Salmon fishing in S.E. Alaska has wild, whipsaw swings in numbers of fish from moderate abundance to near population crashes from occasionally because of the advanced technology of the commercial salmon fishery, management paradigm and perhaps deep ocean over-harvest. The long range outlook for salmon numbers is probably downward- like that of many fish stocks around the planet. Sports and subsistence share of the fishery has dwindled too. Modernizing fish traps to replace net fishing would probably remedy that. Fish traps equipped with virtual intelligence controllers could seperate fish from those legal to take and those that need be released.
Fish traps have a bad reputation because of their efficiency at catching salmon in the past when the lack of management oversight by government allowed taking salmon until the population crashed. Competent government management quotas (some cynics would say competent government is an oxymoron) could assure that 51% of returning fish were free to go upriver to spawn and just 49% caught in traps and fish wheels with modern designs to catch or release fish for human food or upstream spawns.
A Tlingit somewhere explained to me once how Tlingits (that have been using traps for salmon from well before Columbus arrived in the Caribbean) long ago took great care with the fish and gave them respect, holding up the first fish to the sky, to spirit, in thanks. Maybe that was something I saw in a Trevor Howard film- too long ago to recall accurately. Other fish were brought ashore for some other purpose for the well being of the fish. That account of tradition is something I cannot recall concisely years later, it may have been that female fish full of eggs were released or squeezed out of eggs as in that job search commercial with Russian fish squeezers, yet the salient point is that salmon were not caught to extinction with the region-wide network of traps- perhaps 1500 sites have been found by archaeologists, and were sustainably harvested.
If an exact number of fish were caught and a slightly greater number released free to return to spawn the actual number of fish returning should increase from year to year if their habitat isn’t destroyed by encroaching effluence from mines, human sewage in great quantity with only primary treatment (nine island cities have been given federal waivers from secondary treatment because the alternative is to decree they must have mass constipation several decades), construction along salmon bearing streams, waterfront areas, usual human carelessness oblivious or indifferent to externalities harmful to wildlife and other contaminated water input from storm drain releases etc.
I should note that it should be possible to develop new forms of sewage treatment or to give tax incentives to people that use electric no-flush toilets in the region. It might be possible to process human sewage and sewage from fish farms (filtering out the crap in so,me way) together (if clean, pollution-free fish farming legal criteria can be created that would permit fish farms meeting that criterion) to produce exportable fertilizer for agricultural sales.
There are people that don’t realize that deep pocket capitalization fundamentally rules the world these days. Environmental laws can be rolled back by politicians in the pocket of wealth- and that usual includes most. Environmental protections need be effective forever while environmental exploiting legislation need occur just once for victory. Despoiling the environment has the odds on its side in the long run. To defeat that a little better approach need be made to supplement environmental protection. That is, economic need be made to cohere within environmental protection so despoilers and exploiters of natural resources face economic competition with local politicians that support the local environmentally compatible industry such perhaps, as clean fish farming could present that potentially might be able to produce as many fish as natural fish taken from fish traps, sports and subsistence fishing.
Human activity makes change occur to the environment. ecological economics for sustainability are required if mal-adaptations with global investment pressuring resource exploitation is not to be the default use. To get ahead of population, demographic and political pressure deleterious to long-term salmon numbers stabilizing the salmon fishery and probably eliminating bi-catch in the process with new design paradigmata fish traps simultaneously with the rise of a clean fish farming industry may be optimal. The competition to conserve salmon is from Wall Street logic rather than white and black immigrants to S.E. Alaska. The human population may be stable now, yet that is unlikely to remain the case in twenty years to the rest of the century. Global warming and illegal immigration will drive more people north. Gold and silver mines will impact fishing and development of more business will reduce the influence of salmon fishermen whom are petty bourgeois yet not deep pocket capitalists. As S.E. Alaska becomes more like Puget Sound and every soul in the region can afford an electric powered boat traveling at high speed, like even the Atlantic coast S.E. Alaskan wildlife may fade to become a memory. The pressure of global warming and over population can drive humanity to plunder the environment like locust. Getting sustainable fish farming in on the ground floor- buying in early, may serve to catalyze the environmental protection of the waters and land that sustain fish farming and plentiful fish traps, sports and subsistence fishing. Deep planetary capital would face higher environmental challenges when exploiting the natural resources of the region, unlike today when many oppose any change to a reduced salmon fishery with little political power compared to that of Wall Street.