Is it possible for trout …even large trout…in a particular lake to have as their main source of food…zooplankton…and still thrive and grow at a more than respectable rate?
What kind of zooplankton? I once had a marine bio prof who defined plankton as “anything which swims so feebly as to be at the mercy of the current”. Dead blue whales, for instance.
I once saw a trout in the 10# class sipping #26 midges. I cannot imagine how many #26 midges it takes to make a 10# trout. So, I would say, quite possibly, yes.
But, consider this. Do you know of any way there can only be large fish in this lake? Is there natural reproduction? If so, there must be small fish… And, are you sure there are no other food sources in the lake?
Good questions…all…DG
I wasn’t going to get into those details…yet…let’s see what others have to say about the basic question.
It is a good question…
My only thought is that I know the Kokanee (landlocked silver salmon) here in Oregon eat mostly zooplankton. And can get to fairly large sizes, though not ten pounds…I wish! My guess is the trout may use the same food source, but it may not be its primary source.
Any other thoughts out there?
Just try to relate fish to other animals such as a horse which only eats grass and grain and they grow so large. Makes sense to me…
My thoughts are that Kokanee consume zooplankton in open water, at God knows what depth, because the zooplankton does not relate to the shoreline??, where trout feed. I was told that there is a Kokanee spot in Paulina Lake that has to be found by using a Fishfinder & GPS, so I really don’t think trout would bother with food that would be Kokanee food. I think freshwater shrimp is another food that Kokanee eat. The rainbow and browns I have caught in Lakes, had plenty of bugs and chubs to chase in shallow water.
Doug
I’ve been told, but haven’t confirmed it, that many fish species can take in nourishment from microorganisms that they get into their system through their gills, basically ‘filter feeding’.
If that’s at all possible, then I’d say that trout could survive on a such a food source. I’m just not sure how large they could get on such a thing alone.
Be interesting to know, though.
Buddy
Most of the largest aquatic organisms in the world make a living by eating plankton. Whales, whale sharks etc. Eating lower on the food chain gives you access to much more food. You just need to eat a lot of it.
Kevin
ducksterman -
Not sure what you mean by “large trout” and “grow at more than a respectable rate.”
This may not be directly on point, but most of the stuff I’ve read indicates that trout do not grow beyond about 14" unless they are meat eaters. In other words, without sculpins, minnows, baitfish, other smaller trout, crawfish, etc. in the system you won’t get “large trout” ( unless you consider 14" large ).
There may be some exceptions, but without the meat, trout that “grow at more than a respectable rate” still won’t get beyond the 14" threshhold.
John
P. S. You can let the other shoe drop any time !!
ducksterman -
Still waiting for the other shoe ?!
John
OK, John…not really another shoe…
I don’t know about your 14" premise…
I asked this question because a buddy and I have this lake we have access to and are kind of managing…trout lake.
We planted it …June 06 with 2 inch fingerling’s…triploids…now we are catching 16 / 19" fish from that plant…last year none…maybe they only ate zooplanton…we thought we lost that plant…
Last years plant …June 07… was 4 inch fingerlings and they are 13" fish now…we think a fair amount survived…
I have pumped a few stomachs and…except for an occasional midge /water boatman and once a lot of bloodworms they [even up to 19 inches] are loaded with zooplankton.
Bottom line is …I’m wondering if there can be a fishery that is so based on zooplankton that the usual fishing methods only work a little bit…we find woolybuggers / the usual nymphs /etc. to be slow fishing.
Oh, and there are fish in there that are 8 years old…22+ " and thick but I haven’t pumped any of them…[out if respect]…and I don’t want to be too cruel…that’s for Buddy;)
I’ll bet you wished you never asked ,John.
ducksterman,
Here is a Quote from an article at “BCFishingReport” “Kokanee”
Author; Nick Basok. "Bead head chironomids and bloodworms in sizes #10 - #16 work best for me in shades of black, green or light orange. Remember to try and find the strike zone and use the correct line to stay there. Once you have tried and had some success with this fishery you will add it to your list of “gotta do’s.” End Quote.
Instead of Woolybuggers, maybe you could try Minnow/Streamer flies, also.
Doug
Ducks, a friend of mine has a fly that is patterned somewhat after zooplankton. He’s also quite knowledgeble on what trout feed on. He told me during the winter, they will survive on zooplankton, but that’s only a part of their diet for the rest of the year.
duck -
Of course I’m glad I asked.
Sounds like you guys have a very interesting situation to deal with. Tough when you have to figure out what kind of flies to use to catch trout like that.
I don’t do any still water fishing to speak of, but I guess I would think in terms of minnows or small trout imitations fished on full sinking lines near the bottom and in the shallows late in the day, in addition to midges fished deep.
John
P.S. If I run across any references to the 14" premise, I’ll try to remember to post it, for what it’s worth.
You might consider the White River in northwest Arkansas. Before the construction of the dams in that area, trout of any kind were unknown, conditions simply were not favorable. Now, after the dam construction and a little settling in time, the White has become one of the great trout hot spots of the country. In fact, where not the last two WORLD records for brown trout recorded in that area?
Maybe it’s that Ozark Mountain sea weed …
I would guess its possible to get healthy, growing trout that feed primarily on zooplankton.
I compare that to a situation I’ve been watching over the past several years. We’ve got some lakes in central Iowa that had the best crappie spawn anybody can ever remember seeing. In some lakes, these fish numbers are incredible! There isn’t really a good forage base in the lake, since shad had winterkilled a number of years ago, and haven’t been seen since. What are these crappies eating?? They are surprisingly fat & healthy and have been growing 1"-2" per year. I haven’t pumped any stomachs, but I figure they must be eating primarily zooplankton. In the winter when we use underwater cameras for ice-fishing, the screens are often filled with tiny zooplankton swimming across the lens.
So…if it is working for the crappies, I don’t see why it wouldn’t work for the trout! :rolleyes:
duck -
It’s a rainy morning here in Rigby, and most of the local water is in tough shape. Your question caused me to do some research on the 14" premise, as you called it, and the triploid trout, which I had heard about, but didn’t know anything about.
About Trout: The Best of Robert J. Benhke from Trout Magazine - Page 124
?In most streams with good natural reproduction and recruitment, great numbers of young, small trout abound, and they will consume most of the small particle food supply. It is true that larger trout are dominant over smaller trout and the larger fish will monopolize the best feeding areas. But at some point the larger fish cannot control sufficient space to consume an adequate daily ration to meet maintenance requirements; negative growth and death will soon follow. For the typical brown trout population under such circumstances the terminal age can be expected to be around four and the terminal size about 12 inches. Streams where the terminal size of trout is considerably greater are characterized by an alternate food supply of large organisms such as scuds, crayfish, and forage fishes. When trout reach a size of about 12?, they can then begin to feed on larger organisms, avoid competition with smaller trout and maintain positive growth. As long as positive growth is maintained, the lifespan can be greatly expanded.?
Benhke’s comments are consistent with the other material I’ve read. They may well apply only to stream trout, since that is what I am most interested in, what I fish for, and mostly what I read about.
Reading about triploids from several articles on the net was very interesting. Sterile. Which is one reason they get so big. Don’t use any time or energy on reproduction. They certainly do get to be HUGE. Found some pictures of record triploid rainbows in lakes in SoCal that went into the high 20’s - as in pounds.
Anyway, like I said above, I am glad that I asked. I always figure it is a good day if I learn something, and I learned several things already today and it’s not even noon !!
John