Monday, November 26, 2018

More Bad News on Bay Oysters

Maryland oyster population down by half since 1999, study finds
Watermen overharvested oysters last winter in a little more than half of Maryland’s portion of the Chesapeake Bay watershed, according to the state’s first-ever stock assessment of the commercially and ecologically valuable shellfish. If those harvest rates continue, the assessment warned, the bivalve population in those areas could eventually be wiped out.

The 359-page assessment report, released Tuesday, estimated that Maryland’s overall population of adult oysters this year is half what it was 18 years ago.

The assessment, prepared by the Department of Natural Resources in consultation with the University of Maryland Center for Environmental Science, sets the stage for a potentially fractious debate in coming months over the state’s management of the keystone Bay species, which is also a pillar of Maryland’s seafood industry.

Watermen who were briefed on the assessment Monday night at the DNR’s Oyster Advisory Commission reacted skeptically to its findings. But Alison Prost, Maryland executive director of the Chesapeake Bay Foundation, issued a statement afterward saying it “confirmed some of our greatest fears about the Bay’s oyster population. The state needs to develop a fishery management plan that protects existing and restored oyster reefs to significantly increase the overall oyster population.”

Mandated in 2017 by the General Assembly, the stock assessment drew on DNR surveys and catch data from 1999 through the wild oyster harvest season that ended last spring. DNR and UMCES scientists used mathematical models to estimate oyster abundance, habitat availability, harvest rates and natural mortality from environmental conditions such as harsh weather and disease.

The study estimated that Maryland’s oyster population plummeted from about 600 million in 1999 to around 200 million by 2002, a period that saw the Bay’s bivalves ravaged by an outbreak of the oyster diseases MSX and Dermo. The harvest hit an all-time low of 19,000 bushels in 2004.

The diseases abated after that, and the study estimates that the state’s oyster stock rebounded to more than 450 million by 2014, with harvests also rising that year to more than 400,000 bushels. Since then, natural reproduction has been lackluster, and the assessment estimated that the population has declined again to an estimated 300 million this year. Last season’s harvest slipped to 180,000 bushels
Some background data, from a paper I published a few years ago:

Note that any landings in the recent past were dwarfed by the tremendous landings of the late 19th century.

Oysters are all but an endangered species in the Bay. Harvest of wild oysters should be halted for 5-10 years (maybe more) to see if oyster populations can survive, and regenerate given freedom from harvesting. If not, it may be time to give up.

The Capital Gazette predicts Oysters will be the big environmental fight when the General Assembly returns to Annapolis
The details of the oyster survey, mandated by the General Assembly, will now be built to management plans being developed by the Department of Natural Resources. By Dec. 1, these plans will be forwarded to the legislature for consideration during the session that begins in January.

Legislators will be asked to decide how Maryland should ensure the future of the oyster as a vital bay species in balance with that of families and businesses that still depend on its harvest.

There have been a handful of environmental fights in the past 30 years that have been turning points in the stewardship of Maryland`s natural resources: the Critical Areas Law, rockfish management and the fracking ban among them.

What to do with the oyster is sure to be the next one.
Never underestimate the ability of a legislature to do nothing when something is needed, and vice versa.

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