Just a quick update on kokanee egg collection. Up here in my neck of the woods, things are getting off to a very slow start. At Granby, we haven't seen fish arrive in any numbers at all yet. They're still running 300 or so CFS out of Shadow dam which makes things really difficult down there. I really have no idea what to expect up there this year.
We took spawn yesterday - Thurday, the 7th - at Wolford for the fifth time. We had 173 ripe females in the trap, which yielded 146,000 eggs. We're now up to about 350K for the year there. Wolford has had an excruciatingly slow start. However, Thursday was our biggest day yet and felt like the run has finally started to pick up. On Monday the 4th, we took 105 spawns. Each time we spawn we clear the trap out. So from Thursday the 31st (or previous spawn day) to Monday the 4th, we had an average of 26.25 ripe females per day swim into the trap. From Monday the 4th to yesterday (the 7th), we had an average of 57.7 females per day. So the rate of activity essentially doubled this week.
I'm very optimistic that this coming Monday will be our biggest day at Wolford yet this year. We've got Wolford covered for next year, but we would really like to see Wolford cover Williams Fork (need 360K eggs) and Granby (need 1.2 million). Last year Wolford did that. I don't know about this year, but I remain optimistic.
We've seen nothing encouraging yet at Granby, but we're going to try to take spawn there next Thursday and see what happens. At this point there is pretty much no possibility that Granby will cover itself.
From Vanish, regarding the last post about the whitefish in Parshall:
Neat! I bet they used to be in the upper colorado. Many anglers find them to be trash fish but I really enjoy taking a trip to NW CO once a year to fish for them. They can give a pretty good tussle.
Vanish, I agree with you that the whities get the short end of the stick from anglers sometimes. It hasn't always been that way.
But I want to address your first statement about whitefish occurring in the upper Colorado at some point. I want to make it absolutely clear that there is NO historical account - not from John Wesley Powell, any of the original settlers, any old-time surveyor - of whitefish ever occurring in the upper Colorado. We are certain that they are not native to the Colorado River. They are native to the White and Yampa rivers. They were first introduced into the Colorado and Roaring Fork rivers in Glenwood by Colorado Fish & Game in the 1910's. Prior to that introduction, they had not lived anywhere in the Colorado.
It may seem like a minor point, but I want to make sure that the biological significance of this is clear. Whitefish re-invading a place where they had previously lived would be a very different thing than whitefish pioneering a place they have never been. The latter scenario is the case here.
We seem to have two distinct whitefish populations on the Colorado: one upstream of Glenwood Canyon and one downstream. I honestly can't say if the whitefish up in the Pumphouse neighboorhood really originated from the historic stocking downstream from Glenwood Canyon. Another theory that I have has to do with a trans-basin diversion that takes water from Yamcolo Reservoir, which is loaded with a native whitefish population (being a tributary to the Yampa River). When they're running water through that ditch, it dumps into Egeria Creek, entering the Colorado River at McCoy. So, this is a trans-basin diversion. I don't know all the details but I do know that the owners of the water in that ditch use it to pay back water owed to the Colorado. So there can be a significant volume of water making that trip. It's entirely possible that larval or young whitefish from Yamcolo Reservoir have been entrained into that ditch, made their way down Egeria Creek and into the Colorado. It makes sense to me because that population of whitefish seems to have its "nucleus" in the vicinity of McCoy.
The original stocked whitefish around Glenwood came from the White River. If the above theory is true, we have White River whitefish downstream, and Yampa River whitefish upstream. We are not able to distinguish between the two genetically at this point, but it would be an interesting question to answer in the future. It would be a great subject for someone to do a masters' thesis on.
I can't figure out how to post PDF's on this blog. But here is a link to the Wild Trout Symposium that has an interesting article about whitefish. It's a huge document. But check out the article that starts on page 106, entitled "Becoming Trash Fish", about how people's perceptions of whitefish have changed over the past century. It's interesting stuff.
http://www.wildtroutsymposium.com/proceedings-10.pdf
Out of curiosity, do you know what the percentage of eggs you harvest to fingerlings released back into the lakes? I keep wanting to come out and volunteer for one of the harvest days, but it never seems to work for work schedule. I'm guessing you are almost done for the year?
ReplyDeleteSpent some time up at Leavenworth National Fish Hatchery a couple weeks ago. I worked on the designs for rehabbing Coleman National Fish Hatchery a few years back. What has surprised me is the lack of consistency in rearing techniques and communication between hatcheries. Both are based around Chinook, Coho and Sockeye salmon. Both are moving in similar directions now, but took way different paths to reach the same conclusions. I know Roaring Judy was originally designed/built by Reclamation, and I am not sure where else DOW raises Kokanee in Colorado. Just sort of interested in how DOW operates their Koke rearing facilities and harvesting techniques. Hopefully next fall I can make it out and try and learn a few things.
We're looking at about two more weeks of effort - this coming week and then the week after Thanksgiving. I'm anticipating that Thursday, December 5 will be our last attempt to take eggs at Granby. As expected, the Granby run has been pretty much a disaster and indicates a collapse of the kokanee population there.
ReplyDeleteRegarding your question about egg hatch rates, we figure about an 80% hatch success rate on the eggs that we take. So as a rule of thumb, if I want to stock 100K fish into a water, I need to take 125K eggs to cover it. As far as your questions about aquaculture techniques go, see my most recent post. I'm not the guy to give you details about that. I can say that every hatchery's water supply is very different and that is the ultimate limiting factor that they are all working with. As far as I know, they are communicating with each other quite a lot because there is a lot of egg shipment that happens among them all at various times. Thanks for your input!