Salmon mortalities associated with a bloom of Alexandrium fundyense in 2003 in the Bay of Fundy, and subsequent early warning approaches for industry

Abstract

In early September 2003, >3.0 × 10⁵ cells l⁻¹ of Alexandrium fundyense were detected in close proximity to salmon aquaculture sites near Grand Manan Island in the Bay of Fundy, eastern Canada. High concentrations persisted throughout the month, peaking to >8 × 10⁵ cells l⁻¹ on 18 September. Concurrently, some salmon farms in the area experienced elevated mortalities. Although the cause of mortality is not yet fully understood, it appears to be related to the high concentrations of A. fundyense. Paralytic shellfish poisoning toxins were not detected in the edible flesh of salmon (by mouse bioassay and high-performance liquid chromatography), but were detected at low levels in viscera and gills. Blue mussels Mytilus edulis analysed from areas affected by the bloom reached levels of 18 000μg STX equivalents 100g⁻¹ of tissue. As a result of the salmon mortalities, a project was initiated to establish a monitoring approach for harmful algal blooms to provide an early warning of potential events and to act as a tool for mitigation actions.