THE STATUS OF CALIFORNIA HALIBUT Paralichthys californicus AS A TECHNOLOGICALLY FEASIBLE SPECIES FOR MARINE U.S. AQUACULTURE

California halibut (CH; Paralichthys californicus) is a highly valued species that supports an important commercial and recreational fishery along the Pacific coast of the United States.  It is the largest of 18 species recognized in the genus Paralichthys, reaching a maximum size of 33 kg.  This species is considered a promising candidate for marine aquaculture in California, with interest for both food and stock replenishment.  It has been reared on an experimental level since the early 1980's, with limited commercial efforts in Mexico.

Culture of CH in the United States has mostly been done on a small scale and has shown that it is technologically feasible to rear this species.  Broodstock maturation and egg production can be accomplished without hormone therapy and fish will produce eggs for approximately six months of the year when ambient water temperatures are between 15 and 20° C.  Larval culture of the species includes both rotifers and Artemia as live prey, along with the addition of greenwater during the rotifer phase.  Larval survival to settlement (at ~28 dph) is typically very high (70-80% from egg), however losses during settlement in high density conditions can reduced this to 15-20% by the time metamorphosis to a juvenile is complete at ~50 dph.  Juvenile growout to market size has been done on a very limited basis in flow through tanks.  Females grow faster than males but even so, it takes up to three years to reach a market size of 1kg.  A live market for this species exists and is currently being supplemented in California by the importation of Korean flounder, Paralichthys olivaceus. Among the known disease agents affecting P. Californicus are ectoparasites including Trichodina sp., Uronema sp. and Cryptocaryon sp.; endoparasites including Anisakis sp.; and bacterial agents including Pseudomonas sp. and members of the family Vibrionaceae, such as Photobacterium damselae subsp. damselae which has been associated with mass mortality events.

While culture of this species is technologically feasible, research still needs to be done in certain areas in order to realize commercial readiness.  These areas include: improved nutrition across all life stages, selective breeding to improve growth rates, development of all female populations; and improved juvenile pigmentation; developing methods for disease prevention, diagnosis and control.