Fungal Diseases of Abalone

Category

Category 3 (Host Not in Canada)

Common, generally accepted names of the organism or disease agent

Various fungal diseases of abalone including foot tubercles and shell mycosis.

Scientific name or taxonomic affiliation

a) Haliphthorous milfordensis.
b) A fungus provisionally identified as a member of the Class Deuteromycotina.

Geographic distribution

a) Abalone held in a live-storage facility in Japan.
b) Jacks Bay on the South Island of New Zealand. A mild infection was also noted in an underweight H. iris (about 47 mm shell length) from an abalone culture facility in New Zealand.

Host species

a) Haliotis sieboldii.
b) Haliotis iris, Haliotis australis and Haliotis virginea virginea.

Impact on the host

a) Infection caused tubercle-like swellings (up to 5 mm in length) on the mantle and foot of H. sieboldii held in captivity (Hatai 1982).

b) Blisters of conchiolin and occasionally nacreous material on the inner shell surface near the shell apex. Lesions in some severely affected abalone extending into the foot-muscle attachment site. In some cases, the external surface of the shell apex was crumbling and caving-in. Although fungal hyphae were consistently found within the conchiolin and shell matrix, none were observed in the adjacent soft tissue of the abalone and abalone condition was apparently not affected (Friedman et al 1997, Grindley et al. 1998). The presence of infection in cultured abalone is of concern because the chronic progressive nature of the mycosis may become problematic if the abalone are reared to a large size (Diggles and Oliver 2005).

Diagnostic techniques

Histology and Culture: Fungal hyphae (mycelium) can be observed histologically and/or isolated from the lesions via various culture techniques.

Endoscopy: Nollens et al. (2002) reported that endoscopy applied to anaesthetised H. iris was more accurate than radiography and ultrasonography for the detection of the shell lesions caused by the invasion of a fungus. Although endoscopy was invasive, apparently no discernible effects on survival of the abalone, attributable to the procedure, were observed eight months after screening (Nollens et al. 2002).

Methods of control

No known methods of prevention or control. To avoid the risk of introducing these pathogen, or other fungi capable of invading abalone tissues, to other culture facilities or natural stocks, only animals certified to be free of infection should be considered for transplantation from areas where the diseases occur. In addition, imported animals must be held in quarantine and assayed for cryptic or subclinical infections prior to release into the new environment.

References

Bower, S.M. 2000. Infectious diseases of abalone (Haliotis spp.) and risks associated with transplantation. In: Campbell, A. (Editor), Workshop on Rebuilding Abalone Stocks in British Columbia, Vol. 130. Canadian Special Publication of Fisheries and Aquatic Sciences, NRC, Ottawa. pp. 111-122.

Bower, S.M. 2003. Update on emerging abalone diseases and techniques for health assessment. Journal of Shellfish Research 22: 805-810.

Diggles, B.K. and M. Oliver. 2005. Diseases of cultured paua (Haliotis iris) in New Zealand. In: Walker, P.J., R.G. Lester, M.G. Bondad-Reantaso (eds.) Diseases in Asian Aquaculture V. Proceedings of the 5th Symposium on Diseases in Asian Aquaculture. Fish Health Section, Asian Fisheries Society, Manila. pp. 275-287.

Friedman, C.S., R. Grindley and J.A. Keogh. 1997. Isolation of a fungus from shell lesions of New Zealand abalone, Haliotis iris Martyn and H. australis Gmelin. Molluscan Research 18: 313-324.

Grindley, R.M., J.A. Keogh and C.S. Friedman. 1998. Shell lesions in New Zealand Haliotis spp. (Mollusca, Gastropoda). Journal of Shellfish Research 17: 805-811.

Hatai, K. 1982. On the fungus Haliphthorous milfordensis isolated from temporarily held abalone (Haliotis sieboldii). Fish Pathology (Tokyo) 17: 199-204.

Nollens, H.H., J.C. Schofield, J.A. Keogh and P.K. Probert. 2002. Evaluation of radiography, ultrasonography and endoscopy for detection of shell lesions in live abalone Haliotis iris (Mollusca: Gastropoda). Diseases of Aquatic Organisms 50: 145-152.

Citation Information

Bower, S.M. (2006): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Fungal Diseases of Abalone.

Date last revised: December 2006
Comments to Susan Bower

Date modified: