Saturday, November 23, 2013

Brookies, etc.

A couple great questions from Keith:
   Jon-Thanks so much for doing this blog. I find it to be very infomative. I've got a couple of questions for you. First, I've found waters with large brookies to be rare and highly coveted by fisherman. Do you or does the department manage any bodies of water for trophy brookies, and if so what characteristics do you look for in a prospective body of water? The rare gems I've found with large brookies seem to be relatively small and eutrophic. Also, just out of curiousity, are hatchery fish all fed the same thing, regardless of species? I remember as a kid we had some bullheads in an aquarium that we fed Purina Trout Chow and they seemed to like it. Then again, they seemed to enjoy eating pretty much everything we threw in there. Thanks again!

Thanks Keith. We really don't have waters that are specifically managed with the goal of trophy brook trout production that I'm aware of. There could be in some other part of the state. It seems that more often, the conditions turn out to be right for brookies to get larger than average, and so we do what we can to encourage or perpetuate those conditions. I'm not aware of a regulation on any specific body of water that is aimed at trophy brook trout production. Again, there may be one somewhere that I'm not aware of. We do have the statewide regulation that allows for extra brookies to be harvested if they are under 8". For the most part, the deal with brookies is that the more harvest pressure you put on them, the better the quality is going to be. As I'm sure you know, they're very good at reproducing in Colorado.
     I've got a few bodies of water that have larger-than-average brook trout fisheries, and a couple others with some potential for that.
     There are a small number of high lakes in my area that happen to have quality brook trout, and sometimes that's just by chance. One of them, Crater Lake, I've written about previously. It has lake trout in it, that were stocked as a means to maintain constant predation pressure on the brook trout. It works there and it appears to be a self-sustaining fishery with natural reproduction of both species and brookies to over 12". 
     There's another obscure high lake that you'll have to find, or might know about already, that grows brookies to a solid 14" or so. It's not on any established trail and in fairly rugged country. It does not get a lot of visitation and so definitely doesn't have a lot of harvest pressure. It's not eutrophic, and sits in a pretty geologically sterile area. There are no lake trout. We don't stock it with anything. The only explanation I have for that one is that there doesn't appear to be a lot of good spawning habitat. So, I think that the number of brookies born every year is fairly low, and there's probably a lot of predation pressure on the ones that are born. It's relatively low in elevation as far as alpine lakes go, so probably has decent insect production, even if it doesn't get a lot of nutrient input. So the lake just seems to maintain itself at an equilibrium level of good quality. 
     Red Dirt Reservoir is an above-average brookie fishery. There are a combination of factors leading to that. First of all, it sits in a biologically-productive basin, in part because it's all cattle country. So there are a lot of nutrients going into the lake. Also, there is a lot of harvest pressure there because for whatever reason, the angling demographic of folks who use that reservoir leans toward the meat-fishing side of the spectrum. Lastly, and probably most importantly, there is a very robust population of fathead minnows in that lake. I was unaware of this until a couple of years ago when I went up there to see what the water level looked like. I went walking along the shore, and it happened to be when the fatheads were in spawning, and there were thousands of them everywhere. It seems strange that I hadn't realized they were there, but the gillnets that I use for sampling do not catch fish as small as fathead minnows, and I just hadn't noticed them before. So that combination of factors produces brookies up to 14".
     Monarch Lake is another one that has good brookies in it. I'm not aware of any fatheads there. But it gets a lot of traffic and a lot of harvest pressure. It also has browns in it, that probably keep quite a bit of predation pressure on them. It's a fairly productive lake. It doesn't drain any cattle country but it does have a ton of shoal area and submerged vegetation, etc., that provides good forage production.  I have received word-of-mouth accounts of brookies being caught there that came very close to breaking the state record but fell just short. I have not seen such a fish personally, but there are some nice ones.
     I've got two lakes that have the potential to be better brook trout fisheries than they are right now. One of those is Meadow Creek Reservoir. That lake is a classic stunted brookie fishery. There are a ton of fish up to 8" but hardly anything over that. It's one of those lakes that if you're there on the right still summer evening, at dusk the whole surface of the lake just boils with rise forms. But they're all made by tiny fish. So for 2014, I've put in a request for tiger trout for that lake. Hopefully they can perform the same function that the lakers in Crater Lake do, and thin things out a little. I haven't heard yet if my counterparts were even successful in making any tigers this fall, so we'll see about that one.
     Another one that could produce some better quality is Lower Cataract. It's got both browns and harvest pressure, but the spawning conditions must be good enough to overcome both of those pressures because the brookies are still somewhat stunted. I think that this lake is a great candidate to introduce fatheads into. The water level doesn't fluctuate because it's a natural lake, and there is a ton of shallow productive area with rooted vegetation that would be fantastic fathead habitat. So I'm looking into that. 
     So, I guess the take home message here is that for every place that has nice brook trout, the combination of factors to produce that effect is slightly different. There are common themes, but it's definitely true that no two waters are the same.

     Regarding your question about feed types in the hatchery. This is one area that I don't know much more than you do. I work closely with the hatcheries on a certain level, but on another level I am totally naive to what goes on there on a day-to-day basis. I've never had an aquaculture job, so I don't have that background. We have a spectacular group of hatchery managers that know their systems intimately and are always doing everything to stretch their production to the absolute limit. So if there is a particular feed type that works best for a certain strain or species, I'm sure they're using it. It's just a detail that I am not involved with. 
     When I got this job, one of the steepest learning curves for me was figuring out how to interact with the hatchery system. My tendency at first was to think of the hatchery as a static machine that cranks out the same number, type, and sizes of fish at the same times every year. It took me a few years to understand that this is not the case at all. In fact, no two years are ever the same in any given hatchery. The volume and temperature regime of a hatchery's water supply fluctuates every year, which can have a big impact on production. Add to that infrastructure problems or improvements, disease outbreaks, personnel limitations and various other complications, and it becomes nearly impossible to predict exactly what the output of a hatchery is going to be. So as a biologist you have to be able to have enough flexibility to adapt, take advantage of opportunities when they arise, and on the flip side, figure out how best to work around limitations or shortfalls.

1 comment:

  1. I am a brook trout fan, so this blog entry has been very informative and helpful.

    There are a couple lakes I will leave nameless for now that are brimming with 6-9 inch brooks. Often, you can catch over a hundred per day per fisherman on one line. It is a hike in lake which is inaccessible in the winter without a snowmobile, so it doesn't receive much pressure from anglers. Problem is, there are no predators in that lake. Brookies go unchecked this has been the case there for decades.

    I wonder if tiger trout or mackinaw would be a potential solution... It is not in your particular area of the state, Jon...but tigers or mackinaw might be an option to help the fishery.