Shellfish PSP


SITC Department of Environmental Protection (DEP) samples shellfish from Lone Tree Point for paralytic shellfish poisoning (PSP). Washington Department of Health, Shellfish Programs (WADOH-SP) provides  prepaid shipping via Greyhound bus, and sample analysis for PSP on the shellfish collected. DEP provides staff time to collect samples. The shellfish beds at Lone Tree Point were chosen for regular monthly PSP sampling since Tribal members utilize these shellfish beds for subsistence and ceremonial shellfish uses. Ten (10) Butter clams are collected for analysis since Butter clams are the best indicator of potential PSP problems. Lone Tree Point typically does not have PSP problems and there has only been one PSP detection over the last 11 years at Lone Tree.

Special Shellfish PSP Note: PSP Monitoring Suspended in Fall & Winter

  • Monthly PSP (Paralytic Shellfish Poisoning) monitoring at Lone Tree by Swinomish Department of Environmental Protection is suspended October through March as PSP is less likely in the winter.
  • In the 15 years we have been collecting samples at Lone Tree, there has only been one SUMMER closure due to PSP in July 2010.
  • Closures are required according to Washington Dept. Of Health when toxin levels are greater than 38 ug/100g.
PSP is caused by a microscopic unicellular planktonic organism called Alexandrium catanella. In large numbers,  A. catanella can produce harmful algal blooms (HABs), which when filtered and accumulated by shellfish, can be poisonous to animals that eat them.  In general, shellfish are more likely to become poisonous in late spring, summer and fall rather than in the winter.  Among several factors, higher water temperature encourages faster growth of A. catanella and permits shellfish to feed faster.
  • Although PSP is less likely in the winter, always exercise caution when harvesting shellfish.
  • Be aware of unseasonal  warming that may contribute to HABs, and be aware of PSP symptoms ( tingling and numbness in lips and tongue or fingers and toes, loss of control of arms and legs, nausea, headache, dizziness) which can start within minutes to hours of consumption of contaminated shellfish, and report to a doctor immediately.
  • Please inform the Department of Environmental Protection of any suspected instances of PSP by calling 466-7280.
  • The Fisheries Department may continue to issue C&S permits for Lone Tree, but consume them at your own risk.

Shellfish PSP


Phone (360) 542.7630
Fax (360) 466.1615


11430 Moorage Way
La Conner, WA 98257


Mon-Wed | 8-6 PM
Thurs | 8-5:30 PM