Pacific cod may have learned to hunt seabirds, research indicates

Yereth Rosen

Alaska Dispatch News

November 9, 2015

You could call it revenge on the birds.

While many marine birds are well known for their skills at diving into the sea to pluck out fishy meals, there is now solid evidence that some Pacific cod have turned the tables on the avian species.

The practice came to light a few years ago when seafood workers in Dutch Harbor noticed that some of the cod they were processing came with extra features -- partially digested birds in the fish stomachs.

Scientists from the Alaska SeaLife Center and University of Alaska have now examined remains of 74 birds collected from cod stomachs in 2011 and have some findings described in a study published online in the journal Marine Ornithology.

The bird remains come from cod caught in the Aleutian Islands region, off Cape Sarichef in Unimak Pass, using trawl and pot gear. The fish were processed at the UniSea plant in Dutch Harbor; the plant froze the bird remains and sent them to the scientists for analysis.

There have been other known cases of big fish eating small seabirds elsewhere in the world, the new study says, and past surveys by the National Oceanic and Atmospheric Administration have turned up, in very rare instances, bits of birds inside cod. In one case, a NOAA researcher found a murre foot in a cod stomach.

But the evidence from Dutch Harbor appears to be the first documentation of Pacific cod making a practice of eating birds, said study co-author Tuula Hollmen, science director at the SeaLife Center and an associate professor at the University of Alaska Fairbanks' School of Fisheries and Ocean Sciences.

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