Predator fish's origin a mystery
Snakehead secret survives dissection
By Michael Hawthorne
Published October 31st, 2004
Dissecting the northern snakehead, a fish scooped out
of Burnham Harbor this month, has failed to solve the
mystery of how the dreaded predator ended up in Lake Michigan.
After thawing out the 18-inch fish Friday and taking
a closer look, scientists now know the snakehead was a
It wasn't carrying eggs, a sign that the fish might have
been a loner. But its stomach was empty, depriving researchers
of evidence that could have revealed where it came from.
If there had been goldfish inside, that almost assuredly
would have meant the snakehead had been dumped out of
an aquarium. Bluegills or round gobies would have suggested
it had been lurking in the lake for a while.
"Nothing definitive, I'm afraid," said Philip
Willink, a Field Museum biologist who examined the fish.
When a Tinley Park angler captured the snakehead Oct.
7 near the Adler Planetarium, state and federal wildlife
officials feared another troublesome import had invaded
the Great Lakes.
The northern snakehead, a native of China, Korea and
Russia, is a voracious eater that could crowd out native
fish such as bass and walleye, scientists fear.
Unlike most other fish, the snakehead breathes air in
addition to absorbing oxygen through its gills, a trait
that allows it to survive out of water for days if kept
moist. It also can flop short distances over land to other
bodies of water.
To check for other snakeheads, scientists sank gill nets
and traps along the concrete walls and steel pilings that
line the harbor and brought in boats equipped with electrodes
that bring stunned fish to the surface.
They found several fish that aren't native to Lake Michigan,
but no snakeheads.
Wildlife officials have ended that intense search, but
they urged local anglers to keep looking.
After reading that the snakehead was caught in a net,
Willink said somebody probably dumped it in the harbor
without realizing that doing so is illegal.
"They normally stay near the bottom of shallow,
vegetated areas, and wait for a meal to pass by,"
he said. "This one seemed lost, as if it had just
Matt Philbin, who caught the fish, said it was moving
slowly near the surface and didn't resist when he scooped
it out of the water. He posted a picture of the odd-looking
fish on a Web site devoted to local fishing, setting in
motion a chain of events that led from a 5-gallon bucket
in Philbin's garage to a laboratory at the Field Museum.
"That's some fish story," Philbin said.