As the Cessna 205 float plane touched down on the tundra lake in Alaska earlier this month and taxied toward a gravel shore, our pilot and guide Glen Alsworth Jr. began to explain bear etiquette: the expectation for our behavior in territory with a significant number of brown bears.  “Stay together. Make ourselves appear as a single object so the bears only have to pay attention to one thing, and not four different things. It will make it easier for them to move around us if they want without getting agitated. They’ll keep an eye on us, but they are much more interested in what the other bears are doing.”
Glen had my attention. During the final five minutes of our flight from Port Alsworth down to Katmai National Park and Preserve on Bristol Bay, we counted eight bears feeding in the creek below us. The bright red sockeye salmon were thick in the water, and big enough to see from the plane. We understood why so many bears were there.
“We carry everything with us,” Glen continued. “If a bear decides he wants to come our way, we want to be able to clear out space for it quickly without leaving anything behind.”  Glen didn’t say this because he thought we were in danger; his concern was for the long-term safety of the bears. If we left anything edible behind, the bears would come to associate humans with free food. He also noted that pretty much anything we leave behind — edible or not — will get chewed on.
Before we got to the bears, however, we had to do some fishing. We weren’t interested in the myriad sockeye. They had already climbed upriver dozens of miles from the ocean, gaining over a thousand feet in elevation. Though they hadn’t spawned yet, they were spent and would not have tasted good.  But just as huge numbers of egg-laden salmon had brought in bears from all around, so also they had brought rainbow and Dolly Varden trout, which lay on the river bottoms behind the sockeye sucking up eggs that dislodged. They also dined on chunks of salmon flesh floating downstream. With so much easy protein at hand, these trout were fat. We hoped to catch some.
We climbed out of the plane, set up our rods, stuffed our lunches and whatever gear we needed into our packs and pockets, and started around the lakeshore toward the outlet. We were well above the timberline. The tundra was soft and spongy, covered with blueberry plants that looked more like ground-creeping vines than bushes. The nearby hillside had patches of snow still melting down a ravine.
There were four of us on the trip: myself, Glen, and also David O’Hara and his son Michael, both Middlebury College graduates. At the end of the lake, we descended a low bank to the river and began to fish. The water was only ankle deep in many places, with a few knee-deep runs, and an occasional waist-deep hole or undercut bank. It was also clear, and the fish had spent the last several days dodging bears splashing through the river after them. Between the bears and the shallow clear water, the fish were skittish. But there were plenty of them. Bright red sockeye salmon were spread across the river, sometimes in water so shallow their fins were in the air.
Mixed among them were the trout I hoped to find. They were much more difficult to see with their mottled backs blending with the river bottom. But we knew they were there. We began to cast flies. We fished a variety of patterns: egg-sucking leeches, and leeches without eggs, gaudy red streamers, little imitation eggs, and even flies imitating chunks of rotting salmon flesh.
With water so clear and shallow, the hardest challenges were spotting the trout without spooking them, and keeping from accidentally hooking the salmon. It was impossible not to accidentally hook salmon from time to time, especially since the trout we were trying to catch lay in the river directly behind or in the midst of the salmon trying to eat their eggs. Sometimes our movement would spook a bunch of salmon, and they would dart off in all directions — including right through our lines. We were fishing with five-weight rods and leader size appropriate for trout, so it was very difficult to bring in a ten-pound sockeye.  I did manage to land one accidentally-hooked salmon. And on other occasions I was able to wiggle a hook free. More often, though, the accidentally hooked salmon resulted in broken line.  A lot of time was spent tying on new hooks, and I had far few flies at the end of the day.
After trying a leech pattern through some deeper water where the salmon were just passing through, I got into an ankle-deep stretch where they were actively spawning. I switched to an egg pattern and drifted it through the middle of the salmon. As my fly passed over a slightly deeper depression, a dark shadow separated from a rock and slammed my fly. I had on a big Dolly Varden trout. I landed it, and a few minutes later just a few yards downstream I landed a fat rainbow trout.
Those would be the only two trout I landed that day. We all saw many more, but some wouldn’t hit, some broke us off, some spit hooks. And we kept hooking sockeye and getting our lines broken. Eventually, we fished our way down to some waterfalls.  As we came over a crest in the hill, we saw four brown bears in the river below us, only 70 yards away. At our appearance, two of the bears loped off up a steep hill. The other two stayed around.
We descended the slope and watched the bears as we ate our lunch atop a rock ledge. They were chasing salmon as they passed upriver through the shallows.  The bigger bear had the prime location. A slightly smaller bear watched. Five or six salmon would make the run at time, which seemed to confuse the bear. It would start after one salmon and then change its mind and turn and chase another, splashing this way and that as though playing some grand game of tag.
We watched for several minutes as the big bear worked in futility. Finally the smaller bear stepped in, and in about 30 seconds grabbed a big salmon in his jaw. The bigger bear charged at him at once, and like a playground bully made the smaller one give up his lunch. He took it and headed 10 yards up the hill to eat. The smaller one didn’t seem bothered. A minute later it had caught another. It stood up on its hind legs and played with its food for a while before ripping the fish open and eating the eggs out.
The scenes repeated. After an hour, the bears wandered a few yards further down river. Glen told me it was safe to get the video I had come to get. I climbed down to the river and shot some underwater footage of the huge numbers of salmon preparing to leap the falls and continue upstream. Then we headed back toward the plane, following the salmon upriver on their final journeys. 
So much of the Alaskan ecology depends upon salmon and their eggs. We might have made use of that fact and stopped to fish once or twice on our way back to the plane.