Bluegills,
or as they are often called in Louisiana brim or perch, are
a popular freshwater sportfish. In man-made bass/bluegill
ponds, they are also the primary food source for bass. Most
desirable for fishermen are the large colorful males, which
can grow to more than 8 inches in length.
Unfortunately,
some waterbodies, especially ponds and smaller lakes, can
develop a dense population of “stunted” small
fish. It is usually assumed that this occurs because there
are too many bluegills present for the food supply. In response,
fisheries biologists usually recommend fishing bluegills harder
to “thin them out” and make room for larger fish.
Sometimes this works, but often it doesn’t. Researchers
in Illinois have recently done some work to figure out why
these stunted populations develop and their research indicates
that too much fishing pressure rather than too little may
be the problem.
Large
male bluegill are easiest to catch in the warm summer months
when they are concentrated on their spawning beds. A bed may
have up to 500 individual nests in a small concentrated area.
Each nest is about the size of a large dinner plate or platter
and is swept clear of silt and guarded by the male fish against
other fish that will eat their eggs.
During
the four month spawning season, males will be almost continuously
on their nests for repeated spawnings. While on the nest,
a male will eat very little and as a result grow very little.
The best nest sites are those in the center of the bed, because
egg-stealers enter a colony from the edges and usually don’t
make it to the center.
Male bluegill
compete intensely for these best sites and larger males usually
win. In a population with a lot of large males, smaller males
can’t compete and instead of becoming sexually mature,
they delay maturation and grow for another year.
If, however,
large numbers of big males are removed from the nests by fishing,
these younger, smaller males stop growing and start spawning.
This results is a stunted population, not because of slow
growth, but because of early maturation.
Production
of a healthy population of large male bluegills may be helped
along by fishing heavily on smaller, younger bluegills, reducing
the harvest of large male bluegills and keeping a strong bass
population in the waterbody.
Download:
bullbream.pdf
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