In Unalaska, the increase in algal blooms due to climate change has been causing blue mussel habitat to decline in quality and increases the instance of Paralytic Shellfish Toxins (PST) in mussels. As blue mussels are an important subsistence food for Unalaskan residents, increasing PST occurrences elevates the risk of Paralytic Shellfish Poisoning (PSP) in community members. The Qawalangin Tribe of Unalaska received funding to develop a Natural Resource Conservation Plan (NRCP) to restore blue mussel habitat in the area and minimize the risk of PSP to community members.

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Accompanying the NRCP, TBEC also conducted a Mussel Propagation Pilot Study to assess the condition of blue mussels on Unalaska Island, and to investigate the feasibility of propagating mussels there in the future to reduce PSP risk and increase food security. Along with the pilot study, a habitat suitability assessment was conducted to locate the best habitat for blue mussels around Unalaska.

 

Natural Resource Conservation Plan:

TBEC was asked to help the Qawalangin Tribe of Unalaska develop this Natural Resource Conservation Plan to help restore mussel habitat on the island and increase mussel populations. TBEC worked to develop this plan with the goal of increasing food security, reducing instances of PSP, and improving habitat quality around the island. TBEC used maps, data, and research to identify priorities for conservation and establish goals and targets to track future progress. The NRCP outlined action tasks to meet the set goals, objectives, and priorities. The plan also identified critical habitat areas and discussed ways to protect, improve, and expand existing habitat.

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A Habitat Suitability Assessment for blue mussels was conducted and included in the plan. This evaluated locations around Unalaska Island that were most suitable for mussel survival. Research was conducted to determine optimal water conditions for blue mussels, and water data was gathered to find locations that best meet the needs of blue mussels. The water data, which included information about temperature, salinity, and nutrient concentrations, was analyzed in ArcGIS Pro and produced maps that showcased highly suitable mussel habitat and unsuitable habitat in the area.

 

Mussel Propagation Pilot Study:

Also included in the NRCP were the results of a Mussel Propagation Pilot Study conducted by TBEC and the Qawalangin Tribe of Unalaska. The goal of the study was to test conservation and rehabilitation measures and successes, and to determine the feasibility of using mussel aquaculture in Unalaska Bay to address PSP risk and declining wild populations. Mussels were collected from an existing harvest site and then deployed at three potential future propagation sites that had varying environmental conditions and human activity levels. A subset of those collected were sent for PSP testing instead.

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Along with the mussels’, monitoring equipment was also deployed to log environmental conditions such as temperature and pH throughout the study. After three months, the mussels were brought back up to check survivability at each site. Live mussels were measured to compare starting and ending sizes. Another subset of mussels was sent out for PSP testing to compare PSP levels between the beginning and end of the study. The pilot study ultimately provided the QTU with important insight on the viability of mussel propagation on Unalaska Island, and areas where future research and attention needs to be directed for mussel aquaculture to be successful in Unalaska

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Project Deliverables:

• Blue Mussel Natural Resource Conservation Plan

• Mussel Propagation Pilot Study data, analysis, and results

• GIS habitat suitability maps

• Permit-required reports

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External Links:​

Qawalangin Tribe of Unalaska Website