Spaghetti
worms are common parasites of saltwater fish in the drum family,
which include speckled and white trout, black drum, redfish,
and croakers. While they look alike to most fishermen, several
different worms use these fish as hosts. Most common in sea
trout is Poecilancistrium caryophyllum. Worms found
in black drum are most often Pseudogrillotia pIeistacantha.
For ease of discussion, we will dispose of these tongue-twisting
Latin names and refer to them all as spaghetti worms.
Fishermen
frequently find these white, one to three inch long worms
when filleting their catch. In trout they are usually found
in the middle of the fillet in the area just below the dorsal
fin. Research has shown that approximately 40% of Louisiana
and Mississippi speckled trout are host to spaghetti worms,
with an average of between one and two worms occurring per
fish. It may appear that many more worms exist, but often
one worm is cut into several pieces during filleting. Spaghetti
worms in black drum are more common near the tail of the fish
with a typical fish hosting 5 to 15 specimens.
The spaghetti
worms we see in these fish are really parasitic tapeworms
of sharks, who are just using the trout or drum as an intermediate
host. The cycle begins with eggs produced by an eight-inch
long adult worm which lives in a shark's intestine. After
being passed into seawater, the egg hatches into a tiny swimming
larva called a coracidium. If this larva is eaten within two
days by a small marine crustacean like a copepod, it develops
into another stage called a procercoid.
At this
stage some uncertainty exists as to what happens. The copepod
may be eaten by a trout, passing the larval worm on the trout.
However, since small animals like copepods are seldom eaten
by larger trout and since very few trout under ten inches
long have spaghetti worms, another host is suspected. More
than likely, a small bait fish like an anchovy eats the copepod
and it in turn is eaten by the larger trout. In any case,
once the larval worm is in the trout's digestive tract, it
tunnels its way into the trout's flesh where it may live for
several years. The life cycle is completed when a shark eats
the trout and serves as host for the adult worm.
The fact
that a spaghetti worm may live several years (up to 6 or 7)
may surprise many fishermen, since they often claim that more
fish are infected in one season than another. This may possibly
be due to different populations of trout with different infection
rates, moving up and down in a marsh system seasonally.
The number
of trout carrying worms seems to be directly related to the
characteristics and quality of the water in which the trout
live. In general, the saltier the water and the less polluted
it is, the higher the levels of infection are. This may be
due to either one of the intermediate host's or the larval
worm's needs for saline, unpolluted waters.
Another
interesting fact is that once a trout becomes host to one
or several spaghetti worms, it seems to develop an immunity
to further infections. If this were not the case, large, old
fish would have many more worms than a 12- or 14-inch fish,
but they don't.
Finally,
while the spaghetti worm may be somewhat unappealing to the
eye, it certainly doesn't prevent good eating. Since, they
are large enough to easily see, they are simple to remove
during the filleting process. Simply grab the worm between
the knife blade and thumb and gently pull it out. With a little
practice, it becomes easy.
Many people
don't even bother to remove them before cooking. After cooking,
they are unnoticeable and cannot be tasted. In a survey conducted
at Mississippi fishing rodeos a few years ago, less than 25%
of the trout fishermen avoided eating fish with worms.
While
cooking does, of course, kill the worm, even without cooking
they are not a human health problem. No human infections have
been recorded and researchers have been unable to infect warm-blooded
animals with the parasite.
So good
fishing and "bon appetit.”
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