CommonHow Clams, Toxic Are Cockles, Alaska's Most Scallops, Common Shellfish Oysters ? of Alaska Concentric Pacific Littleneck Clam rings Protothaca staminea Pacific Razor Clam Distribution: Aleutian Islands to mid-California Alaska Razor Clam Siliqua patula Habitat: Midtidal to subtidal zone, mud to coarse Siliqua alta Distribution: Bristol Bay to southern gravel beaches 1 Distribution: Bering Sea to Cook Inlet California Size: Up to 2 ⁄2" Habitat: Intertidal zone, open coasts in sand Identification: External surface of shell with radiating Habitat: Intertidal zone to 30 feet on open sandy beaches Size: Up to 8" and concentric grooves Horse (Gaper) Clam Size: Up to 6" Identification: Long narrow shell, thin and Tresus capax brittle, olive green to brown color Identification: Long narrow shaped Distribution: Shumagin Islands, Alaska to shell, shell thin and brittle, brown to olive California green color Habitat: Intertidal zone, imbedded deeply Butter Clam Spiny Scallop Size: Up to 8" Saxidomus giganteus Chlamys hastata Identification: Shell large and thick, wide gape Radiating Distribution: Aleutian Islands to mid- Distribution: Gulf of Alaska between shells at posterior end when held grooves California to California together, dark covering on shell surface often or rib Habitat: Intertidal zone to 120 feet depth, on Habitat: Low intertidal area to partially worn off protected gravel, sandy beaches 400 feet depth Blue Mussel 1 Size: Up to 5" Size: Up to 3 ⁄2" Mytilus edulis Identification: Dense shell, external surface Identification: Shell thin and flattened, Distribution: Northern Hemisphere with concentric rings, prominent growth rings auricles uneven size, 20-30 ribs on each shell, Habitat: Rocky intertidal areas of exposed and ribs spiny textured protected coastline Size: Up to 4" Identification: Blue-black to brownish shell, shell pointed at one end and round at the other, has a thread-like structure to attach to substrate Cockle Clinocardium nuttalli Distribution: Bering Sea to southern California Pacific Oyster Habitat: Intertidal zone to 90 feet, mud to Crassostrea gigas sand beaches Purple Hinge Pink Scallop Distribution: Kachemak Bay to California Size: Up to 6" Chlamys rubida Rock Scallop Habitat: Intertidal in mud to rocky beaches. Identification: Thick cupped shells, up to Geoduck Distribution: Bering Sea to Crassadoma gigantea In Alaska only on aquatic farms, but may be 35 strong ribs spreading from the hinge to Softshell Clam Panopea abrupta mid-California Distribution: Aleutian Islands to southern a few small populations in southern shell margin Mya arenaria Distribution: Sitka, Alaska to Gulf of California Habitat: Low tidal area to 900 feet California southeastern Alaska. Does not reproduce in Distribution: Worldwide north of mid-California Habitat: Intertidal to deep water, buried deeply in sand depth, rocky shoreline Habitat: Low tidal area to 200 feet depth, Alaska waters Habitat: Upper tidal level mud flats and mud bottom 1 attached to rocks and in crevices Size: Up to 2 ⁄2" Size: Up to 8" Size: Up to 6" Size: Shell up to 8" Identification: Shell thin and Size: Up to 10" Identification: Shell irregular shape, rough Shellfish drawings from Intertidal Bivalves: A Guide to Identification: Shell soft, easily broken, one end of Identification: Shells heavy, one end of shell rounded flattened, 20-30 ribs on each shell, Identification: Very heavy rough shell, purple surface, upper shell cupped while lower shell Common Marine Bivalves of Alaska, Nora R. Foster. shell rounded, other end pointed, concentric rings the other end flat, rough concentric grooves on shell color hinge area when shell open 1991. University of Alaska Press. auricles uneven size, red-pink on flat only surface one shell, opposite shell color pale Truths and Myths about PSP Outbreaks of paralytic shellfish poisoning A Little Bit Goes a Are months with an “r” safe for eating shellfish? emphasize this point, none of the five PSP outbreaks in Alaska, 1973-97 (total=83) Long Way! No. Months without an “r” occur during the summer when Kodiak in 1993 were preceded by a red tide. However, if a red tide is in progress, do not eat the shellfish! You may not It doesn’t take much PSP toxin to kill you—just 738 toxic dinoflagellate blooms that cause PSP most often micrograms can kill a 180-pound person. That’s equal in occur. With the unlikely possibility that shellfish will know what is causing the red coloration. volume to about 10 grains of table salt. And even that is become toxic outside the summer season, consumers assume 20 invisible because it’s dissolved throughout the shellfish body shellfish are safe to eat. This answer is wrong in three ways. Is shellfish purchased at a seafood retailer safe to eat? tissue. So BEWARE! No matter what you may hear, there’s no way to tell without a laboratory test whether or not 1. In some locations in Alaska shellfish remain highly toxic 15 Yes. Shellfish sold for human consumption must meet the shellfish you gather are contaminated. in the spring and fall. PSP outbreaks have occurred in all Food and Drug Administration standard of less than 80 µg seasons. of PSP toxin per 100 grams of shellfish tissue. Alaska 10 Blue Mussel regulations require regular monitoring of commercially 2. Toxic dinoflagellate algae can form cysts that reside in harvested shellfish or batch certification that requires each Toxicity: 20,000 µg toxin the sediment during the non-bloom seasons. These cysts are commercially harvested or farm grown batch of shellfish to 5 as toxic as the suspended vegetative form that are present pass the PSP test prior to market. Spiny Scallop during a toxic bloom. Shellfish, being bottom dwelling filter Toxicity: 11,945 µg toxin feeders, can continue to consume cysts during non-bloom Are some clam beaches in Alaska certified to be periods and accumulate PSP toxin. free from PSP toxin? January February March April May June July August September October November December Pink Scallop 3. Some shellfish can retain the PSP toxin for a long period. No. Unlike other West Coast states, Alaska does not certify Department of Environmental Conservation then fills in Toxicity: 11,945 µg toxin Blue mussels in the Skagway area took 28 days before they recreational beaches for evidence of PSP toxin. The term Symptoms of 143 people with paralytic “certified beach” is used in Alaska, but a certified beach is the remainder of the sampling schedule. This massive most deadly were safe to eat. Such a long retention time could extend shellfish poisoning, Alaska, 1973-94 into the fall season. Other shellfish like the butter clams one that has passed a fecal coliform test. This test certifies a testing program has not found PSP levels that exceed the Butter Clam beach free from sewage-caused pollution and indicates the FDA standard. The same is true for the littleneck clam can chemically bind PSP toxin and retain it for as long as µ two years. shellfish are free of human pathogens like cholera or fishery in Kachemak Bay. However, reliance on commer- Symptom Number Toxicity: 7,750 g toxin hepatitis. cial fishery sampling has a major drawback since you do Paresthesia (tingling on skin) 113 Is there an antidote for PSP? not have immediate knowledge of the commercial fishery Perioral (lip) numbness 64 Pacific Razor Clam Can I test for PSP in shellfish by chewing a small PSP test results. Perioral (lip) tingling 61 No. PSP is a neurotoxin that blocks movement of sodium Toxicity: 3,294 µg toxin piece of shellfish tissue and see if I feel tingling in Nausea 45 through membranes of nerve cells. Without sodium Shellfish from other locations around the state—southeast Extremity numbness 43 transmission, nerve cells cannot function. This leads my lips? If no tingling or numbness occurs, is the Alaska, Prince William Sound, Kodiak, and the Aleu- Extremity tingling 39 Alaska Razor Clam ultimately to the symptoms of PSP: numbness, paralysis, shellfish OK to eat? tians—have PSP toxin problems. Commercial harvest of Vomiting 34 µ respiratory failure, and coma. There is no specific antidote Toxicity: 3,294 g toxin No. Only a mouse bioassay is approved by the U.S. Food shellfish in these areas requires certification of the Weakness 33 to stop the effect of PSP toxicity. and Drug Administration for detection of PSP toxins. The harvested batch before marketing. Again, as a personal use Ataxia (immobility) 32 test procedure first extracts PSP toxins from 150 grams of harvester, you do not have access to the PSP test results. Cockle Is there a treatment for PSP? Shortness of breath 29 shellfish tissues. The extract is injected into 3 Swiss Dizziness 28 Toxicity: 2,252 µg toxin Yes. Induce vomiting by sticking a finger down the throat, Webster strain white mice 18-23 grams in weight. The Does cleaning the intestinal contents of the Floating sensation 24 drinking warm saltwater, or taking Syrup of Ipecac to expel amount of time required for the mice to die is recorded then shellfish make them safer to eat? Dry mouth 23 µ shellfish from the victim’s stomach. Treat the victim for converted to micrograms ( g) of toxin by substitution into a Diplopia (double vision) 19 Purple Hinge Rock Scallop prescribed mathematical formula. Sometimes. The digestive tract of the shellfish is the first µ shock and transport to a medical facility. Application of life tissue to accumulate PSP toxin from the food they Dysarthria (difficulity speaking) 16 Toxicity: 2,000 g toxin support services at the medical care facility may be Diarrhea 10 Chewing on a small piece of shellfish gives you no clue as to consume, and cleaning the intestinal contents can reduce necessary to sustain the life of the victim. Reduction of your risk if done during the early part of the toxic bloom.