Bight ’18 finds local sportfish within ‘safe to eat’ thresholds

Contamination levels in the tissues of commonly caught Southern California sportfish were found to be within “safe to eat” thresholds for consumption at least once a week during the Southern California Bight Regional Monitoring Program’s second sportfish bioaccumulation survey.

The Bight ’18 study, published in December as a SCCWRP technical report, analyzed sportfish tissues to measure concentrations of five common contaminants that pose risks to human health. The regional study was conducted by Bight ’18 in partnership with the State Water Board’s Surface Water Ambient Monitoring Program (SWAMP).

None of the average contamination levels reported in the sportfish would place them in the most restrictive “Do not consume” consumption advisory threshold, as defined by California’s Office of Environmental Health Hazard Assessment (OEHHA). However, not enough samples were collected to make such a determination for public-health reporting purposes. OEHHA requires more data from more species – and from more composites of each species – to set consumption advisories.

The study was the Bight program’s first follow-up to its original Bight ’08 sportfish bioaccumulation study, which was incorporated into a statewide SWAMP bioaccumulation report.

Compared to a decade ago, average contamination levels fell across the Southern California Bight, suggesting that consuming locally caught sportfish may overall pose less of a health risk to humans than it did during the initial survey. (Even so, seafood contamination hotspots still exist in the Bight; local consumption advisories can be found on OEHHA’s website.)

Mercury and total PCBs (polychlorinated biphenyls) were the only contaminants of the five examined that exceeded thresholds that would trigger advisory limits on the number of weekly servings to consume.

But even for mercury, average concentrations in the two most contaminated species were still below advisory thresholds that would restrict consumption to one serving or less per week, even for children and other vulnerable populations. Mercury was the contaminant that most frequently exceeded health thresholds during the Bight ’18 study.

Both the Bight ’08 and Bight ’18 bioaccumulation studies analyzed sportfish tissue collected from areas along the Southern California coast where sportfishing is common. Concentrations of five common contaminants that can impact human health were measured: mercury, selenium, DDTs (dichlorodiphenyltrichloroethanes), PCBs and arsenic.

Bioaccumulation is the process by which contamination in sediment and the water column passes through marine food webs from prey to predator, eventually reaching humans who consume locally caught seafood.

Although production and use of some bioaccumulating contaminants have ceased, legacy contaminants like DDT and PCBs that were discharged into the coastal ocean for decades have accumulated in seafloor sediment, enabling them to continue to bioaccumulate in marine food webs.

Meanwhile, contaminants like mercury remain a global problem; distant inputs could potentially be responsible for the mercury concentrations observed during the Bight ’18 study.

For more information, contact Dr. Karen McLaughlin.