Prevalence of microsporidian infection in commercially caught pink shrimp, Pandalus jordani

Abstract

Pink shrimp ( Pandalus jordani), a commercially harvested species in Oreegon, Washington, and California, hosts four species of microsporidian parasites: Thelohania butleri, Pleistophora crangoni, and two undescribed species placed in the collective group, Microsporidium. All parasitize the skeletal musculature giving shrimp a whitish, opaque appearance. The prevalence of microsporidian infectionin P. jordani was studied over a 6-year period (1975–1980) and was found to be very low. Of the 207, 942 shrimp exmined, 0.19% were infected with one of the four species. No substantial differences in prevalence were observed between different sampling areas in Oregon and Washington or during the years sampled. The four species occurred in each sampling area in about the same portion. T. butleri was predominant and accounted for 78.7% of all infections. Heavy exploitation of host shrimp is suggested as a possible explanation for the low microsporidian infection rates in the P. jordani population.