11
Overharvest
In the early 1900's, freshwater
mussels experienced heavy
commercial pressure for the button
industry which tapered off after
plastics were invented. The thicker
shelled mussels were harvested and
drilled for button blanks like that in
the photo at the right. More recently,
the cultured pearl industry has
created great demand. The shells are
drilled out and the blanks made into
seed pearls which are inserted into
oysters. Apparently, the best seed
comes from freshwater mussels. The
problem is that it takes decades to
grow mussels large enough to make
buttons or seed pearls. Couple this
with their low reproductive rates, they
are easy to overharvest.
Physical Damage
When we are talking about physical
damage, we mean damage like that shown
in these photos. The most common cause of
this may be trampling by livestock.
Livestock pastured on bottomlands and the
riparian zones of streams often walk in the
streams for watering and for cooling off in
summer. It has been my observation that
when there are obvious signs of overgrazing
or trampling of a streambed, that no
mussels will be found.
Another form of "trampling" is the practice
of running up and down streambeds in
ATV's and four-wheel drive vehicles. This
has been observed on most any stream
where there is easy access, especially
during the low-flows of late summer.
Remains of Threeridge that has been cut for
buttons, collected from banks of Mississippi
River in Moline, IL
Pink heelsplitters that were severely
damaged and lived for several more years
