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Contaminated Fish
Are Your Fish Safe To Eat?

Contamination of fish is becoming a growing concern for many recreational and commercial fishermen. Recently, results from the first statewide study of contaminants in fish caught off the California coast revealed high levels of methylmercury, a toxin that damages the central nervous system, in more than one-third of the locations sampled. High levels of mercury, greater than 0.44 parts-per-million (ppm), were detected in fish tissue at 25 of the 68 locations sampled (SWAMP 2012). However, location was not the key driver, rather the main factor linked to contamination level was the type of fish. Older, predatory fish such as sharks and some forms of rockfish were found to have the highest levels of mercury. The North Coast (from the Oregon border to Point Reyes) had the highest percentage of locations with at least one species above 0.44 ppm of mercury (11 out of 15, or 73%). The Central Coast (from Point Reyes south to Point Conception) had the second highest percentage (10 of 26, or 38%) while the South Coast (from Point Conception south to the Mexican border) had the lowest percentage of locations above 0.44 ppm of mercury (4 of 27, or 15%) (SWAMP 2012). All of the species with high concentrations of mercury were high-level predators, which can be explained through bioaccumulation of mercury up the food chain.


Mercury is released from ores, minerals and fossil fuels into the atmosphere where it can circulate through out the world and accumulate in living organisms in the water and on land. These releases are through natural events or during human activities. Among the largest sources of mercury emissions in the U.S. are coal power plants and mining operations (especially gold mining). A potentially growing source of mercury is disposable products such as compact fluorescent light bulbs and electronic devices, which both contain mercury. The mercury eventually leaks into the atmosphere when the products are crushed in a landfill.


Polychlorinated biphenyls (PCBs) were the only other contaminant detected in fish tissues at concentrations that pose potential health concerns to consumers of fish caught in coastal California waters. Far fewer locations fell into the high contamination category for PCBs (5 of 68, or 7%) than for methylmercury. PCBs have been banned in North America since the 1970s when they were widely used as insulation in electrical equipment, but they are still showing up in coastal California waters. PCBs are insoluble in water and not readily excreted by marine organisms; as a result they are often passed up the food chain. The results from the statewide survey will be used to prioritize coastal areas that are in need of cleanup or identify areas that need continued monitoring.


The Southern California coast may have had the lowest percentage of locations with high contamination of mercury, but a new study has recently found elevated levels of radioactivity in blue fin tuna off the coast of San Diego. This radiation is directly linked to the nuclear power plant disaster in Japan following the March 2011 earthquake. Blue fin tuna are a highly migratory fish traveling across the Pacific Ocean from Japan all the way to Southern California, but researchers were shocked to learn the fish were not able to flush out all of the contamination from their system during their journey across the ocean. This summer, researchers plan to repeat the study using a larger sample size to determine just how radioactivity may affect tuna populations. Scientists are also interested in tracking other migratory species for contamination such as sharks, sea turtles and seabirds.


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Cute or ugly?

The staff at FISHBIO have linkstraveled far and wide in their current careers, as well as for their previous research. A few of us have had the opportunity to work on research vessels off the West Coast of the U.S. and we've seen quite a few interesting sea creatures in our time. In the case of the Pacific spiny lumpsucker, Eumicrotremus orbis, most would probably agree that this peculiar looking fish is downright adorable! Typically about the size of a grape (even the largest individuals rarely grow larger than a ping-pong ball), these poorly studied fish occur mainly in shallow waters to a depth of about 500 feet all along the Pacific Rim, ranging from the Washington Coast to the northern islands of Japan... Read more >

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IN THE NEWS: Recent stories you might have missed...
WCB Funds Environmental Improvement and Acquisition Projects

DFG News   

At its May 31 quarterly meeting, the Wildlife Conservation Board (WCB) approved $29.4 million to help restore and protect fish and wildlife habitat throughout California. The 30 funded projects will provide benefits to fish and wildlife species, including some endangered species, and others will provide public access opportunities to important natural resources... Read more > 

Mercury Bigger Worry Than Radiation in Tuna

Huffington Post

Few things get a media frenzy going like the combination of two words: radiation and food. Despite the ubiquitous availability of truly unhealthy foods 24/7, just raise the specter of radioactivity on our plates, and people suddenly get very serious about what they are eating. And the media fans the flames. So when scientists reported traces of radioactive chemicals from the Fukushima nuclear meltdown found in bluefin tuna caught off the California coast,.. Read more > 
B.C. salmon farmers on 'high alert' for lethal virus

CBC News 

B.C. salmon farmers say most of their operations have been untouched by a lethal fish virus, but the industry is "not out of the woods yet."

Infectious hematopoietic necrosis virus, a highly contagious disease, first showed up more than two weeks ago in routine testing at a farm near Tofino, on the west coast of Vancouver Island, owned by Mainstream Canada.

The Dixon Bay site was quarantined and more than 500,000 fish were destroyed... Read more > 

Exploring ecosystems takes plenty of guts

Sydney Morning Herald 

At the headquarters of the Secretariat of the Pacific Community in Noumea, Elodie Vourey pulls the stomach of a bigeye tuna from a large plastic bag and puts it on a white tray. With tweezers in one hand and a scalpel in the other, the laboratory assistant carves a deep incision into the fleshy organ, revealing the fish's last meal. Inside, a few partially digested fish are mixed with squid and other morsels too mangled to identify without a microscope... Read more > 

The Problem of Overfishing

National Center for Policy Analysis   

While environmentalists have clamored to take on a number of issues in recent years, the substantial issues involved in overfishing have remained relatively quiet.  Overfishing is international in scope, has been ongoing since the end of the Second World War, and is generally caused by bad government policy.  And it poses real problems for the world's aquaculture-dependent nations, say Iain Murray and Roger Abbott of the Competitive Enterprise Institute... Read more >