Several antiparasitic drugs have been developed for control purposes. Atlantic and Pacific salmonids, respectively. The family Caligidae is eric cressey high performance handbook pdf to contain around 559 species in 37 genera. How planktonic stages of sea lice disperse and find new hosts is still not completely known.
Several field and modeling studies on L. Atlantic salmon return and travel upstream in the fall to reproduce, while the smolts do not return to saltwater until the next spring. April, and ending in late August, dependent upon species and run timing. It is possible that sea lice survive on fish that remain in the estuaries or that they transfer to an as yet unknown alternate host to spend the winter. Smolt get infected with sea lice larvae, or even possibly adults, when they enter the estuaries in the spring.
It is also not known how sea lice distribute between fish in the wild. It acts like a suction cup in holding the louse on the fish. The second antennae and oral appendages are modified to assist in holding the parasite on the fish. The second pair of antennae is also used by males to grasp the female during copulation. The adult females are always significantly larger than males and develop a very large genital complex which in many species makes up the majority of the body mass. One female can produce 6-11 pairs of egg strings in a lifetime of approximately 7 months. All stages are separated by moults.
17 to 72 days depending on temperature. The copepodid stage is the infectious stage and it searches for an appropriate host, likely by chemo- and mechanosensory clues. Currents, salinity, light, and other factors also will assist copepodids in finding a host. Preferred settlement on the fish occurs in areas with the least hydrodynamic disturbance, particularly the fins and other protected areas. Copepodids once attached to a suitable host feed for a period of time prior to moulting to the chalimus I stage.
Sea lice continue their development through 3 additional chalimus stages each separated by a moult. A characteristic feature of all 4 chalimus stages is that they are physically attached to the host by a structure referred to as the frontal filament. There are differences in the timing, method of production and the physical structure of the frontal filament between different species of sea lice. With exception of a short period during the moult, the pre-adult and adult stages are mobile on the fish and, in some cases, can move between host fish. Adult females, being larger, occupy relatively flat body surfaces on the posterior ventral and dorsal midlines and may actually out-compete pre-adults and males at these sites. The naupliar and copepodid stages until they locate a host are non-feeding and live on endogenous food stores. Once attached to the host the copepodid stage begins feeding and begins to develop into the first chalimus stage.