Close proximity - There isn't much you can do. Except perhaps get down on your knees, making yourself small, nonthreatening, and submissive. If one comes upon you while you are fishing, camping or busy doing anything, best not to make any sudden moves. Appear as nonthreatening as you can. Slowly lower yourself. Do not make yourself appear larger. Not with this animal. That would be asking for it. Don't look them in the eyes. Do not scream. Wait for it to leave. Depending upon the situation, you might be alright to continue fishing or whatever it is that you are doing, while it watches you and then leaves. But if you feel there may be a problem, then I would do those things. - Until we learn otherwise.
Exact speed is uncertain. However, it should raise your eyebrows. A grizzly bear can charge 39 feet in one second. Bigfoot is much faster than that. Not to mention, they also have longer strides than a grizzly. In the target area, a 6 foot stride when walking, and 15 feet when running. That was only one individual. Some could spread farther than that. This individual only had a 11 inch long track. The males out here have 18 inch tracks, and they can be larger than that too. Doug and I have heard them running in front of our camp, back in 2013. They are so fast, it will mess with your mind. I still can't get over it. Makes me wonder if this animal is worthy to be listed with the cheetah. It must be close. They have long strides too. 21 feet I believe. This information should help give you an idea of what you can be up against. They are wild animals, and will behave as such. No matter how you may want to believe otherwise. Let wild, be wild.
Do not let this knowledge ruin the thought of you wanting to be out there in the wilderness. Nothing has changed, except for the fact that you are now aware something unknown may be out there. You now have information that might be useful. It is always better to be prepared. You are exercising caution for grizzlies, are you not? Predators do not want any trouble. Most especially Bigfoot. They do everything possible to hide their activities. Why draw attention to themselves?
They may be short tempered.
Bigfoot would be of far greater value than the grizzly.Concerns with killing one.
A person might get away with shooting one, but you will have the rest of the family to deal with. The thing to consider is, will retaliation stop there? Or will it continue on in to town limits? (Entire ancient village brutally killed near Damsumlo Lake. Was told to Stephen Doyle. I am assuming the Bukwas acted out of revenge if the villagers had killed one. The ancient people were found with their heads missing.)
Concerns with tranquilizing one.
A person needs to consider, the very same outcome as killing one.
Researchers need to figure out what they plan to do once they have found them. As for myself, my job (self appointed) is to locate them and then point them out to a scientific team. I am not qualified to go on from there. This needs to be done properly. However they decide to do this, God help them. Keep safe everyone. Sometimes I wonder if the only way to do this, is to plant someone in there who is familiar to the family unit. To be permitted to observe them. Film them and possibly grab those samples necessary. This would take time.
Don't just suddenly turn and run. You are only asking for trouble. A predator's instinct is to give chase. They may not want to eat you but do enjoy the chase.
Never go alone! At the same time, never assume you are safe just because there are more of you. You still need to be on guard.
Bring your dogs with you. They can alert you to something nearby and also give you the opportunity to make your escape. The dogs will look after themselves. You are not as quick and agile.
If your planning on hiking in high country, carry a transponder. If you fail to return, this will help searchers find you. You can also use flares or a flare gun to signal for help. If anything has happened to you, the transponder will be more useful.
Women should avoid entering the wilds when menstruating. The smell of blood attracts predators. The smell of sex will do the same. I also avoid using perfumes, deodorants, makeup, smelly soaps and shampoos etc.
Avoid wearing bright colors. This could bring unwanted attention.
Check weather forecasts ahead of time. If a storm is coming a day or two ahead, change your plans. If the weather looks like it is changing for the worst, turn around. Don't let your attention turn away from being cautious about your surroundings. Many people have suddenly vanished prior to a storm. Storms make search and rescue very difficult. In some cases, impossible.
Never assume that just because you are in a National or Provincial Park that you are safe. Many people have disappeared from those areas. In some instances, predators have become habituated to humans. A predator could be using walking trails as human trap-lines.