Geoducks are clams, so recreational digging on public beaches is permitted only when the clam season on a particular public beach is open. Clam seasons vary from beach to beach, and from year to year, so check the annual Sport Fishing Rules pamphlet or this website to find the current rules. Geoducks may be taken with a hand-operated instrument only. It is unlawful to thrust any instrument through the "neck" (siphon) of a geoduck, and it is unlawful to possess only the siphon of a geoduck.The daily limit, unchanged for over fifty years, is three geoducks per person. These must be the first three you dig, since adult geoducks will not survive replanting.

You'll also need a tide chart, available at sporting goods stores and in many phone books, to find the days and times of low tides. Most geoducks are exposed only during low tides of -2.0 feet or below. Such tides generally occur during daylight hours only from mid-April to mid-August.

You'll generally need to excavate a hole up to three feet deep to unearth a geoduck. Many people use a big metal or plastic tube to prevent the sides of the hole from collapsing while digging. The tube needs to be wide enough so that you can reach in with a shovel and move the sand and mud out. Some harvesters buy a galvanized garbage can and cut out the bottom, although the angled sides occasionally make it difficult to remove the can from the hole. Other harvesters use a three-foot length of commercial heating/air-conditioning duct (18-inch width). Still others weld a sheet of aircraft aluminum into a tube , or make a tube with PVC (see photo below).

Using a PVC tube for geoducks.

To avoid being cut by the sharp edges in all these homemade tubes, you should cover the top rim with a protective layer of flexible tubing or duct tape. Stainless steel and plastic tubes made especially for geoduck digging are also commercially available. The only other equipment you really need is a good shovel and gloves. Some harvesters prefer a posthole digger to a shovel. And don't wear your good clothes; you're going to get plenty dirty digging for geoducks.

Getting dirty digging for geoducks.

Geoducks accessible to sport harvest are generally found in sandy or muddy ground and live at depths anywhere from 18 inches to four feet below the surface of the beach. Identification is made by the appearance or feel of the siphons, which are covered with smooth, leathery skin and do not have horny plates attached to the tip. Barnacles and seaweed rarely attach to the tip of geoduck siphons. The two halves of the siphon are joined along their full length, rather than being split. The entire siphon tip has an oblong shape when viewed from the top, and usually measures about two inches across when the siphon is open. Neither of the siphon openings has an inner row of tentacles or "fringe," and the siphon walls are thick. The exterior of the siphon is usually a creamy brown. When the siphon is partially withdrawn, an oblong "dimple" often remains in the substrate, sometimes surrounded by small pellets (pseudofeces).

If you are lucky, the geoduck siphon will be exposed above the surface of the substrate, with both halves of the siphon open as shown in these two photos (Click on photos to enlarge).

You are more likely, however, to find siphons that are partially or fully withdrawn, as shown below.

The siphon near the center of the photo is partially withdrawn, and closed. A second geoduck siphon appears in the upper right, completely withdrawn but leaving a hole at the surface. You would need to probe this hole with your fingertip to determine if it was a geoduck or some other species.

Can you spot the geoduck siphon in this photo? Click on the photo to see location of siphon.

Geoducks are most often confused with two other clam species: piddocks (Zirphaea spp.) and horse clams (Tresus spp.). Piddocks are boring clams that live only in clay, shale, hardpan or wood (although sometimes these substrates are covered by a thin layer of sand or mud). Geoducks cannot bore into these hard substrates, and therefore are never found in clay or hardpan. A piddock siphon has a split tip that is usually obvious when the siphon is open, and very thin siphon walls. Unlike the geoduck siphon, which has a leathery feel, the piddock siphon feels slippery and slimy. The exterior of the piddock siphon also has a pattern of tiny white bumps and ridges set against a dark brown background.

Piddock siphon.

Horse clam siphons are frequently mistaken for geoduck siphons, although when they are open it's easy to tell the difference: horse clam siphons have an inner ring of tentacles near the tip (as seen in the photo below), geoduck siphons have no tentacles.

Horse clam siphon, note tentacles.

This photo shows a partially withdrawn horse clam siphon. It looks very similar to a geoduck siphon, so you would need to probe with your fingertip to determine which species it was.

Some harvesters wait until the tide is out to look for siphon "shows" or "dimples." Others like to wade in about six to eight inches of water as the tide recedes. This technique often makes it easier to spot siphons that are fully extended and pumping, but it only works if visibility in the water is good. When the water is stirred up by wave action and wind, you'll need to wait until the tide recedes to look for siphon shows. Many people like to flag siphon shows with a small marker, so that they can come back later, even after the siphon retracts, to dig the geoducks.

Once you've located a geoduck siphon, you can begin digging. As soon as it is disturbed, the geoduck will retract its siphon downward, but the geoduck itself cannot move, so you can take your time digging. If you've got a can or tube, center it on the siphon show, and force it down around the siphon as far as you can. Some diggers like to place a length of 2x4 across the top of the can, standing on it to force the can into the substrate.

Others simply balance themselves on the can rim itself.

Then carefully dig out the sand and mud, without slicing the siphon. As the hole is excavated, it's usually possible to force the can further down.

Excavating the hole to expsose the siphon.

A few hardy souls prefer to dig before the tide has receded, while the substrate is still soft and soupy. Once the can is in place, they partially excavate the hole using a razor clam gun and then complete the job by breath-hold "diving" to loosen the geoduck as shown here (photo by Nanette Stark).

But whichever harvest method you choose, remember that teamwork is essential when digging geoducks

Rinse the clams well with seawater, then keep them moist by putting them in a wet gunny sack or covering them with wet cloth. Before leaving the beach, refill the holes you've dug. Failure to fill holes is extremely damaging to many species of clams. Small seed clams are smothered and killed by high earth piles left after digging, while other clams are killed by the higher temperature of water that collects in unfilled holes. Harvesting regulations require that all holes created while digging clams must be refilled. Failure to do so may result in fines of up to $75 per hole.

How to Clean a Geoduck

Blanch the entire clam in boiling water for ten seconds (no longer!). Using a paring knife, carve the clam away from the shell. Use gloves for this process to prevent slicing your hand on the sharp shell edges. Separate the viscera (gut) from the meat of the "neck" (the siphon) and the "breast"(the mantle, or tissue at the base of the siphon and along the shell margins). Peel the skin off the siphon and mantle; it should slip off like a glove. Wash the clam thoroughly. Split the siphon by inserting a knife or scissors and cut the siphon lengthwise. Wash the siphon, removing all traces of sand and grit. The meat below the siphon is the breast meat, and may be split down the median line and cut into small lengths. Once the tough outer skin is removed, the remaining breast meat is quite tender. The siphon meat is much firmer. It can be sectioned and pounded gently with the smooth side of a meat mallet to tenderize the sections into thin steaks. Tenderizing is not necessary if you intend to use the siphon meat in chowder or if you intend to eat it raw as sashimi, sushi or ceviche.

Geoduck Enhancement on Public Beaches

WDFW began enhancing certain public beaches with hatchery-reared juvenile geoduck "seed" on an experimental basis in 1991. The seed, roughly a half-inch in size, were produced at WDFW's Point Whitney shellfish hatchery beginning in the 1980s and were first planted experimentally on subtidal plots. Since that time, a total of 15 public beaches have been planted with geoduck seed, the most recent plant taking place in the year 2000. Of these 15 beaches, only 10 remain suitable for future plantings and only two have significant numbers of harvestable geoduck remaining. An additional five beaches could be considered suitable based on successful small-scale tests.

Few public beaches are suitable candidates for geoduck seeding. Obviously, there is no need to seed beaches that already have abundant natural populations of geoducks. Many beaches have unsuitable substrate, or are subject to heavy wave action that would dislodge the plastic tubing used to protect geoduck seed during their first year on the beach. In order to protect eelgrass beds, geoduck enhancement does not occur on public beaches near such beds. Likewise, geoduck seed is not planted on beach areas that already contain significant populations of other clams or oysters.

Even on suitable public beaches, WDFW's geoduck seeding takes place on a very small spatial scale. Planting areas range from a tenth of an acre to a half acre in size, within a tidal range of +3 to -3 feet. Predation on the juvenile clams require that they be protected at planting with short pieces of PVC tubing, each tube covered with a piece of netting. This technique, which has been adopted by commercial shellfish growers in both Washington and British Columbia, was first conceived and developed by WDFW biologists at the Point Whitney facility in the late 1980s.The tubes are installed by hand at a density of one per square yard, and each tube is then seeded with four juvenile geoducks. The tubes are all removed by hand a year later, at which point the surviving juvenile clams have reached a depth refuge from predators of roughly one foot. The planted areas are typically closed to clamming for four years to protect the young geoducks during their grow-out phases.

Besides involving only small areas, WDFW's geoduck seeding occurs over a very short time span. A beach enhanced with geoducks generally does not need to be replanted for another 10 years, depending on the amount of sport harvest that the beach receives. Geoducks on public beaches may only be removed one at a time, using shovels and other hand-operated equipment; the use of high-pressure water jets is not allowed on beaches open to the public.

WDFW's geoduck enhancement project has proved immensely popular with sport harvesters. At Kopachuck State Park, for example, over 6,800 people dug for enhanced geoducks in June and July 2004 alone. Prior to WDFW's geoduck enhancement in the mid-1990s, the beach at Kopachuck State Park was essentially devoid of shellfish due to natural conditions. Sport harvesters have, at this time, taken most of the enhanced geoduck at Kopachuck.

The closure of WDFW's Point Whitney geoduck hatchery facilities in 2001 ended the seeding of public beaches. Due to the difficulty in obtaining permits, WDFW is not planning further seeding of geoducks on public beaches at this time.

Geoduck Biology

Geoducks have been the subject of extensive scientific studies since the 1970s due to their commercial importance in Washington and British Columbia. Because geoducks are commercially fished by divers, and because the bulk of the population lives in deep water, virtually all the biological research has focused on subtidal populations, rather than intertidal populations on beaches.

Male and female geoducks reproduce in the spring, primarily from April to May, when increased water temperatures and plankton blooms trigger the release of sex products. Females have huge ovaries that contain many millions of eggs, but they are "dribble spawners," normally releasing only one or two million eggs during each spawning event. The largest release observed from a single female during one spawning episode was 20 million eggs. Geoducks release their sperm and eggs directly into the water, where fertilization occurs. The microscopic larvae drift with the currents for two to seven weeks, after which they settle to the bottom and metamorphose into non-swimming juvenile clams. Due to the long planktonic larval period, the young may be carried by water currents many miles from their parents before settling. The newly-settled young clams have not yet developed a siphon, so they stay at or near the substrate surface for several weeks until and adult siphon develops. At this point, they are able to dig into the substrate. Geoducks pass through seven distinct life stages from fertilized egg to adult clam.

Geoducks have been successfully spawned in the laboratory, and biologists at WDFW's Point Whitney Shellfish Laboratory in Brinnon were the first to produce geoduck larvae on a large scale. The hatchery-reared "seed" was planted on public tidelands beginning in 1991. Commercial aquaculturists later adapted WDFW's hatchery and planting methods on a large scale, and geoduck farms on private tidelands are now responsible for a growing share of the commercial market.

Juvenile geoducks are good diggers, and generally reach a depth of about a foot within their first year of life. As they become older, however, geoducks lose the ability to dig and become completely sedentary. Contrary to popular belief, the geoduck does not dig down to escape capture, since the adult's muscular "foot" is too small to permit active digging. However, the retraction of the long siphon frequently gives the impression that the clam is "escaping" like a razor clam. In fact, the body of an adult geoduck remains in one spot for its entire life.

Yet few geoduck larvae survive to reach adulthood, and "recruitment" - the percentage of the total population composed of clams less than about three years old - is roughly 2%. This is normal for an animal population where the annual death rate averages about 2% for adult clams. The death rate of geoducks has been estimated from the accumulated age classes of clams in natural populations, and also from WDFW tagging experiments, where plastic rods were placed next to geoduck siphons and monitored over the course of a year.

Young geoducks are most susceptible to predators - including shrimp, crabs, flounders, sea stars, and snails -- near the surface of the seabed. Once the clam buries itself deeper than two feet, it is beyond the reach of virtually all but human predators.

Geoducks can only be reliably aged by cutting a micro-thin section from the hinge of the shell and examining it under a microscope. This reveals a series of annual lines similar to tree rings that reflect the growth of the clam's shell over time. After about 15 years of age, the shell grows only minutely, but these closely spaced rings can usually be read under high magnification with reasonable accuracy. To date, the oldest aged geoduck from Washington was an impressive 163 years old, while British Columbia researchers have aged a 168-year old specimen. Undoubtedly, older specimens will be aged as research continues. It is important to note, however, that only a very small proportion of the total geoduck population attains this advanced age. The average age of adult geoducks (those more than about 3 yrs old) on unfished subtidal beds, for example, is 46 years.

Adult geoducks use their siphon to feed, filtering the water for microscopic plants called phytoplankton. Geoducks become far less active in the winter months, when phytoplankton is scarce, and they spend a considerable amount of time with their siphons retracted between October and February.

Geoducks grow rapidly when they are young, adding more than an inch per year to their shell in the first 3-4 years in some areas. Average size varies greatly among locations, and geoducks grow larger in sand, or a mixture of mud and sand, than in pure mud or gravel. Geoducks growing in areas with large rocks, gravel or shell debris often have misshapen shells.

Commercial Geoduck Harvest