Why does a salmon cross the road? That's not hard to answer, in the case of Wolf Creek salmon. They cross the Alaska Highway near Whitehorse and swim up little Wolf Creek to spawn.

How they cross the road is quite a different question, and one that has cost engineers, fisheries officials, and salmon enthusiasts a good deal of trouble and expense over the years.

No one knows how long chinook salmon have fought their way up Wolf Creek to spawn, but we know roughly when they stopped coming. There were sightings of salmon in the early 1960s and possible sightings in the early 1970s, says Al von Finster, Resource Restoration Biologist with the Department of Fisheries and Oceans in Whitehorse. There is also traditional knowledge that salmon ascended from the Yukon River.

"And that's basically all we have."

During the 1970s, chinook salmon stocks in the Yukon River declined until only 121 returning adults were counted at the Whitehorse Rapids Fishway in 1976. Sometime during this period chinook salmon stopped swimming up Wolf Creek.

Then, in 1984, a restock and restoration project was begun for Wolf Creek chinook.

The Yukon Fish and Game Association proposed and started the project, says von Finster, who was involved as an advisor from the beginning. The Association has continued its involvement with the creek in the years since. Other participants have included the Department of Fisheries and Oceans, Yukon Corrections, Yukon Community and Transportation Services, the Whitehorse Rapids Fish Hatchery, and Hudson Bay Mining, and others.

Identification and removal of obstructions was an important activity from the beginning of the project. Natural blockages, such as debris jams resulting from blow down, were cut out with chain saws by Fish and Game Association volunteers. Beaver dams were breached to allow upstream migration of returning adults. Human-made obstructions included a steel barrier below the culvert that carries the creek under the Alaska Highway. Another was a haul road leading to one of the Whitehorse Copper mine's exhausted pits.

The disused haul road remained a barrier until the summer of 1990 when the owner, Hudson Bay Mining, removed it as part of the mine abandonment plan.

That left the Alaska Highway stream crossing.

The Alaska Highway crossing has been a problem for both salmon and road engineers since it was installed during the Second World War. The original crossing was a set of two four foot square box culverts that were washed out in 1948. The water was so high that a large D8 Caterpillar bulldozer trying to cross was submerged to the top of its engine.

The culverts were replaced by a bridge, and the bridge by the existing culvert. A sheet piling steel retaining wall was installed downstream to control erosion under the outlet of the culvert. It did this, but resulted in erosion downstream of the retaining wall.

To assist the Fish and Game Association, the Department of Fisheries built a stepped-weir fish ladder downstream of the retaining wall in 1986. This created a series of pools to allow the fish to make their way up the creek. However, the rush of water, particularly the high levels of run-off during spring freshet, eroded and broke down the weirs.

Finally, in 1997, the Association successfully applied to the Yukon River Salmon Enhancement Fund for construction of a solid concrete fish ladder. This time the structure is designed to lead the fish around the retaining wall while avoiding the full force of the spring freshet.

Along with opening the creek channel to returning salmon, the Wolf Creek salmon enhancement program has involved reintroducing chinook fry to the upper reaches of the creek. The restocking program began in the mid 1980s, and by the early 1990s a few adult salmon were spotted making their way back up the creek, von Finster says.

In the past few years, the return rate has ranged from 242 salmon in 1995 down to 61 in 1997. The reason for the swing in numbers is a mystery so far, says von Finster.

"We don't know what the natural variability is in small streams without significant lake storage," he says. "Most of our information is about larger streams like the Yukon River or streams with lakes immediately above the spawning grounds, like Tatchun Creek."

For more information about salmon enhancement and research on Wolf Creek, contact the Department of Fisheries and Oceans in Whitehorse at 393-6721.