If the LMB were human we would simply check their DNA fingerprint and track them backwards to determine 'origin' Could characteristics include genetics link them to their stocking origin?
Here we go again... They could have been bird stocked (not possible), bucket stocked (I watched it happen at my house), but in your case more likely came in with the stocked fish especially since you have more than a few of them.
It seems that since it happens more than 'rarely' that unwanted fish show up with stocked fish that the next thing us customers will want to demand is some sort of proof of the fish being what they were promised to be, similar to certified disease free etc. Seems like there could be some way that suppliers could do random checks of their CNBG, FHM etc and determine (through an independent or 3rd party verification system, or even someday maybe gene tests like they do for asian carp) the percentage of fish that are in the sample and are not supposed to be in the sample of fish netted out that day.
Unwanted LMB can be as bad/hard to control as unwanted asian carp in some ways
Since a few unwanted 'extras' can be a nightmare and very expensive to fix, isn't the burden of proof squarely resting on the supplier and not the customer, after the fact, when the supplier can always say that a stray pelican mistakenly burped when flying over and 12 LMB fell into your pond and you couldn't say for sure if that happened or did not happen?
I guess if i was in the fish raising/hauling/stocking business, this would be an important way to separate my business from others and assuring quality and PURITY of the bags of fish and standing behind it would easily make up for the extra efforts of daily quality control checks of my fish supplies.
