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Colorado Walleye - Spawn Operation

by: Matt Snider 3/23/2018
139 million walleye eggs.  That is the goal that CPW aquatic biologists are shooting for collecting this year.  The hardest part of this job?  Counting them all.

Sorry, that is just something I made up.  ďOfficial Egg CounterĒ is not one of the titles of the dozens of officials that take part in the annual walleye spawn operation conducted in Colorado.  The counts actually come from scientific measurements at the hatcheries that care for the fertilized eggs collected by staff.  

Some of you have heard of the Colorado walleye operation, some have acted as volunteers, and most of you probably have no idea what I am talking about.  In essence this is the breakdown of what the annual walleye spawn operation is: CPW officials set nets out in optimal lakes in strategic spots, leave them overnight, pull the nets into a boat the next morning, remove and place live walleye in aerated tanks, deliver them to holding tanks in a docked boat station, squeeze eggs from females, squeeze milt from males over top of the eggs, mix with water using a feather-stirrer (literally feathers) for a while, pour in some sort of clay mixture and stir some more, fill with more water, slowly and carefully pour out that water and refill until the eggs are clean, transfer the eggs to a screened box in aerated water, move the eggs to a Gatorade cooler for transportation, and drive them to the hatchery.  Phew!  But thatís not it.  

They then check the females for tags, record data for those found, insert tags in those without, and release the fish back into the lake.  If the fish are not quite yet ready for the birds-and-bees stuff, they go in a holding tank under the pontoon station where theyíll be checked again later.  Then the nets pulled earlier, in all their tangled mess, get re-sorted and placed back into the containers to set out again afterwards so the whole process can be done again the next day.  

The most difficult job in doing this isÖ let me think about it for a second, all of them.  Iíve been on some of these jobs in the past and none of it is easy.  Iíve gotten wet and slimy, worn the filthy float jackets, donned rubber gloves with soaked knitted gloves over, and handled the fish and equipment.  It is taxing, and Iíve only done it one day at a time.  These guys and gals have been doing this for roughly two weeks at this point, and are in it for potentially another 2 weeks, day in and day out, including weekends. 

And all this for what?  You may be asking that question yourself.  Just so we can have some more walleye to fish for?  Itís not that simple.  Beyond the standard economics of this operation there are some very real ways in which we fishermen benefit from the work put in by these folks.  Economically, the figure I was given was that walleye would cost about 1.5 cents to purchase, and with 75% of the eggs collected expected to reach maturity, that equates roughly to about 1.5 million dollars that the CPW uses to stock our lakes.  But on top of that the eggs, and the resulting fry and fingerlings, are traded with other states such as Nebraska, Oklahoma, and Texas for other species such as tiger muskie, bass, stripers, wiper, sunfish, etc.

The fish species diversity that makes Colorado such an interesting state is thanks in large part to this program.  Amazing trout fisheries are a wonderful natural part of fishing in Colorado, but adding a wide berth of other opportunities makes this one of the greatest places in the U.S. for freshwater fishing.  

Could we just let the walleye spawn in the lake and leave it at that?  Apparently not.  The walleye in most lakes (but not all!) in Colorado do not reproduce naturally due to the silty waters.  The silt interferes with the egg fertilization by clogging up some scientific-word process which I donít remember the name of nor fully understand.  I am not a scientist, just an avid fisherman you see, so a lot of what these guys know like the back of their hand flies over my head. 

Collecting the essentials for the walleye operation is grueling, but you get a sense from the operators that this is why they have this job Ė to get outside, get dirty, and play with fish.  Underneath all the comradery and laughs shared among them, they are undyingly professional when it comes to the science of the process.  It might not be evident when you first run into them donned in a raggedy set of waders covered in who-knows-what, but these men and women are scientists.  Care of the fish and the samples are essential, the data collected is scrutinized, and the process is continuously analyzed and improved.  

I took a handful of pictures when I was out with the crew at Cherry Creek Reservoir last Monday, uploaded below with captions.  The day produced really good numbers of fish and fertilized eggs.  Roughly 50 females ready for the task were handled, leading to about 4 Gatorade coolers full of eggs, which were promptly taped up and driven to the Wray Fish Hatchery.  In a few days the fry will be stocked and/or traded, and in several weeks the fingerlings will be ready for the same.  The fish you catch in the future may just be one of these walleye, or the fish could be a result of these walleye.  Donít forget to hug your biologist today.  
Transporting fish from the boat to the spawning stationDetermining whether this fish should go in the male or female tankWhat a load of fish looks like in the on-board holding pens - ones you`d love to catch on any day, and will be able to after they`re put back, in about an hour from this picPlenty of BIG fish are handled, and even after handling thousands over years, yes these guys still get giddy about the bigger ones.Walleye: simple bottom-hugger slow-trolling feeders?  Not so fast.  They`re as predacious as other toothy critters.
First comes the eggs...Then comes marriage, of the milt...Add water...And stir the concoction...Add some sort of clay and stir some more...
Add more water and stir some more...Clean the mixture, pour out water, and so on...Do this over and over again...Transfer the fertilized eggs to a container for shipment...Prep the shipment for more eggs and delivery...
Check females for tags, to track spawning dates and growth rates, etc.Inserting tags in fish that are caught without one already for later data collection to hone the processData collection on fish with tags that were caught and spawned in years past 
Blog content © Matt Snider
Member comments
Flyrodn, CO   3/23/2018 7:41:59 AM
Nice write up. One of those operations I'd wanted to attend, but never managed it.
 
Coyute, CO   3/23/2018 8:12:11 AM
Good stuff. Thanks for sharing.
 
IceFishingFool, CO   3/23/2018 8:36:24 AM
Would be interesting to know the numbers of repeating spawner's Do they even chart or keep track of the males ?
 
Matt Snider (Matt), CO   3/23/2018 8:41:30 AM
IFF - out of the couple dozen or so females checked for tags, only a few on this day had them. I am sure they'll find more and likely had prior. It'd be cool to get a layman's report from them to see what they learn from the data. They're very interested in charting the spawn cycle of specific fish so they can nail down the dates better. When it came to tracking males, the overall feeling was, "only the females matter". Where have I heard that before?
 
panfishin, CO   3/23/2018 8:49:49 AM
great write up! this would be very interesting to volunteer for...
 
OldMikkDale, CO   3/23/2018 10:12:11 AM
Great blog! Very good article front page of the Dever Post today about this subject collecting eggs in Pueblo Res.
 
Americanwolf, CO   3/23/2018 1:46:49 PM
Yet on the western slope CPW keeps trying to remove walleye, pike, bass, ECT. Oh and Fyi most trout fisheries are not "natural" in CO. Glad CPW has a program like this, but it should be inacted on the western slope too, or treat the browns and rainbows as an invasive spices like the warm water spices.
 
opencage, CO   3/28/2018 8:29:24 PM
Sweet, this sounds like a blast. 4 gatorade coolers of eggs... damn.
 
bron, CO   3/28/2018 9:16:18 PM
Very good read Matt!
 
Swigs, CO   3/30/2018 9:17:13 PM
Thx Matt, The project became full circle today, restocked 2.4 million walleye today with plenty other going to regional waters.
 
Hawaiian Punch, CO   4/1/2018 1:04:08 PM
Question Matt? Any special reason they use Gatorade coolers (round) vs. a rectangular cooler?
 
panfishin, CO   4/2/2018 8:30:38 AM
Hawaiian Punch - the first thing that comes to mind would be that there likely wouldn't be as much knocking into the walls with could potentially damage the eggs. Instead they would flow more in a circle around the cooler...sure there is going to be some damage but I think that it would be a lot less than a rectangular cooler. just a thought, i'm not actually sure about that.
 
Matt Snider (Matt), CO   4/3/2018 11:47:46 AM
Good question HP, good answer panfishin. I am not sure, didn't ask about that, but will!
 
Matt Snider
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