RECENT DEVELOPMENTS IN SHELLFISH CULTURE ON THE U.S. PACIFIC COAST

Two species of oysters are produced in the States of Washington, Oregon, and California in the bays shown in Figure 1. The small native oyster, Ostrea lurida Carpenter, 1863, is found in all three states, but is raised commercially only in the southern part of Puget Sound, Wash. Production is low, but prices are extremely high since this oyster is served as a specialty in seafood restaurants.

The major species produced on the West Coast of the United States is the ''Pacific" oyster, Crassostrea gigas Thunberg, 1793, which was first introduced from Japan about 40 yr ago. Except for the period 1941-46 seed oysters have been imported from Japan each year. Periodically local reproduction occurs and U.S. growers are able to augment their seed supply by collecting spat locally.

Major oyster producing areas are Willapa Bay, Grays Harbor, and Puget Sound in Washington; Tillamook, Yaquina, and Coos Bays in Oregon; Humboldt Bay, Tomales Bay, Morro Bay, and Drakes Estero in California.

The major part of U.S. West Coast production comes from Washington, as shown in Figure 2. Peak production of over 10 million pounds of shucked meats was reached in 1954 to 1956. Since that time production has decreased to a mean of 6.4 million pounds for the period 1966-70.

Oyster production in California increased rapidly from 1954 to 1957, exceeded I million pounds of meats from that time until 1965, and decreased somewhat in the following years, but again exceeded 1 million pounds in 1970.

Oyster production in Oregon reached nearly 1 million pounds per year in 1950 to 1952 and then dropped to about one-half million per year, and continues at about that level.

Several species of clams are harvested commercially on the U.S. Pacific coast. The razor clam, Siliqua patula (Dixon, 1788), and the Pismo clam, Tivela stultorum (Mange, 1823), occur on the open wave-swept ocean beaches. Although both of these species were originally harvested commercially, the growing trend toward recreational fisheries has resulted in a disappearing commercial fishery. Only a few areas remain on the Washington coast where commercial harvesting of razor clams is still permitted; but each weekend during the open season up to 25,000 recreational diggers attack the beaches hoping to obtain their limit of 18 clams each.

Other species grouped in the category of "hard" clams found in protected bays and inlets provide a significant commercial fishery. Species include the native littleneck or rock clam, Protothaca staminea (Conrad, 1837); the butter clam, Saxidomus nuttali Conrad, 1837; and the introduced Japanese littleneck or "Manila'' clam, Tapes semidecussata ( Reeve, 1864).

The commercial demand for hard-shell clams is very good and prices are high in comparison to oysters. Production does not meet the demand and significant quantities of hard-shell clams are imported from British Columbia, Canada. There is very little "farming'' of these clams and production is based on harvesting natural populations, principally upon privately-owned or privately-leased intertidal lands.

Clam production on the U.S. Pacific coast is centered in Washington with production ranging from 400,000 to nearly 1 million pounds of meats per year, as shown in Figure 3. Although production has varied during the past 20 yr, no clear production trend is evident from these records which include all species of clams. Decreases in commercial production of razor clams are largely offset by increased harvests of hard clams.

The few protected bays and inlets along the Oregon coast produced between 100,000 and 200,000 pounds of clam meats per year for the period 1948-55 and have since dropped to a relatively low level.

Commercial clam production in California was never great and has been negligible in recent years.

In both Oregon and California the tourist demand for hard-shell clams, as well as razor and Pismo clams, has utilized an increasing proportion of the available supply.

There are several factors which help to explain the decrease in production of Pacific oysters during the past decade, as shown on Figure 4. A major factor is the limited U.S. market for oysters. The United States per capita consumption of fishery products generally has remained nearly static for a number of years at about 11 pounds, and per capita consumption of oysters during this period has actually decreased. There has been little or no market promotion by the oyster industry which is poorly organized and made up of many small companies.

Although the quality of oysters produced and marketed as a refrigerated, raw, shucked product is generally good at the time the oysters leave the plant, the delay in the distribution, especially to more distant areas, results in a significant decrease in quality.

Distribution to the Rocky Mountain and MidWest states from the Pacific coast is more difficult now because Railway Express, which utilized rapid passenger trains, has become less available as trains are being discontinued because of the general trend toward air travel. Transportation of oysters by air to many of these locations is not economical because of the small volume to be shipped. All of this has resulted in curtailment of oyster markets in a large portion of the United States.

Another factor is the competition for the fresh-oyster market from East Coast or Gulf of Mexico, the American oysters, Crassostrea virginica Gmelin. Much of the production in these areas is from public beds which results in a low price when oysters are abundant, and a high price when oysters are scarce.

Oyster production on the Atlantic coast was generally low for several years following the major mass mortalities of oysters caused by the Haplosporidian Minchinnia nelsoni which began in Delaware Bay in 1957 and spread to Chesapeake Bay during the following 2 or 3 yr. During this period the demand for Pacific oysters expanded and prices increased during the years 1960-61 and again between 1966 and 1967. More recently, production of low-priced oysters on the East Coast has increased, causing a reduction in market demand for Pacific oysters. Market price of oysters on the Pacific coast has remained static for the past 4 yr even though costs generally have increased during this period, as indicated by Table 1 and Figure 4.

The price per gallon of oysters shown in Table 1 is somewhat misleading since this is the price paid by wholesalers for shucked oysters delivered to Seattle, Wash., for the fresh-oyster trade. During recent years when supplies have exceeded the market demand for fresh oysters, it has been necessary to divert a part of the production into canned oysters, smoked oysters, or oyster stew. The price of oysters for a processed product must necessarily be lower than the price for fresh oysters. Therefore, the average price received by many growers was significantly less than that indicated on Table 1.

Efficient growers have reduced production during this period and now use only their best land. This reduces their costs by increasing the yield per unit area and by reducing the time required for a crop to reach marketable size.

Another factor which has increased costs has been the lack of local setting during the past 3 yr. Locally produced seed is generally less costly than imported seed, especially for those growers who are able to collect their own seed from natural reproduction. Also, the price of imported seed has increased recently and many growers hesitate to invest in seed because of the squeeze between increasing costs of production and limited demand at static prices.

In summary, production of Pacific oysters has decreased to fit the present market. Marginal producers have dropped out, and efficient producers have curtailed production. Prices have remained generally static, whereas costs have increased producing a generally unfavorable profit picture for the Pacific coast oyster industry. Given increased demand at profitable price levels, production could be greatly increased.

Hidden in the statistics, because of low volume, is a newly developed market for "specialty" oysters. These are partially grown Pacific oysters, usually marketed under the trade name "yearling" oysters. These oysters are about 3 inches in length, similar to the size marketed in Japan, and are suitable for the raw half-shell trade, oyster cocktails, stews, sauteed oysters, etc. This product has a much better market acceptance than large Pacific oysters which must be blanched and cut into pieces before cooking.

The market for yearling oysters is rather limited, production costs are high and volume is low, but these oysters sell for two to three time the price of standard-sized oysters. Turnover is rapid because of the short time required to grow marketable-sized oysters. All factors considered, several small companies have been able to improve their profit picture by producing this specialty product.

Another development is a patented process which reportedly produces superior frozen oysters. This process consists of hand-shucking, partial cooking, breading, and rapid freezing. This product retains the flavor wel! and resists oxidation during frozen storage. Although relatively expensive to produce because of the costs of hand-shucking, this product is finding good market acceptance. Frozen oysters can be shipped by surface transportation which is cheaper than the air shipment required to deliver fresh shucked oysters to distant markets.

Although off-bottom culture of Pacific oysters has been used in Japan for many years, this method has only recently gained acceptance on the Pacific coast of the United States. This is mainly because extensive intertidal areas have been available for oyster culture and production of oysters on bottom is less costly than production off-bottom.

Within the past 3 yr, however, several oyster growers have begun oyster culture using rafts or racks, and those who have been able to market a specialty product at a higher price have been quite successful. One company has constructed simple rafts using Styrofoam for flotation and suspends seed oysters on wires below the rafts in a protected part of Puget Sound, Wash. After 15-18 mo those oysters which have reached commercial size are marketed, and the rest are placed on-bottom for another growing season. These small oysters are well accepted in the Seattle market at higher than average prices, and it appears that this production method will be economical.

Several Oregon growers in Yaquina Bay near Newport, Oreg., suspend Fiberglas² trays of oysters below rafts and market these oysters at a small size in restaurants in Portland, Oreg. These growers have found that tray culture is somewhat more expensive than "string" culture, and they may discontinue the use of trays.

One company at Eureka, Calif., has an extensive system of racks placed along the banks of channels in Humboldt Bay. Oysters raised on these racks grow faster than those on bottom and are generally in better condition.

It has also been observed that mortality of oysters suspended from racks is lower than that of oysters placed directly on the tide flats. Oyster mortality on the beds in Humboldt Bay in 1971 was recorded as 40% by pathologists of the California Department of Fish and Game, whereas mortality of oysters suspended from racks was 10%.

Although rack culture generally is more costly than "on-bottom" culture and requires special locations, there is a belief that Pacific oysters raised off-bottom have a milder flavor than those raised on-bottom. An organoleptic test to compare the flavor of oysters reared under various conditions will be conducted by the Washington State Department of Fisheries and the National Marine Fisheries Service in Seattle during November 1971.

Raft culture has many of the advantages of rack culture and also provides more latitude in selection of locations since rafts can be anchored in waters of various depths. The principal requirements for raft culture are 1) shelter from storms, 2) sufficient depth. and 3) permits from local zoning authorities and Corps of Engineers for anchoring rafts.

An anticipated development is a system of growing oysters on submerged rafts or racks. This system will probably be necessary in areas where recreational use of the water surface for fishing, boating, etc. would make it difficult to obtain permission for raft culture. Engineering designs for structures needed for this type of culture have not yet been completed, but might be patterned after the submerged racks which are used in French Polynesia for pearl oyster culture to avoid storm damage and fouling.

Pacific Mariculture, Inc. near San Francisco, Calif., has patented a process of producing individual seed oysters which have several advantages. This seed is readily available at any time of the year and can be shipped economically by air freight. Survival during shipment and after planting has been excellent and the individual oysters develop a uniform shape which makes a very attractive product.

Disadvantages of "unattached" seed are that it requires special handling in screen trays, and this requires a large amount of hand labor. Growth is generally poor in trays unless there is adequate circulation of water which contains adequate food supplies. These individual oysters must be quite large before they will stay in place on oyster beds which are exposed to waves, currents, or storms. This limits the use of this seed for traditional oyster farming and requires development of new aquacultural systems. It appears that "unattached" seed will become an important factor during the next few years, provided specialty markets can be developed for the product.

During March 1971, I made experimental plantings of "unattached" Crassostrea gigas seed from the Pacific Mariculture hatchery at several locations inthe Fiji Islands. Survival of this seed was excellent and growth was satisfactory after the spat were cemented to fiberboard (Masonite or asbestos hoard) squares strung on wire or rope and suspended below rafts. It appears that this method will be applicable any place where hydrographic conditions permit the use of rafts or racks and where laborcosts are low.

Pacific Mariculture, Inc. has recently patented a method for temporarily suspending activity of mature oyster larvae. With this method it is possible to air ship large quantities of mature oyster larvae in small containers from California to oyster culture areas. At these locations larvae are placed in tanks of warm water with suitable cultch materials. Attachment is completed within 2 hr. This method avoids the cost of shipping heavy "mother" shells or other cultch materials since one-half million larvae can be shipped in a Yz-liter bottle. Oyster growers can then "set" the larvae on desired cultch materials and plant them on their oyster beds. This method needs further development to improve its reliability, but it appears probable that this will be accomplished in the near future and that this method will find application in many places.

Mortalities of 10-70% during the second or third summer after planting Pacific oyster seed has been observed at several locations along the Pacific coast. The most severe mortalities have occurred in southern Puget Sound and part of Willapa Bay in Washington, and Humboldt Bay in northern California. Negligible mortality levels have been observed in British Columbia, northern Puget Sound and Hood Canal in Washington, Oregon bays, and elsewhere in California.

Generally, heavy mortalities occur near the heads of bays which are warm and muddy with high nutrient levels, abundant phytoplankton, where oysters grow rapidly and fatten well. Mortalities generally occur during a few weeks in midsummer when the oysters are in spawning condition. It has been observed that mortalities have been more severe during warmer years.

Investigations during the past 5 yr by state fisheries agencies of Washington, Oregon, and California and by the laboratory of the National Marine Fisheries Service in Oxford, Md., have failed to detect a specific cause for this mortality. Tests for Labyrinthomyxa marina which causes extensive losses of oysters in the Gulf of Mexico and Minchinnin nelsoni which kills oysters in Chesapeake and Delaware Bays have proved negative. Although numerous microorganisms have been observed in the thousands of oysters examined from the Pacific coast, none have occurred consistently enough to indicate that they are associated with the observed mortalities.

In a new project, a graduate student at the University of Washington College of Fisheries in Seattle is investigating the relationship between the bacterium Vibrio anquillarum or V. parahaemolyticus and oyster mortalities. He has observed that Vibrio can kill oysters at elevated temperatures in laboratory experiments, but field tests have not yet been made.

Efforts of Washington State Department of Fisheries have recently been reoriented to develop new oyster culture techniques which will circumvent or offset mortalities. For example, transplanting partially grown oysters to low mortality areas before the second summer when heavy mortalities begin seems to be a practical solution. Also, improvement of handling methods for seed to reduce losses would help to offset mortality which might occur during the second summer.

In summary, mass mortalities significantly reduce production and profits in specific locations, but other areas remain unaffected. Research to determine causative factors is still in progress.

Ocean beaches on the Pacific coast are owned by the states and held for public use. This prevents the private commercial development of farming for species such as the razor clam or Pismo clam which occur only in this habitat.

The intertidal zone in bays or estuaries is also owned by the states, but much of this land, especially in the State of Washington, has been sold to individuals who are usually the owners of the adjacent upland. Large areas of intertidal zone have also been leased by the states to individuals or companies for special purposes, such as oyster and clam culture. Subtidal bottoms also can be leased to individuals or companies for aquaculture.

Farming of clams has not reached the stage of development attained by oyster culture. The few commercial clam farms on the U.S. Pacific coast still depend upon natural setting to restock their beds. Clam farming is still only selective harvesting of a natural crop to obtain the greatest yield.

Until recently there has been no source of "seed" clams which might be used for planting on private lands and this has been a major deterrent to clam farming. Now a commercial hatchery in California has successfully produced large quantities of young Manila clams and has offered these for sale. Test plantings have been made in Willapa Bay, Wash., and in some other locations, but it is too soon to evaluate the success of these ventures.

I had the opportunity in March 1971 to obtain a small quantity of these seed clams from California and to plant them in trays in the Fiji Islands. Survival of clams was excellent, but growth was not outstanding. This experiment is still in progress, but it is already apparent that the first step in the development of commercial farming for clams, availability of seed, has been accomplished. With the large demand for clams and the limited supply, it is likely that a new clam farming industry will develop in Washington State within the next few years.

Three new developments in the utilization of natural stocks of mollusks occurred in Washington. Exploratory diving and population assessment by scientists of the Washington State Department of Fisheries have shown that less than 5% of the geoduck clam, Panope generosa Gould, 1850, are exposed at extreme low tide. Before this discovery it was thought that the geoduck was a scarce species which needed stringent regulation to prevent overharvesting. No commercial digging had been permitted and the recreational or personal use limit was set at three clams per day.

Now Washington has surveyed subtidal beds and established a system for leasing areas for commercial harvest by scuba divers using suction pumps. The product is now achieving market acceptance and a new industry has been established.

Another species of clams, Mya arenaria Linnaeus, 1758, known as the soft-shell clam in New England and Chesapeake Bay, is present in Washington but has not been utilized commercially. This clam has a somewhat less attractive appearance than the local littleneck and butter clams, and traditionally it has not been marketed in the Pacific Northwest. Heavy concentrations of soft-shell clams are found in muddy or sandy beaches, usually at the mouths of rivers, but areas suitable for these species are rather limited.

Recently several individuals or companies have begun harvesting soft-shell clams using two types of hydraulic dredges to minimize labor costs. One type similar to that used in Chesapeake Bay is operated from a boat and consists of a digging head which is forced through the bottom and a conveyor to bring the clams to the surface. The second type is hand-operated at low tide, but uses water pressure to wash the clams out of the bottom.

The quality of the soft clams in Washington is comparable to those from Chesapeake Bay or New England. If harvesting and shipping costs are not prohibitive, it is likely that a new industry for softshell clams will become established in the Pacific Northwest.

Large populations of the blue mussel, Mytilus edulis Linnaeus, 1758, occur in Puget Sound, Wash., but this species also traditionally has not been fully utilized in the United States. Puget Sound mussels are comparable to the European mussels in quality and the paralytic shellfish poisoning caused by their feeding on the dinoflagellate Gonyaulax, which sometimes limits mussel harvesting along the ocean coast, is not a problem in the inshore waters of Puget Sound.

Recently, through efforts of the marketing specialists of the National Marine Fisheries Service, local restaurants have begun to serve mussels and the product seems to be gaining acceptance in the Pacific Northwest. There are substantial natural stocks of mussels which could be harvested if a market develops. Also, it would be possible to supplement natural production by applying mussel farming techniques used in Holland, Spain, and elsewhere as the market expands.

People in the United States are becoming increasingly aware of the need to protect the environment from industrial or residential development. This need is especially apparent along the shoreline where several classes of users compete for space. Shellfish farmers are finding difficulty in obtaining approval from local "zoning boards" to anchor rafts for oyster culture in areas where shoreline residents want to use the water surface for boating, fishing, water skiing, etc. Even the installation of pilings or stakes marking boundaries of shellfish beds or wharfs for unloading the product are being questioned.

At the same time there is a major effort to maintain or improve water quality in the bays and estuaries and to eliminate sources of industrial and domestic pollution. These public efforts will help to assure continuation and expansion of aquaculture which is a "clean" industry. Furthermore, aquaculture provides a good economic justification for maintaining high water quality in inshore areas.

Federal and state legislation has been passed or is being considered to establish authorities and procedures for zoning the shoreline for special purposes. If fish and shellfish farmers can present a convincing argument, it is likely that certain areas will be reserved for aquaculture with assurance that water quality will be maintained at acceptable levels.

In conclusion, oyster production on the Pacific coast is limited by demand, but the potential exists for greatly increased harvests through application of modern methods of aquaculture.

Clam production is limited by natural supply. Clam farming has not been developed but, now that seed of at least one species is available, it is likely that commercial clam culture will develop rapidly in the Pacific Northwest.

Water quality will not be a limiting factor if the present awareness of the importance of the environment is translated into action to control pollution. Coastal zoning is a threat to aquaculture in some areas but could protect those areas which are most important for production of fish and shellfish.

¹ Deputy Regional Director. Northwest Region. National Marine Fisheries Service. NOAA. Seattle. WA 98109.

² Reference to trade names does not imply endorsement by the National Marine Fisheries Service. NOAA.