The US Food and Drug Administration (FDA) sent several warning letters to seafood firms last month.

The FDA sent a letter to Roy Bolling, owner and president of Minnesota-based seafood company Day Fish Co., Inc. on March 16.

The FDA inspected the facility from January 17 to 23. The facility manufactures lutefisk from imported dried cod and distributes pickled herring cutlets.

"The inspection revealed serious violations of the seafood Hazard Analysis and Critical Control Point (HACCP) regulation" in regards to its "refrigerated, ready-to-eat seafood products, such as your pickled herring products," according to the FDA letter.

The FDA also sent a warning letter on March 20 to Philip Sinz, owner and managing member of Seattle-based fish processor Northwest Frozen, LLC dba Banzai Sushi.

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