When the province recently suspended logging indefinitely along the Hidden Creek tributary of the upper Oldman River, it heeded a study done by local Alberta Conservation Association fish biologists.

The suspension protects a four-kilometre stretch of prime bull trout spawning redds, identified in the study started in 2007 with Devonian Foundation support to better define the status of bull trout in the area.

Earlier indications suggested bull trout occupied only 33 per cent of their historical distribution in the Oldman watershed, says Trevor Council, ACA fisheries program co-ordinator in Lethbridge. As a result, the native fish, adopted in 1995 as the province’s official fish, has been designated a species of special concern.

“The decline at Hidden Creek and across the province has been attributed to a variety of human activities, including angling pressure, habitat degradation and fragmentation, creation of barriers to fish migration and introduction of non-native species that compete with bull trout,” says Council. Intense recreational and industrial activities such as forestry and gas and oil exploration have taken a toll on the upper Oldman area.

The decision also reclassifies hidden Creek as a Class A stream under Alberta’s Water Act, a designation severely restricting watercourse crossings in the drainage and limiting disturbance to the aquatic ecosystems.

The ACA study found the four kilometers of Hidden Creek now protected produced 75 per cent of the Oldman migratory bull trout population. Bull trout spawn in the fall and migrate downstream to various parts of the Oldman above the dam.

Biologists tagged 176 adult bull trout in Hidden Creek ranging between 320-760 mm (12-30 inches) over the past two years. The study identified 108 bull trout redds within the four- kilometre reach, all of which were located downstream from the proposed Spray Lakes Sawmills logging area.

The concern was logging in the area would result in sedimentation during runoff that would smother the redds. As well, new logging roads into the area could increase fishing pressure during critical bull trout spawning periods, further adversely affecting the bull trout population.

Since bull trout are top predators in the upper Oldman drainage, a decrease in its population could affect the rest of the Oldman aquatic ecosystem and thus affect the fishery, including cutthroat trout.

Hidden Creek is vital to the survival of bull trout in the system, says Council. The conservation measures, taken as a result of data from the ACA study, “will benefit the species, the fishery resources and, ultimately, the angling public.”

The Oldman Chapter of Trout Unlimited Canada has nominated the ACA for a Canada National Recreational Fisheries award for its efforts.

Council expects Fish and Wildlife officials at Blairmore will complete regulation changes for Hidden Creek this fall.

The ACA study included Dutch and Racehorse Creeks and the Livingstone River in 2008 and continues this summer. As well, a minimum four-year survey of the Castle River drainage is planned starting next year, resources permitting.