Stocking is a necessity for several reasons including stocking waters that have had a fish kill, etc or otherwise decimated fish population. Additionally it's a superb tool for introducing a species where none lived before and the abundance of great Rainbow fisheries across the US, or the many farm ponds across the midwest, as evidence of that. Adding to that we have a huge number of fisheries across the US and elsewhere that are put and take fisheries and these would collapse without supplemental stocking. A huge stocking success is the trout fishery that exists today in the North Platte river and tributaries here in Wyoming and Colorado which was devoid of salmonids (trout) prior to the pioneers stocking them there. On the other hand, as the article points out, stocking is often used in situations that dictate otherwise. Stocked, Native, Wild and mixed fisheries all have their place and it often takes paying attention to nature that tells us which is best (humans being part of nature).