On the strength of cooperating salinity levels driving “astounding, historic, phenomenal and miraculous” sets of oyster spat across wide swaths of Maryland’s Chesapeake Bay waters, the state’s recovering oyster industry continues in a positive trend.
Watermen harvested a 36-year record 722,850 bushels of oysters in the 2022-2023 wild harvest season with a dockside value of more than $25 million. That season ended last March 31.
Those 722,850 bushels were up 24 percent from the previous year’s 548,558 bushels. There were 1,354 oyster license holders in Maryland during the 2022-2023 season with an estimated 85 percent of them actually harvesting. That was the highest number of license holders in 29 years.
Due to harsher weather and other market conditions hampering demand, the 2023-2024 harvest at this midpoint in the season may fall slightly short of last season.
“The decline we expect in harvest this year is market driven – not because watermen are pummeling the oysters,” said Maryland Shellfish Director Christopher Judy this week. “The good news is that the oysters being left behind will be there for next season. We have an active fishery, a robust fishery with our oysters. And in the presence of all of this activity, we’re still not seeing a decline in the population, we’re seeing a major increase.”
He said the strong sets of oyster spat – baby oysters that attach themselves to oyster shells and other hard bottom structure to grow – bode well for the overall future population of oysters in the Bay.
Judy spoke at the Jan. 9 meeting of the Maryland Oyster Advisory Commission where he presented findings from the fall 2023 survey. Conducted between Oct. 3 and Nov. 15, surveyors dredged 354 samples from 281 bars throughout Maryland’s portion of the Chesapeake and its tributaries. The higher levels of salinity in the system in the summer of 2023, helped produce the fifth highest volume of spat on shells recorded in the 39 years of annual testing.
“Salinity is the main driver for oyster production in the Chesapeake,” said Judy. “It factors into feeding, reproduction, growth, disease and mortality. 2023 was a dry year, with high salinity and low freshwater flow. That led to greater instances of MSX and Dermo disease than we’ve seen in several years. That in turn led to higher than usual mortality. Not disastrous levels at all like the four dry years between 1999 and 2002, but still trending upward. The wet and cold weather we’re having this winter is encouraging. It’s lowering salinity and helping tamp down diseases for next spring and summer. That should help survival of these great spat sets.”
Judy explained further: “The spat set was enhanced by the high salinity through the summer. The recent salinity decline had no effect on the spat set event since it occurred after the set. The ‘perfect’ scenario for oysters is a dry summer to generate a spat set, then rain to enhance survival due to the lower salinity (which deters disease).”
Most notable, however, said Judy, is the wide-spread distribution of strong oyster spat sets found in the fall. “Dramatic improvement,” he said. “We found strong sets on the Eastern Shore – Choptank River, Broad Creek and a once-in-a-generation set in the Tred Avon River – and even stronger sets in the lower Eastern Shore areas like Tangier Sound. Those are areas where we wouldn’t be surprised by strong spat sets. But all across Maryland’s lower Bay waters – both sides – and up the Potomac and Patuxent rivers, our crews found oysters in areas that were actually phenomenal. Decades and decades have gone by and we haven’t seen anything like this.”
Judy said the fall survey found the Bay’s overall biomass of oysters – which considers size and numbers of oysters – increasing steadily since 2017. The 2023 numbers were the third highest in 19 years for smalls and the second highest for market size in that same time period. Smalls are oysters under the three-inch legal size for market oysters.
“The market oysters being taken this year will be back-filled next year with this year’s smalls, and the great spat sets of the last several years will begin growing into the smalls.”
Shellfish managers kept harvest limits for this season in place from last year while letting the industry know they would re-evaluate those limits after seeing results from the fall survey. Judy said with positive trends in spat sets and biomass, it was decided to keep current limits in place for the rest of the season which ends March 31.
Even with the law allowing harvesting from Oct. 1 through March – Mondays through Fridays – tongers and dredgers have nonetheless found harvesting limited by foul weather, and low demand evidenced by No Market signs posted on certain days of the week.
Responding to questions about where spat originate, Judy said when oysters spawn, larvae disperse and mix with the currents.
“The Bay becomes a large bowl of larvae soup. It is unknown and unknowable where the larvae came from (a sanctuary or a harvest area….or a lease that has brood oysters on it) or where they ended up as spat. The most one can say is that all the broodstock have value – given that the salinity is right – and it happens that the majority of the brood oysters occur in both sanctuary areas and harvest areas. In other words, where the prevailing thought might be that certain sanctuaries are the only place where broodstock exist, in fact the major harvest areas also have an abundance of broodstock. It’s not a competition – it’s nature providing a massive boon to the oyster population.
“Bottom line,” said Judy, “is that a recovering Bay with healthy salinities, strong brood stocks – biomass – and good spat sets is all leading to lots of oysters. The spat counted on the annual survey aren’t hatchery spat that have been planted in numerous large scale projects but are all natural spat; the result of oysters reproducing in the summer of 2023. These are not from hatcheries – this is a natural event.”
In a follow-up email for this article, Judy wrote:
“What occurred is accurately characterized as astounding, amazing and historic. The 2023 spat set positions the oyster population for a very strong near term future. I say near term because further down the line things could change if there is a hurricane or a tropical rain deluge, or a multiyear drought and serious disease outbreak. ….That’s been seen before….”
Chesapeake Bay Foundation’s Maryland Executive Director Allison Colden issued the following statement in response to the stock assessment update from mid-year 2023:
“The dramatic increase in oyster harvests during the past two years comes as no surprise after several record years of oyster reproduction. We’ve seen this pattern before – without adequate controls on fishing effort, increases in the oyster population are quickly followed by increases in harvest and then declines in years where environmental conditions are less conducive for oyster productivity. Unfortunately, these boom-and-bust cycles undermine the long-term recovery of the species, by wiping out years of good productivity with increased harvest.
“However, fishing effort has not increased uniformly across the Bay. Of concern is a significant increase in fishing effort on Maryland’s most productive public oyster grounds, including Tangier Sound. In this region, the assessment indicated overfishing occurring for more than three years.
“Our best available science indicates that fishing rates like those seen in Tangier Sound, St. Mary’s, and the lower Patuxent River, are not sustainable. We are encouraged that DNR has proposed a more responsive approach to oyster management, based on the fall dredge survey, and urge them to consider further regulations that aim to end overfishing in the regions where it is occurring.
“It is critical,” said Colden, “to protect the oyster population gains made from strong spat sets during the past three years if we are to reverse the long-term trajectory of oyster decline. Oysters are a vital component of the Bay ecosystem that filter water and provide habitat and nursery grounds for fish and crabs. Despite the recent increases in oyster abundance, the current population remains far below levels needed to deliver these critical ecosystem functions.
Dennis Forney has been a publisher, journalist and columnist on the Delmarva Peninsula since 1972. He writes from his home on Grace Creek in Bozman.