Advocacy

• when and to what level does a rapid downward drop in river level affect fish populations

• Looked at the most critical time periods in fish life history –hydro-peaking and down-ramping have highest impact on fish populations during spawning ramping rates less than 10 cm/h are the generally accepted threshold (BC, WA studies) in which to minimize impacts. The rate lowers to less than 5cm/hr to best protect fry.

• Suggestion: higher than 10cm drop per hour should be avoided and limiting down-ramping to night hours may help minimize impacts

• Suggestion: implement a minimum flow with the down-ramping event that will maintain connectivity and ensure temperature changes are minimized

• emergency drops vs non emergency drop rates were discussed.

• Suggestion: appropriate drop rates to mitigate down ramping effect for the non emergency situations. The modelling shows there are some fishery gains or, at a minimum less negative effects, to be made here.

• Cormorants – are opportunistic feeders and will eat most readily available species with studies showing primary diet is minnow species and suckers and very low trout numbers (both brown and rainbow) in diet.

• Determined based on the 2.5% diet of trout that Cormorants are having negligible effect on the Bow River trout population.

• Pelicans – do eat more trout than cormorants so is being built into the model.

• Looking at available research, the Pelican diet can consist of enough trout to build into the model based mostly around stocked trout pond research as that is what is primarily available. It would be safe to assume that wild trout would be more adept at avoiding pelican predation than stocked trout but using the stocked pond data does build in a level of caution.

• There were assumptions made on how many pelicans were on the river and how many days they were on the river. They multiply the number of birds x the number of days x the number of kilos of fish eaten x the % of trout in diet (5%) and then compare that to the approximate population of trout in the river.

• End result was the estimated maximum population level of effect was 3.2% of the trout population was being affected with 120 Pelicans eating every day on the Bow for 150 days. To get a much better handle on this number the province is asking for a better count on the actual numbers of pelicans on the Bearspaw Dam to Caresland Weir as well as the number of days they are actually around. A plan for some AOGAA volunteers is being developed to help with a more accurate count.

• The result of this discussion is that yes Pelicans do have some effect on the population but it is low enough that no action would be taken because that has the potential to cause way more public relations problems and isn’t socially acceptable. Ultimately reduction in Pelican predation would not have a significant effect on improving the trout population. If the number had worked out to a much higher percentage other options could possibly be considered but that would have to be in the 60 – 70% range!

• There was significant interest in this stressor by all involved.

• A very thorough historical review of both fish and aquatic invertebrates was completed. Fish, in particular Rainbow Trout (think Steelhead) have a MUCH higher tolerance level to salinity than many of the bug species using the most sensitive life history stages (eggs, fry, larvae, etc). March is historically the worst month on the Bow River for salinity due to snow melt and the subsequent road salt runoff into the storm drains.

• Very significant information was available from the City of Calgary water quality database. This data went back upwards of 20 years. The readings are taken monthly.

So, there may be peak or lows that occur which are above/below the monthly sample value but this data is likely representative of overall baseline chloride concentrations in the Bow.

• The end result was the BOW river is WAY below any level of concern in regards to

chlorides. The water quality guidelines used to evaluate this are the Canadian

Environmental Quality Guidelines for chlorides, which includes a short-term/acute

threshold and a long-term/chronic threshold for the protection of aquatic life. For

example, in the 1,895 chloride water samples available in this reach of the Bow River,

there was only 1 recorded reading over the short-term CCME threshold. Note, a detailed review of all water quality data for the tributaries was not reviewed as the scope of this exercise was for the Bow River, but this data is available through the City of Calgary website if anyone wants to dig in deeper.

• This summary was a significant surprise to most people but it was very important to look at this as I, and many others, thought for sure salinity was a significant issue on the Bow. It was abundantly clear that the Bow doesn’t have a salinity issue. However, this does raise other questions of is there a different chemical/heavy metal that is having an affect on the Bow. A challenging question. Luckily the U of C is partnering with the City of Calgary on a multi-year research program targeting this exact question and initially primarily looking at waste and storm water effluent within and upstream of the city to identify if there are any problem areas. I was very encouraged to learn this.