Another Rainbow Trout Hatch Last Year

Another New Generation of Rainbow Trout Spotted on the Bow River

On some mornings I will walk down to the Bow River, very early in the new day, and watch the river for a while. If my timing is good, along with my luck, I will sometimes see trout rising on the surface. If there is small trout, they usually come to the surface near the shoreline, to feed on small floating midges, mayflies or caddis. This close observation is a good way to see if there are new rainbow trout in the system.

The only problem is; that you need to catch a few on a fly rod to actually see if they are rainbow trout or brown trout. This can be done by fishing a very small trout fly, in the correct manor. My preference is to use a small nymph pattern. Sometimes it is not an easy task, but that is fishing. There is a sudden burst of excited jubilation when you catch your first small trout of the season. This is often accompanied by a little laughter and contentment, knowing that there is a new generation of trout in the river.

In July of this year, while doing one of these morning walks, I discovered a few small trout breaking the surface of a quiet pocket of water along the shoreline on the Bow River. Later that morning I returned with my fly rod and a good selection of small nymph patterns. The flies ranged in size from size 20 to 14, but it was the minus 16’s that I would fish on that outing. Just about anything that was medium to dark in color usually works, and there is always the possibility of a larger trout taking your pattern.

On that July morning I did manage to capture a small rainbow trout on my trout fly. This was great news for us fly fisher’s that cast on this local reach of the river. Last year, I also captured some small rainbows from a hatch that occurred the year before, in 2016. So this latest trout confirms that we had two rainbow trout hatches in 2016 and 2017. Much better than previous years, when it was hard to find a small rainbow trout on the Bow, from any hatching that happened in 2014 and 2015.

This is the small rainbow trout that I captured in late July of 2018.

I know that there are more rainbow trout in the river than the one that I fooled into taking my fly, because I had a few other hits by trout that were too small to be caught on my fly pattern. Bottom line; it is really great to see that the Jumpingpound Creek strain of rainbow trout are still holding on, despite the whirling disease infestation.

Does It – Or Doesn’t it?

Every time I catch a small rainbow trout these days, I wonder it this is the one that has a whirling disease resistance? The whirling disease resistance topic is growing in popularity, now that some strains of rainbow trout are showing that they can fight the outbreaks of this new threat to our trout fishery.

Recently, I caught a small rainbow trout near the mouth of Bighill Creek and discovered a small lesion on its side. I don’t know if this was signs of the whirling disease parasites attacking the trout or not. Whirling disease spores attack a rainbow trout thru its skin, so this may be a possibility. In any case, my first thought was is this trout developing a resistance to the disease. I safely release the trout back into the creek.

You can see a small lesion on the side of this juvenile rainbow trout. This trout seemed to be very healthy, other than the mark on its side.

My next post will be a brief report on the plants from this year’s “Bow Valley Riparian Recovery and Enhancement Program”. Enjoy your summer!


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 40 years!
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