[troutman]

50% drop in rainbow trout puts Bow River's 'world-renowned' sport fishery at risk

https://www.cbc.ca/news/canada/calga...G-19q8hjU-N61s

From 2003 to 2013, the population of rainbow trout in the river dropped between 43 and 50 per cent, biologists from the University of Calgary and the provincial government found in the study published in the Canadian Journal of Fisheries and Aquatic Sciences.

The researchers weren't able to pin down a specific cause leading to the decline, but instead flagged multiple stressors that Cahill described as "smoking guns."

The first is flooding. Major floods in 2005 and 2013 likely displaced fish downstream and modified habitats enough to impact populations.

Another factor is whirling disease — a parasite that infects trout and makes them swim in circles. It's usually fatal.

One factor that might surprise people is the increased mortality rate from practising catch and release.

Sean F. Britt I am not in agreement with this study. When you look at the methodology and some conclusions, there are some fatal flaws which sets up the results to be what they are. Two major ones are time and location of fish count. They were done at places and times where fish naturally won’t be. [Facebook]