Oh, I’ve got the blues so bad, it hurts down to my bones!” In fact, it’s the height of summer, the blackflies have taken a short sabbatical, and I’ve eaten my fill of strawberries so, other than the disgraceful antics going on in Washington, D.C., there’s little to be blue about. In keeping with the theme of the weekend’s North Atlantic Blues Festival, however, I devote this week’s column to one marine creature that connects ever so slightly to “the blues.”

We are progressing into the season of bluefish. The sturdy pelagic fish is slate-blue in color, fading on its underside to a white belly. Bluefish move in large schools from southern waters eastward along the coast during the summer months. They prefer ocean water temperatures around 68°F; thus fishermen in Maine don’t see them until late July and August.

A bluefish is not the sort of creature to keep as a pet. Bluefish are aggressive predators. They move fast, chasing and attacking schools of prey, typically menhaden and herring. Once in the school they chomp on anything that moves. Often they will chase the menhaden into shallow bays along the coast, where the fish become trapped. The menhaden will exhaust all the dissolved oxygen in the bay and then die, resulting in a mass of dead fish decomposing along the shore. In August last year, bluefish and striped bass corralled menhaden in areas around Peaks, Cushing and Long islands in Casco Bay. The menhaden expired and did what dead fish do — stink.

Anglers call bluefish the piranhas of the sea because they have extremely powerful jaws outfitted with rows of sharp teeth that fit together like a zipper. After they bite down, it takes a lot of pressure to open those jaws. A landed bluefish will snap at the line and leader, the fisherman’s hand, his boots, and just about anything within range of its teeth. Sport fishermen favor bluefish because the fish puts up such a fight when hooked. In Maine, recreational fishermen may take up to three fish per day with no restriction on minimum size.

Because the fish are migratory and powerful swimmers, their flesh is dark-colored, like tuna or swordfish. Some consider it less palatable because it is more oily than white-fleshed cod or haddock. Bluefish are best eaten extremely fresh, within a day of their catch. An old bluefish smells bad, looks grey, and has a powerfully unpleasant taste. This is because the fish contains two chemicals that change once the animal is dead.

Trimethylamine oxide, or TMAO, is a type of fish antifreeze which bluefish have in abundance. When the fish dies, TMAO converts into another chemical, trimethylamine (TMA). TMA is what makes any fish smell rank and fishy. People have the ability to detect the presence of TMA at levels as low as 10 parts per billion. That is extraordinarily sensitive. By comparison, one part per billion is equivalent to adding a pinch of salt to a ten-ton bag of potato chips, according to the National Environmental Services Center. So when a bluefish goes into its TMA phase, you notice. 

The other chemical in bluefish is called myoglobin. Myoglobin is a protein that acts as an oxygen-storage unit for the body’s muscles, allowing migratory fish to move great distances through the water. In bluefish it is found within the animal’s fat. When myoglobin is exposed to the air, it begins to degrade. A neglected bluefish — one that was not filleted and put on ice immediately — begins to go rancid fast. 

Despite or perhaps because of their ferocious behavior, bluefish are popular with fishermen. In 1987 and 1991, nearly half a million bluefish were caught by anglers in Maine, according to Department of Marine Resources data. Since that time the number has hovered around 100,000 fish each year, slumping to nearly zero during the past three summers. On the other hand, landings of striped bass, another fish noted for its blue color (shimmering blue stripes along its sides), have ticked upward. Earlier this summer recreational fishermen throughout the mid- and south coasts of Maine flocked to the shore to catch incoming striped bass, which appeared in record numbers. 

I have always like bluefish, perhaps because they were so common at summer suppers when I was a child in Rhode Island. A simple way to prepare freshly caught bluefish is to mix mustard and mayonnaise together, plaster it over the fillets, broil under the broiler until the covering blisters and browns, remove from the oven and serve sprinkled with chopped chives. It’s a recipe that belies the old joke about the best way to eat a bluefish: cook it on a wooden shingle until charred, then eat the shingle!