I've heard stories of sturgeon leaping out of the water for no apparent reason but now I'm a believer.
I was just up on the Fraser, practicing a little Dental Hygene on the locals, when all of a sudden a Gator about 4 ft long came out of the water right beside my boat!
It was about 8am. Boy did that wake us up!
It was awesome!

Have any of you seen this happen before? It must be a rare site?

I have been fishing on the North jetty on the columbia looking north towards north head and saw as many as three in the air at once. The first time My dad and I saw it was about ten years ago, and we could not figure out why "sharks" were jumping. Then one came up right in front of us with its back toward us and there was no mistaking the white diamonds down each side. I have had a lot of people look at me like i'm crazy when I talk about that. Have never found out why they do it...and it only seems to happen at the same time every year...

The first time I saw one one jump I couldn't beleive what I was seeing. It is awsome to see an 8 foot fish jump out of the water like it was a salmon.

I've seen them jump in the Snohomish River a couple of times, but not in the past few years. About 7 or 8 years ago I was fishing the Snoho with my buddy in my 14' Lund, a HUGE sturgeon rose out of the water right next to the boat. I could have hit him on the head with my rod tip. He went back under and I glanced at my fishing partner, who was so scared he almost "dirtied" himself. They are impressive beasts!

They were jumping non stop yesterday down on the columbia. If you really want to see some exciting jumps go up to bonneville and watch the big ones jump.

I've seen it on the Chehalis. Seems like right around tide change the would start going for it. One night my Bro and I were way up river in a little Jon boat. Dark as all get out and all of a sudden they started going. Big ones and little ones. Kinda scary in a small boat just praying one dosn't land in the middle of it. It would of folded that boat up like a folding chair.

down in the deep south on a certain river, they have been known to hit boats and cause serious injuries when jumping..

Down on the Columbia in the deep hole at Portugues Point they jump almost all the time down there. Been there in February and March and still see them jump. Nothing like the early Spring though, when you see a hundred or more in a day at the deep hole.

Having guided out of Hermiston on the Columbia for 6 years I have seen a lot of jumping Sturgeon (not just hooked ones).
Like AuntyM says, there are many theories out there, but the one I have most resigned myself to, after these years of watching/catching them, is that it mostly but not always happens in hard current. When a big fish is worn out and they empty their air bladder and sink (you old Sturgy fisherman know what I'm talking about), the only way to get them off the bottom was to get their head up and then the current would force them to the top. I think they cruise around in the hard current and occasionally get their nose up while they are swimming along at a good clip and the current causes them to shoot to the surface. Maybe when the light starts getting brighter, they swim faster, and the next thing they bust the surface. I know this cannot account for all the jumps, but I think it surely accounts for many of them.

MC :p