Unusual Sighting of an Alaska Pollock (Theragra chalcogramma)

Observation by Jaclyn Christensen:

On Sunday May 26, our family took a drive out to North River to possibly catch some fish in the river (aka Reindeer Creek). Our son, John III, stopped by this unusual fish. He said there was a crow eating from it. You can see the visible chunk of meat taken from the back. People say it can be a pollock or a sturgeon. For a few years now, Port Heiden has been noticing more and more unusual or out of the ordinary fish and sea life behavior in our area.

Tom Okey with Ocean Integrity Research writes:

This is an Alaska pollock (Theragra chalcogramma). The FAO-FIGIS Fact Sheet on Alaska pollock says that Alaska pollock aren't normally found shallower than 50-m depth, but this stranded individual was found within its normal range, and there are various ways that it could have ended up on this beach. The Alaska pollock fisheries, which remove over 3 Million tonnes annually from the region, operate not too far from where this individual was found, and so it could have been killed in the fishery floated there. It is interesting that local observers consider it unusual to see Alaska pollock stranded on the beach. I wonder if there is some low oxygen event in the Bering Sea, which can push fish shallower to find more oxygenated water. This news article on the NOAA Fisheries website describes the Bering Sea as "...one of the fastest warming parts of the world" and discusses the particular vulnerability of fish stocks to low-oxygen waters among other stressful conditions. So such observations could indicate such environmental changes in the Bering Sea, especially if more such observations emerge. But as for this individual observation, it's difficult to know why this one was on the beach there.

Literature cited

FAO-FIGIS, 2001. A world overview of species of interest to fisheries. Chapter: Theragra chalcogramma. Retrieved on 05 May 2005. 3p. FIGIS Species Fact Sheets. Species Identification and Data Programme-SIDP, FAO-FIGIS

Elizabeth Siddon, Research Fisheries Biologist with National Oceanic and Atmospheric Association, writes:

During summer 2018, we tracked observations of adult pollock washing ashore near Pilot Point (Ugashik River), which is very close to Port Heiden. We received information and samples from an observer at Pilot Point. At that time, we heard from locals, subsistence fishers, and salmon set netters around Bristol Bay that adult pollock in the area were 'behaving odd' and observations of adults washing ashore. We included a summary of these observations in our "In Brief" report on page 4 Hot Topic "Pollock in Bristol Bay." We would be very interested in tracking similar observations during summer 2019 and potentially receiving samples to help determine what caused the mortalities.

Comments from LEO Editors:

The 2018 Eastern Bering Sea Ecosystem Status Report Brief is included in the documents section of this post. The section on pollock notes the unusual timing of pollock observations during salmon season, as well as the unusual swimming behavior. Pollock samples revealed low weight, normal stomach contents, and the presence of PSP toxins (below levels safe for human consumption).