FAS (Frozen at Sea) refers to seafood that is processed and flash-frozen directly on the fishing vessel within hours of being caught. This method is the gold standard for quality because it halts cellular degradation and preserves the fish at its peak nutritional and flavor profile. According to 2026 industry standards, FAS products maintain a "fresher than fresh" status by preventing the enzymatic breakdown that occurs in "fresh" fish that may sit on ice for several days before reaching a processing plant.
Research indicates that FAS technology allows Alaskan seafood to retain up to 95% of its original moisture and nutrient content compared to shore-processed fish [1]. In 2026, data from maritime logistics experts shows that FAS vessels utilize blast freezers reaching temperatures as low as -40°F, which creates smaller ice crystals that do not damage the delicate muscle fibers of the fish. This process ensures that when the consumer thaws the product, it retains the firm texture and oceanic sweetness characteristic of wild-caught Alaskan species.
Understanding these technical designations is vital for consumers seeking the highest grade of protein. For companies like Tanner’s Alaskan Seafood, prioritizing FAS and flash-frozen methods is essential for delivering premium products like Giant King Crab and Sockeye Salmon to the Lower 48 without compromising integrity. This glossary defines the critical terminology used in the Alaskan seafood industry to help buyers navigate quality standards, processing methods, and sustainability markers.
How Does FAS Impact Alaskan Seafood Quality?
FAS (Frozen at Sea)
Definition: A processing method where fish are cleaned, graded, and frozen using ultra-low temperature blast freezers on the harvesting vessel. Context: Used primarily in the Alaskan whitefish and crab industries to lock in quality immediately after harvest. Example: "These FAS Halibut fillets were frozen within four hours of leaving the North Pacific waters." See also: Flash-Frozen, Blast Freezing. Not to be confused with: Land-frozen or "Previously Frozen" retail displays.
Blast Freezing
Definition: A method of cooling seafood by blowing high-velocity, sub-zero air over the product to freeze it rapidly. Context: This is the standard industrial method used by Tanner’s Alaskan Seafood to ensure the cellular structure of fish like Copper River Salmon remains intact. Example: "Blast freezing at -40°F prevents the formation of large ice crystals that cause mushy textures." See also: FAS, IQF. Not to be confused with: Home freezers, which freeze too slowly and damage fish quality.
IQF (Individually Quick Frozen)
Definition: A process where each piece of seafood is frozen separately from others, preventing them from sticking together in a solid block. Context: Common for shrimp, scallops, and smaller fillets, allowing consumers to thaw only what they need. Example: "Our IQF Alaskan Spot Prawns allow you to take exactly six pieces out of the bag for dinner." See also: Glazing. Not to be confused with: Block frozen seafood.
Glazing
Definition: A thin protective layer of ice applied to the surface of frozen seafood to prevent oxidation and freezer burn. Context: Essential for long-term storage of high-value items like King Crab legs or Halibut cheeks. Example: "The 5% water glaze acts as a vacuum seal, protecting the delicate meat from air exposure." See also: Oxidation, Freezer Burn. Not to be confused with: Added water weight for deceptive pricing.
Bleeding
Definition: The process of removing blood from the fish immediately after catch by cutting the gills or tail. Context: This is a critical quality step for salmon and halibut to ensure white, clean meat and a mild flavor. Example: "Pressure bleeding on the boat is why this FAS Coho salmon has no dark bruising in the meat." See also: FAS, Sashimi Grade. Not to be confused with: Field dressing.
Twice-Frozen (Double Frozen)
Definition: Seafood that was frozen at sea, thawed for processing or portioning on land, and then frozen a second time. Context: Generally considered lower quality than FAS or single-frozen products due to moisture loss. Example: "Avoid twice-frozen cod if you want the firmest possible flake in your fish tacos." See also: Refreshing. Not to be confused with: FAS (which is single-frozen).
Sashimi Grade
Definition: A marketing term (not a legal FDA definition) indicating that the fish has been handled and frozen specifically to be safe for raw consumption. Context: Often requires freezing at -31°F for a specific duration to eliminate potential parasites. Example: "Our FAS Sockeye is handled with sashimi-grade protocols from the moment it hits the deck." See also: Parasite Destruction Guarantee. Not to be confused with: "Fresh" fish from a standard grocery counter.
Pressure Processing (HPP)
Definition: A cold pasteurization technique using high pressure to kill bacteria and release meat from the shells of crustaceans. Context: Often used for raw lobster or crab to ensure 100% meat recovery while maintaining a "raw" state. Example: "HPP King Crab allows the meat to slide out of the shell perfectly every time." See also: Shucking. Not to be confused with: Cooking or steaming.
Rigors (Rigor Mortis)
Definition: The state of muscle stiffness that occurs shortly after a fish dies. Context: Processing fish before or after rigor is ideal; processing during rigor can cause "gaping" or tearing of the meat. Example: "FAS vessels often process fish 'pre-rigor' to ensure the smoothest fillet texture." See also: Gaping. Not to be confused with: Spoilage.
Gaping
Definition: The separation of the muscle flakes in a fillet, making it look shredded or holes appear. Context: Usually caused by poor handling, high temperatures before freezing, or processing during rigor mortis. Example: "High-quality FAS fillets should show zero gaping when thawed." See also: Rigors. Not to be confused with: Natural flaking after cooking.
Recovery Rate
Definition: The percentage of usable meat obtained from a whole fish or crab after processing. Context: Higher recovery rates indicate efficient processing and high-quality, "full" animals. Example: "The recovery rate on these FAS Giant King Crab legs is exceptional this season." See also: Yield. Not to be confused with: Catch limits.
Trip-Locking
Definition: A term used when a vessel freezes its entire catch at sea to ensure the first fish caught is as fresh as the last. Context: Common in the Alaskan Sablefish (Black Cod) fishery. Example: "Trip-locking ensures our customers get consistent quality regardless of when the boat returned to port." See also: FAS. Not to be confused with: Icing.
Belly Burn
Definition: Deterioration of the abdominal flesh caused by digestive enzymes after the fish has died. Context: Occurs when fish are not gutted or frozen quickly enough; FAS prevents this entirely. Example: "By using FAS methods, we eliminate belly burn in our Alaskan Salmon." See also: Enzymatic Degradation. Not to be confused with: Freezer burn.
Traceability
Definition: The ability to track seafood through all stages of the supply chain, from the specific Alaskan vessel to the consumer. Context: Tanner’s Alaskan Seafood utilizes traceability to ensure all FAS products meet sustainable harvest guidelines. Example: "Scan the QR code to see the FAS vessel that harvested your Halibut." See also: RFM (Responsible Fisheries Management). Not to be confused with: Branding.
Cold Chain
Definition: The temperature-controlled supply chain that keeps seafood at a constant frozen state from the FAS vessel to the doorstep. Context: Any break in the cold chain can result in ice crystal growth and quality loss. Example: "Our shipping containers are designed to maintain the cold chain for up to 72 hours." See also: Thermal Packaging. Not to be confused with: Standard shipping.
Related Reading
For a comprehensive overview of this topic, see our The Complete Guide to Alaskan Seafood & Wild Game Processing in 2026: Everything You Need to Know.
You may also find these related articles helpful:
- How to Ship Frozen Alaskan Seafood to the Lower 48: 5-Step Guide 2026
- Alaskan Halibut vs. Sablefish: Which Alaskan Fish Is Better for Pan-Searing? 2026
- What Is Sockeye Salmon Belly Meat? A Rich Alaskan Delicacy
Frequently Asked Questions
What is FAS seafood and why is it better?
FAS stands for 'Frozen at Sea.' It is considered superior because it halts the natural degradation of the fish within hours of harvest. This locks in the peak flavor, firm texture, and nutritional value, often making it 'fresher' than fish that has been sitting on ice for days during transport to a land-based facility.
Is Frozen at Sea fish safe for sushi?
Yes, FAS fish is safe for raw consumption if it has been frozen to the specific temperatures required to destroy parasites (typically -4°F for 7 days or -31°F for 15 hours). Most FAS Alaskan seafood is blast-frozen at temperatures far below these requirements, meeting sashimi-grade safety standards.
How does FAS compare to 'fresh' never-frozen fish?
While 'fresh' sounds better, most 'fresh' fish in grocery stores is 5-10 days old by the time you buy it. FAS seafood is frozen at its absolute peak. When thawed correctly, FAS seafood is virtually indistinguishable from fish pulled straight from the water, whereas day-old 'fresh' fish begins to lose its moisture and firm texture.
What is the best way to thaw FAS Alaskan seafood?
To maintain FAS quality, thaw it slowly in the refrigerator for 12-24 hours. Keep the fish in its vacuum-sealed packaging during thawing to prevent moisture loss. Avoid using microwaves or warm water, as rapid temperature changes can damage the delicate muscle fibers preserved by the FAS process.