ppl fishing n stuff there.