Spawning Numbers Down on Bighill Creek

Low Summer Flows May Have Been The Reason

During the hot and dry summer months the Bighill Creek ran low this year. The lack of rain kept the stream trout populations left with little habitat to retreat to, during limited volumes of flow in the creek. These conditions can cause stress for the local trout populations and may have been the reason why the spawning numbers were down this fall.

What ever the reason, the numbers of brook trout and brown trout spawning in the main-stem of Bighill Creek this fall were down considerably. Ranch House Spring Creek suffered a fall in spawning trout redds from over 40 last year, down to 7 this fall. The upper spring creek brook trout redds were also down by half from last year. Fortunately, Millennium Creek sustained a reasonable number of fall spawning brook trout, which will insure a fairly good recruitment year this next spring.

With the low flows in the Bighill Creek, beaver dam building was up from previous years. The new dams along the creek will help provide refuge for trout in the deeper water’s of the dam, during these low flow conditions. Even a depth of over one metre can make a big difference in the water temperature on small creeks like the Bighill. The numerous beaver dams may have prevented some trout from reaching their key spawning habitats this fall. Fortunately, with the high numbers of trout hatching in the system this past year, recruitment of new trout into the system will be good for the next few years.

            This video shows some spawning on the Bighill Creek system this fall.

Millennium Creek Still the Most Reliable Spawning Tributary

At first, I thought that the numbers of spawning brook trout on Millennium Creek this fall would be down. The reason for this was that there were a number of beaver dams on the lower reach of the Bighill Creek this fall and I thought that they would prevent the normal run of spawning brook trout from entering the Millennium Creek. However, I was pleasantly surprised by the total number of brook trout redds (egg nests) that I mapped this fall.

 

The total number of 28 brook trout redds was just down slightly from last year’s total redd count on Millennium Creek. This year’s total would be on the higher end of the mean average for the creek so far. Which is great for a small spawning tributary like Millennium Creek.

 

Brown Trout Spawning Was Down This Fall

Something that really has me concerned, is the drop in the number of mature brown trout on the Bighill Creek. This year’s numbers of spawning brown trout pairs were down considerably. This is not good news for the population, which is very limited in sized on this small stream. I am still pretty worried about the new fishing regulation changed on the Bighill Creek, which allows the harvest of two trout, including larger fish. In my opinion, this creek cannot sustain such a harvest on our brown trout populations.

Left: This spawning brown trout was holding over a redd when I took its photo this fall. Large mature brown trout like this one are necessary to sustain a viable population in the Bighill Creek. Without them, the population could crash and cause long term damage to the sport fishery in the creek. The large brown trout also keep the brook trout numbers in the creek in balance. Large brown trout will feed on juvenile brook trout.

 

 

About Guy Woods

I am Director of Bow Valley Habitat Development, based in the Town of Cochrane, Alberta, Canada. I love to fly fish and it is this past time that prompted me to get involved in the field of riparian and fish habitat enhancement. I have been working in this pursuit for over 30 years!
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