Seabird Die-off Near Kodiak Island, 2015

Ten years ago this month, my wife and I took a fishing charter off the south coast of Kodiak Island.  We launched into the ocean from a gravel beach near our lodge.  As soon as we were in open water, we noticed a dead sea-bird floating on the water.  Then another.  Then another.  There were dead birds on the water, spaced about every 50 to 100 yards (meters).  As we sailed, we saw more dead birds.  We traveled about 20 or 30 miles from shore that day, going into deeper waters to fish for halibut.  We saw dead birds the whole day – dead birds all the way to the horizon.

The birds were murres and kittiwakes.  Murres look a bit like penguins, and kittiwakes look like seagulls.  The die-off near Kodiak was part of a much bigger die-off of seabirds along the entire south Alaska coast.  Biologists’ autopsies showed that the birds starved to death.  Reports say that 4 million murres died, about half of the total population.  It was one of the largest single-species die-offs on record.  The biologists’ maps that I saw didn’t even include the birds that died near Kodiak. 

The waters near Alaska are normally some of the most productive in the world.  Deep waters normally rise to the surface in a process called “upwelling”, carrying nutrients from the ocean floor.  Those nutrients sustain a robustly abundant marine food chain from plankton to humpback whales.  Arctic waters are prolific because the water is the same temperature, and therefore density, from the sea floor to the surface.  Nutrient-rich deep waters easily rise to the surface because temperatures are constant from the surface to the sea floor.

In 2015, the northern Pacific experienced an abnormal, persistent area of warm water, termed a marine heat wave, or less technically, “The Blob”.  The warm water stratified the water column, with warm water floating on top of the denser cold water below and blocking the upwelling currents.  Deep waters no longer flowed to the surface.  Nutrients didn’t reach shallow water, and millions of birds starved to death.  Other species were noticeably impacted.  Chinook salmon abundance declined.  The following winter, the number of humpback whales migrating to Hawaii fell by 50%.  After ten years the population of murres has still not recovered.  

This morning, I saw a report that “The Blob” had returned to the North Pacific, which prompted me to write this post.

Oceans are warming world-wide, from the surface downwards.  Warmer surface waters increase the chances of a marine heatwave. 

We understand what is happening, why it is happening, and we can expect more damage to the North Pacific birds, fisheries and whales as warming continues.

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Common Murre image credit: Dick Daniels (http://carolinabirds.org/), Wikimedia Commons
Kittiwake image credit:  Yathin S Krishnappa – Wikimedia Commons.  (https://commons.wikimedia.org/w/index.php?curid=24551364)