By K. Pica Kahn
Oysters are good for the Texas Gulf Coast for numerous reasons including the economic impact on the state. An unusual species, they also contribute to the health of the surrounding ecosystem through filtration of the area in which they live.
“Here are the oyster landings (meat-weight, lbs) and ex-vessel value ($) for each year from 2000 through 2016,” said Lance Robinson, deputy division director, Coastal Fisheries Division Texas Parks & Wildlife Department. “This includes the data for 2017 through May, leaving six months of landings from June through December that will need to be added.
“Landings are calculated in pounds of ‘meat-weight’ which subtracts the weight of the shell. The value is reported as ex-vessel value, which is the price paid to the fisherman by the dealer/buyer. To calculate the value of the oyster fishery to the state’s economy, economic multipliers are used to account for how these dollars move through the economy (e.g. fisherman takes money earned from catching/selling oysters and buys gasoline, groceries, clothes, etc.)”
For commercial fisheries in Texas, this multiplier is 1.8. In taking the ex-vessel value for the 2016 season ($13,715,122) and multiply by 1.8, the total value is $24,687,219.60, which would be the contribution to the Texas economy from the commercial oyster fishery for that year.
“Regarding the ecological value of oysters to coastal ecosystems, combine the ecosystem services and the valuation estimates of these services,” said Robinson. “Another analogy in trying to explain the value of oyster resources is through their water filtering capacity and thus improvements to water quality. A single adult oyster can filter up to 50 gallons per day as they filter out microscopic algae (phytoplankton) upon which they feed.
“Algae and other particles that are too big to ingest, are encapsulated in mucous material within the shell. These materials are not ingested by the oyster, but the encapsulated packets, known as pseudofeces, are extruded from the shell and falls upon the reef where other small organisms (shrimp, crabs, etc.) feed upon this material. Using an average density of 10 oysters per square meter, 130 acres of oyster reef would be capable of filtering approximately 260 million gallons of water per day.”
“According to the Greater Houston Partnership, by comparison, the city of Houston’s 39 wastewater treatment plants had a combined average daily wastewater treatment flow in 2009 of 252 million gallons per day,” said Robinson.
“Oysters don’t purify the water like a wastewater treatment plant, but it’s an impressive statistic that 130 acres of oyster can remove sediment and other particulates from our bays at the same volume that is used by the city of Houston.”