W&M ScholarWorks VIMS Articles Virginia Institute of Marine Science 1980 A Review Of Introductions Of Exotic Oysters And Biological Planning For New Importations Jay D. Andrews Virginia Institute of Marine Science Follow this and additional works at: https://scholarworks.wm.edu/vimsarticles Part of the Aquaculture and Fisheries Commons Recommended Citation Andrews, Jay D., A Review Of Introductions Of Exotic Oysters And Biological Planning For New Importations (1980). Marine Fisheries Review, 42(12), 1-11. https://scholarworks.wm.edu/vimsarticles/1250 This Article is brought to you for free and open access by the Virginia Institute of Marine Science at W&M ScholarWorks. It has been accepted for inclusion in VIMS Articles by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. A Review of Introductions of Exotic Oysters and Biological Planning for New Importations JAY D. ANDREWS Introduction ber of coastal communities around the seed from acclimated broodstocks pre­ world. In the temperate zone of the cariously established in Boothbay Har­ Oysters have been transported by Northern Hemisphere only the Atlantic bor, Maine (Welch, 1966). mankind since Roman times because coast of North America does not now Extensive transplantation of native they are superbly adapted to with­ depend on this species for oyster pro­ oysters along major coasts has long stand long journeys out of water. In duction. Crassostrea gigas was suc­ been used to sustain fisheries without this paper, the consequences of man's cessfully introduced to western North regard for adaptations of local races to movement of oysters and the biological America, western European, and Aus­ new environments. Transplantation of requirements for future introductions of tralasian coasts. Most introductions be­ flat oysters from one country to another oysters are reviewed. gan as casual unplanned events that in Europe has a long history. It was Only one species of oyster, Crass­ were soon followed by deliberate ones instigated primarily because of failure ostrea gigas, the Pacific oyster, has on a larger scale. With the aid of man, of reproduction in the cold waters been introduced as a successful mem- the oysters spread on the coasts to the of northern countries such as France, limit of their tolerances of climates Great Britain, the Netherlands, and and salinities. Denmark (ICES, 1972). Crises such as Some scientists desire to culture C. continent-wide unexplained mortalities ABSTRACT-Importation and trans­ gigas in New England. A major prob­ in 1920-21 and recent (1967-76) mortal­ plantation of exotic oysters has probably resulted in the introduction into new areas lem is keeping it confined to New ities from diseases also caused exten­ of more marine invertebrate species than England and away from large oyster sive importations from the Adriatic Sea any other ofman's activities. Unintentional fisheries of C. virginica to the south. and Greece as well as Spain and Portu­ imroductions have resulted from careless Crassostrea gigas is a vigorous, fast­ gal. No consideration was given to movements of oysters without planning or growing oyster that could compete ad­ racial traits of these diverse stocks for consideration of consequences. Diseases and parasites of marine invertebrates are vantageously with the native oyster, adaptation to various local climates poorly known and oysters cannot be ade­ and possibly replace it, in the warm (Andrews, 1979b). However, the Neth­ quatelv diagnosed or inspected for prob­ waters of Chesapeake Bay and Dela­ erlands is trying to build up stocks of lems by biologists. The vigorous Pacific ware Bay. isolated native oysters which exhibit oyster. Crassostrea gigas. was introduced to the Atlamic coast of western Europe in The famous European flat oyster, greater winter hardiness than imported the past decade with serious effects on OSlrea edulis, has been tried on both French seed oysters now sustaining the native oyster species. Some scientists pro­ coasts of North America and in Japa­ industry (Drinkwaard, 1978). Trans­ pose to introduce it to the Atlamic coast of nese waters with Iittle success as a plantation between regions on a coast North America. primarily for culture in self-sustaining species. It is frequently New England. If imroduClion is carried out is a short-term marketing expedient properly, diseases and parasites mav be grown in hatcheries in North America that is not expected to contribute to excluded bv breeding selected brood oysters for experimental plantings. This favor­ rehabilitation of native stocks. How­ in hatcheries under quarantine conditions. ite raw-bar oyster sustains a small ever, it may result in genetic mixing The progeny mav then be tested in con­ industry in Maine by use of hatchery and the spread of pests and diseases. trolled natural environments for growth rates and reaction to native diseases and The impact of exotic marine species parasiles. Selection of races. strains. and Jay D. Andrews is Senior Marine Scientist, on endemic communities is difficult to hybrids may be pursued in hatcheries to fit Virginia Institute of Marine Science and College predict until they are widespread in the of William and Mary, Gloucester Point, VA exotic oysters to new ecosystems. Intro­ new area and irrevocably established. duction -of an exotic species is a serious 23062. This paper is Contribution No. 968 from the Virginia Institute of Marine Science and Introductions of marine exotics are irreversible evel1t which merits careful con­ College of William and Mary. Views or opin­ more difficult to isolate and to co~­ sideration of the reasons for culture of ions expressed or implied are those of the author a new shellfish and Ihe consequences to and do not necessarily reflect the position of the trol than terrestrial ones because of native biOla Gnd coastal ecosystems. National Marine Fisheries Service. NOAA. rapid dispersion of larvae by currents. December 1980 Inadequate monitoring and limited be considered accidental. The risks and trast, organisms acclimated to mild knowledge of identity, abundance, and consequences are the same as for strict­ oceanic cI imates are usually not able distribution of native species may leave ly accidental importations, i.e., inad­ to survive either summer or winter ex­ exotic species obscured for long peri­ vertent introductions. Most large-scale tremes in severe climates of continen­ ods. Often diseases of marine inverte­ importat:ons of oysters were preceded tal-type coasts. These adaptations to brates become known only after mass by accidental ones on a small scale. climates explain in large measure the mortalities of the host species (Sinder­ These accidental importations may pre­ numerous invasions of exotic species in mann, 1976). Seldom can such diseases pare the way sociologically for sub­ the temperate zones on the western be proven to be introduced. The strong­ sequent large-scale deliberate ones. coasts of continents (Hanna, 1966) est circumstantial evidence is that of Importee oysters may exhibit excellent whereas introduced species are rare on timing when stocks were transplanted growth and survival while native spe­ eastern coasts. Tropical coasts are more or imported immediately before an cies are destroyed by exotic diseases easily invaded (Courtenay and Robins, epizootic mortal ity. associated with the importation. This 1973). series of events occurred recently in In general, Ostrea species are adapt­ Categories of Importations France following importation of C. ed to oceanic climates and Crassostrea The transport of endemic oysters of gigas in 1966 (Marteil, 1976). to continental ones, although excep­ the same species along a coast is de­ tions occur as waters along a coast fined as transplantation (Mann, 1979). Adaptations of Marine Organisms become more tropical. Consequently, This is not the primary concern of this to Oceanic and Continental Climates Ostrea species breed at lower summer discussion. After hundreds of years of Continental air masses cro sing large temperatures (usually < 20° C) and are transplantation the potential for further land masses exhibit the rapid heating more sensiti ve to low salinities and low damage may be minimal. However, and cool ing attri butes of the land with winter temperatures. They will not care should be exercised in moving strong warming during summers and withstand intertidal exposure to heat or endemic oysters from regions of a coast prolonged cooling from back-radiation cold. Ostrea edulis and O. lurida are that have been isolated by land barriers, in winters. Coastal waters on the east­ the endemic species of western Europe ocean currents, or even temperature ern shores of continents share these and western North America, respec­ differences for many centuries. Ex­ extremes of atmospheric temperature tively; Crassostrea virginica and C. changes between such areas on a coast with cold winter and warm summer gigas are respective endemic com­ carry the same dangers from diseases temperatures. In contrast, coastal wa­ mercial oysters of eastern shores of and pests as from importation of exotic ters on western shores of continents, North America and Asia. These adap­ oysters of a different species. Examples bathed by moderated oceanic air mass­ tations to respective climates should be of isolated regions in North America es, receive mi Id weather, therefore, considered before irreversible conse­ include the Gulf of Mexico and the exhibit cool summers and mild winters. quences of importations are incurred. Gulf of St. Lawrence from which trans­ Hydrocl imographs for estuaries on the Examples of serious alterations of bi­ plantings to and from the Middle Atlan­ eastern coast of North America show otic communities by importations of tic coast have been rare. The Mediter­ annual temperature ranges of 20°C or exotic oysters with their associated ranean Sea and the Atlantic coast of more inshore, whereas those for the faunas are found on the maritime coasts Europe could also be hazardous regions western coast exhibit only about 10°C of western Europe and western North for exchanges of oysters.