by Dave Beauchamp, March 19, 2002

This is a letter and response between guide Anton Jones and David Beauchamp of the University of Washington. A little background - the WDFW is considering lifting limits on lakers in lake Chelan in order to allow anglers to remove the lakers from the lake. They are then planning on stocking back into the lake a strain of cutthroat trout that are genetically related to the original fish that were in the lake. The intent as I understand it is to more closely return lake Chelan to the original species it had prior to introduction of lake trout. Stay tuned for more information as this develops on this very critical issue. Mike, Editor

Reprinted with permission of the authors:

Questions from guide Anton Jones to David A. Beauchamp, Asst. Unit Leader
WA Coop. Fish & Wildlife Research Unit
University of Washington
School of Aquatic & Fisheries Sciences


1. Mysis shrimp have always been the #1 stomach content of the lake trout here. Yet the mysis shrimp have bimass has quadrupled between 1984 and 1996. Aren't the mysis the real danger here? If they crash all of our
zooplankton population, won't that prevent all the fish species from growing through the fry stage?

Answer: Mysids can very well be the main issue for a couple reasons:
A. As a direct competitor with kokanee and juvenile stages of many species
for zooplankton prey.

B. We believe that mysids really improved survival of juvenile lake trout in
Flathead which created a glut of predators which then wiped out kokanee. The
mechanism is not so much improving growth of young lake trout, but rather
that smaller lake trout can feed while in or close to cover which can
dramatically reduce mortality from cannibalism by larger lake trout or
predation by burbot, etc.

C. Virtually impossible to remove mysids from a system once they've become
established.

2. Isn't our bias for Indigenous fish illogical? Especially when you consider not only our irreversible species introductions, but also our artificial lake level fluctuations that constantly adversely affect all fish that spawn in flowing water, particularly spring spawners when our lake level is down 10 to 19 feet from summer pool?

Answer: It's possible that some species cannot be sustained under the current
conditions of water management, fish management, climatic trends, and
species assemblage. What the current process should achieve is an
identification of what the biological bounds are for the current species
mix, the factors of decline (or limiting recovery), what measures would be
needed to improve the situation, and how biologically feasible these
remedies might be (probability of success, time frame, etc.). That then
fuels the political debate about what should occur, once the biological
possibilities have been examined as objectively as possible. Right now, I'm
too much of a neophyte to this system to say anything meaningful other than
the management strategy should evolve into a program that is sustainable and
internally consistent (e.g., don't stock things that eat each other unless
that is the intent).

3. Could the shape of our lake and it's bottom contour provide significant differences from Flathead, Yellowstone as well as the Idaho and BC lakes that have evolved into this mysis / laker crisis? What I mean is we have a long narrow riverine-like lake. Also, the lower basin has many bowls which really tend to concentrate the shrimp on their diurnal migration.

Answer: Absolutely- bottom morphology could play a very pivotal role in
determining the presence/absence and relative density of mysids, different
life stages of lake trout, kokanee production and distribution, etc.

4. Is the variation in flesh color in the lakers a result of diet, or some other factor(s)? It has always been something that we fishermen here claim, with the oranger / redder fleshed fish assumed to be primarily shrimp eaters and the whiter/greyer fleshed fish being assumed to be primarily fish eaters.

Answer:Having some significant fraction of mysids or other crustaceans in the
diet is the primary cause of red flesh in salmonids. Some other factors can
play a role (e.g., genetics or a dysfunctional enzyme), but are less likely
in Chelan. The coloration may shift back and forth seasonally somewhat as
the diet shifts to more or less mysids.

5. Observations.

a. For the 9 years that I have been fishing for the lakers here, the number 1 stomach content has been and continues to be mysis shrimp. That is irrespective of size. 18 inch and 20 lb fish both appear to be mainly mysis feeders.

b. In the last year the #2 forage has shifted from kokanee to sticklebacks. The lakers appear to be able to forage on them in great numbers to depths greater than 200 feet.

c. As a percentage of the catch, the smaller fish of 16" to 22" are making up a greater portion of my catch now than they were 3 to 5 years ago. However the actual catch rate for bigger fish 5-10 pounds and trophy fish over 10 pounds has remained about the same. I am catching a lot more fish. I used to think that 3 fish in an 8 hour day was about average. Now, 8 to 10 fish in an 8 hour day seems to be normal. I am more limited by the number of licensed fishermen at 2 fish per day, than what I can actually put in the boat. Of course, I can't tell whether my technique changes are the cause, or if it is because of a population increase.

d. A fish that has a big head and small body is a real rarity here. I have seen 1 in about 55 fish so far this year. Most of these fish have little heads and big fat bodies

e. I had a burst of fish in December that were stuffed full of little clams. That was the first time I had seen that. I gave a sample of them to Art Viola at our Dept. of Wildlife Office in Wenatchee.

f. I am picking up a few fish with 3 to 5 inch lakers in their stomachs.

Answer: These are really valuable observations! Your logbooks would be very
important sources of information. Many of these indicate to me that lake
trout recruitment is potentially increasing (although you're right to
consider factoring out a potential increase in your catch efficiency through
time):
-The increase in smaller fish without a decline in catch of larger fish
-Lack of poor-conditioned fish. Mysids may actually reduce the growth rate
on your largest fish, but tends to enhance growth of the juveniles and
smaller adults (we've seen this in Tahoe and Flathead) because they're a
more consistent predictable meal. But if mysids impinge on the prey fish
community (i.e., kokanee), then lake trout have less biomass of high quality
prey fish (fewer and/or smaller) and shift to lesser quality prey (i.e.,
sticklebacks, perch, etc.)

Hope this helps.
Best regards,
Dave