Gill Maggots

What is it?

• Gill maggots• parasitic copepod in the

genus Achtheres

Photo by Jim Negus, TWRA, Norris Reservoir Striped Bass, December 2003

Parasitic copepod from Cherokee Reservoir, TN largemouth – Jim Negus

No legs and little segmentation

Reduced mouth parts

Modified maxillae

Umbrella shaped bulla

Egg sacs

Female

* Mature males are much smaller and are free swimming

Life Cycle

• Females produce eggs in eggs sacs• Nauplii stages are passed within the egg sac• First copepodid stage is released from the egg sac and is free

swimming plankter.• After a short while they attach to fish and mature to adults• Females remain attached, males mature and become free

swimming.• Free swimming males attach to females during copulation.

Recent Reported Infestations

2000 Watts Barr Reservoir, TN - striped bass

2000 Tim’s Ford Reservoir, TN - striped bass

2001 Melton Hill Reservoir, TN - striped bass

2001 Watauga Reservoir, TN - 1 smallmouth bass

2002 Old Hickory Reservoir, TN - striped bass

2002 Norris Reservoir, TN - striped bass

2002 Smith Mountain Lake, VA - striped bass

2003 Kerr Reservoir, VA - striped bass

2003 Leesville Reservoir, VA - striped bass

2004 Lake Norman, NC - striped bass

2004 Gaston Reservoir, NC - striped bass

2004 Tellico Reservoir, TN - 1 striped bass

2004 Smith Mountain Lake, VA - largemouth

2005 Congaree & Saluda Rivers, SC striped bass

2005 Cherokee Reservoir, TN - white bass

2006 Ouachita Lake, AR - striped bass

2006Fort Patrick Henry Reservoir, TN - striped bass (angler report)

2006 Keowee Reservoir, SC – spotted bass

2007Cherokee Reservoir, TN - striped and hybrid striped bass

2007Holston River - Cherokee Res. tailwater, TN - striped bass

2007 Santee Cooper, SC - striped bass

2008 Lake Murry, SC - striped bass

Myths

1) They kill fish. NOT!

2) They render fish non-eatable. NOT!

3) They spread to people who swim in the lake. NOT!

SCDNR Research

The End