Northwest Fishing Magazine September 2025 Volume 5 Issue 1 - Flipbook - Page 18
the water column to feed in
the evening because they
avoid light. They descend
the water column in the
morning.
DUDE: OK so far. So I guess
zooplankton are like
lawnmowers -- consuming
the green algae and
keeping it in check. But
what do the Mysis shrimp
eat?
KOKANEE: They eat the
zooplankton that the
kokanee depend on. In fact,
the Mysis way is to devour
all of the Daphnia. Kinda
like water Vikings. Mysis
are vast consumers of the
Daphnia and easily outcompete kokanee for that
food source. The remaining
zooplanktons, such as
the copepods, are much
smaller and less efficient
at keeping the algae in
check, and are much less
of a nutritious food source
for the kokanee. It has
been thought that Mysis
consumes more than six
times the zooplankton as
the kokanee do.
DUDE: Why don’t the
kokanee eat the Mysis?
KOKANEE: In case you had
not noticed, when kokanee
emerge as fry, they are tiny.
Mysis being 1-2 centimeters
would be more than a
mouthful. And the Mysis
are eating the food that the
kokanee fry and fingerlings
need. No food, no survival.
The two-year-old kokanee
don’t eat them. With less
and less available food,
kokanee become sizechallenged. Of course, there
was a temporary exception
over in Wallowa Lake in
Northeast Oregon. Mysis
were introduced, and the
chain reaction started.
But somehow the adults
managed to develop a taste
for Mysis, and as a result
grew to record sizes. But
when these monster kokes
were caught or spawned,
the kokanee fishery
collapsed. And putting
huge numbers of kokanee
fingerlings into that lake
made no difference.
