Pond Boss Forums INTRO Questions & Observations Bird leg fish transport

I have gizzard shad in my pond. The nearest lake with gizzard shad is 9 miles away by air. I still have no idea how they got in my pond. Gizzard shad are difficult to keep alive even if you try to. I have a breeding population, so more than one made it in there. All fish I have stocked have been hauled and hand sorted and stocked by me. There is an obvious difference between gizzard shad and other fish, even when very small, so I still have no explanation as to how they arrived. I'm located at nearly the highest point in the county and there hasn't been a flood at my place ever. My watershed is 100% ag fields. There is a seasonal creek 300' away and 8' lower than my pond that my 8" overflow connects dump in to. My overflow pipe has never been more than 1/3 full. I find it extremely unlikely that a fish could/would swim 300' upstream in 2 or 3" of rushing water in the pipe and it's even less likely that it would be a gizzard shad.