Gill Lice

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The Majority of streams I have fished this year in the Driftless Area with a brook trout population have gill lice.

http://lenharris.blogspot.com/2010/0...thwestern.html

[kglissmeyer]

Len, is this a threat to the fishery, or is it something that comes and goes? Looks pretty bad.

Kelly.

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the fish managers say it has been here a long time.

[Steven McGarthwaite]

Copepod
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Maxillopoda
Subclass: Copepoda

Copepods are a group of small crustaceans found in the sea and nearly every freshwaterhabitat. Many species are planktonic (drifting in sea waters), but more are benthic (living on the ocean floor), and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests, bogs, springs, ephemeral ponds and puddles, damp moss, or water-filled recesses (phytotelmata) of plants such as bromeliads and pitcher plants. Many live underground in marine and freshwater caves, sinkholes, or stream beds. Copepods are sometimes used as bioindicators

Gill Louse (Lice)
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Maxillopoda
Subclass: Copepoda
Order: Poecilostomatoida
Family: Ergasilidae
Genus: Ergasilus

The Gill Louse are a genus (Ergasilus) of copepod crustaceans occurring in both the ocean and fresh water. The females are parasitic upon the gills of fishes. This is similar to members of the crustacean subclass Branchiura (fish lice). Being copepods, gill lice have a single median eye on their head. The second antennae are modified into prehensile pincers. Male gill lice are free-living.

http://en.wikipedia.org/wiki/Copepod
http://en.wikipedia.org/wiki/Gill_louse

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Gill Lice will not kill all by themselves but if the fish is stressed they may die.
Stressed in my book is fishing for them in this hot weather and streams temps
here in Wisconsin.

[Steven McGarthwaite]

Young fish eat Copepods. Copepods are a major source of food for many aquatic species, saltwater and freshwater. Some species of Copepods help reduce the the mosquito population by eating the mosquito larva and nymphs. Many areas in the world stock standing water areas with the male copepods for this reason to reduce the population of mosquito's that transmit dangerous infections to humans.

If the balance of the aquatic species are maintained in the aquatic ecosystem, there should not be any major problems with the habituate. Yellow Perch are infamous for carrying parasitic worms in their flesh, because of their habit of grouping on the bottom of lakes and rivers. Yet they still can be eaten if properly cooked.

So when it comes to coepods, there are positives and negatives that balance out, when the aquatic environment is in balance. ~Parnelli