Leaderboard

danhut: An ever-increasing number of anglers – Not sure this is true. I couldn’t find older data, but the total number of licenses sold in AB seem to be trending the same way as the resource economy in the province and have gone from 280425 in 2014, 318106 in 2015, 312064 in 2016, 309006 in 2017 to 281568 in 2018. I would agree that these numbers don’t necessarily give an accurate measure of how many anglers use the Bow. I have been waiting for AEP to report the most recent component of the federal Stats Canada Recreational Fishing Survey and compare it to what had been generated previously. The 2018 AEP creel survey is about to be released that should shed light on angling pressure. But a good anecdotal piece of evidence are the numbers of drift and jet boats on the river. From probably less that 40 boats 15 yeas ago there are upwards of 200 using the Bow river on a regular basis now. In addition when floating the Bow River I an surprised just where we see bank anglers downstream of the city limits. Nevertheless, some firm numbers are needed. The AEP Bow River Fish Population Survey suggests that recruitment of trout stocks is adequate in the Bow River to sustain the population – Fair enough, but this doesn’t reflect the experience of myself and other anglers who have noticed a distinct lack of smaller fish in the river in recent years. It also ties in with the next point; Unknown fish population and reproduction dynamics – Don’t mean to nitpick, but if the fish population and reproduction dynamics are unknown then how can the AEP Bow River Fish Population Survey suggest that recruitment of trout stocks is adequate in the Bow River to sustain the population? Seems like a chicken/egg debate? I will comment on both these items together. AEP biologist have indicated that the fish population survey information supports adequate numbers of juvenile trout to support recruitment and survival of the fishery. What is unclear is what is causing mortality in 1+, 2+ age class. Lots of speculations here. Whirling Disease is one, hook damage is another. But no one seems to know. The 2018 AEP Whirling Disease Report link adds some useful information. Although there were no clear clinical signs of Whirling Disease in the Bow River, there are in the lower Crowsnest River: https://open.alberta.ca/dataset/9f9268b6-377d-4f91-a99e-ee944f143752/resource/b10b0d33-d531-40e4-9f5f-cc7fc177320e/download/aep-whirling-disease-2018-annual-report-2019-10.pdf Restocking the Bow River appears to be a no go! Bow River fishing stamp together with enhanced protection for the fishery is possible.

Dan: We need to go back beyond the the Cahill publication that reported a decline of 40 to 50% in the rainbow population from 2003 to 2013 that sparked much of the debate we are seeing now. To some degree we are all grabbing at straws to identify just what the cause of the decline can be. But one thing is clear the fishery is suffering and continues to decline. Although frustrating on our part, AEP are being very cautious with the release of the data from both the recent creel survey and population assessment. The discussions I've had with AEP on this subject would suggest they need to get the interpretation of the data right before being formally released to the public. In the meantime two things do line up: The Bow River trout population is probably 50% of what is was in 2003 (and possibly lower) The Creel Surveys indicate that catch rates have generally been similar over the same period of time. This would indicate fishing techniques have changed to accommodate a declining trout population and fish are getting caught more frequently, with more facial damage, reduced ability to feed resulting in increase mortality rates. Add to this, hook size and configuration has a greater impact on the smaller class of fish. There is no doubt that all other probably cause does play a roll but are almost impossible to manage. But angling does appear to have a significant impact on fish survival. Therefore what can be done to halt the decline? Regulations - closures - special licenses appear to be the only option available without a fundamental change in our society use of the Bow River, water management and protection of the City of Calgary against flooding. Toolman: Thank you - A good debate is always worthwhile!!

So on the one hand AEP is saying that there are enough juvenile fish to support natural recruitment, but something is happening to the 1+ & 2+ age classes that is causing a significant portion of these fish to die (presumably before they can spawn?). The parasite that causes whirling disease is in the upper Bow Watershed, but no clinical cases have been observed in the “Blue Ribbon Stretch” of the Bow, so it is unknown what impact (if any) whirling disease is having on the fish population. That said, the report notes that biologists on the Colorado river in 1993 & 1994 observed a complete collapse in the 1+ & 2+ age classes and that such a collapse did not occur in the older age classes of fish. So what anglers have been observing on the river in recent years is exactly what might be expected if the Bow was following the same sort of pattern that the Colorado did 25 years ago. But on the other hand, it could be hooking mortality in those 1+ & 2+ age classes that anglers are reporting that they are not catching. Because they are not there as evidenced by the population samples. How is an angling restriction going to help protect fish that aren’t there and aren’t being caught?