Atlantic salmon with adult females (C. rogercresseyi). Note the lesions on the skin surface. Note also the paired trailing egg sacs.
Skin

Caligus Rogercresseyi – Gross Pathology

by Carlos Sandoval

Caligus rogercresseyi is a predominant parasitic problem in the salmonid industry in Chile. It mainly affects Atlantic salmon and Rainbow trout. Coho salmon is not considered susceptible due to a well-developed inflammatory response.

Atlantic salmon with a severe infestation by Caligus rogercresseyi.
Figure 1. Atlantic salmon with a severe infestation by Caligus rogercresseyi (Picture courtesy of Jaime Santana – VM).


The life cycle of C. rogercresseyi is composed of eight stages of development, two nauplius stages I and II, an infested copepodite stage, four chalimus stages and an adult stage (young adult and mature adult).


The amount of time it takes for a louse to develop depends greatly on the temperature. Under laboratory conditions the C. rogercresseyi life cycle is completed in 45 days when the water temperature is 10°C, 32 days at 12°C and 26 days at 15°C.

Atlantic salmon with adult females (C. rogercresseyi). Note the lesions on the skin surface. Note also the paired trailing egg sacs.
Figure 2. Atlantic salmon with adult females (C. rogercresseyi). Note the lesions on the skin surface. Note also the paired trailing egg sacs (Picture courtesy of Marcelo Vera – VM).





The external gross findings include loss of body condition, haemorrhages, petechiae and abrasions on the surface of the body causing immunosuppression in the host.

Life cycle of Caligus rogercresseyi.
Figure 3. Life cycle of Caligus rogercresseyi (Picture courtesy of Jaime Santana – VM).


















REFERENCES

  • González, L., & Carvajal, J. (2003). Life cycle of Caligus rogercresseyi,(Copepoda: Caligidae) parasite of Chilean reared salmonids. Aquaculture, 220(1-4), 101-117.
  • Revie, C. W., Gettinby, G., Treasurer, J. W., Rae, G. H., & Clark, N. (2002). Temporal, environmental and management factors influencing the epidemiological patterns of sea lice (Lepeophtheirus salmonis) infestations on farmed Atlantic salmon (Salmo salar) in Scotland. Pest Management Science: formerly Pesticide Science, 58(6), 576-584.

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Carlos Sandoval Hurtado is a Veterinary doctor at Universidad Católica de Temuco, Masters in Science, specializing in Animal Health at Universidad Austral de Chile. He has over 15 years experience in the area of pathology and histopathology of fish and other species, becoming one of the most renowned histopathologists in Chile. He is currently the Director of VeHiCe (Veterinary Histopathology Center) a leading laboratory in histopathology whose clients include laboratories, universities, aquaculture industry and avian industry mainly.

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