DO WE KNOW ABOUT PIRATE PERCHES?
June 12, 2011
is certainly the most unusual pirate on the scene these days, but I recently
encountered a different sort of pirate with its own intrigue. I caught
two little fish in a flooded area of some nearby woods and recognized
them as pirate perch. Knowing the name of a plant or animal is the first
step in identifying it; knowing someone who can tell you about its lifestyle,
its behavior and other interesting facts is the next step.
the fish in a minnow trap, a small wire mesh cylinder with inward-pointing
funnels at both ends. My grandson and I had placed some in a shallow woodland
pool alongside a swampy area. We also caught other captivating creatures,
including leopard frog tadpoles and some seldom-seen aquatic salamanders
called sirens. We brought the fish home in a plastic sandwich bag filled
with swamp water and I took them to a colleague who is an ichthyologist
to confirm their identity and to find out more about their biology. Dean
Fletcher, a research scientist at the University of Georgia's Savannah
River Ecology Laboratory, probably knows more about pirate perches than
any other living person, whether angler or fisheries biologist. The coauthor
of a book on freshwater fishes, he has written one of the few modern scientific
papers on pirate perches.
perch, a freshwater fish but not a true perch, is the only living species
in its family. It is common and widely distributed along the Atlantic
and Gulf coastal plains and up the Mississippi River Valley to the Great
Lakes. But most people, even seasoned anglers, are not likely to see one.
Adults are usually less than 4 inches long and are primarily nocturnal.
In addition, not many people fish in small tributary streams, in weedy
waters thick with root masses or in the floodplain swamps of larger rivers.
biological trait of pirate perches involves the adult anatomy. As with
other fishes, reproductive products (eggs and sperm) and body wastes are
released through the vent, which is usually situated under the body near
the tail. The vent is in this location in juvenile pirate perches. But
as a pirate perch approaches adulthood, something strange happens. The
opening gradually migrates along the underside of the fish until it is
positioned under the throat, just behind the gills.
have speculated on the function of this odd placement of the vent since
it was first described in 1824. As the scientific paper by Dean Fletcher
and his colleagues says, "We solve[d] the conundrum through a combination
of intensive field investigations, underwater filming, and molecular parentage
analysis." In other words they studied the fish extensively in its
murky habitat, filmed its behavior and used DNA analyses to see who the
parents were of various offspring. Their discoveries were made in the
cool waters of late winter and early spring when pirate perch begin spawning.
Through the use of modern technology, laboratory genetics and plain old-fashioned
behavioral observations in the field, the scientists revealed why a fish
would have a vent located in the front of the body instead of toward the
back. They documented for the first time that the female actually thrusts
her head into a tangled root mass and lays her eggs, a behavior unconfirmed
for any other North American fish. The male quickly follows suit, putting
his head into the same opening in the roots and depositing sperm to fertilize
the eggs. The DNA analyses confirmed that particular offspring indeed
had the parents predicted based on the mating observations.
and I released the two fish we had caught, still in good condition, back
into their wetland home. Let's hope they find the right root masses to
produce their young, leading to future generations of this unusual little
fish. And why are they called "pirate" perch? If you put one
in your home aquarium, it will apparently have no qualms about attacking
smaller fish--to eat them, of course, not to take their money and jewels.
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