Éditeur(s) : Université de La Rochelle
Résumé : Shrimp aquaculture in New Caledonia is a developing industry, exclusively based on the species Litopenaeus stylirostris. However, it is subject to mortalities during grow out as observed all over the world. Since 1993, shrimp reared during the cold period are affected by a disease named "syndrome 93". As a consequence, the whole industry has become seasonal and produces essentially during the warm season. The climatic conditions during the periods of transition between the two main seasons could be responsible for an environmental stress and the origin reason for mortality outbreaks. Stocking density is the main risk factor. It increases the probability of the appearance and development of the epizooty in the pond. The "Summer Syndrome", a septicemic vibriosis caused by Vibrio nigripulchritudo, was identified for the first time in December 1997 in an intensive shrimp farm (DF). It has become enzootic ever since and is expressed after 50d of rearing. Since 2003, two others farms located near DF have developed the disease. As a consequence, the summer syndrome is considered to be a potential threat for all the industry. Between 1991 and 2005, the increase of feed input and nitrogen levels in feed has led to a significant increase in the growth rate over the years in the farms affected by the disease. In consequence, an early eutrophication of the water is observed, which is concomitant with the beginning of the mortality outbreaks. An early eutrophication and the virulence level of the pathogen are considered as the main risk factors of the disease. Factors may act synergistically to explain the summer syndrome. As part of a multidisciplinary approach (pathology – physiology – environment), two high-frequency surveys were carried out to analyse the pond ecosystem. Since the feed quantity increases with the biomass of shrimp, the eutrophication level of the pond ecosystem will also tend to increase with the duration of rearing. During the first part of the rearing, the abundance of each picoplankton type is exceptionally high and picophytoplankton dominated the autotrophic compartment. The nanophytoplankton dominated the second part of the rearing and was more unstable. The shift from pico to nanophytoplankton could be considered as an environmental stress and was observed in relation to the beginning of the mortalities, whatever the disease. Shift intensity could play a role by inducing directly or indirectly a stress for shrimp and/or a growth and/or virulence factors of the pathogen. Results from sediment studies show that mortality was best characterized by TAN concentration in pore water and even more when the TAN concentration was high. TAN and pH are potential stress factors for shrimp reared in ponds affected by these diseases.
L'aquaculture mondiale de crevettes est un secteur à très forte croissance. Toutefois, les problèmes liés aux maladies dans les élevages ne cessent d'augmenter depuis 1980. Au cours du développement de la filière de Nouvelle-Calédonie, deux épisodes saisonniers de mortalités associées à la présence de Vibrio pathogènes sont apparus et ont fortement perturbé les techniques et les schémas de production. Les premières mortalités hivernales, décrites sous le nom de « syndrome 93 » ont été observées en mai 1993. Elles ont affecté depuis tous les élevages de saison froide de toutes les fermes de production. Les conditions climatiques pendant les périodes de transitions entre les deux principales saisons caractérisant le climat de la Nouvelle-Calédonie, seraient responsables d'un stress environnemental à l'origine du déclenchement du syndrome 93. La densité initiale d'ensemencement, apparaît comme le principal facteur de risque, augmentant la probabilité d'apparition de la maladie et l'ampleur de ses effets. Le « syndrome d'été » a été identifié pour la première fois en 1997 dans une ferme pratiquant une production intensive. Il s'est déclaré depuis 2003 dans deux autres fermes géographiquement proches. Les mortalités apparaissent 58 jours en moyenne après l'ensemencement des post-larves dans les bassins. La recherche d'une croissance maximale des animaux a induit, avec les années, une intensification progressive du système caractérisée par une augmentation de la quantité d'aliment distribuée. L'examen des données historiques fait apparaître une eutrophisation du milieu de plus en plus précoce concomitante au déclenchement des mortalités. En l'état actuel de nos connaissances, cette évolution précoce de l'écosystème en présence de façon récurrente de la souche hautement pathogène du Vibrio incriminé et à une période où la fréquence des mues des crevettes est élevée, constitue le principal facteur de risque de la maladie. Avec l'apport croissant en aliment, la colonne d'eau évolue vers une autotrophie croissante alors que le sédiment devient de plus en plus hétérotrophe au fur et à mesure que l'élevage progresse. Au cours du processus d'eutrophisation, le compartiment autotrophe montre une succession de deux assemblages. Le picophytoplancton domine sur la première partie de l'élevage et laisse place à du nanophytoplancton en seconde partie. Cette phase de transition, concomitante à l'apparition des mortalités quel que soit le syndrome, caractérise un stress environnemental dont l'intensité pourrait favoriser ou non le déclenchement des mortalités. Les suivis de différents indicateurs dans les sédiments - pH, potentiel d'oxydoréduction et concentration en ammoniaque dans l'eau interstitielle – indiquent dans les bassins déclarant les épizooties des conditions qui ont été définies expérimentalement comme potentiellement plus stressantes pour les animaux.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2007/these-2643.pdf
http://archimer.ifremer.fr/doc/00000/2643/

Éditeur(s) : Elsevier
Résumé : Regardless of the degree of closure of a recirculation system, effluents are produced and replacement water is needed, which limits the possibility of locating a seawater production system away from the shoreline. At the Palavas Ifremer station, in the south of France, a High Rate Algal Pond (HRAP) was operated during several years to treat the effluent from a recirculating aquaculture system before reusing it. The effect of the HRAP-treated water on the recirculation system and on the fish was investigated and the optimal algae growing conditions were defined. The experiments were carried out in three rearing systems: one flow through, one recirculating and one recirculating with a HRAP. The water flow rate, temperature, pH and salinity conditions were similar in all systems. The effect of reusing the HRAP-treated water is very limited (1) on the functioning of the recirculation system and (2) on fish performance, but it allows a significant reduction of the dissolved inorganic nitrogen and phosphorus concentration in the rearing water. HRAP treatment reduced metal accumulation in muscle and liver of RAS fish, except for chromium and arsenic. All biomarkers presented no significant difference between systems, except for Superoxide Dismutase (SOD) and EROD, which showed a higher concentration in RAS and in both recirculating system respectively. (c) 2005 Elsevier B.V. All rights reserved.
Aquaculture (0044-8486) (Elsevier), 2006-03 , Vol. 252 , N. 1 , P. 92-101

Droits : 2005 Elsevier
http://archimer.ifremer.fr/doc/2006/publication-2306.pdf
DOI:10.1016/j.aquaculture.2005.11.053
http://archimer.ifremer.fr/doc/00000/2306/

Éditeur(s) : PSIC 11 - 11th Pacific Science Inter-Congress : Pacific Countries and their Ocean: Facing Local and Global Changes / 2nd Symposium on French Research in the Pacific. March 2 - 6, 2009 Tahiti, French Polynesia.
Résumé : Meiofauna is a functional group made of small benthic metazoans 45 to 500µm in size. Although protista, foraminifera living in this kind of environment are often put in to the meiofauna. Meiofauna has been studied in New Caledonia for its double role as biological indicator for monitoring pond health status and as shrimp forage. Suitability of EOM (easily oxidized material), SOD(sediment oxygen demand),as new biochemical tools for monitoring shrimp pond health was assessed in an environmental survey aiming to assess the role of the water/sediment interface in the occurrence of the summer syndrome vibriosis. EOM, SOD and redox were correlated with shrimp survivals. Lowest meiofauna biomass and abundance were concomitantly found in the most polluted station. Proportion of abnormal tests over exceeding the one found in areas subjected to natural ecological stress were collected and were positively related to EOM and SOD and negatively to redox. Shrimp pond dominant species are common to estuaries and lagoons. But foraminifera abnormal behaviour indicates specific shrimp pond conditions

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00198/30876/29244.pdf
http://archimer.ifremer.fr/doc/00198/30876/

Éditeur(s) : Inter-research
Résumé : Vibriosis is a major disease problem in shrimp aquaculture. 'Syndrome 93' is a seasonal juvenile vibriosis caused by Vibrio penaeicida which affects Litopenaeus stylirostris in grow-out ponds in New Caledonia. This study assessed the toxic activities of extracellular products (ECPs) from V: penaeicida, V. alginolyticus and V, nigripulchritudo using in vivo injections in healthy juvenile L. stylirostris (= Penaeus stylirostris) and in vitro assays on shrimp primary cell cultures and the fish cell line epithelioma papulosum cyprini (EPC). Toxic effects of ECPs were demonstrated for all pathogenic Vibrio strains tested both in vivo and in vitro, but for shrimp only; no effect was observed on the fish cell line. ECP toxicity for New Caledonian V. penaeicida was found only after cultivation at low temperature (20 degrees C) and not at higher temperature (30 degrees C). This points to the fact that 'Syndrome 93' episodes are triggered by temperature drops. The assays used here demonstrate the usefulness of primary shrimp cell cultures to study virulence mechanisms of shrimp pathogenic bacteria.
Diseases Of Aquatic Organisms (0177-5103) (Inter-research), 2000-03 , Vol. 40 , N. 2 , P. 101-107

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00000/10543/7600.pdf
DOI:10.3354/dao040101
http://archimer.ifremer.fr/doc/00000/10543/

Éditeur(s) : Elsevier
Résumé : Shrimp farming is a small but growing industry in New Caledonia. Since 1993, "Syndrome 93" has been affecting New Caledonian shrimp farming industry every cold season, causing severe epizootic mortalities in grow-out ponds and significant losses. Highly pathogenic strains of Vibrio penaeicida are considered the etiological agent of the disease in Litopenaeus stylirostris. On one hand, studies demonstrated that healthy shrimp may carry V penaeicida for weeks with a high overall prevalence, regardless of any seasonal pattern or temperature conditions. On the other hand, larvae are free of V penaeicida and are also resistant to experimental infection. V penaeicida is frequently detected in incoming water pumped from the bays, which was shown, by a molecular typing study, to be the infectious source. This particular epidemiological pattern highlights the major role of the factors that trigger and aggravate the disease in grow-out ponds, where shrimp populations carry the pathogen all year round. In order to gain a better understanding of "Syndrome 93" epidemiology, quantification of V penaeicida both in shrimp and the shrimp farm ecosystem is necessary. This article describes the steps in the successful development of a real-time PCR quantification assay of V penaeicida in shrimp haemolymph, seawater (from ponds or bays) and sediment pore water, including the choice of an accurate extraction technique. The entire detection method; including sample processing, DNA extraction and real-time PCR amplification, can be completed within 4 h. (c) 2006 Elsevier B.V All rights reserved.
Journal of Microbiological Methods (0167-7012) (Elsevier), 2006-10 , Vol. 67 , N. 1 , P. 27-35

Droits : 2006 Elsevier
http://archimer.ifremer.fr/doc/2006/publication-1903.pdf
DOI:10.1016/j.mimet.2006.02.013
http://archimer.ifremer.fr/doc/00000/1903/

Éditeur(s) : Elsevier Science Bv
Résumé : Shrimp aquaculture in New Caledonia is subject to seasonal mortalities during grow-out due to highly virulent Vibrio nigripulchritudo (Vn). To understand the mechanisms affecting shrimp resistance and leading to significant mortality, a shrimp ecophysiology and immunology survey was conducted on two farms, the first considered as a "control" farm (HC), the second affected by the disease (DF). Mortality observed during the survey at DF started 50 days after stocking and was typical of this disease. The main observations regarding shrimp were: (a) growth was not affected by the disease and was faster in the DF than in the HC pond; (b) disease did not affect one sex more than the other, or a specific part of the population in terms of weight; (c) the physical condition of shrimp did not specifically allow us to foresee disease outbreak; (d) shrimp at late premolt stage D-2 and early postmolt stage A appeared to be at some points of the mortalities - but not continuously - the most sensitive to disease; (e) physiological, immunological and nutritional parameters of uninfected shrimp in the DF pond were altered, suggesting that environmental stress occurred just before the first mortalities; (f) data suggest that Vn-infected shrimp are more stressed than the presumed healthy shrimp. Combined with pathological and environmental knowledge gained in parallel during this survey, a conceptual model is proposed. Results suggest that an unstable environment induced conditions (i) stressful for the shrimp, increasing their susceptibility to bacterial infections and (ii) favoring the proliferation of the pathogen in the pond. The combination of these two processes could lead to significant mortality.
Aquaculture (0044-8486) (Elsevier Science Bv), 2013-04 , Vol. 388 , P. 105-114

Droits : 2013 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00176/28764/27567.pdf
DOI:10.1016/j.aquaculture.2013.01.010
http://archimer.ifremer.fr/doc/00176/28764/

Éditeur(s) : Europe Aqauculture Symposium, October 14-17, San Sebastian, Spain
Résumé : Shrimp farming in New-Caledonia faces up to difficulties. A fluctuating quality of broodstock prevents sustainable production of larvae in quantity and quality. The traditional extensive rearing method of broodstock in outdoor earthen ponds used in New Caledonia raises several issues: poor water quality control and biosecurity. Therefore it is fundamental to modify the broodstock culture strategy in order to achieve an easier water quality management and maximal biosecurity. Biofloc technology (BFT) offers easier water quality management, higher natural productivity, higher level of biosecurity, and could be a good alternative. Since 2011 a R&D program started under the supervision of IFREMER in New Caledonia and French Polynesia in order to study and develop biofloc technology for rearing shrimp L. stylirostris broodstock. In a first step we showed that biofloc (BFT) improved significantly the reproductive performances of shrimps and the quality of their larvae compared to Clear Water (CW) or Earthen Pond (EP), with: • A better final survival rate of broodstock from BFT compare to CW. • Females from BFT produced more eggs per spawn and spawned more frequently compared to females from CW or EP. • The larvae from BFT females had a significantly higher survival rate compared to larvae from CW females, respectively 70% (n=4) and 45% (n=4). In a second step we studied the underlying biological mechanisms explaining the better reproductive performance and health status of the broodstock from BFT rearing system, and the better quality of their larvae. We showed that the juvenile shrimp fed actively on biofloc, which represented 60% of their whole food (40% coming from pelleted diet). Biofloc represents a significant source of essential nutrients (vitamins, antioxidants, highly unsaturated fatty acids, …) or dietary bacteria which could act as probiotic. These dietary complements could explain the improved health status (immunity and oxidative status status), the better resistance to oxidative stress and a systematically better survival rate of the shrimp reared in BFT compared to those reared in CW.

Droits : 2014 Ifremer
http://archimer.ifremer.fr/doc/00250/36084/34635.pdf
http://archimer.ifremer.fr/doc/00250/36084/

Résumé : Penaeus stylirostris shrimp imported from Hawaii for a genetic program and kept at the Saint-Vincent research facility had progressively developed a high sensitivity to IHHNV, the etiological agent of the Infectious, Hypodermic, and Hematopoietic Necrosis. Fears were that the virus could not only be transferred to their offspring, but also that the New Caledonian strain of Penaeus stylirostris, so far considered as resistant, could become sensitive by an off balance of its hosts/pathogen equilibrium. In October 2008, a joint decision between Uprac (shimp owner), Davar (New Caledonian Animal Health Authority) and Ifremer (scientific partner) was taken to terminate all pure breed and hybrid Hawaiian populations remaining in the ponds, and to implement an intensive fallowing protocol, and controlled restocking. IHHNV was also suspected to trouble experiments carried out in the research facility (mortalities, deformities, slow growth), thus affecting research programs. Difficulties pointed out by IHHNV have triggered since 2008 some awareness on biosecurity issues at some level of the New Caledonian shrimp industry. At the St-Vincent research station, it led to a risk assessment and implementation of biosecurity procedures (fallowing, propagation, grow out and use of screened animals) which minimizes the risk of expression of IHHNV. The use of a brand new hatchery building on site also helped in resetting routine hygiene procedures during production and in controlling incoming and outgoing items (shrimp, water, feed, personnel, equipment, pests and wastes). IHHNV has not been detected on analysed samples since then nor have any symptoms been found during experimental or broodstock growout. Keeping this control alive is considered as a useful tool to lower the risk of potential health threats, to get a better understanding in case of an outbreak, and to increase the reliability of experimental results.
Les crevettes originaires d’Hawaii et conservées au LEAD St-Vincent, dans le cadre du programme d’introduction de variabilité génétique dans le cheptel Calédonien, ont progressivement montré une sensibilité importante au virus IHHNV, agent de la Nécrose Hypodermale et Hématopoïétique Infectieuse (mortalité, croissance ralentie, déformations). Les risques d’une transmission génétique de cette sensibilité à leur descendance à moyen terme, et de son développement par rupture de l’équilibre hôte/pathogène sur la souche dite « Calédonienne » jusqu’alors considérée comme résistante à l’IHHN, ont conduit à partir d’octobre 2008, avec l’accord et l’appui de l’UPRAC et de la DAVAR, à la suppression des animaux hawaiiens ou hybrides encore présents dans les bassins de terre du LEAD St-Vincent, au vide sanitaire de ces derniers, et au repeuplement contrôlé du site. D’autre part, le virus IHHN est soupçonné d’avoir pu affecter les animaux utilisés dans les expérimentations menées au LEAD-St-Vincent (mortalités, déformations, croissance réduite), influençant donc potentiellement leur bon déroulement et celui des programmes de recherches. Les obstacles soulevés par l’expression du virus IHHN ont donc initié depuis 2008 une prise de conscience et la mise en place de démarches de biosécurité dans certains points de la filière. A la station de St-Vincent, cette démarche s’est traduite par une identification/évaluation des risques et l’application de mesures (vide sanitaire, reproduction, élevage et utilisation des animaux contrôlés) chacune dotée de procédures qui regroupées, minimisent le risque d’introduction et de dissémination de l’IHHNV. La prise en main de la nouvelle structure d’écloserie sur le site de la SASV a également été mise à profit pour revoir les procédures d’hygiène de routine dans la conduite des productions et dans le contrôle des flux intrants et sortants (animaux, eau, aliments, personnel, équipement, nuisibles, déchets). Aucune détection d’IHHNV sur les échantillons prélevés n’a depuis été observée, de même qu’aucun symptôme de l’expression de cette maladie sur les animaux en élevage sur le site de Saint-Vincent. La poursuite de ces mesures est envisagée comme un outil d’aide à la minimisation des problèmes potentiels, à leur compréhension en cas d’apparition, et à la fiabilisation des résultats.

Droits : 2010 Ifremer
http://archimer.ifremer.fr/doc/00118/22949/20776.pdf
http://archimer.ifremer.fr/doc/00118/22949/

Éditeur(s) : Pergamon-elsevier Science Ltd
Résumé : The present work aimed at better understanding metal and metalloid bioaccumulation in the edible Pacific blue shrimp Litopenaeus stylirostris, using both laboratory and field approaches. In the laboratory, the bioaccumulation kinetics of Ag, Cd, Co, Cr, and Zn have been investigated in shrimp exposed via seawater and food, using the corresponding gamma-emitting radiotracers (Ag-110m, Cd-109, Co-57, Cr-51, and Zn-65) and highly sensitive nuclear detection techniques. Results showed that hepatopancreas and intestine concentrated the metals to the highest extent among the blue shrimp organs and tissues. Moulting was found to play a non negligible detoxification role for Co, Cr and, to a lesser extent, Zn. Metal retention by L stylirostris widely varied (from a few days to several months), according to the element and exposure pathway considered (a given metal was usually less strongly retained when ingested with food than when it was taken up from the dissolved phase). In the field study, Ag, As, Cd, Co, Cr, Cu, Mn, Ni, and Zn were analysed in shrimp collected from a New Caledonian aquaculture pond. Metal concentrations in the shrimp muscles were generally relatively low and results confirmed the role played by the digestive organs and tissues in the bioaccumulation/storage/detoxification of metals in the Pacific blue shrimp. Preliminary risk considerations indicate that consumption of the shrimp farmed in New Caledonia is not of particular concern for human health. (C) 2010 Elsevier Ltd. All rights reserved.
Marine Pollution Bulletin (0025-326X) (Pergamon-elsevier Science Ltd), 2010 , Vol. 61 , N. 7-12 , P. 576-584

Droits : 2010 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/00014/12528/9869.pdf
DOI:10.1016/j.marpolbul.2010.06.035
http://archimer.ifremer.fr/doc/00014/12528/

Éditeur(s) : 11th Pacific Science Inter-Congress / 2nd Symposium on French Research in the Pacific, Tahiti
Résumé : In order to have a standardised database gathering most information on New Caledonian prawn farms a software, called “Stylog-module ferme”, was developed and implemented by Ifremer with the help of shrimp farmers. Data recording results in more than 2 million data from 250 crops since the beginning of the project (2003). The main objective is to help the researchers in understanding the processes taking place in a cultured pond. It also provides a follow-up of the prawn farming industry (evolution of management practices, health surveillance system…) and to facilitate sharing of information between the different partners of the industry (prawn farmers, research and local authorities). Finally, this decision-making tool also helps shrimp farmers for routine crop management. This poster presents the method and tools used to create this database, from the definition of specifications, in close relation with end users, to the implementation of a real project structure, including all partners (users committee and steering committee, agreement of confidentiality). It also shows some examples resulting from the analysis of these data (investigating good management practices indicators, publishing technical bulletins or specific data analysis for research…). Finally, the networking (Extranet) of this base seems to present real perspectives in sharing information, and analysis capacity.
Afin de disposer d'une base de données regroupant un maximum d'informations collectées sur les fermes de grossissement de crevettes de Nouvelle-Calédonie, dans un format informatisé et standardisé, un logiciel nommé « Stylog – module ferme » a été développé par l'Ifremer en lien avec les aquaculteurs. L'archivage des données a permis de collecter depuis le début de sa conception (2003) plus de 2 millions de données représentant près de 250 élevages. Les objectifs principaux de cette base sont d'aider les chercheurs dans la compréhension de phénomènes pouvant survenir dans un bassin d'élevage, d'assurer un suivi de la filière (évolution des pratiques zootechniques, veille clinique…) et de faciliter les échanges d'informations entre les différents partenaires de la filière (aquaculteurs privés, recherche, institutions). Enfin, cet outil d'aide à la décision permet aux aquaculteurs de gérer leurs élevages au quotidien. Ce poster explique d'une part, la méthode et les outils utilisés pour créer cette base de données, de la réalisation du cahier des charges, en lien étroit avec les utilisateurs finaux, à la mise en place d'une réelle structure projet regroupant les différents partenaires (comité des utilisateurs et comité de pilotage, convention de confidentialité). D'autre part, il présente quelques exemples de résultats en termes d'utilisation de ces données (recherche d'indicateurs de qualité d'élevage, édition de bulletins techniques, analyses de données spécifiques à la recherche…). Enfin, la mise en réseau (Extranet) de cette base semble présenter de réelles perspectives en termes de partage de l'information et de capacité d'analyses.

Droits : 2009 Ifremer
http://archimer.ifremer.fr/doc/00065/17659/15189.pdf
http://archimer.ifremer.fr/doc/00065/17659/