The white curds or "boogers" which form on cooked salmon and other oily fish, and sometimes on smoked salmon, is "albumin." For an explanation, see http://www.americastestkitchenfeed.com/cooking-science/2012/12/what-is-that-weird-white-stuff-on-cooked-salmon-its-albumin-and-we-discovered-how-to-minimize-it/ . Apparently you can reduce the amount of albumin on cooked fish by briefly brining it before cooking it. So smoked fish is apparently less likely than cooked fish to develop curds of albumin, because smoked fish is brined. Albumin forms on the surface of fish when the meat reaches 140-150, which is why starting the smoking process at lower temperatures reduces the amount of albumin which forms on the surface.
Very interesting...thanks !!
AkBillyBow