Seth Zuckerman writes on forests, fish, and other ties that bind human beings to the rest of the natural world. His work has appeared in numerous magazines, including Orion, Sierra, and Whole Earth, and in the anthology Salmon Nation: People, Fish and Our Common Home (Ecotrust, 1999).

On a planetary scale, they represent just a few tiny pixels in the Big Picture. Along the north Pacific coast, salmon return annually to their natal streams to spawn and die. It’s their only shot at procreation, after a sojourn of 1 to 4 years at sea.

Unfortunately, they face a number of hurdles, and here’s one: where humans have built roads across salmon streams, we haven’t always been mindful to ensure that salmon can cross beneath our wheels unobstructed. The water is channeled into pipes called culverts, which are sometimes set too high above the stream for the fish to jump into. Sometimes there’s no pool in the creek where the salmon can gather the momentum for their leaps. Sometimes ... well, you get the idea. As a relatively new species on the planet, human beings have stumbled across plenty of ways to screw up. In our industrial incarnation, we act as though we’re the only species in the room.

But we’re learning. A new DVD, Fish Passage Success Stories, shows how conscientious salmonophiles have learned to rebuild those stream crossings as bridges or arches with gravel bottoms, so that the fish can pass through in good health. One installation was so good that a pair of salmon actually decided to spawn right in the culvert itself.

It’s a messy business, far from the world of GIS and datasets, but ultimately that’s how worldchanging ideas are translated into a changed world. Replacing a culvert involves the dogged application of heavy equipment. It’s where the Big Picture comes down to Brass Tacks, after going through a couple of magnifications.

Zoom in once, and you learn that the forests ringing the north Pacific glean nitrogen from marine sources — ocean-borne nutrients that the salmon brought upstream in their bodies, and then left behind when they died. Their lives nurture 137 species of wild animals, plus a 138th that scientists habitually overlook: Homo sapiens.

Look closer at the health of the salmon populations, and you can see how a host of human impacts, from hydro dams to ill-conceived hatcheries, from irrigation projects to poor stream crossings, have conspired to reduce their populations. Keep zooming in, to the solutions that people are beginning to try, and it comes down to something as prosaic as installing a better culvert or replacing flood irrigation with sprinklers.

Along the way to this sort of better Earth housekeeping, people change too. The Fish Passage DVD includes a clip of salmon lovers loitering around the mouth of an impassable culvert, waiting for salmon that failed to make it into the pipe. It must be said that they don’t just love fish because they are magnificent creatures: they know how tasty a good salmon fillet can be. But there they are, ensnaring salmon in nets, and then hustling them across the road to set them free upstream. It’s what we do until the dump trucks and excavators ride over the hill to save the day.

Contact videographer Thomas Dunklin for a copy of the 55-minute DVD, Fish Passage Success Stories.