Report on analysis of shellfish samples for the presence of Yessotoxins (YTX)

Abstract

In order to determine the cause of the positive mouse bioassay results obtained in mussel samples from several shellfish production areas (including Bantry Bay, Kenmare Bay, Cromane and Lough Foyle), samples were sent in December 2000 and January 2001 for analysis. Positive mouse bioassay results were obtained, using the Yasumoto (1978) assay, in the EU Reference Laboratory and using the Yasumoto (l 984) assay in the Italian Reference Laboratory. ASP toxins, Azaspiracid, Okadaic acid and DTXs were not detected. Yessotoxin, homoYessotoxins and analogues of Yessotoxins were not detected in the samples sent to the EU Reference Laboratory or the Italian Reference Laboratory. Prof. Yasumoto detected the presence of Yessotoxin and 45-hydroxyYessotoxin at the Japan Food Research Laboratory. 45-hydroxyYessotoxin is a shellfish metabolite of Yessotoxin, which occurs with time as the YTX is oxidised by the shellfish. The shellfish samples in which Yessotoxin and 45-hydroxy Yessotoxin were detected were taken from Bantry Bay, Roaring Water Bay (Summer 2000) and Mulroy Bay. If the initial detection of Yessotoxin and 45-hydroxyYessotoxin is confirmed in other samples, the Irish biotoxin management regime and the production cycles for shellfish (in particular mussels) will have to be adapted to encompass YTX.