C.2 Introduction

Harmful algal blooms (HABs), are a serious economic and public health problem throughout the world. In the U.S., the most serious manifestation is paralytic shellfish poisoning (PSP), a syndrome caused by human ingestion of shellfish that accumulate toxins from dinoflagellates of the genus Alexandrium. These toxins cause human illnesses and death, shellfish quarantines, the mortality of birds, larval and adult fish, and even marine mammals (White et al. 1989; Geraci et al. 1989). Thousands of miles of U.S. coastline are affected. This reflects the persistence of the problem in some areas and its emergence in other areas historically free from outbreaks.

The economic impacts from PSP are significant. Shellfish quarantines, adverse health effects, and frightened consumers are direct impacts, but constrained development or investment decisions in aquaculture are examples of indirect, hidden costs. No national total is available, but estimates from individual events indicate the scale of the problem. For example, a single PSP outbreak cost Maine an estimated $6 million in 1980 (Shumway et al., 1988); such outbreaks occur annually in many states, and several have been more severe than the 1980 event. PSP on Georges Bank in 1988 closed the surf clam fishery which remains closed to this day - an estimated annual loss of $3 million (ECOHAB 1995). The expense of state-run PSP monitoring programs (typically $100-200,000 per year) should also be considered in an assessment of the total economic impact from PSP.