If it is determined that fishing or shellfish harvesting takes place in the vicinity of a spill, OEHHA scientists use knowledge gained from chemical testing in seafood after previous oil spills to help determine whether harmful levels of chemicals are likely to build up in seafood after a spill. Factors that are taken into account include the:
In some cases, the oil will break down quickly and the area does not need to be closed to fishing and shellfish harvesting, or only needs to be closed for a short time (less than 48 hours).
The likelihood that seafood will retain PAHs in their edible tissues varies greatly depending on the seafood species.
When testing is necessary, OEHHA and OSPR will cooperatively develop a “sampling and analysis plan” based on the type of oil that spilled, how much was spilled, where it spilled, and what fishing activity takes place in the area. A sampling plan will identify sampling goals, including:
After the sampling and analysis plan has been prepared, scientists from multiple state agencies participate in the collection of the seafood samples. Seafood from nearby, but unaffected, areas are also collected for comparison. Samples are then sent to a qualified laboratory for analysis of PAH levels in edible tissues of the seafood. If commercial fisheries have been affected, testing for taint may also be conducted at a separate federal laboratory.
When all factors are combined, the risk assessment process is designed to be conservative so that risk is not underestimated.
Results of the laboratory analysis are sent to OEHHA, where scientists will determine whether any samples have reached or exceeded the “level of concern.” Because PAHs levels in mollusks may not reach their highest level for some weeks after a spill, testing is usually repeated until it is clear that PAH levels are stable or declining. When PAH levels are below the “level of concern” and no longer increasing, then
OEHHA will recommend that a fishery be re-opened.
Even if an area is open to fishing and shellfish harvesting, OEHHA always advises people to avoid fishing in areas where there is a visible sheen on the water and not to eat seafood that smells like oil.
View maps of current statewide and site-specific advisories
1001 I Street
Sacramento, CA 95814
Phone: (916) email@example.com
Sign up for our email updates