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NFC: RE: RE: Native Fish Conservancy Digest

fascinating, Duane,

I tend to jump at your observation that water has something to do with it.
But since I didn't identify the species I saw in the san marco, I can only
surmise either a species trait or water quality.  We did a whirlwind tour of
several streams, & rivers at that time, and not many crayfish were caught on
the whole.  But these blue ones in the san marco were obvious and enough of
them to notice easily.  We caught a few, but released them.  All the fish we
caught during the 3 days were identified, but inverts may have gone to a
different lab (there were also students from a vertebrate class which
collected bats, birds, and road kill if it was mostly in one piece.)

I can say the water in the san marcos was clear at the point we were at.
The sides were also bulk headed with nice cement/stone walls, depth about
1 - 2 feet, reasonable underwater macro algae growth, lot's of stones, and a
fair current.  I don't even think the river was wider than 30 - 40 feet
across.  We waded in the current and did not actively collect anything in
the water (except a dollar I found floating and an empty wallet).

After looking at the link Saffad sent us, I wonder if any of the crawdaddys
around the States could attain such size, blue or no :)

I have also dealt with the RED coloration of P. clarkii numerous  times, and
have caught many here that show more red than usual, but I heard there is  a
species that is normally brighter red....  Guess I will have to get out My
Walter P. Pennak "Freshwater Invertebrates of the United States" and read
the section on Arthropods.

Paul


-----Original Message-----
From: owner-nfc at actwin_com [mailto:owner-nfc at actwin_com]On Behalf Of
Duane Morgan
Sent: Tuesday, April 04, 2000 6:30 AM
To: NFC at actwin_com
Subject: NFC: RE: Native Fish Conservancy Digest


I would like to add something to this discussion of crayfish concerning
coloration.  I have collecting small crayfish from different locations for
several years to feed a spoiled long ear.  My first experience with a small
blue crayfish was one I collected nearly 30 years ago.  I was told by a
university professor friend that this was probably due to a lack of yellow
pigment and that it would not last through the molts.  This particular
crayfish lasted several years and grew to near lobster proportions, and the
blue color only intensified.
I have collected several species of the drab green juvenile crayfish in the
past several years which actually turned blue while in captivity.  One in
particular now is 4.5-inches in length and has molted several times in the
last month.  It is a cornflower blue and each successive molting is getting
paler in coloration.
When I collected these crayfish they were less than a half inch in length
and I feed them on a strict diet of red wigglers that I raise.  My only
conclusion is that the diet or possibly the local tab water in Wichita has
something to do with this anomaly.  Regardless of the species or source,
this has occurred on a number of occasions.  I had collected a number of
juveniles form a source in southeaster Kansas several years ago.  Of the two
that survived my feeding program, one turned blue then red and blue, and
another other turned blue.
I have given several of the blues away to different people in different
areas and the coloration does not seem to diminish.  If there is a
reasonable explanation for this I have not come across it.  Anyone have a
take on this?

morgan
References: