Why the Dead Murres?

Common murres.
Photo: NOAA

By Nina Bubert

The distinctive call of a common murre chick for its father is one of the most endearing sounds you’ll hear while out to sea in late summer. However, lately, there have been fewer calls.

During the past month, a high number of dead common murre chicks have washed up on our coastlines.

We normally see post-breeding peaks of dead common murres from August to October, but our most recent data for September 2008 shows nearly twice as many dead birds than any previous year in our dataset. The majority of the fatalities are chicks. 

Biotioxins are one possible cause of death. Diatoms that produce domoic acid, a biotoxin, have been present between the Golden Gate and Bodega Harbor. However, so far, all of the shellfish samples at sampling sites in Marin have been negative for domoic acid.

Common murre chicks have been necropsied by the California Department of Fish and Game (CDFG), and all that have been examined have been emaciated with no evidence of disease or biotoxin ingestion on gross examination. Results from pathology are pending, according to Elizabeth Philips of California Department of Fish and Game.

History

The common murre population on the central coast has been hard hit due to human-related mortality. Tens of thousands of murres perished in gill nets in the late 1970s and mid 1980s.  Then, as if that wasn’t detrimental enough to the population, in 1986 the oil barge Apex Houston accidentally discharged some 26,000 gallons of oil consequently killing about 6,300 common murres. 

Restitution money from a later oil spill incident (1998 Command) started a Common Murre Restoration Project on Devil’s Slide Rock in Half Moon Bay, Point Reyes Headlands, and Castle and Hurricane Point Rocks in the California Coastal National Monument along the Big Sur Coast. Common murres were attracted to these areas using decoys—including eggs, chicks, and adults—and by using mirrors and speakers playing common murre calls.

The Common Murre Restoration Project has seen much success.  In 2006, Devil’s Slide Rock saw 56% and 87% hatching and fledging success rates, respectively.  Point Reyes had 80% and 79% hatching and fledging success rates, and Castle Rocks and Mainland had 85.4% and 88.5% hatching and fledging success rates. 

How unfortunate it would be to bring this population back from such devastation only for them to not have enough to eat. Beachwatch is continuing to work with CDFG, USFWS, and Department of Public Health in the next couple of weeks to collect more information and hopefully provide a hypothesis abouth the deaths. Is this an increase in mortality or just an increase in carcass deposition?  

For more information on Common Murres or the Common Murre Restoration Project click here.