| Parasite | Rocinela maculata |
|---|---|
| Taxonomy | Arthropoda, Crustacea, Malacostraca, Isopoda |
| Hosts | Coho salmon (Oncorhynchus kisutch), cods |
| Infection site | Fin |
| Clinical signs | Rocinela maculata parasitizes the fin of the host. Haemorrhages are observed in the lesions. |
| Parasitology | Rocinela maculate is a dioecious crustacean originally reported from cods. The body is 1.5-4.0 cm in length (Fig. 1). It is distributed in the coastal waters of Greenland, Siberia, Hokkaido, etc. |
| Pathology | Vibriosis could occur in diseased fish because the wound provided a portal of entry for the secondary infection of the bacteria (Awakura, 2006). Infection of Rotinela belliceps was lethal to the fry of pink salmon and coho salmon (Novontny and Mahnken, 1971). |
| Health hazard | Since this parasite is not infectious to human, it is harmless in food hygiene. It was reported that Rocinela signata bit divers (Garzon-Ferreira, 1990). |
| Diagnosis | This parasite can be visually observed on the fin. Notice the characteristic hook-like appendages in the thorax. |
| Other information | Coho salmon cultured in Pacific Ocean in Hokkaido showed serious vibriosis caused by Rocinela maculate (Awakura, 2006). |
| References | Awakura, T. (2006): Rocinelosis.
New atlas of fish diseases (ed. by Hatai K. and K. Ogawa), Midori Shobo, p. 47. (In Japanese) Garzon-Ferreira, J. (1990): An isopod, Rocinela signata (Crustacea: Isopoda: Aegidae), that attacks humans. Bull. Marine Sci., 46, 813-815. Novotny, A. J. and C. V. W. Mahnken (1971): Predation on juvenile Pacific salmon by a marine isopod Rocinela belliceps pugettensis (Crustacea, Isopoda). Fishery Bulletin, 69, 699-701. |
Fig. 1. R. maculata from coho salmon
(Photo by T. Awakura)