Published May 8, 2024 by chrisco2

Shellfish are a culturally and economically important resource in Southeast Alaska. Harmful algal blooms that produce paralytic shellfish toxins threaten safe subsistence harvest. They can lead to costly shutdowns for Alaska’s growing mariculture industry. To reduce public health risks and economic impacts, monitoring and predicting paralytic shellfish toxin events is crucial. Across Alaska’s vast and remote coastline, it is also highly challenging.   

Paralytic shellfish toxins are produced by certain types of algae. The primary paralytic shellfish toxin-producing species in Southeast Alaska is Alexandrium catenella. Under certain conditions, algae populations can “bloom” to extremely high numbers. 

A new study sought to determine the best methods to provide timely warnings of these events for harvesters in Southeast Alaska. It assessed three methods to determine the most timely, accurate, and practical techniques to detect and quantify Alexandrium catenella and the toxins it produces. 

The study found that eDNA is the best method for early and accurate detection, and should be incorporated into future monitoring efforts. However, further work is needed to refine eDNA analysis to provide timely and effective bloom warnings.

The study compared the following detection methods:

• Microscopy—identifying and counting Alexandrium catenella cells collected from net tows and seawater samples
• eDNA analysis—detecting DNA shed by A. catenellainto seawater
• Toxin texting—quantifying paralytic shellfish toxins in oyster tissue samples (using one of two methods)

Published May 8, 2024 by Tim Lydon

Fisheries experts are concerned about invasive European green crabs spreading in Alaska, especially during this year’s El Nino climate pattern. Research shows the crabs can expand their range during El Nino years, which often bring warmer Pacific Northwest ocean temperatures.

European green crabs arrived in San Francisco Bay in 1989, likely by container ship, and have since spread. They reached Vancouver Island in 1999 and later spread north along British Columbia. In 2022, they were discovered on Annette Island south of Ketchikan, which remains their only known Alaskan population.

Monitoring for the crab is ramping up along south-coastal Alaska, including at the Kachemak Bay National Estuarine Research Reserve (KBNERR) in Homer. Scientists there have worked with University of Alaska Anchorage journalism students to produce media for state-wide education about invasive marine species.

Some scientists say the crab’s continued spread is likely as oceans keep warming. Trapping is the only known way to limit their expansion. Beach walkers are encouraged to become familiar with green crab carapaces, which are shed throughout the year, and report findings to the Alaska Invasive Species Hotline at 1-877-INVASIV.