Pacific Oyster
Pacific Oyster
Crassostrea gigas; Magallana gigas
Also Known As
Japanese oyster, Miyagi oyster, Pacific cupped oyster
Quick Facts
Length
Up to 12 inches
Threats
Disease, Degraded Water Quality, Changing Conditions Due to Climate Change
Region
Alaska,
West Coast
A cluster of bottom-cultured oysters grows in eelgrass in Willapa Bay, Washington. Credit: NOAA
A cluster of bottom-cultured oysters grows in eelgrass in Willapa Bay, Washington. Credit: NOAA
About the Species
The Pacific oyster, introduced from Japan in the 1920’s by the Washington State Department of Fisheries, is now a popular West Coast aquaculture species that is widely enjoyed by consumers. Oysters provide many benefits to the ecosystems in which they live. They are filter feeders, cleaning the water as they eat—an adult Pacific oyster can filter up to 50 gallons of seawater per day. This filtering of the water improves light penetration for submerged aquatic vegetation to thrive. Oysters can also form reefs providing critical habitat for many species including fish and other invertebrates like the native Olympia oyster.
Appearance
Pacific oysters can be long-lived, reaching up to 10-12 inches. Their shells—known as valves—are naturally long, thick, rough, and sometimes sharp around the edges. The inside of the shell is white to off-white, with purple stains where the abductor muscle attaches to both valves. The outer shell can be white or off-white, sometimes with purple streaks from the hinge (umbo) to the valve edge. One of the two shells is cupped, which is why they are also called "Pacific cupped oysters," while the other is flat. You'll find Pacific oysters on the beach with the cupped side in the sand.
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Biology
Oysters are a type of shellfish—specifically bivalve mollusks—which means they have a hinged shell with two parts, similar to mussels, clams, cockles, and scallops. Adult oysters are sessile—they stay in one place. They inhabit both intertidal and subtidal areas. Pacific oysters can grow quickly, depending on plankton (food) availability and water quality conditions.
In their first year of life, Pacific oysters are male. As they get older, some will change and develop female reproductive organs, while their male organs shrink. When it's time to reproduce, a female Pacific oyster can release anywhere from 50 to 200 million eggs into the water. This is called a spawning event.
Spawning events typically happen when conditions are ideal. Male oysters release their sperm by clapping their shells together, often when the water is warm and coming in with the tide. If there are female oysters nearby that are ready to spawn, they will then release their eggs to be fertilized.
The tiny oyster larvae develop in the upper layers of the water and drift with the currents of the surrounding water. After about 20 to 22 days, the oysters are ready to settle down on the bottom of the bay. They attach themselves to a shell, rock, or other suitable surface, where they will grow their own shells and can live for the rest of their lives.
Scientific Classification
| Kingdom | Animalia | Phylum | Mollusca | Class | Bivalvia | Order | Ostreida | Family | Ostreidae | Genus | Magallana | Species | gigas |
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What We Do
Sustainable Fisheries Management
The wild Pacific oyster harvest is managed by individual states or other jurisdictions. Similarly, aquaculture permitting is run by states. Guidelines and procedures vary from state to state. In some areas, NOAA scientists collaborate with state and other resource managers. They provide the most up-to-date science to help the resource managers make decisions and set regulations.
Science
NOAA supports science that resource managers and decision makers can use as they set regulations about wild oyster harvest and aquaculture operations.
Featured News
Danielle Blacklock, Director of NOAA Fisheries Office of Aquaculture, eating an oyster on the half shell. Credit: NOAA Fisheries.
Pacific oysters travel down a sorting tumbler at Salty Lady Seafood Company in Juneau, Alaska. Credit: Salty Lady Seafood Company.
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Feature Story
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New England/Mid-Atlantic
Pacific Islands
Southeast
West Coast
National
Oyster growers harvest farmed shellfish from the Damariscotta River in Maine. NOAA has awarded several grants to small businesses working to develop new tools to advance sustainable U.S. aquaculture. (Image credit: C. Katalinas/ Maine Sea Grant)
Related Species
Seafood Facts
Are Pacific Oysters Sustainable?
U.S. farmed and harvested Pacific oysters are a smart seafood choice because they are grown and harvested under U.S. state and federal regulations.
Availability
Available year-round.
Source
Estuaries, mostly in the Pacific Northwest.
Taste
Ranges from sweet to briny.
Health Benefits
Oysters are low in saturated fat and excellent sources of omega-3 fatty acids, iron, and zinc.
Nutrition Facts
Servings: 1; Serving Weight: n/a; Calories: 81; Protein: 9.45 g; Total Fat: 2.3 g; Total Saturated Fatty Acids: 0.5 g; Carbohydrate: 0 g; Total Sugars: 0 g; Total Dietary Fiber: 0 g; Cholesterol: 50 mg; Selenium: 77 mcg; Sodium: 106 mg; Zinc: 16.62 mgOyster Recipes
Looking for some ways to add oysters into your rotation? If you need some cooking inspiration, browse these recipes for bourbon grilled oysters, bacon-wrapped oysters, and more!
Seafood News
Credit: Howard Stanbury (left); NOAA Library/NOAA Fisheries circa 1939 (right); NOAA (background)
Feature Story
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New England/Mid-Atlantic
National
U.S. Senators Ted Stevens (R-AK) and Warren Magnuson (D-WA), 1973.
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Alaska
New England/Mid-Atlantic
Pacific Islands
Southeast
West Coast
National
International
Danielle Blacklock, Director of NOAA Fisheries Office of Aquaculture, eating an oyster on the half shell. Credit: NOAA Fisheries.
Aquaculture
The Pacific oyster, introduced to the United States from Japan in the 1920s, is now a leading aquaculture species on the West Coast. Pacific oysters thrive in diverse environmental conditions and can reach market size quickly. Their cultivation provides a sustainable food source, supports coastal economies, and plays a vital role in the aquaculture industry.
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Environmental Impact
Oysters provide net environmental benefits by removing excess nutrients and improving water quality.
Feeds
Growing oysters requires no feed—they filter phytoplankton directly from the water column.
Farming Methods
Pacific oysters are grown in tidal areas. They can be grown directly on the beach bottom or in bags, trays or cages that are either anchored to the substrate or suspended in the water column or suspended from rafts.
Human Health
Shellfish toxins and bacteria occur naturally in the environment and can cause foodborne illnesses. State and federal regulations require monitoring of farmed shellfish to ensure they are safe to eat.
Management
Permitting for shellfish aquaculture is governed by federal, state and local governments. The federal agencies involved in the authorization or permitting of aquaculture in the U.S. include NOAA, the U.S. Army Corps of Engineers, U.S. Fish & Wildlife Service, U.S. Department of Agriculture, the Environmental Protection Agency, the Food & Drug Administration, and the U.S. Coast Guard.
All fisheries and aquaculture farms must adhere to federal regulations including those in the Magnuson-Stevens Act, the Endangered Species Act, the National Environmental Policy Act, the Clean Water Act, and the Marine Mammal Protection Act.
Information on shellfish aquaculture permitting can be found in the Shellfish Growers Guide (PDF, 10 pages). A variety of shellfish aquaculture tools, including maps and models, are also available to coastal managers.
Farming Methods
Juvenile Oyster (Seed) Production
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Oyster larvae are raised in hatcheries and fed algae. After about two to three weeks, the larvae settle out of the water column and attach to a surface, typically crushed or whole aged oyster shells. These settled larvae, now called spat, are then cultured in tanks for a few weeks before being moved to grow-out sites on farms.
Oyster Grow-Out
Pacific oysters are sustainably grown and harvested in tidal areas. They can be grown directly on the beach bottom or in mesh bags, trays or cages that are either anchored in the water column or floated on rafts.
- On-bottom Culture: Oyster spat are spread directly onto the bottom substrate of intertidal areas.
- Off-bottom Culture: Oyster spat are placed in bags on racks, or in cages or hung on long lines attached to anchored frames or poles in the intertidal zone.
- Suspended Culture: Bags or cages are attached to rafts or floats.
Production
In 2022, the United States produced 29.7 million pounds of oysters (both Eastern and Pacific oysters), valued at $199 million.
Environmental Considerations
Habitat
Oyster farming has a benign ecological footprint, with little disturbance of sediments or aquatic vegetation during grow-out. Some oyster harvesting methods involve dredging, but long-term effects on the environment are rare.
Feeds
Once past the larval stage in the hatchery, oysters do not need to be fed because they filter their food from the water column.
Ecosystem Services
Aquaculture farms can provide a wide range of benefits, from creating habitat for fish and crustaceans to helping improve water quality around farm sites. These benefits are referred to as ecosystem services.
Water Quality
Oysters are filter-feeders, removing algae, organic matter, and excess nutrients from the water column as they grow and improving water quality for other species. When oysters are harvested, nutrients such as nitrogen and phosphorus are removed from the ecosystem.
Providing Habitat
Oysters and the gear used to farm oysters can provide habitat for other marine organisms. Oyster beds also stabilize coastal sediments and help minimize impacts from storm surges.
Human Health
Shellfish Toxins
Shellfish can assimilate the toxins from algae on which they feed—such as the harmful algae Alexandrium species, which create harmful toxins that lead to paralytic shellfish poisoning (PSP). When there is an abundance of Alexandrium present in the water this is known as a harmful algal bloom, increasing risk of PSP. Early warning systems exist to detect harmful algal blooms that produce toxins that can make shellfish unsafe for human consumption. New technologies such as the Environmental Sample Processor, provide near real-time detection and monitoring of harmful algal species in the water column.
NOAA’s Harmful Algal Bloom Forecasting Program
Pathogenic Bacteria
The bacteria Vibrio parahaemolyticus (Vp) occur naturally in the environment and can cause foodborne illness from consuming raw shellfish or undercooked shellfish that has Vp bacteria can lead to gastrointestinal illness.
Public health officials monitor shellfish farms, harvests, and the surrounding area to ensure they are safe to eat from biotoxins, bacteria and viruses.
Science Overview
NOAA fisheries conducts various research activities on the biology, behavior, and population health of Pacific oysters related to both wild and farmed populations. The results of this research are used to inform management decisions for this species.
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Researching Farmed Pacific Oysters
Growth and Reproduction
The Northwest Fisheries Science Center’s Kenneth K. Chew Center for Shellfish Research & Restoration includes a modern shellfish hatchery for the research and production of oysters. The Northeast Fisheries Science Center’s Milford Lab is also finding ways to breed larger oysters and increase survival of larvae.
Ocean Acidification
Ocean acidification—caused by increased carbon dioxide absorption into the ocean—can cause a number of changes in water chemistry that may be stressful to oysters and other shellfish by hindering their ability to build and maintain their calcium carbonate shells. NOAA and our partners are actively researching these effects and exploring potential solutions. For more information, visit NOAA’s Ocean Acidification Program.
Ecosystem Services
Oyster farms can provide a wide range of benefits, from creating habitat for fish and other invertebrates to helping improve water quality around farm sites. These benefits are referred to as ecosystem services.
The Northwest Fishery Science Center, in collaboration with The Nature Conservancy, Washington Sea Grant, the Jamestown S’Klallam Tribe, and seven shellfish growers, used GoPro cameras placed around shellfish aquaculture beds to document the diversity of species that use the beds as habitat.
