Zoological Studies

Vol. 43 No. 2, 2004

A Review of the Impact of Parasitic Copepods on Marine Aquaculture

Stewart C. Johnson1,*, Jim W. Treasurer2, Sandra Bravo3, Kazuya Nagasawa4, and Zbigniew Kabata5

1Institute for Marine Biosciences, National Research Council, Canada, 1411 Oxford St., Halifax, Nova Scotia B3H 2Z1, Canada
2Sea Fish Industry Authority, Marine Farming Unit, Ardtoe, Acharacle, Argyll PH34 4LD, Scotland. E-mail: J_Treasurer@seafish.co.uk
3Instituto de Acuicultura, Universidad Austral de Chile, Puerto Mont Campus, Puerto Mont, Chile. E-mail: sbravo@uach.cl
4Nikko Branch, National Research Institute of Aquaculture, Fisheries Research Agency, Chugushi, Nikko, Tochigi, 321-1661, Japan. E-mail: ornatus@fra.affrc.go.jp
5Biological Sciences Branch, Department of Fisheries and Oceans, Pacific Biological Station, Nanaimo V9R 5K6, B.C., Canada

Stewart C. Johnson, Jim W. Treasurer, Sandra Bravo, Kazuya Nagasawa, and Zbigniew Kabata (2004) Parasitic copepods are common on cultured and wild marine finfish, and there is a substantive literature describing their taxonomy, life cycles, and host ranges. Although many species have long been recognized to have the potential to affect the growth, fecundity, and survival of their hosts, it has only been with the development of semi-intensive and intensive aquaculture that their importance as disease-causing agents has become evident. Members of the family Caligidae are the most commonly reported species on fish reared in brackish and marine waters. These species, often referred to as sea lice, are responsible for most disease outbreaks. The impacts of sea lice on marine salmonid aquaculture are well documented, with catastrophic losses reported for disease outbreaks that have resulted in high levels of mortality. With the development of a variety of treatments and management strategies to reduce infection levels, mortality caused by sea lice has been greatly reduced. At present, economic losses due to sea lice are primarily from the costs of treatments, the costs of the management strategies, the costs associated with reduced growth rates that are a direct result of infection and/or treatment, and the costs of carcass downgrading at harvest. Indirect and direct losses due to sea lice in salmonid aquaculture globally are estimated to be greater than US$100 million annually. In other areas of marine aquaculture, the impact of parasitic copepods is not well documented. This is especially true for species such as Atlantic halibut, Atlantic cod, turbot, and haddock that have only recently entered commercialscale production. This review discusses the global importance of parasitic copepods as disease-causing agents in marine aquaculture. We also provide a brief review of the environmental and husbandry factors that may affect parasitic copepod abundance and the potential roles that parasitic copepods play as vectors for other disease agents.

Key words: Sea lice, Disease, Caligidae.

*Correspondence: Tel:902-426-2630. Fax: 902-426-9413. E-mail: Stewart.Johnson@nrc.ca