Summer 2018 I put 2lbs of papershells in.. Fall 2019 I took 3 5 gallon buckets of crawdads out while fall net sampling. I can assure you I didn't hurt the population any and SMB were present at the time of stocking but small enough they didn't start utilizing the craws until 2019 sometime. If you have some nice areas that are rocked, you'll have crawdads last for a long time.