Re: NANFA-- Temps -personal freshwater WI observations

R. W. Wolff (
Sat, 25 Oct 2003 23:36:59 -0500

Freshwater examples locally:

Fundulus diaphanus menona- Western Banded Killifish.

Acting like their brackish cousins, you will find them in steaming hot inch
deep mud slicks on the lake shores they inhabit in Central Wisconsin. This
is in early May, or even April , if we are lucky enough to have some warm
sunny days, which the past 365 days are lacking ( warm that is , plenty of
sun and dry). The main lake water is freezeing ( ok, freezeing for me
swimming wise is under 75) more like the low 60's. I have not measured these
mud slicks, but I would guess they are in the 90's, because they are almost
uncomfortable to touch with my hand. A hand that turns meat on the grill
none the less.

Lepomis cyannelus - Green Sunfish

Another early spring occurence. Finding the fish shallow in warm water ( not
90, but probably the upper 70's) cruising for new insect foods. They see me
comeing, and dart away from the warm dark rocks in the shallows to deep
water, probably in the upper 50's only. Other sunfish species can be seen
doing the same thing, crappies, bass, pumpkinseed, and sometimes others.

Umbra limi - Central Mudminnow

Here is one a bit different. Warm swamp water in the mid 80's, down to the
high 70's at night. Usually this is the early summer pattern. Find them
hovering in shade. Upon being frightened, they dive into the cool muck,
often fed by ground currents and springs, usually this is cold feeling
compared to the water above, probably in the mid 50's to upper 50's. This
can happen mid fall too ( the temp gradient). Mid summer you have to dig
down into the mud to find these cool spots from ground currents and springs.

All three of these fish though are hardy. Things like darters, sticklebacks,
emerald ( milwaukee locally) shiners, blacknose shiners can all be very
touchy when captured and subjected to bait bucket temp changes. I think it
is because of the habits of these fish. Darters hold to the bottom, and that
is usually constant in this area. Sticklebacks are shoreline huggers, no
matter what. The two minnows tend to stick to the largest depth water area
in the spot they are in. Floating with the current away from predation, or
into surround weed bed edges. Golden shiners do this too. Swarm the current,
when danger approaches, the entire mass steadily but with a good pace blends
into surrounding weed beds.

On the more unnatural side. Winter feeder fish. I often bring home dace,
shiners, and mudminnows to feed fish. Plunked from 30 to 40 degree range
water into room temp water, or slightly warmer ( my room temp is atleast
75). Come mid January, the bucket can be an ice lined frothy mess upon
getting home. Often times hours later after not being eaten, these fish are
finning around like nothing ever happened. Even after doing initial spirals
and jumps of shock. Could be they were shocked by water quality, instead of
temps- or both?

Getting back to warm water fish. I think alot of problems arise from
duration. Long term. One year the gar river pond had thousands of small baby
dollar sunfish. They lived a good two months of the ice water of winter.
Then started disappearing. By sprng none remained. However, the adult pair
barely held on, but perished when the water started to warm again. Nothing
like getting that far only to loose the fish. Similar with some exotics in
the ponds. A few nights of low 50's is fine. Being lazy and not catching the
fish out after days of cold temps, and one finds the fish lieing on the
bottom lifeless, but possibly able to be revived with some good warming.
Wait much longer, and that resting becomes permanent.

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