Fish Explorer Logo
Colorado
Colorado Fishing FishExplorer.com
Colorado Fishing
Login Usr:Psd:
Don't have an account? Register now...
 
 
spacer spacer
spacer
Go back to Main FxR Forum listings

CPW biologist report -- Colorado River, Pumphouse-Radium

Post By: Ewert      Posted: 4/17/2018 11:29:46 AM     Points: 18    
Hey all -- finally got a few more reports up on the web. Post questions here, I'll watch this thread for as long as it stays on the front page.


[log in for link]

 Reply by: Freestone303      Posted: Apr. 17, 12:58:33 PM     Points: 442    
Thanks for another great report.
I have always wondered, why does the state stock Rainbows in the watersheds of native cutthroat species? Obviously you could argue that the damage has been done to the gene pool. I assume Rainbows are cheaper/easier to raise in hatchery conditions. But why does the state not focus on stocking Colorado River Cutthroat Trout to help recreate a more natural population and help preserve the species in its native range?
 Reply by: Freestone303      Posted: Apr. 17, 1:46:50 PM     Points: 442    
Thanks for another great report.
I have always wondered, why does the state stock Rainbows in the watersheds of native cutthroat species? Obviously you could argue that the damage has been done to the gene pool. I assume Rainbows are cheaper/easier to raise in hatchery conditions. But why does the state not focus on stocking Colorado River Cutthroat Trout to help recreate a more natural population and help preserve the species in its native range?
 Reply by: Ewert      Posted: Apr. 17, 2:03:16 PM     Points: 18    
Good question Freestone. I've seen that question come up before. The first issue is that our native cutthroats did not evolve in competition with any other trout species. So they don't compete with them. We could stock massive numbers of cutthroats in the Colorado River mainstem and we would rarely see them again. For the most part they would just disappear. The only place they we can stock them and they will be successful is in waters that are occupied by only cutthroats.
Theoretically, you could give them a better chance by raising them to larger sizes before stocking them. Here's the problem with that: cutthroats are a wild species, not domesticated. Rainbows have been heavily selectively bred to have domesticated characteristics. So to produce 1,000 cutthroats that are 12" would be vastly more time-consuming and expensive than producing the same number and size of rainbows. Because they're wild, cutthroats spawn at a specific time of year, in a fairly narrow window (say three weeks). Rainbows have been manipulated to produce eggs over a wide range of timing in order to fill gaps in hatchery production. So you would have a huge amount of hatchery space sitting empty for big portions of the year if you switched over to focusing on growing large cutthroats for stocking. You'd have hatchery personnel sitting around twiddling their thumbs looking at empty raceways.
It's also a question of scale. Just as an example, I ran a couple of quick queries in our database for the year 2010. In that year, statewide we stocked a total of 619,985 Colorado River cutthroats, with an overall average length of 1.9", or 5,252 pounds of fish. That same year we stocked 9,139,081 rainbow trout averaging 6", or 1,625,297 pounds. We actually stock very few rainbows that are 6" -- but we stock a lot that are 10" and a lot that are 3" so you get the average in between.
So on a weight basis, we stocked about 309 times the poundage of rainbows than we did cutthroats. If we were to make some kind of huge shift in the allocation of our hatchery production to cutthroats, we simply wouldn't have the eggs to produce the kind of numbers of fish required.
You could theoretically take some steps back and start modifying cutthroats in all the same ways that rainbows have been modified -- you could get them to spawn over a wider range of dates, grow faster, be more aggressive and competitive toward other species, be more tolerant of crowding and resistant to certain diseases, etc. But at the end you would have a fish that does not reflect the native fish of Colorado any more.
It really comes down to basic goals. The basic goal of our cutthroat program is to perpetuate genetically pure populations of the fish that are native to Colorado, and have them reproducing and sustaining themselves in places on the landscape where they're able to. The goal of our rainbow program is to provide the most recreational opportunity possible, pure and simple. There is not a lot of overlap in those two strategies.
 Reply by: Walleye Guy      Posted: Apr. 17, 2:34:24 PM     Points: 103    
A bit off topic but I saw a shocking crew on a smaller stream (that I would like to keep on the down low) and am interested in their findings. This happened about 5 years ago and I have been unable to find the data if it has been published. Any ideas Ewert?
 Reply by: Freestone303      Posted: Apr. 17, 3:48:00 PM     Points: 442    
Great explanation, and falls in line with my assumptions of what the reality would be of the program.
I know someone who worked on a project at the University of Utah, that removed non-native trout from streams to open them up for a re-introduction of native cutthroat. Mostly brown trout removal on small streams. They pulled some absolute monstrous fish out of these tiny waters. Does any work like this take place (in an on-going regular basis) in Colorado? I am thinking here it would be mostly brook trout and some rainbow removal.
 Reply by: Ewert      Posted: Apr. 17, 5:18:43 PM     Points: 18    
Walleye guy -- you can shoot me an email if you want and I can look it up. jon.ewert@state.co.us

Most of the smaller-water stuff doesn't get officially published -- we visit too many waters in a year to do that.
 Reply by: Fishful Thinker      Posted: Apr. 19, 8:39:10 AM     Points: 9506    
Hey guys, here's a video Mr Ewert and I did detailing trout food sources on this stretch of river. Safe to say it was eye opening...

Thanks Jon for all your efforts! CL

[log in for link]
 Reply by: tjcolorado      Posted: Apr. 19, 10:16:17 PM     Points: 180    
Thank you for all the work you put into posting these and interacting with us fisherman. You've been a great resource for information in your neck of the woods for a long time and it it's greatly appreciated.
 Reply by: bharper      Posted: Apr. 21, 11:21:22 AM     Points: 118    
Great info! Love that Fishful Thinker Segment(Show)!
 Reply by: Lakerman      Posted: Apr. 22, 12:02:12 PM     Points: 0    
Thanks FT you the man when it comes to fishing.