Guide
Shellfish closures, explained
Checked September 13, 2026 against the Washington Department of Health and the Department of Fish and Wildlife.
The Shellfish tile repeats what the Washington Department of Health says about the beach you are reading for. This page explains what a closure is, why cooking does not help, and why the only safe habit is to check on the day you dig.
You cannot see, smell or taste a marine biotoxin, and cooking will not remove it. The Department of Health puts it in one sentence: “Cooking or freezing doesn’t kill or remove toxins. The toxins are part of the shellfish meat.” The only way to know is a laboratory test, which is what a closure is telling you about.
Check on the day. Not the week before.
The Department of Health’s own instruction is exact about the timing: “Check the shellfish safety map for beach closures and advisories on the day of harvest.” A beach that was open on Friday can be closed on Saturday, because a closure follows a test result, and results arrive when they arrive.
Three ways to check, all the department’s own:
- The Washington Shellfish Safety Map, which is what this site reads.
- The recorded Marine Biotoxin Hotline, 1-800-562-5632, twenty-four hours.
- Your local health department, or the Shellfish Growing Area Section on 360-236-3330 in office hours.
One honest gap: the department does not publish how often the map is refreshed, so this page does not claim a figure. What it does say is to look on the day.
The three biotoxins
All three are produced by algae the shellfish eat, and all three concentrate in the meat.
- Paralytic Shellfish Poison (PSP), the one people call red tide. Tingling in the lips and tongue “within minutes of eating toxic shellfish or may take an hour or two to develop,” spreading to fingers and toes, then loss of limb control and difficulty breathing. In severe cases the muscles used for breathing become paralysed, and death can occur in under thirty minutes.
- Amnesic Shellfish Poison (ASP), which is domoic acid, from the diatom Pseudo-nitzschia. Vomiting, nausea, diarrhoea and cramps within 24 hours; headache, dizziness, confusion, disorientation, short-term memory loss, seizures and worse within 48. The department states that severe cases “can result in permanent short-term memory loss.”
- Diarrhetic Shellfish Poison (DSP), from Dinophysis. Nausea, vomiting, abdominal pain and diarrhoea, diarrhoea being the commonest. The department’s clinical guideline puts onset between thirty minutes and thirty-six hours.
Each of the department’s three pages ends with the same sentence in different words: the toxin “isn’t destroyed by cooking or freezing.”
Two different kinds of closure, both shown as Closed
A biotoxin closure is about the shellfish. Algal toxin has been measured in the meat above the level the department allows, and only a laboratory test can find it or clear it.
A pollution closure is about the water. The department: “Floods, sewage spills, and other pollution events can create conditions that make shellfish unsafe for human consumption. When this happens we impose an emergency (temporary) closure on the affected area.” Underneath those sit permanent classifications of each growing area — Approved, Conditionally Approved, Restricted, Prohibited — from sanitary surveys of the shoreline.
Both reach the map as Closed, and for a harvester the instruction is the same either way. The department does not set the two side by side on any one page; this comparison is assembled from two of its pages, and is worth knowing mainly so that “the water looks fine” never reads as an argument.
Vibrio, which is a summer problem and a handling problem
Vibrio parahaemolyticus is a naturally occurring bacterium in salt and estuarine water — not an algal toxin, and not something a closure usually covers. It multiplies in warmth, so the risk runs through the summer. Diarrhoea, cramps, nausea, vomiting, headache, fever and chills, usually 12 to 24 hours after eating, sometimes up to four days.
Unlike the biotoxins, this one you can largely defeat by handling, and the department’s advice is practical: harvest as early in the receding tide as you can; do not take shellfish that have been sitting in the sun for more than an hour; chill them promptly; do not store them in standing water; and cook them properly, especially in summer. The safety map carries its own Vibrio High-Risk Area overlay.
Who decides what
Two agencies, and the map says so itself: “Washington shellfish resources are managed by both the DOH (safety & water quality) and WDFW (harvest regulations).” The Department of Health closes a beach because of what is in the shellfish or the water. The Department of Fish and Wildlife decides seasons, limits and licences. A beach can be biologically safe and still closed to harvest, or open to harvest and closed for toxin. The board shows the health status; the season is a separate question, and for razor clams it has a guide of its own.
One more limit worth stating: the map does not cover everything. Its own legend says “Not all beaches are mapped, call your local health department or district.”
Sources
- Washington Shellfish Safety Map — the status the board reads, and the legend quoted here
- Department of Health, marine biotoxins, and its pages on PSP, ASP and DSP
- Department of Health, shellfish poisoning clinical guideline — the onset times, including DSP
- Department of Health, shellfish harvest planner — “on the day of harvest”
- Department of Health, shellfish growing areas — pollution closures and the classifications
- Department of Health, vibriosis