[basshunter]

Here's an interesting (scientific, not hearsay and opinions) comparison between Granby and Blue Mesa Lakers....

http://www.warnercnr.colostate.edu/~brett/lab/coldwater/poster1.html

I'm not  a biologist, but I can appreciate the info presented here to help understand the requirements to grow big macs.  Check out the girth diference between the Blue Mesa (tunas)and Granby fish (snakes) - those old Granby fish look starved!  Another interesting bit of info shows that the Granby fish growth has decreased to almost a standstill...so even if you release that 26" hoping that it will grow into a trophy fish, it will take another 10yrs for it to grow to 30", and it will still only be 9lbs-so is it actually better for the fishery to keep more and increase the growth rate and have a few healthy fish vs. a ton of skeletons swimming around?

pretty interesting........

 

[_colorado]

Couldn't follow the link - this sounds very interesting. Could you provide any more info or a better link?

Thanks!

 

[beerman]

The link worked for me, and it is very interesting. Thanks for posting.

 

[epic]

I think he ment the link worked but it was information overload and hard to read threw and see what they ment.

 

[basshunter]

I just checked the linke again, and it worked for me....

It is a lot of info, but it's really cool stuff!

I think it's amazing that they've been able to catch the same lake trout multiple times over a period of several years to monitor its growth

 

[Cutthroat]

Here's is the full link to the work that was done on Granby and Blue Mesa. I work with the professor whose grad students were responsible for conducting most of the research. Note that the research has recieved a lot of recognition from competing scientists and was given an award for being the most significant paper (out of literally hundreds of fisheries research articles that are published each year) for the year 2000.

http://www.warnercnr.colostate.edu/~brett/lab/coldwater/trophic.html

 

[beerman]

Cutt, what is your oppinion on that study? Just wondering what somebody that knows what they are reading gets out of it? ???

 

[Cutthroat]

I try to stay out of these things, but they keep pulling me back in. :-[

Well, my opinion is that it is one of the most complete studies ever done on the foodweb of any interior lake.  They have more sources of data than a typical study, and their interpretation is consistent with all the sources of data.  In fact, because they have so many different sorces of data, they are able to rule out a lot of the other explanations that people with less data at their fingertips cling to as "common sense" explanations.  As fisheries data, and ecological data in general, go these are some of the best and most complete to have ever been published as a single unit.

My opinion is shared by fisheries biologists around the country and the world, too.  This study was a landmark that convincingly showed that the "common sense" explanations of the past sounded real good, but probably weren't on the money.

In the grand scheme of fisheries biology research, it is another in a long line of studies to be published in recent years that are collectively showing us the limits of our ability to simply reason the answers to fisheries or wildlife management problems, and strongly suggests that we should be collecting and relying on objective data to guide our management decisions rather than our sense of logic.

That's my opinion, informed by a familiarity with recent research.

 

[beerman]

So in your oppinion Cutt, what needs to be done at granby to get the quality macs back? I like to catch fish all day too, but I would much rather catch a few and have the chance at quality fish, than catch a bunch of under nourished dinks all day long.

 

[TroutFishingBear]

The limit at granby needs to be high if they want trophy macks back IMO. There was a forage crash there and that is bad news. You have to build from the bottom to up when that happens. I think a limit of 4 is probably too small. However, in big blue, where there has not been a forage crash, there needs to be a slot, but a drop of the limit to 4, so the macs can help wipe out the perch. JMO. I'm sure cutt's is different.

 

[Cutthroat]

The best bet for increasing the average size of fish, and making lunkers a little more common (big, but not necessarily monster), is to harvest the small guys, which is not a big problem, because that's most likely what you will catch when you fish at Blue Mesa.  It will not increase the average size of fish, or make it a lot more likely you wil catch a giant fish to C&R all big fish.  Indeed, larger number of big fish, which are harder to catch that their smaller brothers and sister, will result in competition between big fish, which are good at eating high quality prey like kokanee, and the smaller fish, which are not as good at it.  Thus, the big fish deplete the very supply of high quality prey necessary to help smaller fish bridge the gap and grow to larger sizes.

The abundance of giant lakers years ago, was probably the peaking of the lake trout population in Blue Mesa, as they were only introduced 30 odd years ago.  Predatory fish almost always go through a rapid boom and a period of unrivaled fishing, before they depress their prey populations enough to slow their own growth, then the huge fish become less numerous over time.  It has nothing to do with what management does, it's just what happens as foodwebs are impacted by the new predator, and then the predator-prey ratio finds a new balance point.  Anglers are quick to blame the increases and declines on management, but the bag limits during these boom and rebalance periods are probably not the primary cause.  A decline in angler catch usually makes anglers think the fish number is decreasing, but there are other reasons catch of big fish might decrease, too.  There's no easy way for anglers to know whether the numbers have really decreased, or whether their old way of fishing just isn't as effective as it previously was.

TFB is right about granby.  The research link in this thread also shows how water levels effect kokanee and mysis populations.  At granby, the low water was bad for mysis, but good for the kokanee, which is why so many kokanee recruited in the last couple of years, most likely.  That may translate into a short resurgence of bigger lake trout at Granby in a few years. However, because the kokanee populations have increase due to the lower water conditions in 2002 and 2003, it may be less important to harvest large numbers of lakers right now, to increase average size, than it is when the water is high, the mysis ar booming, and the kokes are smaller/less numerous. We have to remember that harvest is not the only thing influencing the fish. Fish are more often dependent on bottom-up effects, so managing to improve habitat and forage production is usually the best longterm approach to improving a fishery.

 

[_colorado]

OK - thanks for the second link - that one works well. Looks like lots of interesting info - need to print it out so that I can read it in the library! ;D