Take a look at Patagonia's Artifishal film[0]. The best thing to support anadromous fisheries might be just leaving them alone - in the rivers, and in the ocean.
[0]: https://www.patagonia.com/stories/artifishal/video-79192.htm...
[0]: https://www.patagonia.com/stories/artifishal/video-79192.htm...
Thanks for the link though, I'll take a look at it when I have some time.