Virginia Marine Resources Commission
Water Chemistry Studies for Oyster Hatcheries in Chesapeake Bay
Project Description as Proposed:
Oysters are an essential part of Virginia’s near-shore ecosystems, and a vital part of life in our coastal communities. A healthy oyster industry means a strong economy in Eastern Virginia, jobs for processors and oystermen, and a healthier Chesapeake Bay. This plan will assist the struggling oyster industry by addressing a bottleneck that is occurring at oyster hatcheries, the major source for replenishing private oyster stocks in Virginia waters. The oyster industry and state funds being secured by Virginia’s Secretary of Natural Resources will be making a significant match to assist our efforts.
Currently, Virginia oyster packers are importing 66% of the oysters they use for processing. They depend on other states’ oyster industries (mainly on the Gulf Coast), but when episodes like the recent Norovirus outbreak in Mississippi or last year’s Deepwater Horizon oil spill impact the Gulf industry, it has a devastating effect on processors in Virginia. To regain our independence in oyster production, we need to ensure that we have healthy stock of oysters, that total numbers of Virginia oysters increase significantly, and oyster beds in the Tidewater region begin to expand once again. To meet these goals, oyster hatcheries are critical.
The Virginia oyster industry processes approximately 500,000 bushels of oysters annually, which are valued at $52 million. Approximately 34% (170,000 bushels, $18 million) of these are harvested from Virginia waters; the remainder is imported - primarily from the Gulf of Mexico. Of the oysters harvested from Virginia waters, approximately 74% are from private production grounds; the rest are taken from approved public oyster harvesting areas. Private areas are generally grown using one of two production methods: cage culture, which produces oysters suitable for serving on the half shell, or spat-on-shell, which produces oysters suitable for shucking. For both production methods, the oyster larvae are initially reared in oyster hatcheries. Over the last 7 years, Virginia’s oyster hatchery industry has developed rapidly, with the number of hatcheries increasing from one in 2005 to eight in 2010. Oyster hatcheries have become the backbone of the private oyster industry, representing approximately $14 million in annual revenue for Virginia and providing jobs at the hatcheries, for the oystermen, and for workers in processing operations. Additionally, oysters are important for the health of the Chesapeake Bay; they provide essential habitat for benthic organisms and spawning fish, and clean the water by filtering out pollutants in the water column.
Recently, Virginia oyster hatcheries have experienced difficulties. Over the last two years, between June and August, production of oyster larvae has been significantly lower than previously reported. In fact, there were periods in 2011 with almost zero production from all hatcheries simultaneously. While some improvement was noted during the month of September, hatchery production was still limited, and was not nearly enough for maintaining a healthy industry. This issue is occurring at all eight oyster hatcheries located in Virginia, within the Bay and on seaside. During the unsuccessful periods, young spat are exhibiting an empty gut (between one and six days post-hatch) and/or significant deformities, resulting in extremely high mortality rates. Water quality testing protocols at these hatcheries are often basic (e.g. dissolved oxygen, pH, and temperature). Analysis of trends in these parameters yields no clues as to what could be happening to affect oyster larvae so dramatically. In this project we will have more accurate monitoring devices to measure physical water chemistry parameters such as pH, carbonate, ammonia, nitrites and nitrates, iron, phosphorus, and potassium in the ambient water and at various points in the hatchery production process. These parameters are routinely monitored in closed, pond type aquaculture operations, but have been taken for granted by the shellfish industry that depends on ambient water from the bay. Other physical parameters may be measured if results suggest problems. Ocean acidification from the increased carbon dioxide in the atmosphere has been suggested as a long term potential problem for hatcheries worldwide, and baseline values from this monitoring effort will be established for current conditions.
Without comprehensive water quality monitoring and a strategic plan to explore the problem, it will be very difficult for the industry to discover a solution. Potential solutions could include implementation of a specialized filtration system, balancing water chemistry through supplementation using salts or other chemicals, or implementation of biosecurity plans. Water quality in surface waters changes over time due to temperature, precipitation, and anthropogenic activity. Moreover, many pathogenic bacteria proliferate during the warmer summer months. It is likely that a chemical constituent or biological agent is causing the detrimental effect on hatchery production. Conversely, some currently-unmonitored water quality parameter that is critical for healthy larval development could be significantly altered during the warmer months.
Jim Wesson, 757.247.2121; firstname.lastname@example.org
1/15/12 - 12/31/12; Project Completed
Final Product Received:
Water Chemistry Studies for Oyster Hatcheries in the Chesapeake Bay Final Report (pdf)
Project Summary Provided by Grantee:
Oyster production in Virginia has increased more than 10 fold over the past ten years. Much of this increase has been the growth of hatchery based aquaculture and private investment on leased ground. All shellfish hatcheries in Virginia are privately owned, and the future of the modern industry rests on their successful production of eyed larvae and seed oysters. In 2010 and especially 2011, there were unexplained production problems at all of the hatcheries throughout the State. Water quality issues were suspected, but there were no standards for water quality monitoring among hatcheries, and there was no way to link production difficulties with changes in water quality. After several meetings between hatchery managers and academia, Dr. David Kuhn from Virginia Tech and Jim Wesson from MRC developed a standardized program to begin monitoring various water quality components at six Virginia hatcheries. Secretary of Natural Resources, Doug Domenech provided funds to begin monitoring water quality, and analyzing the collected data. The Virginia Coastal Zone Management Program provided funds for standardized onsite laboratory equipment for each hatchery. Significant effort and in-kind match has been undertaken by each hatchery. Water chemistry parameters monitored include alkalinity, ammonia, calcium, carbon dioxide, iron, nitrate, nitrite, pH, phosphorus, potassium, salinity, silicate, and temperature. These parameters are monitored several times a week at various location in the hatchery when they are producing larvae. It was anticipated that carbonate chemistry issues resulting from ocean acidification could be involved with larvae production issues, but in 2012 that did not appear to be the case. Water quality in 2012 was much better than in 2010 and 2011, most likely because of the very dry conditions. Oyster larvae production was very good at most hatcheries until after July. Larval production declined in August, and a high level of ammonia was the only abnormal water quality parameter observed. All of the hatcheries will continue with the water chemistry monitoring in 2013. Water quality data is now routinely shared between the six hatcheries, Virginia Tech, and MRC. Meteorological conditions are very different this winter and spring from those observed in 2012. Rainfall has been higher and temperatures colder in 2013, and one hatchery has already had issues with elevated potassium. Monitoring is the first step in recognizing issues, and may suggest possible adaptations that can be implemented in the shellfish hatcheries—even though in many cases there will be no explanation for the water quality changes that are being observed. This is a very new industry, and many other water quality issues, both biological and chemical will be continue to be monitored by the industry and Dr. Kuhn.
Disclaimer: This project summary provides the federal dollars initially awarded to the grantee. Due to underexpenditure or reprogramming of grant funds, this figure may change. For more information on the allocation of coastal grant funds, please contact Laura McKay, Virginia Coastal Program Manager, at 804.698.4323 or email: Laura.McKay@deq.virginia.gov
A more detailed Scope of Work for this project is available. Please direct your request for a copy to Virginia.Witmer@deq.virginia.gov