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MERHAB2021 Project Summaries

MERHAB21: Shellfish killers – an optimized early warning program for the mitigation of HAB impacts on shellfish in the Pacific Northwest.

Investigators: Teri King, Misty Peacock, and Zachary Forster

Institutions: Washington Sea Grant, Salish Sea Research Center- Northwest Indian College, Washington Department of Fish and Wildlife

Abstract/Project description:

Introduction to the problem: Washington is the largest producer of farmed shellfish in the United States (USDA 2014), supporting more than 3,200 jobs and an estimated annual economic contribution of $270 million (Washington Shellfish 2011). A broad-based network of state and federal agencies, tribes, growers, scientists and volunteers successfully monitors for public health threats from harmful algal blooms (HABs). However, in recent years unattributed cases of juvenile and adult shellfish mortalities in Puget Sound and the Washington Coast appear to be increasing; both shellfish farms and natural populations are suffering losses due to HABs that are not traditionally monitored and have toxic effects that are poorly understood. Addressing a top aquaculture industry concern, this project will identify and characterize shellfish-killing HABs, focusing on key aquaculture sites where historical shellfish illness and mortality have been observed.

Rationale: The overall goal of this management driven project is to develop and optimize a monitoring program for shellfish-killing harmful algae and their toxins in Washington State that will transition to State funding at the end of 3 years. It fills an important need for shellfish growers who have experienced unexpected losses and who also have begun selling their product to the European Union (EU) where shellfish killing toxins like yessotoxins (YTX) are regulated. The project will help ensure that shellfish meet export rules and are safe for human consumption and that harvest potential is maximized. Specific scientific objectives of the proposed study are to: 1) identify and spatio-temporally characterize the distribution of phytoplankton species that produce YTX and other shellfish-killing toxins; 2) establish and validate a tiered early warning system, including a web-based mapping system for toxic events, together with routine microscopy by SoundToxins and Olympic Region Harmful Algal Bloom Monitoring (ORHAB) partners and rapid toxin screening protocols in seawater; 3) determine threshold levels of shellfish-killing HABs that cause deleterious physiological changes or death in bivalve shellfish; 4) inform and educate stakeholders about shellfish-killing HAB risks and management; and 5) transition the project to State funding at the end of 3 years.

Work to be completed: The project will comprehensively sample phytoplankton and shellfish at eight key sites where HAB-related shellfish mortalities commonly occur: six SoundToxins sites in Puget Sound and 2 ORHAB outer coast sites. Working closely with local communities and State agencies and integrating activities with other programs that routinely collect plankton, shellfish, and water chemistry samples, the project will develop cost-effective monitoring to provide early warning of shellfish-damaging HAB events. Real-time data sharing and “traffic light” maps showing critical threshold levels of shellfish-killing HABs will provide an early warning to shellfish growers and managers, allowing them to act quickly, thereby minimizing economic losses. Possible actions to reduce the impacts of HABs on the shellfish operations could include: early harvest, slowing or stopping intake of seawater, and filtration.

This cost-effective, peer-based enhanced HAB monitoring program will rely heavily on collaboration from beginning-to-end with end users of the optimized early warning system – the monitoring partnerships ORHAB and SoundToxins, State shellfish managers, and shellfish growers – helping them keep pace with expanding HAB impacts in Washington State.