sign in sign up
<<
Home , Eastern oyster, Oyster, Pacific oyster

University of California, Davis Department of Science

CALIFORNIA CULTURE History of the Industry planted into San Francisco Bay. However, 1850-1878: California's oyster and cool summer water temperatures prevented oyster industry have had a rich and successful natural reproduction of the Eastern colorful tradition. The fishery began in the oyster. As the demand for increased, 1850's when Eastern immigrants with an ap- small one-inch seed oysters from the East petite for oysters were attracted to California Coast were transplanted for further growth in by the prospect of gold and new opportunities. San Francisco Bay. The Shoalwater Bay trade The dramatic increase in population and re- for Olympic oysters was gradually terminated sulting market pressure for oysters had imme- and, from 1872 until the early 1900 's, Califor- diate impact on the state's resources. nia 's San Francisco Bay indus- Natural occurring populations of the only try was the largest oyster industry on the West native oyster, conchaphila (Ostrea Coast. Maximum production was reached in lurida), declined rapidly because of intensive 1899 with an estimated 2.5 million pounds of . In response, native oysters were trans- oyster produced. ported from Shoalwater Bay, 1900-1939: With California's population and (Willapa Bay) and later from other bays in the industrial growth came a degradation of water Pacific Northwest and Mexico. This repre- quality in San Francisco Bay. By 1908, East- sented the initial attempts at oyster culture on ern oyster production fell by 50 percent. By the West Coast. The oysters were transplanted 1921, the quality of oyster produced into San Francisco Bay where they were main- declined to the extent that shipments of seed tained on oyster beds and then marketed (Continued on page 2) throughout central California. The Shoalwater Bay trade of Olympic oysters Contents dominated the California market from 1850 History of the Industry ...... 1 1850-1878...... 1 through 1869. Market demand for a larger, 1875-1899...... 1 half-shell product stimulated experiments in 1900-1939...... 1 transporting the Eastern oyster ( Introduction of the ...... 2 virginica) from the Atlantic states to the West 1940-1980...... 2 Coast. Several failed attempts were made to 1980-Present ...... 2 establish transport of the Eastern oyster to Production Bays ...... 2 California by sailing ships. Successful trans- Culture Techniques ...... 3 port of oysters was achieved only after the Production and Markets ...... 3 completion of the transcontinental railroad. Shellfish Safety...... 4 Biology of Oysters...... 4 1875-1899: In 1875, transcontinental trade for Native and European Oysters ...... 5 Eastern oyster seed was established. Ship- Pacific, Kumamoto and Eastern Oysters ..... 5 ments of market-sized oysters were transported Future of the Industry...... 6 by rail in barrels of sawdust and ice and trans-

ASAQ-A07 1 2-96 University of California, Davis Department of Animal Science from the East Coast were terminated, and by industry initiated other significant changes. 1939, the last of the San Francisco oysters were These included the development of U.S.- based commercially harvested. Oysters were still shellfish hatcheries and the ability to ship transported and held in Tomales Bay until they advanced oyster larvae for setting on cultch in could be marketed in San Francisco, but the heated tanks at remote growout locations. industry, based on the Eastern oyster, did not Currently, over 98 percent of the oysters grown recover. The industry and state began re- in California are Pacific oysters produced from examining earlier experimental plantings with hatcheries in Washington and Oregon and from the Pacific oyster. several smaller specialty hatcheries located Introduction of the Pacific Oyster: In 1929, within the state. Oyster larvae shipped by the California Department of Fish and Game millions are set on the mother shell, or as (CDFG) and commercial companies made cultchless seed where the larvae is set on a experimental plantings of Pacific oysters loose substrate such as sand or crushed shell. (Crassostrea gigas) in Tomales Bay and The latter, a prime California product, results Elkhorn Slough. In the 1930's, experimental in oysters grown as individuals instead of plantings continued in a number of bays, in- clusters attached to a mother shell. cluding Drakes Estero, Bodega Lagoon, Morro, The West Coast hatcheries produce several Newport, and San Francisco Bays. Humboldt and varieties of oysters including the Bay was excluded from plantings as the CDFG Miyagi variety of the Pacific oyster was trying to re-establish natural populations (Crassostrea gigas) and, to a lesser extent, the of native oysters. Several Pacific oyster plant- Pacific Kumamoto oyster (Cassostrea ings proved successful, demonstrating that sikamea). Other minor species produced by imported Pacific oyster seed could be grown hatcheries over the years include the European commercially in California. oyster () and the Eastern oyster 1940-1980: The initial shipments of Pacific (Crassostrea virginica). The ability to ship oyster seed from that began in the 1930's oyster larvae long distance and set the spat at were suspended from 1940 through 1946. the growout areas has significantly reduced the Shipments of oyster seed from Japan were cost of seed. Although the industry as a whole reinitiated in 1947. The seed was inspected in uses domestic seed, small shipments of Japan by CDFG personnel who were looking Japanese seed were periodically imported to for organisms considered harmful if introduced maintain these trade channels as insurance into state waters. Boxes containing old oyster against problems in the domestic hatchery shells (mother shell; cultch) with attached system. The last shipments of Japanese oyster young oysters (spat) were shipped by boat and seed were received in 1989. the industry began its recovery on the West Production Bays Coast. The CDFG lifted its restriction on The production activity within the various bays Pacific oyster seed in in l953, has varied throughout the years, primarily and in the next thirty years, the California based on water quality, site selection, and the industry showed rapid growth. Production was financial viability of oyster operations. Grow- centered in Humboldt Bay, Drakes Estero, ing areas are leased from the state through the Tomales Bay, Elkhorn Slough, and Morro Bay. Fish & Game Commission, Harbor Districts, 1980-Present: In the early 1980's, the oyster (Continued on page 3)

ASAQ-A07 2 2-96 University of California, Davis Department of Animal Science and Navigation Districts. Current production by a tube spacer and the lines are secured to is primarily in Humboldt Bay, Drakes Estero, hang over the rails of racks that are positioned Tomales Bay and Morro Bay. The industry in the bay. Another method, stake culture, periodically tests the feasibility of offshore consists of three mother shells separated by culture of oysters in the Santa Barbara Channel spacers and threaded on a solid stake that is and cultchless oyster production in San Diego driven into the substrate. This method is used Bay. Tomales Bay has recently experienced a in selected shallow areas within the bay. resurgence of production by growers using Tomales Bay growers use a variety of off- cultchless seed and targeting the half-shell bottom techniques including rack-and-bag, markets. At present, about 90 percent of the stake culture, bag and longline, and Stanway state's oyster production is based on cultched tube culture. Rack-and bag culture uses cultch- oyster seed and occurs in Humboldt Bay and less seed that is first grown in trays and then Drakes Estero. transferred to mesh bags that are positioned on Culture Techniques low racks placed in the bay. Bag and longline A variety of oyster culture methods are being culture use cultchless seed in mesh bags that used within the oyster producing areas. Each are attached to an anchored line which sus- production method depends upon the physical pends the bags in the water or secures the bags characteristics of the production bay and the on a stable, hard bottom, intertidal area. Stan- need to protect the younger oysters from preda- way tube culture consists of mesh tubes con- tors such as bat rays, rock , and drills taining oysters that rotate as they pivot about (). Culture methods are influenced by an axle as the change. This method factors such as substrate type, current velocity, reduces the labor involved in hand moving the tidal range, and . containers to maintain the more uniform shape California oysters are grown from spat to of the cultchless oyster. market size in 13 to 18 months, depending on Production techniques in Morro Bay include the bay and the method of culture. bottom, rack-and bag, and stake culture. Pro- The primary culture technique used in Hum- ducers in the Santa Barbara Channel have used boldt Bay is bottom culture. In bottom culture, a system of longlines with attached bags of cultch with attached spat are spread over se- oysters suspended from offshore racks in the lected areas in the bay and the oysters grown to deep waters. San Diego Bay producers have a size of about four inches. The oysters are used rack-and-bag culture for oysters, but have then harvested by hydraulic dredge. Some off- switched to the culture of . bottom techniques are used, including bags of Oyster Production and Markets oysters supported by low racks and oyster bags Total annual oyster production for the state was attached to longlines. about 1.5 million pounds of shucked meat in Drakes Estero has one of the largest off- 1995. Shucked oysters are marketed as meat bottom, rack culture systems in the country. packaged in gallon containers and in 8-and 10- Off-bottom culture is used primarily to avoid oz jars. The shucked product is marketed as predators. Other advantages include greater small (200/ gallon), medium (140/gallon), and use of the water column and less silt accumu- large (100/gallon). lating on the oyster. The system of rack culture Oysters are also marketed in the shell as shell- uses mother shells containing spat that are (Continued on page 4) strung on lines. Each mother shell is separated

ASAQ-A07 3 2-96 University of California, Davis Department of Animal Science stock. Prime markets for shellstock include The Biology of Oysters the half-shell and oyster markets. Oysters are bivalve mollusks that exhibit a Shellstock is marketed as small (2.5-3.5 variety of sizes, shapes, shell textures and inches), medium (3.5-4.5 inches), large (4.5+ colors, and vary in their mode of reproduction inches), and clusters (attached, mixed). Pre- and sexual expression. These biological and mium shellstock include “selects,” which are physical features influence such aspects as individuals chosen from the production lines of where they grow and how they reproduce, producers that grow cultched products, and which in turn influence commercial aspects from cultchless oyster production companies. such as culture practices and marketing strat- The demand for oyster products far exceeds the egy. Individual oysters conform to the shape of state's production level, and the majority of the substrate to which they are attached and are shellfish products consumed in the state are therefore highly variable in shape. Shape is imported from the Pacific Northwest and, to a also influenced by other oysters or substrates lesser extent, the Atlantic and Gulf states. The pressing on their shells. Shell shape, texture, California product is considered prime and the and color are all influenced by the oyster's production areas are among the best in the genetic makeup and the physical environment country. such as salinity, attachment substrate, and Shellfish Safety food. They feed on phytoplankton and The safety of shellfish products is part of the nutrient-bearing detritus by pumping water market attraction of the California product. over their , which filters the food material The California Department of Health Services and passes it into the oyster's mouth. (CDHS) has regulatory authority over the All oysters have typical molluscan commercial shellfish industry. The Depart- larvae that develop into a larval form ment conducts regular monitoring programs capable of filtering food, swimming, and that determine growing area sanitation and selecting a suitable substrate for attachment. safety conditions. Two essential programs are The microscopic veliger settles, cements its left the monitoring of the bays for indications of valve to the substrate, and undergoes metamor- contamination by and for the phosis into an oyster spat. For the rest of its occurrence of natural biotoxins, such as para- life, the attached spat will compete for space lytic shellfish poison produced by toxic phyto- and nutrients and, if it survives, will grow into . These two monitoring programs the adult form. The four oysters now found in provide a safe product for the consumer and California all belong to the same family. They also provide an early warning system for peo- represent two groups characterized by biologi- ple sport-harvesting shellfish in noncommer- cal variations, including different modes of cial areas. The water and meat quality moni- sexual expression, reproduction, and dispersal toring programs also provide an assessment of of young. The exact temperature at which the the biological condition of the natural re- oysters will and the rate of larval devel- sources of the bays in the hope of preventing a opment and growth depend on a variety of repetition of events that led to the contamina- factors, including the genetics of the species tion of San Francisco Bay. and variety and the latitude of the breeding population. Natural spawning is also influ- enced by lunar periodicity and tides. (Continued on page 5)

ASAQ-A07 4 2-96 University of California, Davis Department of Animal Science Native and European Oysters their interior is colored as shades of olive- ( Ostrea) green or with a metallic sheen. The adult Native and European oysters are rhythmical internal shell's muscle scar is usually centrally consecutive ; they can change located and not pigmented. sex either annually or within a closer interval. In California, the Native oyster is found in In their first year, they are strongly protandric many of the state's coastal inlets, especially (i.e. the first expression of sex at maturity is mud flats and gravel bars located near the male). They may become female in the same mouth of small rivers and streams. It cannot year or in the following year if the environ- withstand high temperatures or frost when mental conditions are good and food is plenti- exposed and does not survive low salinity or ful. They are also larviparous (brooders); turbid water conditions. In bays, the natural fertilization of is internal and the larvae beds are invariably located in the subtidal zone are held for awhile before release. Mature, where the oyster is better protected from both -carrying females spawn at about 59-63° prolonged hot summer surface water tempera- F. The eggs are released into the female's tures and extreme cold winter water conditions. own cavity and are fertilized as she They are often found clinging to rocky outcrop- takes in water containing the male's . pings or other structures that offer protection When the eggs hatch, the veliger larvae are from rays and other predatory fish. held by the gillblades and incubate for about European Oyster: European oysters are 10 days before release. Once expelled, the hatchery produced on the West Coast. Adults advanced larvae swim freely and feed on are about three-to four-inches in length, with a phytoplankton for an additional period before poorly developed beak that gives the valves an settlement and (Native, 14-18 oval to round shape. The left or attachment days; European, 10-14 days). valve is larger and deeper-cupped than the right Native Oyster: The Native oyster is Califor- valve, with 20 to 30 ribs and irregular, concen- nia's only indigenous oyster species, and tric lamellae. The upper, smaller valve is flat, occurs along the Pacific Coast from Sitka, with numerous concentric lamellae but no ribs. Alaska to Cape San Lucas, and Baja Califor- The hinge ligament consists of three parts: a nia. The largest concentrations occur in the middle flat part on the left valve and two pro- Pacific Northwest along the coast of Wash- jections on the right. The internal valves are ington's and in Willapa Bay. white and the muscle scar is eccentrically Although still grown commercially in Wash- positioned and not pigmented. ington in specially constructed beds, natural Pacific, Pacific Kumamoto and Eastern concentrations are not abundant enough to Oysters (Genus Crassostrea) support a commercial fishery. In California, The Pacific, Kumamoto and Eastern oysters are populations of the Native oyster are still alternative hermaphrodites; sex change occurs, relatively low and it is a protected species. but its timing is erratic. They have a tendency The adult Native oyster is about two-to three- for protandry in their first year, but the ten- inches in length and more often irregular in dency is not as strong as that of Native and shape. Shell textures vary from smooth to European oysters. They are oviparous rough with concentric growth lines and the (broadcast spawners); the eggs are immediately exterior has purple-brown to brown axial (Continued on page 6) bands. The two shell valves are symmetrical;

ASAQ-A07 5 2-96 University of California, Davis Department of Animal Science released and fertilization takes place in the West Coast from Ariake Bay, Kumamoto environment. Mature, egg-carrying females Prefecture, Japan. It was once considered a spawn at about 63-77° F, depending on the variety (Kumamoto) of the Pacific oyster, but species, variety, and latitude. These oysters recently elevated to species status through require higher water temperatures to establish a genetic studies conducted at the University of natural population than are consistently found California, Davis, Bodega Marine Laboratory. in California. Since spawning and successful Additional studies show that Kumamoto sperm reproduction rarely take place in California, the cannot fertilize Pacific oyster eggs, but the oysters are spawned and reared in shellfish opposite cross produces viable hybrids. hatcheries at about 77° F. The eggs hatch into Eastern Oyster: Adult Eastern oysters may free-swimming and then into vary in length from two-to six-inches. The veliger larvae; within three to five days, these shells are asymmetrical, highly variable in settle, attach to a substrate, and metamorphose texture and shape. The external shell is usually to the spat. a shade of gray and the internal valves are Pacific Oyster: The adult Pacific oyster white with a variable-colored muscle scar, averages about four-to six-inches in length. It usually deep purple. The left valve is longer has large, cup-like shells (valves) with coarse than the right and not deeply cupped. The shell and widely-spaced concentric lamellae. The beak is usually elongated and strongly curved. exterior of the shell has coarse ridges, is thin- The shell margins are usually straight or only ner than that of Eastern oysters, but is more slightly undulating and the inner margins of the deeply cupped. The upper valve is flat and valves are smooth. smaller than the lower (left) valve. The inter- Although not grown in abundance as that of the nal surface is white, often with a faint purplish Pacific oyster, the Eastern oyster remains a stain over the muscle scar or near the edges. valued aquaculture species on the West Coast. The edges of the mantel are deeply pigmented. It is primarily a half-shell product and is still Introduced from Japan, the Pacific oyster is popular among West Coast consumers. now grown in Alaska, , Washington, Future of the Industry Oregon, and California. It is the most common oyster grown on the West Coast and the most The rapid growth in California’s population common variety cultured is the Miyagi. Other has brought increased environmental and social common names used for the Pacific oyster pressures as more people move into the state’s include Japanese Oyster, Gigas, and Magaki. coastal zone. Increased population and human activity continue to have negative impacts on Kumamoto Oyster: The adult Kumamoto the environmental quality of nearshore water oyster is about three-to four-inches in length, and competing interest groups view and value slightly smaller than the Pacific oyster, and coastal resources differently than that ex- demonstrates slower growth. The shell is dark pressed in earlier decades. Nationally, it has gray to purple, wrinkled in appearance, and the been estimated that because of declining water right valve has ridges running toward the quality, available approved oyster-growing margin that give it a wavy appearance. The areas are lost at a rate of 1.0 percent annually. Kumamoto is highly valued as it has a deeply In recent years, the actions of the California cupped left valve and a high ratio of meat shellfish industry and environmental groups weight to total weight. (Continued on page 7) The Kumamoto oyster was introduced to the

ASAQ-A07 6 2-96 University of California, Davis Department of Animal Science have brought local and state-wide attention to ment of development which will, in the issue of water quality. This attention has turn, result in improved lines of commercial contributed to actions that have reduced the oysters. The diversity of product and produc- rate of decline in coastal water quality, but the tion of cultched and cultchless oysters using overall trend is still somewhat negative. new production technology has stimulated new One of the strongest arguments for a strong growth in the industry and has opened addi- shellfish industry is its position as the “canary tional growing areas. One of the more innova- in the mine.” As long as the shellfish industry tive adaptations has been the production of exists, the bays and other shellfish growing- polyploid oysters, or sterile oysters with an areas will be monitored for water quality to extra set of chromosomes. Oysters that do not assure human health safety. The monitoring produce eggs or sperm do not develop a strong programs, including coliform, chemical, and taste and remain in prime market condition biotoxin analysis, are concentrated to a greater well nto the summer months. These technical extent in commercial shellfish production advances are designed to make the shellfish areas. These activities are one of the greatest industry more competitive within the market deterrents to resource exploitation by any place which will result in a stronger industry. group using the coastal zone, including the References & Selected Readings shellfish industry itself. Commercial growers Barrett, E.M. 1963. The California Oyster view the maintenance of coastal water quality Industry. Calif. Dept. Fish and Game Bull. No. as the first line of defense against the loss of 123, pp 103. the industry. Bonnot, P. 1935. The California Oyster Indus- The California oyster industry is the oldest try. California Department of Fish and Game. aquaculture industry in the Western United 21(1):65-80. States. Despite its age, California and the Conte, F.S. and J.L. Dupuy. 1982. The Pacific oyster industry have demonstrated California Oyster Industry. Proc. North Ameri- some of the most innovative adaptations to can Oyster Workshop, World changing times and changing conditions. The Society, Special Publication No. 1. pp. 43-63. development of the hatchery system and re- mote setting of oyster larvae is a West Coast Conte, F.S., S.C. Harbell, and R.L. phenomena that has demonstrated economic RaLonde. 1994. Oyster Culture: Fundamen- advantage and has had international impact. tals and Technology of the West Coast Indus- Hatchery production has led to the develop- try. WRAC Pub. No. 94-101. Sectional Publi- cation (Releases in 1994 and 1996).

Fred S. Conte Department of Animal Science University of California, Davis

The University of California Cooperative Extension in compliance with the Civil Rights Act of 1964, Title IX of the Education Amendments of 1972, and the Rehabilitation Act of 1973 does not discriminate on the basis of race, creed, religion, color, national origin, sex, or mental or physical handicap in any of its programs or activities. Inquiries regarding this policy may be directed to: Affirmative Action Officer, 317 University Hall, University of California, Berkeley, California 94720, (510) 642-0903. University of California and the Department of Agriculture cooperating.

ASAQ-A07 7 2-96