Sea Lice Fact Sheet

Sea lice attach themselves to salmon, among others

A sea louse is a copepod, a microscopic, parasitic crustacean. It feeds on the soft tissue of fish and, especially in salmon-farming circles, is considered a harmful pest.

Description

Sea lice have large heads with long antennae and trailing body/tail sections. Their mouth parts look like siphons and, along with their antennae, hold the parasite to the host fish. Females are larger than males. Sea lice feed on the blood, mucus, and tissue of fish.

Family

Sea lice belong to the family Caligus which has numerous genera, or subfamilies. Those of the genera Lepeophtheirus and Caligus genus tend to feed on farmed fish. Several species have specific host fish. For example, Lepeophtheirus salmonis is a parasite of salmon.

Life Cycle

Sea lice reproduce by laying eggs which later hatch into larvae. The lifespan of a sea louse is around seven months, with the larva moving through four distinct stages before reaching adulthood. The free-floating larva needs to attach to a host fish, or it dies of starvation.

Parasite

Sea louse infection causes the fish stress and may weaken its immune system and stunt its growth. As the louse works its way down, raw skin and even bone may become exposed. A bad infestation will kill the fish.

Control

SLICE(R), a medicine delivered to fish through food, is a common method of control of sea lice. Prevention (i.e., keeping infected fish away from clean ones ) is another method of control.

References

• Schering-Plough Animal Health: Sea Lice and SLICE(R)
• Taxonomy of Caligidae
• Protocols and Guidelines for Sea Lice Research