I am a certified scuba diver. The underwater atmospheric pressure is what really needs to be taken into account. There is a huge change in atmospheric pressure underwater. Underwater, pressure increases by "one atmosphere" (the equivalent of atmospheric pressure, or 14.7 lbs./sq.in.) for every 33 feet we descend into the water. This means, for example, that the pressure at 66 feet below the surface is 44.1 pounds per square inch, or three times that of the atmosphere. It takes more air pressure the deeper you go. As you ascend in water air expands. This is why you see a perches belly come out its mouth when pulled from 50 ft of water. I have never seen a salmons belly come out its mouth. I am not sure if fish get the bends or not. The above test article does not mention about which depth the salmon were caught. The pictures in the article only show streams in the back ground. I would venture to say the mortality rate is higher than the articles. I am not an marine biologist and these are only my views.