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DOW SEEKS TO IMPROVE GRANBY FISHERY WITH NEW REGULATIONS

The start of the new year brings new fishing regulations at Lake Granby. Anglers will now be allowed to keep four lake trout instead of the previous two. The new regulation also removes the size limits for lake trout that were previously in place.

Aquatic biologists with the Colorado Division of Wildlife (DOW) believe the new regulations will better balance the predator-prey relationship and improve the overall fishery.

"In this situation, we have to manage for a sustainable kokanee resource into the future. We don't feel that we can meet this objective given the quantity of smaller lake trout we now have in the reservoir," said Billy Atkinson, DOW aquatic biologist for the area. "We had numerous public meetings and felt that most people support this effort to perpetuate the kokanee resource, which will result in a better quality lake trout fishery."

Over the past few years, biologists have observed an increase in numbers of lake trout, which can negatively impact other species within the fishery.

Lake trout, also known as Mackinaw, have the potential to grow to large size and tend to become aggressive predators as they grow. With higher densities of lake trout in Granby, the other fish species were diminishing and, in turn, the quality of the existing lake trout began to decline.

"It was possible to catch lots of lake trout, but anglers weren't seeing the body mass and quality of fish that they were accustomed to," said District Wildlife Manager Kirk Oldham. "Granby's reputation as a world class fishery would eventually tarnish without this kind of active management."

In addition to increasing the quality of the lake trout population, biologists are also hopeful that reducing overall lake trout numbers will help protect the precious kokanee salmon resource at Lake Granby.

"We have very few lakes that allow us to spawn large quantities of kokanee salmon," explained Sherman Hebein, DOW senior aquatic biologist for the northwest region. "Because the kokanee are such a special resource for Colorado anglers, we need to make sure that they are maintained in viable populations where possible."

The recent discovery of a large yellow perch population in Blue Mesa Reservoir in southwest Colorado has made the need to protect Lake Granby kokanee even more important. Yellow perch can pose a long term risk to the kokanee in Blue Mesa, which is the other major source of kokanee salmon eggs in Colorado.

While they instinctually spawn, kokanee do not naturally reproduce in adequate numbers in Colorado, therefore the DOW spawning operation is critical to perpetuate the kokanee resource.

"The kokanee and lake trout balance is an incredibly complex relationship where both species can thrive if properly managed," said Hebein. "We can make sure that both species thrive, but we also have to make sure that the balance is maintained. In doing so, everybody wins."

For more information about Division of Wildlife go to: http://wildlife.state.co.us.
 

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LoL, get out the bats and lets beat this dead horse again...
I'm with Bernie and the others if you catch lakers over 20 inches in Granby please throw them back. I think these regulations have potential to really hurt this fishery, but hopefully it will help like they think it will.
 

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I feel the new limits at granby are a good thing. The only fish I think should be thrown back are large mackinaw. The smaller ones should be kept until the limit is reached IMO.
 

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Ken Broeren said:
Sounds like we need to put the bats away and go perchin' at Blue Mesa! >:D
From the perch I saw there this summer they are still little no jumbo perch, but I'm sure that will change soon.
 

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I'm with TFB on granby. The situation there is pretty clear cut (lake trout, browns, stocked trout, and kokes. No perch, so mysis are the only wildcard, but we have a pretty good handle on how they work to screw things up, and the conditions that cause them to become more of a problem at times. We can manage around the mysis. They will still have an effect, but it should be less severe if the system is balanced.

All the trophic links are in place at Granby to suggest this policy will lead to better quality lake trout, and larger numbers of kokes. It will be interesting to see how it pans out.
 

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Cutthroat said:
I'm with TFB on granby. The situation there is pretty clear cut (lake trout, browns, stocked trout, and kokes. No perch, so mysis are the only wildcard, but we have a pretty good handle on how they work to screw things up, and the conditions that cause them to become more of a problem at times. We can manage around the mysis. They will still have an effect, but it should be less severe if the system is balanced.

All the trophic links are in place at Granby to suggest this policy will lead to better quality lake trout, and larger numbers of kokes. It will be interesting to see how it pans out.
agreed. Granby had a forage crash and you have to get the forage going FIRST before you get much for higher trophic levels IMO. The lakers will get big in there again it will just take many years for the forage base to get established in there. However, I think fish that are already big should stay because they are well accustomed to the environment and are old. However, smaller high teens to low 20" fish should be harvested. They put a bigger dent in the koke populations than the few big ones left do IMO because there are so, so many of those mid sized high teens to low 20" macks.
Nobody still knows how the perch will effect blue mesa's fishery, but I am guessing badly. Yeah, the lakers are eating the perch like crazy, but are they really prolific enough and numerous enough anymore to control the perch? I doubt the perch will dent the kokanee population much because kokanee are fish that roam high over deep, open water over river channels, and perch are fish of the shallow to mid depth flats. The rainbows and browns are also growing rapidly now from eating the perch, so any of their predation on kokanee is taken away. I also feel that the mid sized lakers are now focusing more on perch than just small kokanee. To me it SEEMS like it could actually help the kokanee, but it won't and probably will not. Yellow perch are just such a damaging fish in so many situations. They've ruined fisheries before, especially here on the west slope. I am in 100% support of the no bag limit for perch west of the continental divide. Epic, I believe you are incorrect. Blue mesa has some extremely large perch in there, perhaps the largest in the state. Most of the ones you saw were bound to be small. How many small bluegills do you always see near boat launches or popular areas in some lakes? A TON. There are bigger specimens in other areas it seems. I think the perch situation was the same thing. I have heard of 15" perch out of blue mesa. They are just going to keep getting bigger and bigger. I hope they are wiped out though, they just present to big of a risk in that fishery. Whether they have a good effect on the fishery, or a very poor one, time will tell. For right now though, every perch I catch there will be killed.
 

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TFB, how many of the macs that you guys catch out of blue are full of perch?? just curious, on how many they are actually eating.
 

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the one my bro kept cuz it inhaled the tube jig was full of perch. The bow I caught also had a perch in its stomach. A guy on another forum caught 9, kept 7, and he said all but one had perch in their stomachs, so I'm guessing they eat a lot of them. It's a big guess though, and I'm sure one that varies based on the time of year. In the fall, winter, and early spring when they are in shallower water would probably be the times they feed more on perch. In the summer, they go to deeper water than the perch and probably then focus more on kokes.
 

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Perch sure are delicious, but they're not worth losing existing good fisheries over.  Why add fish to the mix when you already have a good thing?  You gotta be careful, especially with fish like perch that have the potential to chew up the primary productivity that supports existing foodwebs.  You're rolling the dice when you introduce fish willy nilly.
 

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Not sure. Mysis were introduced by agencies and fisherman in various places around the country with the theory that they would make great forage for the fish, but it was another case of where what made sense in theory didn't work as anticipated in every case. They make for big trout in tailwaters, but limit many lakes.
 

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TroutFishingBear said:
the one my bro kept cuz it inhaled the tube jig was full of perch. The bow I caught also had a perch in its stomach. A guy on another forum caught 9, kept 7, and he said all but one had perch in their stomachs, so I'm guessing they eat a lot of them. It's a big guess though, and I'm sure one that varies based on the time of year. In the fall, winter, and early spring when they are in shallower water would probably be the times they feed more on perch. In the summer, they go to deeper water than the perch and probably then focus more on kokes.
Thanks TFB I was just wonderin how many of 'em were eatin perch, I'm sure you're right about 'em not eatin many in the summertime, but didn't know about the res of the year. Glad to see that they are using them to get fat though.
 

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ePiC said:
The recent discovery of a large yellow perch population in Blue Mesa Reservoir in southwest Colorado has made the need to protect Lake Granby kokanee even more important.
Should I read that as, there is a large perch population in Blue Mesa and the DOW has just now discovered it?
 

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walking eagle, they just admitted they were in there in late 2004, although they've been in there for many years their numbers really started increasing a lot. I have heard hearsay about them for years, of course, I've also heard of pike being caught in there too though.
 

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lynmack said:
Were the mysis put in by DOW,or are they naturally accuring.What a blunder if they were introduced!                               lyn
Mysis were introduced by the DOW in the late 50's. The DOW has admitted this introduction was a "mistake" and has resulted in unitended consequences.

Mysis are a difficult thing to manage around. DOW does not control water levels in Granby for example. Again the DOW is rolling the dice with this management strategy, though their odds are better. The new regs target smaller fish to be harvested. These smaller fish have not made the switch over to pisciverous (fish eaters) but are opportunistically preying on Mysis. So what could happen is that the Mysis population grows, impacting the zooplankton on which the kokanee feed upon, most likely resulting in smaller kokes.

But what do I know, I only play a biologist on the internet after sleeping at a Holiday Inn Express.

Damn Mysis. Get rid of them and the Kokes and Macks can live in harmony.
 
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clacka ram, we have found something we agree on ;D ;D, that is exactly the reason given for the 3 lake trout limit in taylor park, they want to keep the small lake trout population high to feed on the mysis. I have to wonder with Blue  Mesa down river from Taylor how long before mysis establishs itself in Blue Mesa? Any thoughts on the survial of mysis in the river to Blue Mesa? I stayed at a Holiday Inn express last week ..........but I'm still not a biologist.....just another jerk on the internet ;D
 

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You hit all that right on the head, Clakalackawhateveryournameis.  ;D

There are no sure bets in fisheries management.  Rarely does a management strategy quite live up to it's billing.  There are a lot of people absolutely certain about what needs to be done all over the state, and they all have interests in improving some aspect of the multispecies fisheries of the state, but we really don't know what will happen when we try something different.  Sometimes, the results are intuitive, but other times they are counterintuitive, and there's no obvious explanation.

The one thing that changing bag limits doesn't do, and that is probably one of the biggest factors determining fish numbers, is fix problems in the physical habitat.  If the habitat is changing in ways that can't easily be seen above the surface, changing harvest strategies might do very little.

The error that many people make is to assume that if you put a good management strategy in place, that things will balance out where you want them, and that's that...  But harvest, habitat, and various other factors can change in ways that necessitate adjustments in management - trouble is, you don't know you need a change in management until the problem become obvious, and then you're behind the curve.  It's a fact of life.
 

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I'm a biologist AND a jerk on the internet,  ;D and I'm no better at intuiting the right management strategy than anyone else - which is why I encourage people to start with the data rather than just latching on to what seems like the obvious answers. There are usually multiple different possible explanations for any perceived problem in complex biological systems, and the solution you choose depends on which explanation you think is correct. Without the right data, you really are just rolling the dice.
 

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Bobco- Mysis will not survive long in the river. The gauntlet of predators they have to run before reaching Blue Mesa is a pretty tall order. Mysis are also very photosensitive and thus do not like sunlight very much, and the relatively shallow river does not offer a light refuge where they could hide. That being said, I am sure some Mysis have run the gauntlet and made it into Blue Mesa. I would think however the perch would be an effective predator of Mysis due to their similar eye structure as walleye(more rods and cones resulting in more effective nocturnal feeding success). Thus, when the Mysis occupy the water column at night to ravage the zooplankton community the perch could possibly be more predisposed to target the Mysis more effectively than trout species. Perch have also evolutionarily been present in lakes where Mysis are native or endemic.

This is purely hypothetical, and in no way advocates the illegal stocking of Yellow Perch in Granby.
 

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According to the research literature, yellow perch do eat a lot of mysis where they are available, but if you added them to Granby, you'd just have one more problem.
 
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