December 12, 2017
Light from your fillets may be spooky, but not unhealthy.
I'm sometimes a pretty good target for pranksters. So, this summer, when I received Sam Farkas' email, forwarded by Florida Sportsman editor Jeff Weakley, the first thing I did was check the date. It wasn't April 1. But the subject had to do with some fish that Sam found to glow in the dark. Sam said, “My dad was brining some cero mackerel last night and preparing to smoke these fillets and saw this at about 5 this morning—thought I'd share.” Sam, who lives in Jupiter, is a frequent contributor of photography to this magazine.
Convinced I wasn't being “punked,” I decided to call in some expert advice and contacted my go-to fishing expert, Chuck Adams, UF/IFAS Sea Grant Seafood Economist, and asked him about the phenomenon. He contacted George Baker, Florida Sea Grant Seafood Specialist. Chuck's comment to George was simple, and to the point, “What the heck? Do you know what this is? Never heard of it before.”
Even the expert, George got back to us pretty quickly, and attached an interesting document, Glowing Seafood, authored by microbiologist Patricia Sado for the USDA Seafood Products Research Center. The report had five pages, single-spaced!
It seems glowing seafood isn't necessarily rare. But the glow isn't caused by the same phosphorescencing phytoplankton that causes seawater to glow on dark, moonless nights. Nor is it caused by fluorescence, radiation or even micro-critters from outer space. It's simpler than I thought. Bacteria that are capable of emitting light are the culprits—and are not necessarily bad or toxic. In layman's terms, a chemical reaction occurs in some bacteria that create luciferase, a protein similar to that found in fireflies. After that, the detailed report's description of the glow-process gets complicated by scientific terms.
The amount of light emitted by seafood that glows in the dark has much to do with its density, the ambient temperature and salt. All of these factors were no doubt present in Sam's dad's plate of fish. Mackerel have fairly dense flesh and they were brined and refrigerated. Other seafoods that have been reported to glow include shrimp and snapper and not surprisingly, imitation crabmeat (surimi), which is made of the compressed flesh of miscellaneous fish.
Luminescent bacteria occur naturally in seawater, fish, shellfish and marine animals, and may be present in seafood sold at markets or specialty shops. Cooking will destroy the bacteria, so it's a good idea to cook any “glowing” seafood thoroughly.