Virginia combines maps and counts to assess oyster losses
· BehindLines newsroom
In Virginia, two approaches are helping assess oyster losses after the algal bloom observed in September. On 29 October, NASA described how researchers it funds are supporting mapping of affected areas. A Virginia Institute of Marine Science (VIMS) protocol, distributed by Virginia Tech on 28 September, details counts at oyster farms.
Mapping the episode
According to NASA, the Virginia Marine Resources Commission uses maps to identify affected farming and restoration areas. Researchers have analysed images from Europe's Sentinel-2 satellites, among other data, to map high concentrations of microscopic algae.
These observations provide an overview. Researchers also use models to reconstruct water and wind conditions. According to NASA, the project aims to improve water quality forecasts using satellite observations and input from growers.
A connection still under investigation
On 22 September, the Virginia Institute of Marine Science reported that the bloom included Alexandrium monilatum, an alga that can harm marine life. Dead fish and oyster losses had been reported in the affected areas.
However, the institute said researchers were still investigating the link between the bloom and reported deaths. Their occurrence at the same time was therefore insufficient to attribute every oyster loss to the alga. Researchers were continuing sampling and analysis. That dated update does not, on its own, provide a final assessment for each farm.
Counting losses in the field
The VIMS protocol distributed by Virginia Tech describes another part of the work: estimating deaths in a documented way. Counts must distinguish oyster sizes, sections of a farm, and animals that died recently from those that died longer ago.
The protocol calls for randomly selecting bags or cages to avoid biased choices. Photographs and records of earlier stock numbers supplement the counts.
Combining these approaches connects a map of an event with verifiable observations at farms. The documents consulted describe that assessment process; they do not support giving an overall monetary figure for the damage here.