I don't know much about bear/food incidents on the Whitney trail but, overall, incidents are declining -- definitely in Sequoia Kings, less sure about Yosemite. The reason is most everyone's carrying canisters and they work. Definitely a pain to carry but incidents have gone from hundreds per summer in the Charlotte area in the 80s to none reported in the last couple of years (note that's just one area of Kings).
The standard work on bear attacks is Stephen Herrero's "Bear Attacks: Their Causes and Avoidance." I can't quite remember, but believe he (or others he interviewed) theorized that black bear attacks occurred when the black bears were more wild. So the danger would seem to be in the period when human activity is spreading into their areas. There might be better theories now because I'm not sure that explains it all.
There have been a handful of bear injuries on people in Yosemite and Sequoia Kings. They've all occurred when food is present and being disputed.Several with people sleeping with their food in a tent or right by their side. In extreme cases when bears become dependent on human food, there have been bears who will follow people down the trail getting them to drop their packs. I've actually seen this happen, but haven't heard of a case since the 90s.
I've actually got an old slide after a guy chased a bear around a tree trying to get his food sack back in Little Yosemite Valley in 1973. You can sorta imagine the Larson cartoon as it unfolded. Kid (18 or so) chases bear. Bear runs then thinks, "hey, wait. I'm a 250 lb. bear. I've got teeth. I've got claws! Grrrrrr!" So he stops, turns around and swipes the guy twice across the chest. Then scurried off into the woods. Fortunately the claws barely broke the skin but left some photogenic red claw marks.
The original poster asked about sealed food and I'm not sure that was addressed. ALL food needs to be secured in a canister -- cans, foil wrapped, whatever. Bears aren't dumb.
That's all partly to say that even though bears seem no longer a problem in many parts of the Sierra, once canister use drops below some magic level, they'll be back... .
George
