Biological and Economic Evaluation of The Impact of Predators on Oyster Mortality (A Case study in Quiberon Bay, France).

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(A Case study in Quiberon Bay, France)

(Evaluasi Biologi dan Nilai Ekonomi dari Pengaruh Predator Terhadap Kematian Tiram : Studi Kasus di Teluk Quiberon, Prancis)

Ika Meidy Deviarni

GRADUATE SCHOOL

BOGOR AGRICULTURAL UNIVERSITY

BOGOR

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STATEMENT

I, Ika Meidy Deviarni, here by declare that the thesis entitled:

Biological and Economic Evaluation of The Impact of Predators on Oyster Mortality (A Case study in Quiberon Bay, France)

contain correct result from my own work and that it has not been published ever before. All data sources and information used factual and clear methods in this project, and has been examined by the advising commitee and the external examiner.

Bogor, September 2011

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IKA MEIDY DEVIARNI. Biological and Economic Evaluation of The Impact of Predators on Oyster Mortality (A Case study in Quiberon Bay, France). Under the supervision of Prof. Dr. Ir. Fransiska R. Zakaria, M.Sc and Dr. Ir. Hartrisari Hardjomidjojo, DEA

Pacific oysters have been cultured in several country as a result, Crassostrea gigas has become the leading species in world culture, with an estimated production of 4.6 million tons in 2006. France producing around 130 000 tons of the cupped oyster C. gigas annually and a remaining 1 500 tons of the flat oyster Ostrea edulis. Quiberon Bay has a large production of oyster, approximately 15 000 tons annually which contributes to oyster production in France. These small scale industry activities contributes to largely to France economy.

Since the year of 2000 and especially 2006, the oyster mortality rates have reached quite unusual, estimated at 60% mortality in a breeding cycle ending in late 2006, according to the response of 51 companies interviewed by the CRC. This mortality brought a great impact on the France's economy. So, in this study, we observed the effects of oyster mortality in terms of biology and economics.

The objectives of this study are to analyse RISCO data on oyster mortality, to determine effect of predators on oyster culture, mapping the distribution of different types of predators and to calculate the economic analysis of oyster mortality. RISCO project is conducted by Ifremer with their partners. As present in the study area, this project is held in Quiberon Bay, France and the 15 station’s of oyster culture. The observations of this research have been conducted monthly (8 surveys) in May until December 2010. Each month, there are several analyses of RISCO project which have been done, one of them is analysis oyster growth and mortality (Spat and Adult).

In each station, we counted the number of predators (starfishes and gastropods) on the cage and in each bag we calculated the numbers of dead oysters then we took sampling of 30 living oysters for growth and pathology

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analysis. In each dead oyster, we also observed the boring oyster by oyster drill and parasitism by Polydora.

The result of this research showed that there were a potential role of two species of starfishes, Asterias rubens and Marthasterias glacialis and two species of gastropods, Ocenebra erinacea and Ocenebrillus inornatus. Marthasterias glacialis indicated a great impact on mortality of adult oysters. The relation between oyster's mortality and the presence of gastropods depended on time and according to reproductive cycle. Several months show clearly a predation of oysters and others show a concentration of gastropods for spawning. Predators on oyster culture also indicated a great impact in economic value. The economic value on oyster culture model applied in RISCO project shows that BSP was higher than BAP. Based on economic value analysis on RISCO project shows that BSP was higher than BAP. Economic loss in BAP greatly happen in station 2 and 5, approximately €81.28 - €81.83. On the contrary, station 15 indicate has the higher loss in BSP approximately €54.92 or 363 oysters and for the rest, the economic value was varies between €29.67 - €40.30.

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Copyright are protected by law,

1. It is prohibited to cite all of part of this thesis without reffering to and mention the sources;

a. Citation only permitted for the shake of education, research, scientific, writing, report writing, critical writing or reviewing scientific problem. b. Citation does not inflict the name and honor of Bogor Agricultural

University.

It is prohibited to republish and reproduce all part of this thesis without written permission from Bogor Agricultural University.

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Biological and Economic Evaluation of The Impact of Predators

on Oyster Mortality

(A Case study in Quiberon Bay, France)

(Evaluasi Biologi dan Nilai Ekonomi dari Pengaruh Predator Terhadap Kematian Tiram : Studi Kasus di Teluk Quiberon, Prancis)

Ika Meidy Deviarni

Thesis submitted to Graduate School of Bogor Agricultural University (IPB), Indonesia in partial fulfillment of the requirements for the degree of Magister Professional in Master Professional Management of Small and Medium

Industries Study Program and Magister Professional in Master Management of Ressources Biology Study Program in Universite de Bretagne Sud, France.

GRADUATE SCHOOL

BOGOR AGRICULTURAL UNIVERSITY

BOGOR

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Research Title : Biological and Economic Evaluation of The Impact of Predators on Oyster Mortality (A Case study in Quiberon Bay, France)

Name : Ika Meidy Deviarni

Student ID : P054090225

Study Program : Master Professional Management of Small and Medium Industries

Approved by Advisory Board,

Prof.Dr.Ir. Fransiska R. Zakaria, M.Sc Supervisor

Dr.Ir. Hartrisari Hardjomidjojo, DEA Co-Supervisor

Endorsed by, The Head of Master Professional

Management of Small and Medium Industries, Bogor Agricultural University

Dean of Graduate School Bogor Agricultural University

Prof. Dr. Ir. Musa Hubies, MS, Dipl.Ing, DEA Dr. Ir. Dahrul Syah, M.Sc.Agr

Date of Examination: Date of Graduation:

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In the name of God, the Most Beneficient, the Most Merciful. There are many people I should thank in regard to this work no doubt I will not be able to name them one by one. To these I can but beg forgiveness. I wish to thank the following:

1. My supervisor Prof. Dr. Ir. Fransiska R. Zakaria, M.Sc and my Co-supervisor Dr. Ir. Hartrisari Hardjomidjojo, DEA for their guidance, comment and constructive critism through my thesis.

2. Prof. Dr. Ir. Musa Hubies, MS, Dipl.Ing, DEA, The Head of Master Professional Management of Small and Medium Industries for his kindness and providing academic assistance. And also MPI staff Miss Vera, Mr. Haer and Mr. Harris.

3. Prof. Dr. Ir. Irwan Katili, DEA and Dr. Ir. Naresworo Nugroho,M.Si for their official endorsement, kindly permission, allowed me to attend Double Degree Programe Indonesia-Prancis (DDIP).

4. All staff and Lecture in Universite de Bretagne Sud, France for their constant guidence, continues encouragement, and valuable suggestion during my study in France.

5. All MPI students year 2009 and All Biotechnology students year 2010, I really appreciate our togetherness and how we support each other to finish our study.

6. Great thanks to My musician, always accompany me during my thesis, thanks for your love and understanding for me.

Lastly, I dedicated this thesis to my big family, my Beloved father Suwardy, My Lovely Mother Suprihartini, and my Beloved brother Wahyu Dwi Widarto.

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CURRICULUM VITAE

Ika Meidy Deviarni was born in Pontianak, West Kalimantan, Indonesia at May 3rd_{, 1982. She was graduated} from Brawijaya University, Faculty of Fisheries, majoring Technology Fish Processing in 2005. She entered in IPB Graduate School with Double Degree Indonesia-France Program in 2009. She enrolled in Magister Professional in Master Professional Management of Small and Medium Industries Study Program in Bogor Agricultural University, continued her second year in Universite de Bretagne Sud majoring Gestion des Bioressources in 2010 and finally completed her master study in 2011. Her final thesis is “Biological and Economic Evaluation of The Impact of Predators on Oyster Mortality (A Case study in Quiberon Bay, France)”.

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1 Introduction...1

1.1 Background...1

1.2 Objectives...3

2 Literature Riview...4

2.1 Oyster Culture...4

2.2 Factors affecting the oyster mortality...6

2.3 Oyster Culture in the Quiberon Bay...8

2.4 Economic value of oyster culture...9

2.5 Bibliographical Synthesis of Biological Features of The Major Oyster Predators. 10 2.5.1 Gastropod...14

2.5.2 Echinoderm...23

2.5.3 Crustacea, Carcinus maenas...27

2.5.4 Fish, Sparus aurata (Gilthead seabream)...28

3 Materials and Methods...30

3.1 Study area...30

3.2 Data Source...31

3.3 Required Tools...31

3.4 Methodology...31

3.4.1 Determine of Study Area ...31

3.4.2 Data collecting...33

3.4.3 Processing of Risco Data...33

4 Results...36

4.1 The Predators in the Quiberon Bay...36

4.2 Oyster’s mortality ...39

4.3 Oyster’s mortality by predation...42

4.4 Economic value on RISCO Project...47

5 Discussion...51

5.1 Biological Aspect on Risco Project...51

5.2 Economic value on Risco Project...53

6 Conclusion and Suggestion...55

6.1 Conclusion...55

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List of Table

Table 1. Oyster’s Predators of Crassostrea gigas...10

Table 2. Oyster’s Predators of Crassostrea virginica...12

Table 3.Oyster’s Predators of Ostrea edulis...13

Table 4. Variance analysis of gastropods...38

Table 5. Variance analysis of Starfishes...38

Table 6. Variance analysis of BAP...40

Table 7. Variance analysis of BSP...42

Table 8. Variance analysis of BAP-%BSP...42

Table 9. Variance analysis of BAP-%BSP and gastropods...43

Table 10. Variance analysis of BAP-%BSP and Ocinebrillus...43

Table 11. Variance analysis between BAP-%BSP and starfish...45

Table 12. Variance analysis of Asterias and BAP-%BSP per month...46

Table 13. Variance analysis of Marthasterias and BAP-%BSP per month...46

Table 14. Oyster presence on BAP...48

Table 15. Economic value on BAP...48

Table 16. Oyster presence on BSP...49

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Figure 1. Oyster culture...4

Figure 2. Factors affecting oyster mortality...6

Figure 3. The images oyster’s predators of Crassostrea gigas...11

Figure 4. The images oyster’s predators of Crassostrea virginica...12

Figure 5. The images oyster's predators of Ostrea edulis...13

Figure 6. Ocenebra erinacea...14

Figure 7. Capsule of Oyster Drill (Mazurié, 2010)...15

Figure 8. Ocinebrellus inornatus...16

Figure 9. Urosalpinx cinerea...19

Figure 10. Rapana venosa...21

Figure 11. Asterias rubens...23

Figure 12. Asteria's feeding behavior...24

Figure 13. Marthasterias glacialis...25

Figure 14. Cancer maenas (http://www.glaucus.org.uk/c-maenas.htm, 2011)...27

Figure 15. Sparus aurata (Sola et al., 2006)...28

Figure 16.a. Chart of France, b. Quiberon Bay (Menier, et. al., 2010)...31

Figure 17. Risco Stations...32

Figure 18.Sedimentology of Quiberon Bay (Menier, 2010)...32

Figure 19. Experimental Design of Oyster Culture...34

Figure 20. Station RISCO...36

Figure 21. a. The presence of Gastropod in Quiberon Bay, b. The presence of Starfish in Quiberon Bay ...37

Figure 22. Mean density of gastropod and starfish per month...38

Figure 23. Oyster’s mortality in on-bottom culture (BAP adult)...39

Figure 24. Matrix of BAP...40

Figure 25. Oyster mortality in on-bottom culture (BSP adult)...41

Figure 26. Matrix of BSP (adult)...41

Figure 27. Interaction gastropods between BAP and BAP-%BSP per month...44

Figure 28. Interaction between starfishes BAP and BAP-%BSP...45

Figure 29. Interaction Marthasterias in BAP and BAP-%BSP...46

Figure 30. Interaction between the presents of Asterias and Marthasterias in BAP and BAP-%BSP...47

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6 Conclusion and Suggestion

6.1 Conclusion

The present study confirm that the highest mortality of oysters is happened in the cultured of adults oysters exposed to predations on the bottom (BAP) and it happened greatly in the deeper zone (almost 100%). Indeed, we have identified that there was an impact of predators, gastropods (Ocenebra erinacea and

Ocinebrillus inornatus) and starfishes (Asterias rubens and Marthasterias

glacialis), which existed in Quiberon Bay.

Identification with the statistic, showed that starfishes (Asterias rubens and

Marthasterias glacialis) gave significantly great impact with oyster mortality. In

each month and station, Marthasterias consumes about 10 oysters and the both starfishes consume 11 oysters. The impact of gastropods is clear apart from in autumn during the reproduction phase of O. inornatus. The relation between oyster's mortality and the presence of gastropods were depend on time and according to reproduction cycle. Several months show clearly a predation of oysters and others show a concentration of gastropods for spawning.

Based on economic value analysis on oyster culture model at RISCO project shows that BSP was higher than BAP. Economic loss in BAP greatly happen in station 2 and 5, approximately €81.28 - €81.83. On the contrary, station 15 indicate has the higher loss in BSP approximately €54.92 or 363 oysters and for the rest, the economic value was varies between €29.67-€40.30.

6.2 Suggestion

Several suggestion for this study, (1) in the oyster culture, it would be better to use a cage (2) to reduce the predator, it is better to use an empty cage to attract gastropod and during the time of reproduction (spring and autumn), lift up the cage and throw the eggs of gastropods, (3) it is better to use a cage which is

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containing the mussels to avoid oysters from predation by predators, and (4) consult with other countries that cultivate more than one species of oyster.

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Reference

Allen, P.L. 1983. Feeding Behaviour of Asterias Rubens (L.) On Soft Bottom Bivalves: A Study in Selective Predation. J. Exp. Mar. Biol. Ecol., 1983, Vol. 70, pp 79-90.

Anderson, M.J. and Connell, S.D. 1999. Predation of Fish on Intertidal Oysters. Marine Ecology Progress Series. 187:203-211

Arin. G and Arin. A., 1976. Farming the European Flat Oyster (Ostrea edulis) in the Classical Style in Brittany, France. A Multi Disciplinary Treatise. Development in Aquaculture and Fisheries Science 3. Elsevier Scientific Publishing Company. Amsterdam-Oxford-New York. 73-106

Arzul. I., Langlade. A, Chollet. B., Robert. M., Ferrand, S., Omnes. E., Lerond. S., Couraleau. Y., Joly. J.P., Francois. C., and Garcia. C., 2011. Can the Protozoan Parasite Bonamia ostreae Infect larvae of Flat Oysters Ostrea edulis ?. Veterinary Parasitology. In Press. 2011. http://archimer.ifremer.fr/doc/00028/13898/11061.pdf.

Barker. M. F. and D. Nichols (1983). Reproduction, recruitment and juvenile ecology of the starfish, Asterias rubens and Marthasterias glacialis. Journal of the Marine Biological Association of the United Kingdom, 63: 745-765 Barthelemy, G. 1991. Les Principaux Prédateurs et Compétiteurs de la

Conchyliculture. C.I.C.Section Régionale de Bretagne-Sud avec la collaboration Scientifique de la Station IFREMER de la Trinité/ Mer

Baud, J.-P, Gerard. A, and Naciri-Graven. Y. 1997. Comparative growth and mortality of Bonamia ostreae-resistant and wild flat oysters, Ostrea edulis, in an intensive system. I. First year of Experiment. Marine Biology. 130: 71-79

Beaudesson, P. 1992. Bibliographie Ocenebra erinacea. Trinite sur Mer

Bennet-Clark. H. C. 1976. Marine Mussels: Their Ecology And Physiology. International Biological Programme 10 Edited by B. L. BAYNE, Cambridge University Press, 1976. Pp. xvii+506. Exp Physiol.October 1976. 61(4):359

Bisker, R and Castagna M. 1987. Predation on Single Spat Oysters Crassostrea-virginica Gmelin by Blue Crabs Callinectes-sapidus Rathbun and Mud Crabs Panopeus-herbstii Milne-Edwards. Journal of Shellfish Research. 6 (1): 37-40

Brown, K.M., 1997. Size-spesific aspects of the foraging ecology of the southern oyster drill Stramonita haemastoma (Kool 1987). Journal of Experimental Marine Biology and Ecology. 214: 249-262.

Buestel D., 2007. History, Status and Future of Oyster Culture in France. Oysters Research Institute News. 20 (6):1-28.

Buestel, M. Ropert, J. Prou And P. Goulletquer. 2009. History, Status, and Future Of Oyster Culture In France. Journal of Shellfish Research. 28 (4): 813– 820.

(17)

Chandler, E. A., McDowell, J. R. and Graves, J. E. (2008), Genetically monomorphic invasive populations of the rapa whelk, Rapana venosa. Molecular Ecology, 17:4079–4091.

Capace.C., Guelorget.O., Vergne. Y. and Ouignard. J.P., 2007. Reproductive Biology Of The Common Eagle Ray Myliobatis Aquila (Chondrichthyes: Myliobatidae) From The Coast Of Languedoc (Southern France, Northern Mediterranean. Vie et Milieu. 57(3):125-130.

Christian. C., 1976. Etude du régime alimentaire de l'Aigle de mer Myliobatis aquila (L., 1758) des côtes tunisiennes. Oxford Journals. Life Sciences. ICES Journal of Marine Science. (1976) 37(1): 29-35

Choi, K.S. 2008. Oyster capture-based aquaculture in the Republic of Korea. In A. Lovatelli and P.F. Holthus (eds). Capture-based aquaculture. The Global overview. FAO Fisheries Technical Paper. No. 508. Rome, FAO. pp. 271– 286.

Cole H. A. (1942). The American whelk tingle, (Urosalpinx cinerea) (Say), on British oyster beds. Journal of the Marine Biological Association of the United Kingdom, 25, pp 477-508

Connell, S.D and Anderson, M.J. 1999.Predation by Fish on Assemblages of Intertidal Epibiota: Effect of Predator Size and Patch Size. Journal of Experimental Marine Biology and Ecology. 241: 15-29

Crothers. J.H., 1968. The biology of the shore crab Carcinus maenas (L.). I. The background anatomy, growth and life history. Field Studies 2_{.3: 407–434.} Culloty, S.C., Mulcahy, M.F., 1996. Season-, age-, and sex-related variation in the

prevalence of bonamiasis in flat oysters (Ostrea edulis L.) on the south coast of Ireland. Journal Aquaculture. 144: 53-63

Dare, P. J., Davies, G., & Edwards, D. B. (1983). Predation on juvenile Pacific oysters (Crassostrea gigas Thunberg) and mussels (Mytilus edulis L.) by shore crabs (Carcinus maenas (L.)). Fisheries Research Technical Report UK Ministry of Agriculture Fisheries Food Directorate of Fisheries Research. Directorate of Fisheries Research (Gt.Brit.).73: 1-15

Eggleston, D.E. 1990. Foraging Behavior Of The Blue Crab, Callinectes sapidus,

on Juvenile Oysters, Crassostrea virginica: Effects Of Prey Density And Size. Bulletin of Marine Science, 46(1): 62-82.

Eggleston, D.B. 1990 Behavioural Mechanism Underlying Variable Functional Responses of Blue Crabs, Callinectus sapidus Feeding on Juvenil Oyster, Crassostrea virginica. Journal of Animal Ecology. 59 (2): 615-630.

Faasse. M and Ligthart. M., 2009. American (Urosalpinx cinerea) and Japanese oyster drill (Ocinebrellus inornatus) (Gastropoda: MUricidae) flourish near shellfish culture plots in The Netherlands. Aquatic Invasion. 4(2): 321-326 FAO. 1999. The Living Marine Resources Of The Western Central Pacific.

Volume 3. Batoid Fishes, Chimaeras And Bony Fishes Part 1 (Elopidae To Linophrynidae). Food And Agriculture Organization Of The United Nations. Rome.

(18)

FAO, 2004. Crassostrea virginica (Gmelin, 1791). Cultured Aquatic Species

Information Programme. Text by: Kennedy, V.S.

http://www.fao.org/fishery/cuturespecies/Crassostrea-virginica/en [cited 20 January 2011].

FAO, 2005. Cultured Aquatic Species Information Programme. Sparus aurata. Cultured Aquatic Species Information Programme. Text by Colloca, F.; Cerasi, S. In: FAO Fisheries and Aquaculture Department [online]. Rome. Updated 8 February 2005. [Cited 22 June 2011]

FAO, 2009. Crassostrea gigas. In Culture Aquatic Species Fact Sheets. Text by. Helm.M.M. Edited and compiled by Crespi and Michael. http://www.fao.org/fishery/cuturespecies/Crassostrea-gigas/en [cited 20 January, 2011].

FAO, 2011. National Aquaculture Sector Overview France. http://www.fao.org/fishery/countrysector/naso_france/en [cited September 30, 2011].

Fleury P.G., Bouget J.F., Langlade A., Mazurier J., Philippon X., 2008. Bilan des études méthodologiques 2007 pour le projet d’analyse des risques de mortalité d’huîtres en Baie de Quiberon. Rapport Ifremer.

Frid, C. L. J. 1992. Foraging behaviour of the spiny starfish Marthasterias glacialis in lough Ine, Co. Cork. Journal Marine and Freshwater Behaviour and Physiology.19 (4): 227-239

Gallagher. T, Richardson A, Seed, R, and Jones. T., 2008. The seasonal Movement and Abundance of Starfish, Asterias rubens in Relation to Mussel Farming Practice: A Case Study from the Menai Strait, UK. Journal of Shellfish Research 27 (5):1209-1215

Garcia-Meunier P. (coordinateur), 2004. Etude d’une population invasive de bigorneaux perceurs (Ocinebrellus inornatus) dans le bassin de Marennes-Oléron: Etat des lieux, histoire de l’invasion et caractérisationi génétique. Compétition spatiale et trophique avec les taxons indigènes, Gestion du risque dans les écosystèmes conchylicoles. Rapport du Conseil Général de Charente Maritime, 86 pp.

Gera, S.M., 2009. Egg Capsule Hatching Success in Rapana venosa and

Urosalpinx cinerea in Relation to Temperature and Salinity. Thesis. The Faculty of the School of Marine Science. The College of William and Mary in Virginia.

Gollasch,S. 2009. Carcinus maenas (crustacean). Global Invasive Species Database. Ingo Narberhaus & IUCN/SSC Invasive Species Specialist Group (ISSG). http://www.issg.org/database/species/ ecology.asp? fr=1&si=114

Grangeré K., Caractérisation du comportement trophique d’Ocenera erinacea et

Ocenebra inornata vers l’huitre creuse Crassostrea gigas. Sous la direction de Stéphane. M.R et Pascal G.M. Département de Biologie. Université de La Rochelle.

(19)

Handcock, D.A., 1954. The Destruction of Oyster Spat by Urosalpinx cinerea

(Say) on Essex Oyster Beds. J. Cons. Int Explor. Mer. 20 (2): 186-196. Handcock, D.A., 1955. The Feeding Behaviour of Starfish on Essex Oyster Beds.

J. Mar. boil. Ass. U.K. 34:313-331.

Handog, L.G. 1990. Oyster Culture. Selected Papers on Mollusc Culture. UNDP/FAO Regional Seafarming Development and Demonstration Project (RAS/90/002). National Inland Fisheries Institute. Kasetsart University Campus. Bangkhen, Bangkok. Thailand.

Harding, J.M., Kingley-Smith. P, Savini. D, and Mann. R., 2007. Comparison of Predation Signatures Left by atlantic Coast Oyster Drills (Urosalpinx cinerea Say, Muricidae) and veined rapa Whelks (Rapana venosa

Valencienciennes, Muricidae) in bivalve prey. Journal of Experimental Marine Biology and Ecology. 352 (1): 1-11

Hayward, PJ. and Ryland J.S., 1995. Handbook of the Marine Fauna of North-West Europe. Oxford University Press Inc., New York. United State.

Henderson, J and O'Neil, J. 2003. Economic Values Associated with Construction of Oyster Reefs by the Corps of Engineers. ERDC TN-EMRRP-ER-01.September 2003.

Hughes, R.N and Elner, R.W. 1979. Tactics of a Predator, Carcinus maenas, and Morphological Responses of the Prey, Nucella lapillus. Journal of Animal Ecology. 48(1):65-78

Jardas. I, Anti. M, And Pallaoro. A., 2004. Diet Composition Of The Eagle Ray,

Myliobatis Aquila (Chondrichthyes: Myliobatidae), In The Eastern Adriatic Sea. Cybium, 28(4): 372-374

Joly, J-P, Bouget. J-P and Hirata. T., 2002. Le gastropode predateur Rapana venosa. Point sur le connaisances et observation en Laboratoire. Direction des Ressources Vivantes- Departement Ressources Aquacoles. Laboratoire Conchylicole de Bretagne.

Karhan, S., Kalkan, U and Yokeş M.B., 2007. First record of the Atlantic starfish,

Asterias rubens Echinodermata: Asteroidea) from the Black Sea. JMBA2 - Biodiversity Records. Published on-line. 4 May 2007.

Kerckhof, F.; Vink, R.J.; Nieweg, D.C.; Post, J.J.N. (2006). The veined whelk

Rapana venosa has reached the North Sea Aquat. Invasions 1(1): 35-37 Khanna, D.R and Yadav,P.R. 2005. Biology of Echinodermata. Discovery

Publishing House. India.

Kroeck, M.A and Montes. J. 2005. Occurrence of the haemocyte parasite

Bonamia sp. in flat oysters Ostrea puelchana farmed in San Antonio Bay (Argentina). Disease of Aquatic Organisms. 63: 231-235

Landers, W.S., Rhodes, Jr. E.W., 1970. Some factors Influencing Predation by the Flatworm, Stylochus ellipticus (Girard), on Oysters. Chesapeake Science. 11 (1): 55-60.

Lavoie, R. E. 2005. Oyster culture in North America - history, present and future. The 1st_{International Oyster Symposium Proceedings, Oyster Research}

(20)

Lovatelli A, 1988. Network of Aquaculture Centres in Asia, Status of oyster

culture in selected Asian countries.

http://www.fao.org/docrep/field/003/AB716E/AB716E00.htm#TOC

Manzi, J.J., 1970. Combined Effects of Salinity and Temperature on the Feeding, Reproductive, abd Survival Rates of Eupleura caudata (Say) and

Urosalpinx cinerea (Say) (Prosobranchia: Muricidae). Biological Bulletin. 138 (1): 35-46.

Marteil, L. 1976. La Conchyliculture Française. Deuxieme Partie. L’ostreiculture et La Mytiliculture. Institut Scientifique et Technique des Peches Maritimes. Nantes.

Marteil, L, Dardignac-Corbeil, M-J, Le Dantec, J, Raimbault, R, Hamin, P, Delreil, J-P, His, E, Gras, P, Berthome, J.-P, Razet, D, Grizel, H, Auger, Ch, and Kopp, J. 1979. La Conchyliculture Française. Troisieme Partie. L’ostreiculture et La Mytiliculture. Institut Scientifique et Technique des Peches Maritimes. Nantes.

Martin, C. 1978. Etude du Captage sur Tuiles du Naissain d’Ostrea edulis Linne en Fonction de Divers Parametres en Baie de Quiberon. Station Marine d’Endoume.

Menier, D. 2010. Cartographie Synthetique des Principeaux Faceus Sedimentaires Seperficiels de La Baie Quiberon et Baie Vilaine. Rapport pour le Conseil General du Morbihan. 41 p.

Menier D, Tessier B, Proust J.-N, Baltzer A, Sorrel P and Traini C., 2010. The Holocene Transgression as recorded by Incised-Valley Infilling in a Rocky Coast Context With Low Sediment Supply (Southern Brittany, Western France). Bull. Soc. Geol. Fr. 2010. 181 (2: 115-128)

Minchin. D.1987. Sea-water temperature and spawning behaviour in the seastar

Marthasterias glacialis. Journal Marine Biology. 95(1): 139-143.

Miossec. L, Le Deuff. RM and Goulletquer. P,. 2009. Alien Species Alert:

Crassostrea gigas (Pacific Oyster). ICES Cooperative Research Report No. 299. 42 pp.

Nawawi. M.Y. B.H. 1993. A Guide to Oyster Culture in Malaysia. Fisheries Research Institute, Department of Fisheries. Ministry of Agriculture, Penang, Malaysia. BAY OF BENGAL PROGRAMME, Madras, India. Newel, R.I.E, Kennedy, V.S and Shaw K.S., 2007. Comparative vulnerability to

predators, and induced defense responses, of eastern oysters Crassostrea virginica and non-native Crassostrea ariakensis oysters in Chesapeake Bay. Marine Biology. 152:449–460.

Park. B.H., Kim. B.Y., Hur. S.B., and Kim.S.J. 1988. Culture of the Pacific oyster (Crassostrea gigas) in the Republic of Korea. In Cooperation With The Regional Small Scale Coastal Fisheries Development Project, Bay Of Bengal Programme For Fisheries Development and The Indonesia Seafarming Development Project June 1988. Prepared for the Training Course on Oyster Culture conducted by the National Fisheries Research and Development Agency Pusan, Republic of Korea. June 1988.

(21)

Papineau. C. 1978. Element de la Biologie D’Ocenebra erinacea. Aplication a la protection des cultures de Pectinides en rade de Brest. Raport de Stage Realise au Centre Oceanologique de Bretagne. DEA D’Oceanographie Biologique. Paris VI. Annee 1977-1978.

Perry. H., 2011. Carcinus maenas. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. http://nas.er.usgs.gov/queries/factsheet.aspx? SpeciesID=190 RevisionDate: 4/25/2008

Pratt D.M, 1974. Attraction to Prey and Stimulus to Attack in the Predatory Gastropod Urosalpinx cinerea. Marine Biology. 27 (37:45).

Pauley, G.B, Van der Raay. B., and Troutt. D., 1988. Pacific Oyster. Species Profile: Life Histories and Enviromental Requirements of Coastal Fishes and Invertebrates (Pacific Northwest). Perform for Coastal Ecology Group and US. Department of the Interior. Fish and Wildlife Service. Biological Report 82(11.85). September 1988.

Penney. A.J. and Griffiths. C.L. 1984. Prey selection and the impact of the starfish

Marthasterias glacialis (L.) and other predators on the mussel

Choromytilus Meridionalis(Krauss). Journal of Experimental Marine Biology and Ecology. 75(1) :19-36.

Pigeot. J,Miramand. P, Garcia-Meunier. P, Guyot. T and Séguignes. M, 2000. Presence d’un nouveau predateur de l’huitre creuse, Ocinebrellus inornatus

(Récluz, 1851), dans le bassin conchylicole de Marennes-Oléron. Science de la vie/ Life Sciences. 323. 697-703.

Prince William Sound Regional Citizens “Advisory Council”. (2004). “Fact Sheet 3”. Non-indigenous aquatic species of concern for Alaska. Prince William Sound Regional Citizen Advisory Council. Retrieved 2011-01-09

Rodriguez. LF, 2009. Impact of Native predatory whelk on cultivated oyster (Crassostrea gigas) crops in San Quintin Bay, Mexico. Aquaculture Research. 40. 419-427.

Saier, B. 2001 Direct and indirect effects of seastars Asterias rubens on mussel beds (Mytilus edulis) in the Wadden Sea. Journal of Sea Research 46: 29-42.

Sauriau P.-G. 2002. Les bigorneaux perceurs des Pertuis Charentais : Élément de Biologie-Synthèse des moyens de lutte. Rapport de Contrat au Conseil General de Charente-Maritime et à l’Université de la Rochelle : 23 pp. Shelmerdine, R. L. and Leslie, B. (2009). Restocking of the native oyster, Ostrea

edulis, in Shetland: habitat identification study. Scottish Natural Heritage Commissioned Report No. 396

Savini.D, Occhipinti. A, and Ambrogi. 2006. Consumption Rates and Prey Preference of the Invasive Gastropod Rapana venosa in the Northern Adriatic Sea. Hegoland Marine Research. 60 (2):153-159.

Seyhan K, Mazlum E.R, Emiral H, Engin S, and Demirhan, S., 2003. Dial Feeding Periodicity, Gastric Emptying, and Estimated Daily Food Consumption of Whelk (Rapana venosa) in the South Eastern Black Sea (Turkey) Marine Ecosystem. Indian Journal of Marine Science. 32(3): 249-251.

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Sola, L., A. Moretti, D. Crosetti, N. Karaiskou and A. Magoulas et al., 2006. Gilthead seabream Sparus aurata. Proceedings of the WP1 Workshop on Genetics of Domestication, Breeding and Enhancement of Performance of Fish and Shellfish. June 12-17, Viterbo, Italy, pp: 6-6.

Spencer BE,. 1990. Cultivation of Pasific Oyster. Lab. Leafl., Maff Direct. Fish. Res., Lowestoft, (63), 47 pp

Synder S and French N., 2006. Distribution of Asterias on a Rocky Shore: A Study at Moose Point State Park. Unity College Marine Biology Journal. 7: 4-7

Tun. T., 2001. Étude de cas de mortalité massive chez les huîtres perlières. L’huître perlière - Bulletin de la CPS n° 14 :17-20

Valentinčič.T., 1973. Food finding and stimuli to feeding in the sea star

Marthasterias glacialis. Netherlands Journal of Sea Research. 7th_European

Symposium on Marine Biology.

Venables, W.N, Smith, D.M and the R Development Core Team. 2010. An Introduction to R. Note on R: A Programming Environtment for Data Analysis and Graphics Version 2.13.0(2011-04-13). R Development Core Team.

Verling E, Crook A.C, Barnes DKA and Harrison SSC., 2003. Structural dynamics of a sea-star (Marthasterias glacialis) population. Journal of the Marine Biological Association of the United Kingdom. 83: 583-592.

Villalobos. F. B, Tyler. P.A, and Young. C.M., 2006. Temperature and pressure tolerance of embryos and larvae of the Atlantic seastars Asterias rubens and

Marthasterias glacialis (Echinodermata: Asteroidea): potential for deep-sea invasion. Marine Ecology Progress Series. 314:109–117

Webster, D. 2007. Oyster Aquaculture Production.. University of Maryland (November 2007).

Wickert, G.L 2007. Subrogation and the Economic Loss Doctrine: A 50 State Survey, NASP Subrogator, Spring/Summer,

Yin, R K., 1984. Case Study Research: Design and Methods,: Newbury Park, Sage Publications, page 23.

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Appendix (oyster mortality data and the presence of predators)

s t a t i o n m o n t h B A P ( % ) B S P ( % ) B A P l i f e B S P l i f e B A P ( n b ) B S P ( n b ) B A P - % B S P o c i n o c e n a s t e r i a s m a r t h a s g a s t r s t a r f i s h

1 1 0 . 0 3 0 . 0 2 1 4 6 2 9 4 4 6 1 0 0 0 0 0 0

1 2 0 . 0 1 0 . 0 1 1 4 5 2 7 0 1 4 - 1 0 0 0 3 0 3

1 3 0 . 0 4 0 . 0 0 1 3 9 2 4 9 6 1 5 0 0 0 1 0 1

1 4 0 . 0 6 0 . 0 0 1 3 1 2 1 8 8 1 7 1 0 0 0 1 0

1 5 0 . 0 1 0 . 0 0 1 3 0 1 8 8 1 0 1 0 0 0 0 0 0

1 6 0 . 0 5 0 . 0 1 1 0 1 1 4 3 5 1 4 0 1 0 0 1 0

1 7 0 . 2 5 0 . 0 0 6 1 1 1 2 2 0 0 2 0 0 3 0 1 3 1

1 8 0 . 1 9 0 . 0 1 4 7 8 5 1 1 1 1 0 0 0 0 2 0 2

2 1 0 . 9 9 0 . 1 9 2 2 2 7 1 4 8 5 3 1 2 0 0 0 0 1 6 0 1 6

2 2 0 . 0 5 0 1 9 7 2 1 1 2 0 0 0 8 0 8

2 3 0 . 9 9 0 . 1 4 1 1 5 3 9 9 2 4 8 5 0 0 2 7 0 9

2 4 1 . 0 0 0 . 0 1 0 1 2 2 1 0 2 1 1 0 1 0 0 0 5 0 5

2 5 1 . 0 0 0 . 1 1 0 8 2 9 7 1 0 8 6 0 0 0 2 0 2

2 6 1 . 0 0 0 . 3 9 0 3 3 4 8 2 1 2 9 0 0 0 1 0 1

2 7 1 . 0 0 0 . 0 3 0 9 5 4 9 3 4 8 0 0 1 2 0 3

2 8 1 . 0 0 0 . 1 1 0 5 8 4 3 7 3 8 0 0 0 1 0 1

3 1 0 . 0 0 0 . 0 1 1 5 0 2 7 9 0 4 - 2 1 0 0 0 1 0

3 2 0 . 0 1 0 . 0 2 1 4 8 2 5 3 2 6 - 1 0 0 0 0 0 0

3 3 0 . 0 0 0 . 0 1 1 4 8 2 3 1 0 2 - 1 2 0 0 0 2 0

3 4 0 . 3 3 0 . 0 1 9 0 1 9 8 4 5 3 4 3 0 0 1 0 0 1

3 5 0 . 8 2 0 . 0 3 1 8 1 6 3 8 3 5 8 0 0 0 1 3 0 4

3 6 0 . 0 7 0 . 0 6 4 3 1 2 5 3 8 0 0 0 0 0 0 0

3 7 1 . 0 0 0 . 2 4 0 7 4 5 0 2 4 3 8 0 3 0 0 3 0

3 8 1 . 0 0 0 . 0 9 0 3 9 4 6 4 4 2 0 5 0 0 5 0

4 1 0 . 0 1 0 . 0 2 1 4 8 2 8 3 2 7 - 2 0 0 0 0 0 0

4 2 0 . 0 1 0 . 0 3 1 4 7 2 5 5 1 8 - 4 0 0 0 0 0 0

4 3 0 . 0 7 0 . 0 0 1 3 6 2 3 4 1 1 1 1 0 1 0 0 0 1 0

4 4 0 . 0 4 0 . 0 0 1 3 1 2 0 3 5 1 4 0 0 0 0 0 0

4 5 0 . 0 0 0 . 0 1 1 3 1 1 7 2 0 1 - 1 0 0 0 1 0 1

4 6 0 . 0 1 0 . 0 6 1 3 7 1 3 4 1 8 - 7 0 3 0 0 3 0

4 7 0 . 0 2 0 . 0 1 1 2 8 1 0 8 3 1 2 4 4 2 0 0 4 6 0

4 8 0 . 1 8 0 . 0 0 9 3 7 7 2 1 0 2 1 0 1 0 1 1 1

5 1 0 . 9 9 0 . 1 0 2 2 6 2 1 4 8 2 8 1 3 4 0 0 1 0 5 0 1 5

5 2 0 . 1 6 0 2 0 5 2 3 8 2 0 0 2 5 0 7

5 3 1 . 0 0 0 . 0 7 0 1 7 2 1 0 0 1 3 9 3 3 1 2 1 4 3

5 4 0 . 9 9 0 . 0 2 1 1 3 9 9 7 3 9 5 2 0 0 1 2 1

5 5 1 . 0 0 0 . 0 2 0 1 0 7 1 0 0 2 9 8 5 3 0 1 8 1

5 6 1 . 0 0 0 . 0 3 0 7 1 5 0 2 4 9 2 1 1 0 3 1

5 7 1 . 0 0 0 . 0 3 0 3 8 4 5 1 4 4 1 1 0 0 2 0

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6 1 0 . 1 5 0 . 0 1 1 2 7 2 8 7 2 3 3 2 1 0 0 1 0 0 1 6 2 0 . 2 0 0 . 0 0 1 0 2 2 6 6 2 5 1 2 5 0 0 1 0 0 1 6 3 0 . 0 3 0 . 0 3 9 9 2 3 8 3 8 0 0 0 0 0 0 0 6 4 0 . 0 4 0 . 0 0 9 5 2 0 7 4 1 4 0 0 0 0 0 0 6 5 0 . 0 2 0 . 0 0 9 3 1 7 7 2 0 2 0 0 0 0 0 0 6 6 0 . 0 0 0 . 0 1 7 8 1 4 3 0 1 - 1 0 0 0 0 0 0 6 7 0 . 0 6 0 . 0 1 5 8 1 1 1 4 1 3 5 5 0 0 1 0 0 6 8 0 . 0 2 0 . 0 1 5 5 7 9 1 1 0 0 5 0 0 5 0 7 1 0 . 0 0 0 . 0 1 1 5 0 2 9 7 0 3 - 2 0 0 0 0 0 0 7 2 0 . 0 2 0 . 0 0 1 4 7 2 7 6 3 1 2 0 0 0 0 0 0 7 3 0 . 0 1 0 . 0 0 1 4 6 2 5 5 1 1 0 0 0 0 0 0 0 7 4 0 . 0 1 0 . 0 1 1 4 5 2 2 1 1 3 - 1 0 0 0 0 0 0 7 5 0 . 0 1 0 . 0 0 1 4 3 1 9 1 2 0 2 0 0 0 1 0 1 7 6 0 . 0 5 0 . 0 1 1 2 1 1 3 8 6 1 5 0 1 5 0 0 1 5 0 7 7 0 . 0 3 0 . 0 4 1 1 4 1 0 4 4 4 0 0 1 4 0 0 1 4 0 7 8 0 . 0 0 0 . 0 0 1 0 9 7 3 0 0 0 0 1 4 0 0 1 4 0 8 1 0 . 0 5 0 . 0 2 1 4 2 2 7 4 8 6 5 4 0 0 0 4 0 8 2 0 . 0 9 0 . 0 2 1 2 9 2 5 0 1 3 4 1 1 4 0 0 0 4 0 8 3 0 . 1 9 0 . 0 0 1 0 4 2 2 9 2 5 1 2 4 1 2 0 0 0 1 2 0 8 4 0 . 3 1 0 . 0 4 7 2 1 9 1 3 2 8 2 8 7 0 0 0 7 0 8 5 0 . 5 3 0 . 0 1 4 5 1 5 9 5 1 2 5 0 1 1 2 6 0 0 3 7 0 8 6 0 . 4 9 0 . 0 2 2 5 1 2 9 2 4 3 2 3 1 5 2 2 0 0 3 7 0 8 7 0 . 5 1 0 . 0 6 2 4 9 3 2 5 6 2 2 2 6 2 1 0 0 4 7 0 8 8 0 . 1 1 0 . 0 2 3 9 6 1 5 1 4 0 3 0 0 3 0 9 1 0 . 0 4 0 . 0 3 1 4 4 2 7 3 6 7 2 0 0 0 1 0 1 9 2 0 . 0 2 0 . 0 2 1 4 1 2 4 8 3 6 0 2 0 0 0 2 0 9 3 0 . 0 1 0 . 0 1 1 3 9 2 2 6 2 2 1 2 0 0 0 2 0 9 4 0 . 0 4 0 . 0 4 1 3 3 1 8 9 6 8 0 0 0 0 0 0 0 9 5 0 . 0 0 0 . 0 1 1 3 3 1 5 7 0 2 - 2 0 0 0 0 0 0 9 6 0 . 0 0 0 . 0 0 1 1 5 1 2 3 0 0 0 0 0 0 0 0 0 9 7 0 . 1 7 0 . 0 0 8 0 9 4 1 6 0 1 6 0 0 1 0 0 1 9 8 0 . 0 0 0 . 0 0 7 2 6 2 0 0 0 0 2 0 0 0 2 0 0 1 0 1 0 . 4 8 0 . 0 3 7 8 2 7 3 7 2 7 6 8 2 8 0 2 0 2 8 2 1 0 2 0 . 1 7 0 . 0 2 6 5 2 4 8 1 3 5 1 1 4 0 0 0 4 0 1 0 3 0 . 5 0 0 . 0 1 5 0 2 2 6 5 0 2 4 9 1 4 0 0 0 1 4 0 1 0 4 0 . 5 9 0 . 0 4 4 1 1 9 1 6 0 7 5 6 1 5 0 0 0 1 5 0 1 0 5 0 . 4 6 0 . 0 2 5 0 1 5 7 4 2 4 4 0 1 3 3 0 0 1 6 0 1 0 6 0 . 3 6 0 . 0 2 3 2 1 2 7 1 8 2 1 7 7 0 0 0 7 0 1 0 7 0 . 2 9 0 . 0 2 2 9 9 2 1 2 2 1 1 8 1 3 0 0 2 1 0 1 0 8 0 . 1 0 0 . 0 0 3 8 6 1 4 0 4 3 1 0 0 4 0 1 1 1 0 . 1 5 0 . 0 2 1 2 8 2 9 5 2 2 5 2 0 2 6 0 0 0 2 6 0

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BAP-%BSP = Number dead Oysters (BAP) – ((Number life oysters in BAP + Number dead Oysters in BAP) X Percentage dead oysters in BSP)

1 1 2 0 . 1 3 0 . 0 2 1 1 1 2 7 0 1 7 5 1 5 1 0 0 0 0 1 0 0

1 1 3 0 . 5 3 0 . 0 3 5 2 2 4 3 5 9 7 5 6 1 5 2 0 0 1 7 0

1 1 4 0 . 3 4 0 . 1 1 6 2 1 8 9 3 2 2 4 2 1 6 0 0 0 6 0

1 1 5 0 . 2 3 0 . 0 2 6 2 1 5 6 1 8 3 1 6 9 8 0 0 1 7 0

1 1 6 0 . 0 3 0 . 1 0 7 0 1 0 8 2 1 2 - 5 2 2 4 0 0 2 6 0

1 1 7 0 . 3 2 0 . 0 6 4 4 7 3 2 1 5 1 7 2 3 9 0 0 0 1 1 3 0

1 1 8 0 . 2 2 0 . 0 2 3 5 4 4 1 0 1 9 3 4 6 6 0 0 1 0 0 0

1 2 1 0 . 0 9 0 . 0 5 1 3 6 2 1 9 1 4 1 1 7 1 2 0 0 0 1 2 0

1 2 2 0 . 9 0 0 . 0 7 1 4 1 8 7 1 2 2 1 3 1 1 3 9 0 2 1 9 3

1 2 3 0 . 9 8 0 . 0 5 2 1 5 9 9 6 8 9 1 1 2 0 0 0 1 2 0

1 2 4 0 . 7 6 0 . 0 2 2 3 1 2 7 7 4 2 7 2 1 6 0 0 0 1 6 0

1 2 5 0 . 3 1 0 . 0 1 6 6 9 6 3 0 1 2 9 5 1 9 2 0 2 4 2

1 2 6 0 . 1 3 0 . 0 9 5 8 6 2 9 6 3 1 0 7 0 0 1 7 0

1 2 7 0 . 5 7 0 . 0 0 2 3 3 2 3 1 0 3 1 5 6 4 4 0 0 1 0 0 0

1 2 8 0 . 3 6 3 0 1 7 1 7 2 1 8 0 0 2 0 0

1 3 1 0 . 2 5 0 . 0 5 1 1 2 2 7 5 3 8 1 5 3 0 7 1 4 0 8 4

1 3 2 0 . 8 4 0 . 0 5 1 8 2 4 3 9 4 1 2 8 9 3 0 5 1 3 6

1 3 3 0 . 9 5 0 . 0 5 5 2 1 2 9 5 1 1 9 0 8 0 4 0 8 4

1 3 4 0 . 9 7 0 . 0 3 3 1 7 4 9 7 6 9 4 7 0 3 1 7 4

1 3 5 1 . 0 0 0 . 0 1 0 1 4 3 8 8 1 8 7 5 0 4 0 5 4

1 3 6 0 . 1 6 0 . 0 2 4 7 1 0 9 9 2 8 9 0 0 0 9 0

1 3 7 1 . 0 0 0 . 0 5 0 7 3 4 8 4 4 6 8 0 0 0 8 0

1 3 8 0 . 5 0 0 . 0 2 2 1 4 2 2 1 1 2 0 1 8 2 2 0 2 0 2

1 4 1 0 . 4 0 0 . 0 3 1 0 0 2 7 2 6 6 8 6 1 1 0 2 0 1 2

1 4 2 0 . 0 2 0 . 0 2 9 8 2 4 8 2 5 0 0 0 1 0 0 1

1 4 3 0 . 0 4 0 . 0 1 9 6 2 2 6 4 2 3 1 0 0 0 1 0

1 4 4 0 . 5 2 0 . 0 1 4 8 1 9 4 5 3 2 5 2 1 0 1 1 1 2

1 4 5 0 . 1 1 0 . 0 6 7 5 1 5 4 9 1 0 4 3 0 0 0 3 0

1 4 6 0 . 1 2 0 . 0 3 6 6 1 2 5 9 4 7 2 0 0 0 2 0

1 4 7 0 . 1 0 0 . 0 6 5 6 8 8 6 6 2 2 8 0 0 1 0 0

1 4 8 0 . 1 4 0 . 0 8 4 3 5 6 7 5 3 0 8 1 0 8 1

1 5 1 0 . 1 6 0 . 0 6 1 2 6 2 3 5 2 4 1 5 1 5 2 9 2 0 0 3 1 0

1 5 2 0 . 2 8 0 . 2 6 9 1 1 9 6 3 5 7 0 2 1 4 0 0 0 1 4 0

1 5 3 0 . 2 2 0 . 0 9 7 8 1 6 0 2 2 1 6 1 3 2 1 0 0 0 2 1 0

1 5 4 0 . 5 4 0 . 0 5 4 7 1 2 3 5 6 7 5 0 7 0 0 0 7 0

1 5 5 0 . 7 7 0 . 1 3 2 2 8 1 7 3 1 2 6 1 8 1 8 0 0 2 6 0

1 5 6 0 . 6 3 0 . 2 6 1 8 3 5 3 0 1 2 1 8 2 8 1 9 0 0 4 7 0

1 5 7 0 . 8 5 0 . 6 5 7 3 5 4 0 6 4 1 0 6 6 2 7 6 0 0 3 4 2 0

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ABSTRACT

Since the year of 2000 and especially 2006, the oyster mortality rates have reached quite unusual, estimated at 60% mortality in a breeding cycle ending in late 2006 in Quiberon Bay. This mortality brought a great impact on the France's economy since oyster cultures are activities of collective small scale industry of great importance economic. So, in this study, we observed the effects of oyster mortality in terms of biology and economics value.

The impact of predators in Quiberon Bay France, was examined. The objectives of this study are to analyse Risks in Shellfish Farming (RISCO) located in Quiberon Bay data on oyster mortality, to determine effect of predators on oyster culture, to map the distribution of different types of predators and to calculate the economic analysis of oyster mortality.

We investigated the potential role of two species of starfishes, Asterias rubens and Marthasterias glacialis and two species of gastropods, Ocenebra erinacea and Ocenebrillus inornatus. Marthasterias glacialis indicated a great impact on mortality of adult oysters. The relation between oyster's mortality and the presence of gastropods were time dependent and according to reproductive cycle. Several months show clearly a predation of oysters and concentration of gastropods for spawning. Predators on oyster culture also indicated a great impact in economic value. The economic value on on oyster culture model applied at RISCO project shows that BSP was higher than BAP. Economic loss in BAP greatly happen in station 2 and 5, approximately €81.28 - €81.83. On the contrary, station 15 indicate has the higher loss in BSP approximately €54.92 or 363 oysters and for the rest, the economic value was varies between €29.67-€40.30.

Key words: Crassostrea gigas, Mortality, Predators, Quiberon Bay, Asterias rubens and Marthasterias glacialis, Ocenebra erinacea and Ocenebrillus inornatus.

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