C.3.6 Georges Bank. From 1988-90, high levels of PSP toxins were detected in shellfish on Georges Bank, an important offshore fishing ground (Fig. 1), culminating in harvesting quarantines for surfclams, ocean quahogs, mussels, and scallops (White et al. 1993). Toxin levels remained high thereafter especially in surf clams which were dangerously toxic three years later. Toxicity patterns in those shellfish through time (Shumway et al. 1994) suggest that there were probably one or two high-toxicity events in the 1988-90 interval, but the source of the toxin remains unknown to this day. Three hypotheses were proposed by Anderson and Keafer (1992): 1) in situ Alexandrium growth in the waters on or near Georges Bank, possibly at fronts; 2) dormant cysts produced by blooms at distant locations are advected onto the bank and are consumed by shellfish; and 3) large, nearshore blooms of Alexandrium are advected onto Georges Bank. Given drifter tracks showing direct transit from the EMCC to Georges Bank (Pettigrew, unpub. data), or the established Lagrangian connection between the WMCC and Georges Bank (Chen et al. 1992), both the WMCC and the EMCC could be sources of toxic cells for this offshore site. This is an extension of the plume advection hypothesis proposed for the WMCC habitat (Franks and Anderson 1992a). In ECOHAB-GOM, a modest effort will be devoted to measuring toxicity in Georges Bank shellfish and determining whether cells responsible for that toxicity can be linked to populations originating in the EMCC or the WMCC.