jorcus

I lean toward an environmental explanation vs genetic. According to the DEC a recent study showed 47% of the fish caught were wild reproduction. https://dec.ny.gov/things-to-do/freshwater-fishing/places-to-fish/great-lakes-niagara-river-st-lawrence-river/pacific-salmon-fishing So if is environmental what has changed over the last 20 years? The first hypothesis would be warming waters. In theory that should help the salmon grow but at some point they may have to swim longer and farther to find oxygen rich water or the biomass that they are feeding on. There may be more Biomass in the lake but the distribution of that seems somewhat uneven according to the surveys. A second hypothesis would be that the increasing amounts of pen reared fish is affecting the overall fishery. I believe that 2/3 of the hatchery Kings on the US side are pen reared and 50% on the Canadian side are released in pens. Why could this impact the fishery? More young fish survive increasing the number of older fish competing for the available biomass. I don't know if that is quantifiable but it's something to think about.