Gretel the glider searches for salmon

Gretel the glider.
Photo by Hank Statscewich
UAF’s glider named Gretel is poised on the deck of the research vessel Nanuq for deployment into the Gulf of Alaska in February 2022.

An underwater instrument named Gretel is looking for salmon in the Gulf of Alaska.

The instrument, called a glider because of how it flies through the water, is operated by UAF’s College of Fisheries and Ocean Sciences.  

For this mission, Gretel was launched on Feb. 12 from CFOS’ coastal research vessel Nanuq in Resurrection Bay to help map the distribution of Pacific salmon and their prey during the winter. Its journey can be tracked in near real time on the 2022 Pan-Pacific Winter High Seas Expedition website, along with vessel-based surveys that are part of the project. 

The instrument is diving to depths of 1,600 feet to collect acoustic and environmental data between Resurrection Bay and 150 miles offshore in the deep Gulf of Alaska. This information is transmitted via satellite each time Gretel surfaces and is available to view at a portal managed by the Alaska Ocean Observing System. 

The glider’s battery lasts six to 12 weeks, depending on how many sensors are powered on. Nanuq or another vessel will recover Gretel once it makes its way back toward Seward. 

The fairy tale “Hansel and Gretel” inspired the glider’s name. Once upon a time, Gretel the glider was trapped under an iceberg in Antarctica. It retraced its swim and returned safely using a technique similar to the breadcrumbs employed by the fairy tale's Gretel. 

Gretel’s current mission is a result of collaborations between UAF, the University of Washington, the National Oceanic and Atmospheric Administration and AOOS.

For more information, please contact Seth Danielson at