Petroleum Smell in Chum Salmon (Oncorhynchus keta)

Observation: We have unconfirmed reports from three communities in the Yukon Kuskokwim Delta about salmon that has a petroleum-like smell and taste and may be making people sick. We have heard that people in Chevak, Scammon Bay, and Hooper Bay have reported Chum salmon that tastes like gasoline. The people report feeling ill after consumption and that there is a hydrocarbon aftertaste. There have been no reports of sheen on the water or oil on wildlife or beaches. If you have a local observation that you can provide on this issue, please post it here. Thank you for your help. Mike Brubaker

LEO Consult: Don Wedll in Bethel writes, "An individual at Quinhagak told a friend of mine that there was an oily sheen coming in off the ocean when he was out netting. I will see if he took any pictures and get back with you." On July 6, Don wrote, "the Assistant Manager at Y-K Delta U.S. Fish and Wildlife Refuge said the oil issue with the fish is that there was an algae bloom out in the Bering Sea last winter. The salmon getting this algae ended up smelling and tasting like oil. He said that this happen in the 1960's with the Japanese salmon fisheries. The Japanese were taking salmon out of the Bering Sea and canning them. Once they got back the salmon smell and tasted like oil. They did a pretty significant study of it."

Division of Environmental Health Consult: State Veterinarian, Bob Gerlach provided the study reference, Studies on the Petroleum Odour in Canned Chum Salmon by Terushige Motohiro

A review of the provided literature indicates that the dimethyl sulfide or DMS can cause an oily flavor in fish. It is produced as the byproduct of consuming a sea snail call Lumacina helicina that lives in marine algae; fermentation snail occurs in the gut and then concentrates in the muscle of some herbiverous fish including chum salmon (but not red salmon). In regard to the health effects of consuming fish with DMS, Dr. Bob Gerlach writes: "As with most chemicals the toxic effects are related to the dose, I have not found any reports of illness from ingesting amounts normally found in foods malt preparation, asparagus, cabbage, corn as well as seafoods produce dimethyl sulfide when cooked." Source: State of Alaska, State Veterianarian