Gulf of Mexico Science Volume 17 Article 6 Number 2 Number 2

1999 Biological Feasibility of Freshwater Mussel and Pearl Culture in Gulf Coast States Richard J. Neves Virginia Tech University

DOI: 10.18785/goms.1702.06 Follow this and additional works at: https://aquila.usm.edu/goms

Recommended Citation Neves, R. J. 1999. Biological Feasibility of Freshwater Mussel and Pearl Culture in Gulf Coast States. Gulf of Mexico Science 17 (2). Retrieved from https://aquila.usm.edu/goms/vol17/iss2/6

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Gulf of Mexico Science, 1999(2), pp. 103-108

Biological Feasibility of Freshwater Mussel and Pearl Culture In Gulf Coast States

RicHARD J. NEVES

Production of freshwater pearls from mussels has been shown to be a viable enterprise in Tennessee, and the freshwater enviromnents and mussel species in Gulf Coast states provide ample resources for this fledgling industry to expand. Mussel species such as the washboard (Megalonaias nervosa), threeridge (Amblema plicata), and others in rivers and reservoirs are capable of producing quality pearls once the implantation technique for pearl formation becomes more widely known. Methods for the propagation of freshwater mussels with recirculating aquaculture systems have been developed recently to allow culture of rare or commercial species. Wild-caught mussels could be replaced by cultured juveniles, such that regulated harvest in state waters would have no adverse effect on native populations. The production of quality pearls of various shapes and colors pro­ vides the economic impetus to establish a pilot pearl project on the Gulf Coast.

he freshwater mussel fauna in the south­ amine the conservation biology, fisheries ecol­ T eastern United States is very diverse be­ ogy, and sustainable economic use of freshwa­ cause of the wide variety of lotic and len tic en­ ter mussels and marine mollusks for pearl pro­ vironments. Most tributaries and main stem duction along the Gulf Coast. Thus, the prop­ rivers in the Interior Basin and along the Gulf agation and culture of commercial species of and South Atlantic coasts are rich in mussel freshwater mussels, suitable for use in pearl species. Distinct faunal assemblages are the re­ culture, are important aspects of this project. sult of historical and regional differences in In this paper, I provide a brief history of fresh­ physiography, water chemistry, and other lotic water mussel harvest and propagation efforts factors that interact to create distinct assem­ and summarize recent advancements in cultur­ blages and a high degree of endemism in these ing technology. river basins (Heard, 1970). However, a pleth­ ora of natural and anthropogenic factors have HISTORY OF MUSSEL HARVEST affected species richness in these rivers, caus­ ing significant declines and extirpations. The The exploitation of freshwater mussel shells Endangered Species Act of 1973 and subse­ in the United States for the purpose of making quent amendments provide legal protection pearl buttons dates back to at least 1800 (Cok­ for those species considered to be endangered er, 1919). However, an industry for button or threatened throughout all or a significant making did not develop until john Boepple set portion of their range. A total of 69 of the up a small business along the Mississippi River nearly 300 species and subspecies of freshwater in 1891 (Claassen, 1994). At about that time, mussels in the United States are federally listed the American garment industry began com­ as endangered or threatened, and most of mercial production of clothing, and a need these occur in the Southeast. Between 34% arose for domestically produced white buttons and 71 % of all species are considered to be to replace expensive pearl buttons taken from imperiled, defined to include species that are the ocean. From humble beginnings in Mus­ endangered, threatened, or of special concern catine, lA, in 1891, the pearl button industry (Williams et al., 1993). The declinP- of ru.ussel became a booming enterprise, with automated species is evident ir. coastal rivers as well as In­ factories established along the entire Mississip­ terior Basin watersheds (Neves et al., 1997). pi River and its major tributaries. Because of The impetus to help recover these imperiled the requirements of availability, white nacre, species is federal laws that have specified indi­ and shell quality, only a select group of mussel vidual recovery plans, which has led to the de­ species was harvested by a variety of collection velopment of propagation techniques for these techniques such as clam tongs, pitchforks, endangered species but that are also applica­ rakes, and dredges. Both shallow and deep wa­ ble to all freshwater mussel species. The "Gulf ter areas of lakes and rivers were exploited for Pearls Project" of the Mississippi-Alabama Sea the target species to such an extent that a Grant Consortium has been established to ex- "shell rush" swept through the Mississippi Riv-

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er Valley at the turn of the century (Claassen, shaped pearls are produced in China with two 1994). species of freshwater mussels, Hy1iopsis cumingi Harvested mussels were taken to shell camps and C1istmia plicata. These large mussel species and steamed open in large vats, and the shells grow rapidly, exhibit lustrous nacre, and have were taken to factories to be cut, drilled, pol­ been used for centuries as a source of pearls ished, and packaged for shipment to garment and mother-of-pearl. In the last two decades, a factories in the eastern United States. Mter the profusion of pearl farms and modern tech­ cookout stage, musselers sifted through the niques in China have begun to saturate the cooking vats and pressed through the meats in market with these smaller pearls. By the mid- search of natural pearls. The presence of nat­ 1990s, techniques to produce large semiround ural pearls in freshwater mussels was known to and round pearls had been developed, result­ both Native Americans and early European ex­ ing in improved quality and a quantity suitable plorers (Kunz and Stevenson, 1908), but the for the international market. Chinese fresh­ quest for quality pearls intensified as a result water pearls are nonnucleated, unlike cultured of the commercial harvest of shells and the re­ marine pearls. The pearls are produced by im­ covery of pearls in "cooked out" mussels planting pieces of mantle tissue from a donor (Kunz, 1898). The button business and pearl mussel into the mantle or between mantle and hunting boomed until the early 1940s, when shell of a recipient mussel, resulting in the for­ the discovery of plastics put an end to the need mation of natural pearls. Freshwater pearls are for mussel shells. becoming more widely accepted, and, because of their affordability and beauty, the once dis­

CULTURED PEARLS crete freshwater and saltwater pearl markets have begun to merge. While the button industry was booming in The pioneering work of American Pearl the United States, Mikimoto and associates in Company (APC) in Tennessee has set the stan­ Japan were perfecting techniques to produce dard for an expanded pearl industry in the spherical, cultured pearls with implants of United States. In 1963, APC began experi­ bead nuclei milled from the shells of freshwa­ ments to nucleate various species of mussels ter mussels. That technique was perfected in with appropriate shell qualities to produce the 1940s, and by the early 1950s, the United quality pearls. Founder and chief executive of­ States became the exclusive supplier of fresh­ ficer John Latendresse adapted Japanese tech­ water mussel shell to produce beads for Japan's niques for pearl culture to a few mussel species cultured saltwater pearl industry. That industry in Tennessee. Mter both implants of shell nu­ has now expanded into other Asian countries clei and a mantle tissue nucleating process and the South Pacific, maintaining a demand were tested, a protocol was gradually devel­ for mussel shells to provide nuclei for pearl oped to produce "baroque" (odd-shaped) farms that use a variety of oyster species. Be­ pearls. Pearls shaped as bars, wings, domes, na­ tween 1992 and 1997, annual exports of shell vettes, and other oddities provide a wealth of from the United States have ranged from 665 options for the jewelry trade (Heideger, 1993). to 3,132 metric tons (Neves, 1999). Once beads Beginning with its first successful commercial are produced and implanted, pearl formation harvest in 1983, the company has perfected by accretion is analogous to the mechanism of techniques to produce pearls in 3-5 years and shell formation and repair in bivalves (Panha to hold mortality at less than 20% in implanted and Phansuwan, 1996). However, much of the mussels. From empirical experimentation and descriptive science and techniques for pearl persistence, APC has become an internation­ culture are guarded as proprietary secrets. To­ ally successful competitor in the freshwater day, the cultured pearl industry provides pearl market. The two mussel species in the 230,000 jobs and generates retail sales ap­ Southeast that provide the best white pearls proaching $3 billion worldwide (Hubbs and are the washboard (Megalonaias nervosa) and Jones, 1996). Shells gathered in U.S. rivers and threeridge (Amblema plicata). However, other reservoirs provide the bulk of nuclei for this white-nacred species in the genera Quadrula, international enterprise. Fusconaia, and Pleurobema may be suitable for Lesser known, but more affordable, fresh­ pearl production in Gulf Coast states. A variety water pearls of various shapes have also be­ of other mussel species with colored nacres come available on the world market. Early could be evaluated for pearl-production poten­ freshwater pearls came from Lake Biwa,Japan, tial (Table 1). Vast freshwater resources for the but water pollution essentially eliminated pro­ establishment of pearl farms occur along the duction from this lake. Most of the small, rice- Gulf Coast, and a need exists to test the suit- https://aquila.usm.edu/goms/vol17/iss2/6 2 DOI: 10.18785/goms.1702.06 Neves: Biological Feasibility of Freshwater Mussel and Pearl Culture in NEVES-FRESHWATER PEARL CULTURE 105

TABLE l. Examples of mussel species with colored nacres in the Southeast.

Species Nacre color

Purple wartyback ( Cydonaias tubercula/a) Purple Elephantear (Eiliptio crassidens) Salmon/ purple Spike (EllijJtio dilatata) Salmon/ purple Fragile papershell (Leptodea Jmgilis) Pink Black sandshell (Ligumia recta) ~White/pink Bankclimber (Plec/omerus dombeyanus) Purple Pyramid pigtoe (Pleurobema rubrum) Pink Pink heelsplitter (Potamilus alatus) Purple Pink papershell (Potamilus ohiensis) Pink/purple Bleufer (Potamilus pzojJllratus) Purple

ability of various water body types for the cul­ in the Mississippi River. A research station was ture of mussel species identified as potential established at Fairport, lA, to investigate the candidates for pearl culture (Ward, 1985). biology, life history, and propagation potential John Latendresse predicted that the Southeast of species being harvested by the pearl button would become a major pearl-culturing area industry. The production and monitoring of (Heideger, 1993). Although that potential has juvenile mussels was one aspect of that re­ not been realized, proven implant techniques search effort, but much of the data was anec­ for native mussel species and appropriate en­ dotal, with limited monitoring of juvenile sur­ vironmental conditions certainly exist for an vival and growth during the culture period expansion of pearl culture into neighboring (Lefevre and Curtis, 1912; Coker at a!., 1921; states along the Gulf Coast. Howard, 1922). The main laboratory building was destroyed by a fire in 1917, resulting in the FRESHWATER MUSSEL PROPAGATION loss of most records and materials. The labo­ ratory shifted its emphasis from shellfish to fin­ The reproductive biology of freshwater mus­ fish in the 1930s, and the era of mussel inves­ sels is unique among mollusks. The larvae (glo­ tigation essentially ended. chidia) are obligate parasites on the gills or Renewed interest in freshwater mussel prop­ fins of fish and exhibit various degrees of host agation resumed in the 1980s as a result of the fish specificity. Females are fertilized internally federal listing of 23 endangered mussel species by siphoning in the sperm released by males, in 1976-77. Recovery plans for each of these and eggs are fertilized in the suprabranchial species identified propagation as a means to cavity. Fertilized eggs are retained in the water augment existing populations, expand the tubes of the gills and develop to the glochidial range of extant populations, and reintroduce stage. Females can contain between 50,000 and the species into historic habitat. However, are­ 5 million glochidia, depending on the species view of the earlier literature provided few in­ and size of female (Yeager and Neves, 1986). sights on how to proceed with a propagation When glochidia are mature, they are released effort. Therefore, work began in the early as free-floating individuals or in packets called conglutinates. These glochidia must come in 1980s at Virginia Tech to study the reproduc­ contact with or be ingested by a suitable host tive biology and identify host fishes and envi­ fish for attachment and metamorphosis to the ronmental requirements of adult and juvenile juvenile stage. Mussel species vary in host fish mussels (Zale and Neves, 1982; Neves and Moy­ specificity, but most are restricted to a limited er, 1988; Neves and Widlak, 1988). With these number of suitable hosts (Neves eta!., 1985). studies as a foundation, production and cul­ After tnetamorphosis, juveniles drop from the ture of juvenile mussels for federally endan­ host fish and begin their benthic life, maturing gered species using host fish infestations began in usually 4-8 years. in the early 1990s (Bruenderman and Neves, The culture of freshwater mussels in the 1993; Hove and Neves, 1994; Michaelson and United States has a brief history, beginning in Neves, 1995). Efforts to metamorphose glo­ 1894 (Jones, 1950). At that time, the U.S. Bu­ chidia to juveniles with artificial media, rather reau of Fisheries became actively involved in than host fish, met with some success (lsom mussel research for fear that intensive harvest and Hudson, 1982; Keller and Zam, 1990). for button shells would deplete mussel stocks However, until the survival and fitness of these

Published by The Aquila Digital Community, 1999 3 Gulf of Mexico Science, Vol. 17 [1999], No. 2, Art. 6 106 GULF OF MEXICO SCIENCE, 1999, VOL. 17(2)

Gravid Female Mussel them suspended. Host fish are placed in the tank and become infested with the glochidia. Infested fish then are placed in aquaria for the transformation period (1-3 wk). Newly metamorphosed juvenile mussels are Remove Glochidia siphoned from the bottom of the aquaria and placed into small dishes with sediment that has been boiled or autoclaved to remove inverte­ brate predators and pathogens. Laboratory ex­ Infest Host Fish periments have shown that sediment is essen­ tial for the survival and growth of juveniles (Gatenby et al., 1996). These dishes are placed in a recirculating system consisting of a reser­ voir tank, raceway trough, and small drive Collect Juvenile Mussels pump or airlift pump to circulate the water (O'Beirn et al., 1998). The raceways are 3 m long X 66 em wide, with water flow regulated by an inline flow meter or by the amount of air delivered to the upwelling pipe. Water Prepare Sediment and Algae Culture Tanlcs depth is maintained at 20 em via the standpipe, resulting in a volume of 170 liters in the race­ way. Water hardness is maintained at ca. 200

mg/liters CaC03 . Juvenile mussels are fed unicellular algae, Transfer Juveniles to Culture Troughs cultured in 250-liter Kalwall tubes with appro­ priate nutrient media (Ukeles, 1971). A variety of species, such as Neochloris oleoalnmdans, Sce­ nedesmus sp., Chlorella sp., and others, are fed Maintain Water Quality and Food Supply at a concentration of 20,000 cells/ml, and al­ gae are harvested at the late exponential growth phase (Gatenby et al., 1997). Because the purpose of the juvenile mussel propagation facility at Virginia Tech is to prop­ Rear to Size Suitable for Release agate endangered mussel species, juveniles are not typically retained beyond 3 mo of age. Ju­ Fig. 1. Sequence of steps to produce juvenile veniles are transported to rivers with existing mussels from recirculating culture systems. populations and released to augment natural reproduction or to expand the range of the resident population. To apply these techniques artificially produced juveniles have been test­ to commercial species, juvenile mussels could ed, there is cautious optimism in the applica­ be transported to a grow-out facility to sustain bility of this technique to large-scale produc­ a captive population or to augment natural re­ tion. production in a population where adults are collected for pearl culture. Collection of adults CURRENT PRODUCTION METHODS from a source population, with replenishment by stocking of juveniles, is the most practical Production of juvenile mussels begins with option for pearl production at this time. the collection of gravid females from wild pop­ As judged by harvest records from the Ten­ ulations (Fig. 1). On the basis of previous re­ nessee River system alone (Hubbs and Jones, search, suitable hosl fish are collected, prefer­ 1996), adequate wild populations of wash­ ably from water bodies with few existing mus­ board and threeridge mussels exist in those sels to minimize acquired immunity to glochid­ reservoirs to sustain numerous pearl farms in ia (Reuling, 1919; Arey, 1923). Glochidia are the Southeast. Because of die-offs of Akoya non1ethally flushed from gravid females with a pearl oysters in Japan in recent years, the de­ water-filled hypodermic syringe and needle. mand for shell nuclei has decreased drastically. Glochidia flushed through the water tubes of Shell harvest in U.S. waters has been inconse­ the gills are collected in a dish and placed in quential over the last 3 yr, and size classes in a small tank under vigorous aeration to keep exploited populations continue to increase un- https://aquila.usm.edu/goms/vol17/iss2/6 4 DOI: 10.18785/goms.1702.06 Neves: Biological Feasibility of Freshwater Mussel and Pearl Culture in NEVES-FRESHWATER PEARL CULTURE 107

der minimal harvest pressure. Thus, sufficient fresh-water mussels. Bull. U.S. Bur. Fish. 37:75- mussels of adequate size are available for do­ 181. mestic pearl culture. CLAASSEN, C. 1994. Washboards, pigtoes, and muck­ ets: historic musseling in the Mississippi water­ shed. Hist. Arch. 28:1-145. CONCLUSION GATENBY, C. M., R.J. NEVES, AND B. C. PARKER. 1996. Influence of sediment and algal food on cultured The success of APC provides positive evi­ juvenile freshwater mussels. J. North Am. Ben tho!. dence that economic success is possible for an Soc. 15:597-609. effectively run pearl farm in the U.S. South­ ---,B. C. PARKER, AND R.J. NEVES. 1997. Growth and survival ofjuvenile rainbow mussels, Villosa iris east. However, a detailed economic analysis is (Lea, 1829) (Bivalvia: Unionidae), reared on algal needed to evaluate feasibility of an expanded diets and sediment. Am. Malacol. Bull. 14:57-66. pearl industry in Gulf Coast states. The South­ HEARD, W. H. 1970. Eastern fi·eshwater mollusks (II). east has the greatest diversity of freshwater The South Atlantic and Gulf drainages. Malacol­ mussel species in the world, including an array ogia 10:23.31. of lotic species well suited for pearl produc­ HEIDEGER, C. 1993. A little culture in Tennessee. Am. tion. Because nacre colors of many of these Jewelry Man., Dec. 1993. species include white, purple, pink, magenta, HOVE, M. C., AND R. J. NEVES. 1994. Life history of salmon, orange, and suffusions of iridescence, the endangered James spinymussel Pleurobema col­ the opportunity exists to produce naturally col­ /ina (Conrad 1938) (Mollusca: Unionidae). Am. Malacol. Bull. 11:29-40. ored pearls unlike any of those currently pro­ HOWARD, A. D. 1922. Experiments in the culture of duced overseas. If or when the techniques of fresh-water mussels. Bull. U.S. Bur. Fish. 38:63-89. pearl culture in China, or those perfected by HUBBS, D. W., AND A. JONES. 1996. 1995 statewide APC, become known or are worked out inde­ commercial mussel report. Tennessee Wildlife Re­ pendently, the production of round or semi­ source Agency 96-15. round pearls in U.S. mussel species would cat­ lsoM, B. G., AND R. G. HUDSON. 1982. In viu·o culture apult a fledgling U.S. venture into the world of parasitic mussel glochidia. Nautilus 96:147-151. market as a major player. With strands of 9-mm JONES, R. 0. 1950. Propagation of fresh-water mus­ high-luster round pearls from China selling for sels. Prog. Fish-Cult. 12:13-25. KELLER, A. E., AND S. G. ZAM. 1990. Simplification of up to $8,000 each (Torrey, 1999), the econom­ in vitro culture techniques for freshwater 1nussels. ic incentive is adequate to investigate freshwa­ Environ. Toxicol. Chem. 9:1291-1296. ter pearl culture for areas that are economi­ KUNZ, G. F. 1898. A brief history of the gathering of cally depressed but rich in aquatic resources. fresh-water pearls in the United States. Bull. U.S. The "Gulf Pearls Project" is a somewhat novel Fish Comm. 17:321-330. and intriguing venture, with potential to create ---,AND C. H. STEVENSON. 1908. The book of the new jobs and revenues in coastal states with the pearl. The Century Company, New York. necessary mussel species, water bodies, and en­ LEFEVRE, G., AND W. C. CURTIS. 1912. Studies on the trepreneurs. Once the implantation technique reproduction and artificial propagation of fresh­ becomes more widely known, quality pearls of water mussels. Bull. U.S. Bur. Fish. 38:105-201. MICHAELSON, D. L., AL'ID R. J. NEVES. 1995. Life his­ various shapes and colors could become eco­ tory and habitat of the endangered dwarf wedge­ nomic by-products of our mussel fauna in mussel Alasmidonta heterodon (Bivalvia: Unionidae). southeastern rivers, further justifying the pro­ J. North Am. Benthol. Soc. 14:324-340. tection of water quality and biological resourc­ NEVES, R. J. 1999. Conservation and commerce: es of long-term sustainability. management of freshwater mussel (Bivalvia: Unionidea) resources in the United States. Mala­ cologia. In press. LITERATURE CITED ---,A. E. BOGAN,J. D. WILLIAMS, S. A. AHLSTEDT, AND P. W. HARTFIELD. 1997. Status of aquatic mol­ AREY, L. B. 1923. Observations on an acquired im­ lusks in the southeastern United States: a down­ munity to a metazoan parasite. J. Exp. Zoo!. 38: ward spiral of diversity, p. 43-85. In: Aquatic fauna 377-381. in peril: the southeastern perspective. G. Benz and BRUENDERtvlAN, S. A., AND R. J. NEVES. 1993. Life his­ D. Collins (eels.). Lenz Design and Communica­ tory of the endangered fine-rayed pigtoe Fusconaia tions, Decatur, GA. cuneolus (Bivalvia: Unionidae) in the Clinch River, ---,AND S. N. MOYER. 1988. Evaluation of tech­ Virginia. Am. Malacol. Bull. 10:83-91. niques for age determination of freshwater mus­ COKER, R. E. 1919. Fresh-water mussels and mussel sels (Unionidae). Am. Malacol. 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---,A. V. ZALE, AND L. R. WEAVER. 1985. An eval­ Valuable Shellfish. K. Price and D. Maurer (eds.). uation of host fish suitability for glochidia of Vil­ University of Delaware, Newark, DE. losa vanuxemi and l~ nebulosa (Pelecypoda: Union­ WARD, F. 1985. The pearl. Nat!. Geogr. 168:193-222. idae). Am. Midi. Nat. 113:13-19. WILLIAMS,]. D., M. L. WARREN, JR., K. S. CUMMINGS, O'BEIRN, F. X., R. J. NEVES, AND M. D. STEG. 1998. ]. L. HARRis, AND R. ]. NEVES. 1993. Conservation Survival and growth ofjuvenile freshwater mussels status of freshwater mussels of the United States (Unionidae) in a recirculating aquaculture system. and Canada. Fisheries 18:6-22. Am. Malacol. Bull. 14:165-171. YEAGER, B. L., AND R. J. NEVES. 1986. Reproductive PANHA, S., AND P. PHANSUWAN. 1996. The influence cycle and fish hosts of the rabbitsfoot mussel Quad­ of mantle and neurosecretory cells on pearl fm~ rula cylindrica strigillata (Mollusca: Unionidae). mation in a freshwater pearl mussel, Chamberlainia Am. Midi. Nat. 116:329-340. hainesiana, induced by the nucleated technique. ZALE, A. V., AND R. .J. NEVES. 1982. Fish hosts of four Malacol. Rev. 29:113-129. species of lampsiline mussels (Mollusca: Union­ REULING, F. H. 1919. Acquired immunity to an ani­ dae) in Big Moccasin Creek, Virginia. Can.]. Zoo!. mal parasite. J. Infect. Dis. 24:337-346. 60:2535-2542. ToRREY, R. 1999. Akoya rebut.~ freshwater. Pearl World 7:1-6. Vhginia Cooperative Fish and Wildlife Research UiillLES, R. 1971. Nutritional requirements in shell­ Unit, U.S. Geological Survey, Cheatham Hall, fish culture, p. 42-64. In: Proceedings of the Con­ Vi1ginia Tech, BlacksbU?g, Vhginia 24061. Date ference on Artificial Propagation of Commercially accepted: July 22, 1999.

https://aquila.usm.edu/goms/vol17/iss2/6 6 DOI: 10.18785/goms.1702.06