A Season for Oysters

Environmental Commentary by Kate Livie

For everything in the Chesapeake, there is a season: for geese to descend on the crest of the fall wind from Canada, for crabs and fish to range from the ocean to the Bay’s brackish tributaries as the water warms, and for the oysters, which ripen as winter gnaws the landscape in earnest. The Bay is a vast cornucopia whose seasonality has shaped our culture and our menus for generations. At least it used to.

With recent innovations in seafood cultivation, our Chesapeake seasonal delicacies are becoming increasingly available year-round. But is there a cost to oysters on the half shell in July? Some recent cases of vibrio (a food-borne bacterium) from May-harvested Virginia oysters convey the danger of our tomatoes-in-December food culture. Unlike a Christmas strawberry whose main consequence is its pencil-eraser taste, oysters out of season have the potential to kill. Which begs the question: just because we can consume the Bay’s bounty outside of its natural season, should we?

The concept of a seasonless oyster is a new one. For hundreds of years, the rule of thumb was simple: One only ate oysters in months that had an “r” in them — September to April. These were the coldest months of the year, when Chesapeake oysters were slowly fattening in their mottled, frigid beds. Once caught, the arctic air kept them fresh longer. Spawning summer oysters were thin and milky, and spoiled rapidly in the fug of the Bay’s oppressive climate. In the past, sticking to the seasons was simply common sense — for one’s palate, health and business.

Recent aquaculture advances have encouraged a departure from the “r” month rule for the Chesapeake oyster industry. Particularly in Virginia, where regulations have supported bottom-leasing for more than 100 years, individually cultivated oyster bars represented a small-but-stable portion of Virginia’s overall oyster harvest. But that was before the introduction of the “triploid,” a lab-created sterile Eastern oyster with three chromosomes. Since 2003, triploids and their season-busting growth have created a Virginia aquaculture boom — and caused the old “r” month axiom to go by the wayside.

Triploids never spawn — for them, it is the winter growth-spurt, year-round, and they expand so rapidly their shells are chalky and crumbling. Swelling up to 3 inches in a year, triploids are already market-size while their wild counterparts measure a measly 1.5 inches. But swift growth isn’t their only benefit. Eastern oyster triploids don’t expend energy procreating, so their flesh is always voluptuous and laced with the delicate flavor specific to the Bay region. Fat, native oysters in summer — what’s not to love? A seasonless oyster means consistent income for oyster farmers and briny beauties for consumers to savor at their 4th of July crab feast. Virginia’s oyster grounds are now rich with millions of this triploid white gold.

But there is a steep cost to the windfall of an oyster in summer. A virulent food-borne bacterium, Vibrio vulnificus, grows in water temperatures above 76 degrees, and vibrio-tainted oysters cause symptoms from diarrhea to death. Anxious oyster farmers have creatively attempted to kill the bacteria through freezing, pressurization, high-salinity baths and cooking, which eliminates both vibrio and the oyster’s subtle flavor. But none of these methods are required; in fact, Virginia regulations allow private beds to harvest year-round, as long as the oysters are caught before 11 a.m. and kept cool. These permissive regulations led to a recent rash of vibrio that was traced to Virginia oysters harvested from private beds in May.

It is hot, the water is warm, and vibrio is out there, swarming in the oysters we insist upon eating out of season. It’s roulette on a half shell.

So how do we enjoy our freshly shucked oysters safely in the summertime? It’s easy. We don’t. Oysters are a cold-weather food, meant to come from water so frigid only the salt stops the ice from forming. For taste and for safety, follow the season of our Chesapeake forefathers: Only eat oysters in an “r” month. Technology and its triploids can’t improve upon the wisdom of generations of Bay oystermen. It’s common sense that’s rewarded by a winter serving of oysters, fat as kings, seasoned by a crisp, ice-glazed Chesapeake.

Kate Livie writes from Chestertown, Md. Distributed by Bay Journal News Service.

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