Even relatively fatty fish like salmon can go from tender and moist to chalky and dry in a flash. In the test kitchen, we use an instant-read digital thermometer to tell when salmon is done, and we prefer it cooked to 125 degrees for flesh that has the ideal balance of firm and silky. The majority of the salmon we cook in the test kitchen is farmed Atlantic, but as we’ve cooked more wild varieties, such as king, coho, sockeye, and chum, we started to wonder if this catchall temperature was appropriate across the board. We set up the following test to find out.
We cooked samples of four wild Pacific salmon species—king (Chinook), sockeye (red), coho (silver), and chum—along with farmed Atlantic salmon to both 120 degrees and 125 degrees in temperature-controlled water baths. We asked tasters to pick which sample offered the ideal texture for each type of salmon.
Tasters unanimously preferred the coho, sockeye, and chum samples cooked to 120 degrees and the farmed Atlantic cooked to 125 degrees. While a few tasters preferred the king sample (the fattiest wild variety) at 125 degrees, the majority preferred it at 120 degrees.
Fat Differences Between Wild and Farmed Salmon
All wild salmon leaner is than the farmed kind, but certain species like wild coho and chum have dramatically less fat.
Farmed Atlantic salmon differs significantly from the half-dozen commercial wild varieties caught in the Pacific ocean. Here’s why:
The collagen protein in farmed Atlantic salmon contains fewer chemical cross-links than in wild varieties, which translates into softer flesh.
Farmed Atlantic salmon contains more fat than any wild variety (up to four times as much fat as the leanest wild variety), providing the perception of juiciness when cooked.
With naturally firmer flesh, and less fat to provide lubrication, wild salmon can have the texture of overcooked fish even at 125 degrees. By cooking the wild varieties to just 120 degrees, their muscle fibers contract less and therefore retain more moisture.