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fishteck

The Unseen Impacts of Catch and Release Fishing

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Sorry, I should clarify as the intention of having adult fish return to spawn is also the goal with pacific salmon fisheries.  The difference in my mind is that the salmon fisheries have a commercial component that harvests a certain portion of the return, so continual input is required.

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Re-stocking the river with fertilized, native Bow trout eggs, in biodegradable incubation boxes, is a simple, cost effective way to help rebuild the fishery. The eggs hatch in-stream and the fry will face the same pressures of natural selection. The boxes give the fish some protection from predation in the first few months. The majority of the trout that survive to spawning age, will return to spawn in the same location in a few years. This program has been used effectively all over the world for trout and Atlantic salmon. 

That said, the fisheries biologist would be the folks with the knowledge and experience to know what the best methods/approach should be.

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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.  

 

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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?

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Stop being so logical, Dan. Government policies are agenda based and are supported by selective interpretation and propaganda campaigns. Facts are unimportant.

Regulate C&R fisherman. Save the fishies! Great optics and cost effective. Now that's government in action....(inaction)        

See how it works.

PS. Big thank you to fishteck for taking the time and bringing us the information. (and putting up with us.) Much appreciated.

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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!!

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Fishteck, Does the creel survey capture the average size of fish caught?  Another conclusion that could be drawn from that data is that if the population is falling, and if there is a collapse in certain age classes but catch rates remain relatively stable then those age classes that are collapsing don’t make up a significant portion of the catch and never have. 

I am not trying to say I think I have the right to fish how and when I want, fish populations be damned or something stupid like that.  What I am saying is something more substantial and more meaningful needs to be done to prevent the coming collapse of the Bow River fishery.  Once the actual issues are identified, if angling restrictions need to be part of the conversation then I’m fine with that. But if this is the best the AEP can do then we either need to give the AEP better tools to work with or we need to start lobbying the powers that be to get some new blood in that department because, in my opinion, this isn’t getting it done.

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Danhunt:

The subject of how to stop the decline and hopefully enhance the trout population. is way beyond my knowledge of aquatic biological science. But as with any field studies across the full spectrum of species, one thing is for sure just when you believe you have some of the answers, the variables change and the outcome often gives a totally different interpretation of the data. For example, the historical Bow River fish population studies conducted 10 to 20 years ago generally gave similar results with the investigators concluding that the fishery continued to sustain itself. See following link.  All the variables that could have influenced year to year changes could not be defined or accounted for in the historical analysis and therefore in retrospect the interpretation of the data could have been speculative. It was not until a retrospective analysis of all the historical data was conducted in 2017 that statistically a 4 to 5% annual decline in rainbow trout populations was arrived at. 

.https://bowrivertrout.files.wordpress.com/2018/06/bowriverfishpopulations-report06june20182.pdf

The AEP 2018 and 2019 fish population surveys have indicated the the decline in all trout species has continued. The data will be released to the public over the winter months. And it is my understanding a more extensive analysis of age class of fish has been conducted. There is also a plan to conduct a computer modelling program for the Bow River fish population dynamics that will guide the appropriate fishery management direction to take to sustain the fishery.

I'm not sure this fully answers you questions , but may complicate it further! 

A link to Chris Cahill's paper is also follows and may shed some light on the current thinking withing fishery management circles.

https://docs.wixstatic.com/ugd/c9e0c9_c5a407800c1a4425b91c80b9f2ac8eff.pdf

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Thanks for that, Don. Nice to see folks being proactive in rebuilding their fishery. 

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A complicated issue.  Life is chaotic and often not fully understood, including our impacts.  Even our attempts to improve things run into the law of unintended consequences. 

Consensus is that fish stocks on the Bow have plummeted. But is there a single answer or is it the result of cumulative effects?  I would think it's the latter.

Too much pressure?  Maybe a multi-year closure along with extensive monitoring to determine how much that is as an impact?  I'd be surprised if that didn't show at least some increase in numbers.  Very few people will support that anyway.  Unfortunately, poachers might become even more emboldened by having fewer eyes on the river in the form of lawful fisherpersons.    As part of that, if you provided more access points you will reduce the pressure on the current localities but potentially create the unintended consequence that even more people would be out, eventually extending the heavily pressured areas even more.  Anybody have a sound number on how many rod days there are on the Bow?

Supplement with hatchery fish?  May work as an ongoing project but if numbers are in fact dropping, shortly after you stop stocking history will repeat itself.  At what point would the Blue Ribbon Bow become a miles long stocked fishery and not a source of truly wild fish.  Thinking on it, who cares?  A fish is a fish.  Aquatic targets.  How old does a Rainbow have to be to be considered a reliable spawner?  If it's not going to survive in the wild that long, good money after bad in the ongoing project.  Seasonal, local and size limits, in my mind, are reactions to the problems we either can't identify or control.  But they will help.  If part of the problem is Whirling Disease (and/or similar), I understand that ensuing natural generations become more resistant.  The reason Browns are affected by it nowhere near as much as RB, it's been around in Europe for a loooong time.  Would seem to be at least partially confirmed by the findings in Colorado.  Should the province get into capturing RB from the Bow to try and "breed out" the effect of WD?  Can't see that happening.

Habitat degradation and/or destruction?  Good luck getting the money spent by individuals or government to reverse or even do much to effect meaningful remediation.  You can achieve some feel good successes but I would think not enough to return things to the glory days.  One and a quarter million people within the city of Calgary plus the outlying population centers and individuals living close enough to the Bow or it's tribs to have a negative effect.

Introduction of invasive species?  It has, is and will continue to happen.  Much that could be done to minimize it, IF everybody did what was req'ed.  The bloody white man is the original invasive species to the province.  Followed by others.  And they all either didn't know what the effect of what they were doing would be, or didn't care.

Not as long a post as I could have made, tired of typing already.   My thoughts and two cents.

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