All salmon quit eating prior to spawning. Once that happens they start living off the nutrients they have stored and the meat begins to deteriorate and it will start to get soft. Once in fresh water, the meat starts to get “mushy”. The longer without eating and in fresh water, the mushier it gets. Personally, if it isn’t very bright, I don’t eat it and my wife won’t touch it. A lot of people “smoke” these fish, but I have found smoking fresh bright a lot better. I don’t even bother keeping them anymore, but can you eat it, yes?
BTW… the other thing that might cause soft flesh in fresh ocean caught salmon is a disease called “Kudoa thyrsites”, that is a disease that can be passed. Marine Harvest Canada has reported their fish have been infected with this disease for quite some time?
“ According to IntraFish, an industry newspaper, the kudoa parasite affects 20-50 percent of all salmon produced in British Columbia, costing the industry there at least $30 to $40 million annually. Atlantic salmon, the predominant commercial stock for farming operations, are more vulnerable to the kudoa parasite than Pacific salmon.” Ref:
http://www.puresalmon.org/diseases_parasites.html“ Quality issues related to soft flesh caused discards and complaints amounting to NOK 26 million in 2008. Mortality from a major algae bloom and a sea lion attack resulted in exceptional costs in the amount of NOK 9 million for the year. Actions to strengthen the operational performance were taken towards the end of the year. Operational EBIT for 2008 was NOK 108 million compared to NOK 222 million in 2007”
Ref:
http://hugin.info/209/R/1310360/303078.pdf“The average mortality rate was 0.22% per month in the quarter, which is 0.18 percentage points lower than in the same period last year. With the exception of Kudoa presence, the biological situation remains satisfactory. Slow sea water growth has been recorded in some sites in the spring and summer of 2009.”
Ref:
http://hugin.info/209/R/1334763/317024.pdf