Years ago I was fishing sturgeon with my old university roommate.
For years he ran the fishcounting equipment in Abbotsford.
He talked of seeing several times a sturgeon breach that he estimated at 2000 pounds.
We were hanging out in a large eddy on another buddie's restored 1920's 60' tugboat, catching piles of 3-6 footers....
A nearby 1070s 20' open fiberglass boat hooked up something Big!
First the fish pulled the boat upcurrent in the eddy,
then out to the main river, and continued UPSTREAM!
Despite the heavy fishing tackle, the fish soon broke off....
That boat had to weigh two+ tons with the 4 people on board.
While huge, 4-500 pounds is just a baby compared to a few of the real old-age beasts that are still in that river.