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Prevalence and proposal for cost-effective management of the ciguatera risk in the Noumea fish market, New Caledonia (South Pacific)
Abstract
Ciguatera fish poisoning (CFP) is a common intoxication associated with the consumption of reef fish, which constitutes a critical issue for public health in many countries. The complexity of its epidemiology is responsible for the poor management of the risk in tropical fish markets. We used the example of the Noumea fish market in New Caledonia to develop a cost-effective methodology of assessing the CFP risk. We first used published reports and the knowledge of local experts to define a list of potentially poisonous local species, ranked by their ciguatoxic potential. Based on two 1-month surveys in the market, conducted in winters 2008 and 2009, we then calculated the consolidated ratio of biomass of potentially poisonous species vs. total biomass of fish sold on the market. The prevalence of high CFP-risk species in the market was 16.1% and 18.9% in 2008 and 2009, respectively. The most common high CFP risk species were groupers (serranids), king mackerels (scombrids), snappers (lutjanids), barracudas (sphyaraenids), emperors (lethrinids) and wrasses (labrids). The size (age) of the fish also plays a critical role in the potential ciguatoxic risk. According to proposals of average size thresholds provided by experts for high-risk species, we were also able to assess the additional risk induced by the sale of some large fish on the market. The data collected both from experts and from the market allowed us to develop a cost-effective proposal for improving the management of the CFP risk in this market. However, the successful implementation of any regulation aiming to ban some specific species and sizes from the market, with an acceptable economical impact, will require the improvement of the expertise in fish identification by public health officers and, ideally, the commitment of retailers.
... In this list, the three most implicated fishes (based on MoF survey data) were moray eels, snapper, and pufferfish. This information is consistent with reports elsewhere that snappers (Lutjanus spp.) and moray eels (Gymnothorax spp.) are the most widely implicated species for FP in the Pacific Islands [23,[44][45][46]. The list of potentially toxic fish species and fish families identified in this study appear to be the same toxic species found in Australia [47,48], French Polynesia [44], New Caledonia [44], Cook Islands [45], Kiribati [49], New Zealand [50], and the other Pacific Island territories. ...
... This information is consistent with reports elsewhere that snappers (Lutjanus spp.) and moray eels (Gymnothorax spp.) are the most widely implicated species for FP in the Pacific Islands [23,[44][45][46]. The list of potentially toxic fish species and fish families identified in this study appear to be the same toxic species found in Australia [47,48], French Polynesia [44], New Caledonia [44], Cook Islands [45], Kiribati [49], New Zealand [50], and the other Pacific Island territories. Rongo and van Woesik [45] identified 48 toxic fish species in Rarotonga, Cook Islands, while more than 300 fish species have been reported to be linked to CP cases in all the Pacific Islands. ...
... This information is consistent with reports elsewhere that snappers (Lutjanus spp.) and moray eels (Gymnothorax spp.) are the most widely implicated species for FP in the Pacific Islands [23,[44][45][46]. The list of potentially toxic fish species and fish families identified in this study appear to be the same toxic species found in Australia [47,48], French Polynesia [44], New Caledonia [44], Cook Islands [45], Kiribati [49], New Zealand [50], and the other Pacific Island territories. Rongo and van Woesik [45] identified 48 toxic fish species in Rarotonga, Cook Islands, while more than 300 fish species have been reported to be linked to CP cases in all the Pacific Islands. ...
Fish poisoning (FP) affects human health, trade and livelihood in Fiji, where management has depended mainly on traditional ecological knowledge (TEK). This paper investigated and documented this TEK through a 2-day stakeholder workshop, group consultation, in-depth interviews, field observations, and analyses of survey data from the Ministry of Fisheries, Fiji. Six TEK topics were identified and classified as preventative and treatment options. The preventive approach involves identifying toxic reef fishes, the spawning season of edible seaworms, hotspot areas of toxic fishes, folk tests, and locating and removing toxic organs. For example, 34 reef fish species were identified as toxic. The FP season was associated with the spawning of balolo (edible seaworm) and the warmer months of October to April (cyclone seasons). Two well-known toxic hotspots associated with an abundance of bulewa (soft coral) were identified. Folk tests and locating and removing toxic fish organs are also practised for moray eels and pufferfish. At the same time, various locally available herbal plants are used to treat FP as the second line of defence. The TEK collated in this work can help local authorities better identify the sources of toxicity, and applying TEK preventive measures could stem the tide of fish poisoning in Fiji.
... The term 'software' in risk analysis-related CFP studies primarily concerned programs used for molecular/phylogenetic identification of ciguateric fish and CTXproducing microalgae and secondly web applications assisting record-keeping and communication regarding the presence of ciguateric fishes in trade operations [36][37][38]. Accurate identification of high-risk fish species implicated in CFP and the ability to prevent these from reaching the market, according to regional legislative requirements, are critical in CFP risk assessment, management and communication; therefore, softwarebased tools can facilitate risk analysis processes [39,40]. ...
... Occurrence of keywords belonging to the 'open data sources' group combined to 'ciguatera' was extensively searched, but no studies were found containing 'open data', 'public data' and 'open source', whereas only one publication (a Master's thesis) included the term 'big data' [50]. On the other hand, searching specifically for 'database', after exclusion of instances related to literature/journal databases, resulted in 28 publications containing at least one reference to a data source compliant to the 'open data sources' concept of the present work [11,14,36,37,40,41,[43][44][45][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66]. Another relevant term encountered in a semantic fitting the concept was 'dataset' [67,68], a term frequently used interchangeably to 'database' [69], while the more general term 'data' was the only one present in other works containing records of CFP incidents derived from public databases [39,70]. ...
... The nature of the CFP-related data contained within the identified open data sources varied widely, including data on taxonomy and identification of marine species (fish and microalgae) [11,14,33,36,37,39,43,52,[55][56][57][59][60][61]66], epidemiology and outbreaks occurrence [11,14,[33][34][35][39][40][41]43,44,[51][52][53][54][55]58,60,61,[63][64][65]70], HAB events [11,14,43,53,60,[62][63][64][65][66], climate and environment (temperature, salinity, water quality monitoring, benthic habitats) [33,41,45,50,51,58,62,67,68], public policies and risk mitigation strategies [11,33,43,61] as well as general information on CFP's public health perspective to aid risk communication to the public [11,34,39,41,43,44,51,61,70]. ...
Currently, digital technologies influence information dissemination in all business sectors, with great emphasis put on exploitation strategies. Public administrations often use information systems and establish open data repositories, primarily supporting their operation but also serving as data providers, facilitating decision-making. As such, risk analysis in the public health sector, including food safety authorities, often relies on digital technologies and open data sources. Global food safety challenges include marine biotoxins (MBs), being contaminants whose mitigation largely depends on risk analysis. Ciguatera Fish Poisoning (CFP), in particular, is a MB-related seafood intoxication attributed to the consumption of fish species that are prone to accumulate ciguatoxins. Historically, CFP occurred endemically in tropical/subtropical areas, but has gradually emerged in temperate regions, including European waters, necessitating official policy adoption to manage the potential risks. Researchers and policy-makers highlight scientific data inadequacy, under-reporting of outbreaks and information source fragmentation as major obstacles in developing CFP mitigation strategies. Although digital technologies and open data sources provide exploitable scientific information for MB risk analysis, their utilization in counteracting CFP-related hazards has not been addressed to date. This work thus attempts to answer the question, "What is the current extent of digital technologies' and open data sources' utilization within risk analysis tasks in the MBs field, particularly on CFP?", by conducting a systematic literature review of the available scientific and grey literature. Results indicate that the use of digital technologies and open data sources in CFP is not negligible. However, certain gaps are identified regarding discrepancies in terminology, source fragmentation and a redundancy and downplay of social media utilization, in turn constituting a future research agenda for this under-researched topic.
... Because the more toxic congeners of CTX are generally found higher in the food chain (e.g. Mak et al. 2013), large predatory fish such as barracuda (Sphyraena spp.) are most likely to induce CFP (Dechraoui et al. 2005, Darius et al. 2007, Clua et al. 2011. Large demersals like snappers (Lutjanus spp.) are also considered high-risk, and serranids such as the coral trout have been cited in cases of CFP throughout the Pacific (New Caledonia: Clua et al. 2011;Hong Kong: Wong et al. 2014;Japan: Oshiro et al. 2010;French Polynesia: reviewed by Darius et al. 2007; Hawaii: Dierking and Campora 2009). ...
... Mak et al. 2013), large predatory fish such as barracuda (Sphyraena spp.) are most likely to induce CFP (Dechraoui et al. 2005, Darius et al. 2007, Clua et al. 2011. Large demersals like snappers (Lutjanus spp.) are also considered high-risk, and serranids such as the coral trout have been cited in cases of CFP throughout the Pacific (New Caledonia: Clua et al. 2011;Hong Kong: Wong et al. 2014;Japan: Oshiro et al. 2010;French Polynesia: reviewed by Darius et al. 2007; Hawaii: Dierking and Campora 2009). In the Caribbean, recent evidence that lionfish (Pterois spp.) can attain toxic levels of CTXs (Robertson et al. 2014) has prompted concern about strategies to contain the growing populations of these invasive fish by promoting their consumption (Soliño et al. 2015). ...
... Accordingly, many countries impose size restrictions for consumption of risky fish species in an effort to prevent CFP (reviewed by Yang et al. 2016). In Hawaii, for example, the market sale of great amberjacks is prohibited for individuals larger than 9 kg (details in Clua et al. 2011). In Australia, regulation may be imposed by the market, where some restaurant limit purchase of coral grouper to less than 2.5 kg (Lehane and Lewis 2000). ...
... 32 In New Caledonian, based on the expert assessments and published reports, the ciguatoxic potential of E. fuscoguttatus was considered medium; the size (total length) threshold above which the risk of ciguatera significantly increases was 40 cm (1.0 kg). 33 ...
... 36 In the Pacific Islands, live reef fish from Kiribati caused a serious ciguatera outbreak in Hong Kong and a ban on export (including E. fuscoguttatus) was imposed in 2004. 37 32 2 wild-caught samples contained total P-CTX 0.13-3.1 μg/kg flesh (P-CTX-1 ∼54%), the 8.2 kg fish contained total P-CTX 3.1 μg/kg flesh New Caledonia 33 Size threshold for ciguatoxicity 40 cm (1.0 kg), based on assessment by the local experts and published reports; all 5 specimens (100%) in the local market were significantly above the this size threshold CTX = ciguatoxin; MBA = mouse bioassay; P-CTX = Pacific ciguatoxin. *11 fish samples collected from Okinawa waters over 10 years. ...
... In New Caledonian, a ban on fish > 40 cm (1 kg) from the local market was recommended, after considering the size threshold for ciguatoxicity and prevalence of specimens in the local market with a size larger than the threshold of risk. 33 In Hong Kong, E. fuscoguttatus < 1.8 kg was more popular because the risk of toxicity was assumed to be lower and plate-sized fish was considered the best for consumption. 38 In Mauritius (Indian Ocean), the sales of E. fuscoguttatus and 16 other species were not allowed. ...
To determine the ciguatoxic potential of brown-marbled grouper (Epinephelus fuscoguttatus) in relation to fish size and geographical origin, this review systematically analyzed: 1) reports of large ciguatera outbreaks and outbreaks with description of the fish size; 2) Pacific ciguatoxin (P-CTX) profiles and levels and mouse bioassay results in fish samples from ciguatera incidents; 3) P-CTX profiles and levels and risk of toxicity in relation to fish size and origin; 4) regulatory measures restricting fish trade and fish size preference of the consumers. P-CTX levels in flesh and size dependency of toxicity indicate that the risk of ciguatera after eating E. fuscoguttatus varies with its geographical origin. For a large-sized grouper, it is necessary to establish legal size limits and control measures to protect public health and prevent overfishing. More risk assessment studies are required for E. fuscoguttatus to determine the size threshold above which the risk of ciguatera significantly increases.
© The American Society of Tropical Medicine and Hygiene.
... Since there is no appropriate treatment for CFP (for a review, see [6]), the most efficient solution is to regulate fish consumption [11,12]. Lewis [13], and more recently Clua et al. [11] recommended banning some specific species and sizes from fish markets. ...
... Since there is no appropriate treatment for CFP (for a review, see [6]), the most efficient solution is to regulate fish consumption [11,12]. Lewis [13], and more recently Clua et al. [11] recommended banning some specific species and sizes from fish markets. However, such a strategy can only work if the fish sold are correctly identified and labelled, and it has been repeatedly shown that misidentifications and species substitutions commonly occur in fish markets [14][15][16]. ...
... Groupers (Epinephelidae: rockcods, coralgroupers, hinds, and lyretails) are one of the families most commonly reported as a source of ciguatera poisoning [11]. Some grouper species, like Plectropomus laevis and Cephalopholis argus, are known to be especially contaminated by ciguatera toxins [17][18][19]. ...
Background:
Ciguatera fish poisoning (CFP) is a significant public health problem due to dinoflagellates. It is responsible for one of the highest reported incidence of seafood-borne illness and Groupers are commonly reported as a source of CFP due to their position in the food chain. With the role of recent climate change on harmful algal blooms, CFP cases might become more frequent and more geographically widespread. Since there is no appropriate treatment for CFP, the most efficient solution is to regulate fish consumption. Such a strategy can only work if the fish sold are correctly identified, and it has been repeatedly shown that misidentifications and species substitutions occur in fish markets.
Methods:
We provide here both a DNA-barcoding reference for groupers, and a new phylogenetic reconstruction based on five genes and a comprehensive taxonomical sampling. We analyse the correlation between geographic range of species and their susceptibility to ciguatera accumulation, and the co-occurrence of ciguatoxins in closely related species, using both character mapping and statistical methods.
Results:
Misidentifications were encountered in public databases, precluding accurate species identifications. Epinephelinae now includes only twelve genera (vs. 15 previously). Comparisons with the ciguatera incidences show that in some genera most species are ciguateric, but statistical tests display only a moderate correlation with the phylogeny. Atlantic species were rarely contaminated, with ciguatera occurrences being restricted to the South Pacific.
Conclusions:
The recent changes in classification based on the reanalyses of the relationships within Epinephelidae have an impact on the interpretation of the ciguatera distribution in the genera. In this context and to improve the monitoring of fish trade and safety, we need to obtain extensive data on contamination at the species level. Accurate species identifications through DNA barcoding are thus an essential tool in controlling CFP since meal remnants in CFP cases can be easily identified with molecular tools.
... This observation is in agreement with other works [32,33] who have reported in the Pacific (French Polynesia) no clear relation between CTXs content and the size of fish specimens. The same authors have also reported the presence of CTXs in both herbivorous and carnivorous fish specimens [34]. ...
... The presence of the dinoflagellate Gambierdiscus sp. in the Canary Islands was documented in 2004 [22] and confirmed in 2011 [14]. This coincides with the detection of the first outbreaks in Canary Islands in 2004 and from 2009 is beginning to make a plan for detecting ciguatoxin in the archipelago, beginning itself to detect fish (amberjacks) carriers of the toxin [34]. We present in this work the fish analyzed from September 2011 to December 2014, supporting the existence of fish with toxin yet. ...
... The same authors have also reported the presence of CTXs in both herbivorous and carnivorous fish specimens. 34 Therefore, the range of fish specimens screened for CTXs by the Public Health Authorities may be equally applicable to fish specimens weighing less than 17 kg as well. 35 Besides at the moment, the fish selected for CTXs by Public Health Authorities are specimens of fish weighing more than 15 kg, and this limit is right at the moment, since the smaller amberjack ciguatoxin we found in this study is 16 kg. ...
... 14 This coincides with the detection of the first outbreaks in Canary Islands in 2004 and from 2009 is beginning to make a plan for detecting ciguatoxin in the archipelago, beginning itself to detect fish (amberjacks) carriers of the toxin. 34 We present in this work the fish analyzed from September 2011 to December 2014, supporting the existence of fish with toxin yet. ...
... Meanwhile, the ecological distribution of CTX also shows regional specificity. In the Noumea Fish Market, New Caledonia, as many as 28 high risk species of fish were reported by Clua et al. (2011). These fish were harvested from the southern and northern provinces of New Caledonia. ...
... In New Caledonia, the fish species that are considered as the most toxic are not allowed for sale in the market. In Hawaii, great amberjacks (Seriola dumerilii) above 20 lbs (9 kg) are prohibited to be sold in the market (Clua et al. 2011). In Hong Kong, coral reef fish weighing above 1.8 kg are advised not to be consumed (Centre for Food Safety 2006). ...
Ciguatera food poisoning (CFP) is widespread in tropical and sub-tropical waters, and it is the most common food poisoning caused by marine biotoxins. The toxins involved, ciguatoxins, are produced by certain dinoflagellates of the genus Gambierdiscus, and undergo biotransfer and biomagnification up the food web to planktivorous and ultimately, top predator fishes. In this paper, we reviewed the factors and processes that regulate the production of ciguatoxins, the ecological distribution and the pathways of their biotransfer, and fish consumption guidelines to prevent ciguatera-related food poisoning. Warm waters are commonly suggested as the most important factor that enhances toxic algal blooms and ciguatoxin production. Ecological distribution of ciguatoxic fish shows great regional specificity. In most endemic areas, carnivores such as groupers and other large fish have higher toxicity than their herbivorous and smaller counterparts, supporting the food chain hypothesis proposed by J.E. Randall (J.E. Randall, Bull. Mar. Sci. 8(3): 236–267, 1958); while in other areas, for example, French Polynesia, the opposite situations also exist, questioning the biomagnification hypothesis. Some countries and regions have taken measurements to prevent ciguatera poisoning through consumption guidelines. In this review, we look at some of the measures that could be used to prevent poisoning, while encouraging people to consume fish. For example, choosing smaller and lower trophic level fish are likely to be safer to consume. We suggest an approach to maintain better databases on ciguatera cases to instruct people on fish consumption safety, and develop a general guideline for fish consumption to reduce CFP.
... Thus, avoiding eating fish >2 kg is a reasonable approach, but occasionally fish weighing 0.6 kg or less are also implicated [13]. It should be remembered that the prevalence of ciguatoxicity is also species- [3,4] and, in particular, region-specific [23,61]. ...
... For example, in Okinawa, Japan, L. bohar <4 kg were non-toxic, but the prevalence of toxicity (mouse bioassay ≥0.025 MU/g) rose to 37.7% in fish >4 kg and 61.1% in fish >7 kg [23]. In New Caledonian, L. bohar was considered ciguatoxic, whatever its size [61]. In French Polynesia, there was a lack of relationship between toxicity and size for most of the fish species and families [62]. ...
In the coastal countries of East Asia and Southeast Asia, ciguatera should be common because of the extensive tropical and subtropical coral reefs along the coasts and in the neighboring seas with ciguatoxic fishes. An extensive search of journal databases, the Internet and the government websites was performed to identify all reports of ciguatera from the regions. Based on the official data and large published case series, the incidence of ciguatera was higher in the coastal cities (Hong Kong, Foshan, Zhongshan) of southern China than in Japan (Okinawa Prefecture). In Singapore, ciguatera appeared to be almost unknown. In other countries, only isolated cases or small case series were reported, but under-reporting was assumed to be common. Ciguatera may cause severe acute illness and prolonged neurological symptoms. Ciguatera represents an important public health issue for endemic regions, with significant socio-economic impact. Coordinated strategies to improve risk assessment, risk management and risk communication are required. The systematic collection of accurate data on the incidence and epidemiology of ciguatera should enable better assessment and management of its risk. Much more work needs to be done to define the size threshold for important coral reef fish species from different regions, above which the risk of ciguatera significantly increases.
... In Australia [18], large fish are considered unpalatable due to concerns of possible ciguatera, and commercial fishers have difficulty in selling fish weighing >6 kg. In New Caledonia [19], the ciguatoxic potential of this grouper is considered medium; the size (total length) threshold above which the risk of ciguatera significantly increases is 40 cm or 1.0 kg based on its known length-weight relationships [17]. In Hong Kong [20], fish weighing <1.8 kg are more popular, because the risk of toxicity is assumed to be lower and plate-sized fish are considered the best for consumption. ...
... Regulatory measures should be considered, e.g., bans on high-risk fish and restrictions on fish from high-risk areas [1]. This will be useful to monitor the prevalence of ciguatoxic fish in the market and characterize the size threshold for potential toxicity, so that plans for the cost-effective management of ciguatera risk can be planned [19]. ...
Brown marbled grouper (Epinephelus fuscoguttatus) is an apex predator from coral reefs of the Indo-Pacific region. All five published case series of ciguatera after consumption of brown marbled grouper were reviewed to characterize the types, severity and chronicity of ciguatera symptoms associated with its consumption. Three of these case series were from large outbreaks affecting over 100-200 subjects who had eaten this reef fish served at banquets. Affected subjects generally developed a combination of gastrointestinal, neurological and, less commonly, cardiovascular symptoms. Gastrointestinal symptoms occurred early and generally subsided in 1-2 days. Some neurological symptoms (e.g., paresthesia of four limbs) could last for weeks or months. Sinus bradycardia and hypotension occurred early, but could be severe and prolonged, necessitating the timely use of intravenous fluids, atropine and dopamine. Other cardiovascular and neurological features included atrial ectopics, ventricular ectopics, dyspnea, chest tightness, PR interval >0.2 s, ST segment changes, polymyositis and coma. Concomitant alcohol consumption was associated with a much higher risk of developing bradycardia, hypotension and altered skin sensation. The public should realize that consumption of the high-risk fish (especially the ciguatoxin-rich parts and together with alcohol use) and repeated ciguatoxin exposures will result in more severe and chronic illness.
... On the contrary, Chan et al. (2011) observed a positive relationship between CTX concentration in muscles and liver of moray eels (Gymnothorax spp.) from Kiribati Islands and the weight of the individuals. Such observations suggest that CTX concentration in fish tissues may be the result of biological and physiological processes more complex than the merely positive relationship with the size or weight of individuals currently postulated by several authors (Oshiro et al., 2010;Clua et al., 2011). ...
... The relative total length of individuals within a family did not appear as being a good predictor of the levels of CTX concentration or of the proportion of toxic fish. From the results of the present study, we conclude that CFP risk in French Polynesia cannot be properly managed by defining size thresholds above which fish species should not be sold and consumed, as proposed by Clua et al. (2011) for New Caledonia and Lin et al. (2012) for all the coral reef fish species. In French Polynesia, restricting the consumption to small individuals only, or to individuals below a given size, does not appear to be an effective strategy. ...
... Therefore, since poor information exists on the species presenting a ciguatera-risk in Macaronesia, unequivocal species identification is required in order to understand definitively the source of the disease in that area. As supported by results of this study, fish species identification using DNA sequence analysis as well as an improvement of the expertise in fish identification are highly recommended (Stewart et al. 2010;Clua et al. 2011). ...
... In that sense, the use of morphometric data for preventing the CFP risk may sometimes be useless for high risk species. As an example, US authorities are using such an approach in Hawaii where the high-risk species Seriola dumerilii cannot be sold above a threshold weight of 9 kg (Clua et al. 2011). However, even if this study included the analysis of only 13 fish samples, the present results suggested no clear relation between CTX content and size of specimens. ...
The ouabain/veratridine-dependent neuroblastoma (neuro-2a) cell-based assay (CBA) was applied for the determination of the presence of ciguatoxin (CTX)-like compounds in ciguatera-suspected fish samples caught in the Canary Islands. In order to avoid matrix interferences the maximal concentration of wet weight fish tissue exposed to the neuro-2a cells was set at 20 mg tissue equivalent (TE) ml(-1) according to the sample preparation procedure applied. In the present study, the limit of quantification (LOQ) of CTX1B equivalents in fish extract was set at the limit of detection (LOD), being defined as the concentration of CTX1B equivalents inhibiting 20% cell viability (IC(20)). The LOQ was estimated as 0.0096 ng CTX1B eq.g TE(-1) with 23-31% variability between experiments. These values were deemed sufficient even though quantification given at the IC(50) (the concentration of CTX1B equivalents inhibiting 50% cell viability) is more accurate with a variability of 17-19% between experiments. Among the 13 fish samples tested, four fish samples were toxic to the neuro-2a cells with estimations of the content in CTX1B g(-1) of TE ranging from 0.058 (± 0.012) to 6.23 (± 0.713) ng CTX1B eq.g TE(-1). The high sensitivity and specificity of the assay for CTX1B confirmed its suitability as a screening tool of CTX-like compounds in fish extracts at levels that may cause ciguatera fish poisoning. Species identification of fish samples by DNA sequence analysis was conducted in order to confirm tentatively the identity of ciguatera risk species and it revealed some evidence of inadvertent misidentification. Results presented in this study are a contribution to the standardisation of the neuro-2a CBA and to the risk analysis for ciguatera in the Canary Islands.
... For another grouper, Variola louti, a significant yet weak correlation was reported between CTX content and fish size, age, and weight [58]; suggesting that although large size, age, and weight are risk factors, consuming small specimens yet remains risky. These observations call into question the relevance of the regulations adopted in several countries with regards to weight and/or size limits of certain commercially important fish species, such as in the Canary Islands [37], New Caledonia [30], Australia [27], and Hong Kong [31]. ...
Ciguatera poisoning (CP) results from the consumption of coral reef fish or marine invertebrates contaminated with potent marine polyether compounds, namely ciguatoxins. In French Polynesia, 220 fish specimens belonging to parrotfish (Chlorurus microrhinos, Scarus forsteni, and Scarus ghobban), surgeonfish (Naso lituratus), and groupers (Epinephelus polyphekadion) were collected from two sites with contrasted risk of CP, i.e., Kaukura Atoll versus Mangareva Island. Fish age and growth were assessed from otoliths’ yearly increments and their ciguatoxic status (negative, suspect, or positive) as evaluated by neuroblastoma cell-based assay. Using permutational multivariate analyses of variance, no significant differences in size and weight were found between negative and suspect specimens while positive specimens showed significantly greater size and weight particularly for E. polyphekadion and S. ghobban. However, eating small or low-weight specimens remains risky due to the high variability in size and weight of positive fish. Overall, no relationship could be evidenced between fish ciguatoxicity and age and growth characteristics. In conclusion, size, weight, age, and growth are not reliable determinants of fish ciguatoxicity which appears to be rather species and/or site-specific, although larger fish pose an increased risk of poisoning. Such findings have important implications in current CP risk management programs.
... For another grouper, Variola louti, a significant yet weak correlation was reported between CTX content and fish size, age, and weight [58]; suggesting that although large size, age, and weight are risk factors, consuming small specimens yet remains risky. These observations call into question the relevance of the regulations adopted in several countries with regards to weight and/or size limits of certain commercially important fish species, such as in the Canary Islands [37], New Caledonia [30], Australia [27], and Hong Kong [31]. ...
Ciguatera poisoning (CP) results from the consumption of coral reef fish or marine invertebrates contaminated with potent marine polyether compounds, namely ciguatoxins. In French Polynesia, 220 fish specimens belonging to parrotfish (Chlorurus microrhinos, Scarus forsteni, and Scarus ghobban), surgeonfish (Naso lituratus), and groupers (Epinephelus polyphekadion) were collected from two sites with contrasted risk of CP, i.e., Kaukura Atoll versus Mangareva Island. Fish age and growth were assessed from otoliths’ yearly increments and their ciguatoxic status (negative, suspect, or positive) was evaluated by neuroblastoma cell-based assay. Using permutational multivariate analyses of variance, no significant differences in size and weight were found between negative and suspect specimens while positive specimens showed significantly greater size and weight particularly for E. polyphekadion and S. ghobban. However, eating small or low-weight specimens remains risky due to the high variability in size and weight of positive fish. Overall, no relationship could be evidenced between fish ciguatoxicity and age and growth characteristics. In conclusion, size, weight, age, and growth are not reliable determinants of fish ciguatoxicity which appears to be rather species and/or site-specific, although larger fish pose an increased risk of poisoning. Such findings have important implications in current CP risk management programs.
... In this regard, an estimate of the real age of fish via the analysis of otoliths of fish appears much more relevant [232,233] and could prove useful to inform fish toxicity predictive models. In conclusion, current management practices based on the simple avoidance of fish of certain sizes [146,183,[234][235][236][237] do not seem of much use to the consumers to minimize CP risk, but may cause significant financial losses to the fishing industry instead. ...
... In affected countries, CP may lead to a significant drop in local fish consumption (Nellis and Barnard, 1986;Biaggi, 1990;Sadovy, 1997), or to a drastic modification of local populations' lifestyle, resulting in a progressive dietary shift in favor of imported and/or canned products (Rongo and van Woesik, 2011). Moreover, current risk management practices including bans on the sale of high-risk fish species, specimens over a certain size, or those from known toxic locations, may cause severe financial losses to both local and international fish trades (Sadovy, 1998;Chan, 2000;Clua et al., 2011;Sumner et al., 2011;Sydney Fish Market, 2015;Sanchez-Henao et al., 2019). Finally, CP also can represent a major source of concern to the tourism industry in endemic regions. ...
CIGUATERA POISONINGS:
A GLOBAL REVIEW OF OCCURRENCES AND TRENDS
Chinain M.1*, Gatti C.M.1, Darius H.T.1, Quod J.-P.2, Tester P.A.3
1Laboratory of Marine Biotoxins, Institut Louis Malardé – UMR EIO, BP 30, 98713 Papeete, Tahiti, French Polynesia
2ARVAM-Pareto, Technopole de la Réunion, 14 rue Henri Cornu, 97490 Sainte-Clotilde, La Réunion, France
3Ocean Tester, LLC, 295 Dills Point Road, Beaufort, North Carolina, 28516, USA
ABSTRACT
Ciguatera Poisoning (CP) is the most prevalent, phycotoxin related seafood poisoning across the globe, affecting between 10,000 to 50,000 people annually. This illness results from the consumption of seafood contaminated with lipid soluble toxins known as ciguatoxins (CTXs) that are produced by benthic dinoflagellates in the genera Gambierdiscus and Fukuyoa. The present work reviews the global occurrence of CP events and outbreaks, based on both scientific and grey literature.
Ciguatera prevalence is significantly underestimated due to a lack of recognition of ciguatera symptoms, limited collection of epidemiological data on a global level, and reticence to report ciguatera in CP-endemic regions. Analysis of the time-series data available for a limited number of countries indicates the highest incidence rates are consistently reported from two historical CP-endemic areas i.e., the Pacific and Caribbean regions, a situation due in part to the strong reliance of local communities on marine resources. Ciguatera-related fatalities are rare (<0.1% of reported cases). The vast majority of outbreaks involve carnivorous fish including snappers, groupers, wrasses, and barracudas. Since 2000, an expansion of the geographical range of CP has been observed in several areas like Macaronesia and east and southeast Asia. In some of these locales, random surveys confirmed the presence of CTXs in locally sourced fish, consistent with the concurrent report of novel CP incidents (e.g., Canary Islands, Madeira, Selvagens Islands, New South Wales). One characteristic of outbreaks occurring in Asia is that they often present as large disease clusters due to group consumption of a single contaminated fish. Similar observations are reported from the Indian Ocean in the form of shark poisoning outbreaks which often lead to singular types of CP characterized by a high fatality rate. Other atypical forms of CP linked to the consumption of marine invertebrates also have been documented recently. Owing to the significant health, socioeconomic and socio-cultural impacts of ciguatera, there is an urgent need for increased, standardized, coordinated efforts in ciguatera education, monitoring and research programs. Several regional and international initiatives have emerged recently, that may help improve patients' care, data collection at a global scale, and risk monitoring and management capabilities in countries most vulnerable to CP's toxic threat.
Keywords: Ciguatera Poisoning, outbreaks, epidemiology, atypical forms, global occurrence, Gambierdiscus spp., Fukuyoa spp., ciguatoxins; toxin analyses
... There are limited regulatory measures preventing the sale of toxic fish in some places in the world, but several countries have imposed a ban or recommended avoiding certain species for consumption (Chan, 2015;Clua et al., 2011;Laurent et al., 2005). Several countries analyse CTX toxicity in fish in order to better understand the risks according to species, weight, time of the year and geographical area among others. ...
Local population frequently consumes moray eels and dusky groupers from the Canary Islands. These species are top predators and the interactions between them include predation but also, in some cases, collaborative hunting. These fish are well known to cause ciguatera (CFP) outbreaks in several marine areas such as Japan, Hawaii, French Polynesia and Caribe. Groupers have been involved in CFP events in the Canary Islands, however, moray eels have not yet been well studied in this regard. The present research seeks to describe the finding of a black moray in the stomach of a positive dusky grouper during its necropsy, and to clarify the implication of groupers and moray eels in the food webs, accumulating CTXs in the Canarian environment. The study also updates statistics on the presence of toxic groupers in this archipelago. For these purposes, 248 grouper samples from the CFP official control in the Canary Islands (2018-2019) were analysed and 36 moray eels (5 species) were collected under the EuroCigua project and one was obtained during a dusky grouper necropsy. All samples were analysed with the Neuro-2a cell-based assay (CBA) to evidence CTX-like toxicity. Regarding the necropsied grouper and the moray eel found in its stomach content, the LCMS/MS method allowed the identification and quantification of CCTX1 in both fish at similar levels while none of the P-CTXs for which standards were available were detected. Among groupers, 25.4 % displayed CTX-like toxicity with differences between islands. For moray eels 38.9 % showed toxicity, involving 4 species. Black moray exhibited a high proportion of positives (9/12) and a positive correlation was found between CTX-like toxicity quantification and the black moray weight. Regarding the grouper, and the moray eel found in its stomach, the LCMS/MS method allowed the identification and quantification of C-CTX1 in both fish at similar levels. This found suggests a trophic interaction between these species and their role in maintaining CTXs in the Canary waters where local population commonly demand those species for consumption. The island of El Hierro stands out above all the other Canary Islands with the concerning percentage of positive grouper samples and the high CTX toxicity levels obtained in moray eel specimens analysed in this marine area. This is the first report of CTX-like toxicity in flesh of moray eels fished in the Canary archipelago and the confirmation of the presence of C-CTX1 by LCMS/MS in a black moray from this marine area.
... Une étude menée à Raivavae a cherché à évaluer (Gaboriau et al., 2014), ce qui contredit l'idée reçue selon laquelle les spécimens les plus gros seraient aussi les plus dangereux. Cette observation pose la question de l'efficacité réelle des pratiques en vigueur au sein des populations locales, consistant notamment à se limiter à la consommation des poissons de petite taille pour tenter de diminuer le risque d'intoxication (Clua et al., 2011). ...
... Yet, fisheries regulations in regions with endemic ciguatera are often based on size (e.g. Chan, 2015a;Clua et al., 2011;reviewed by Yang et al., 2016) where larger fish of the same species are assumed to contain higher CTX concentrations in the Fig. 4. Accumulation of CTX (CTX3C equiv) in fish muscle tissue throughout the experiment as measured by RBA. A) CTX concentrations in mean μg CTX3C equiv kg −1 muscle ± SEM, at each time point (init = initial control; 2, 4, 8 and 16 weeks exposure to G. polynesiensis; 16 week exposure control), where concentrations in both controls were below limits of detection (0.32 μg CTX3C equiv kg −1 ; dashed line). ...
Ciguatoxins (CTXs) are potent algal toxins that cause widespread ciguatera poisoning and are found ubiquitously in coral reef food webs. Here we developed an environmentally-relevant, experimental model of CTX trophic transfer involving dietary exposure of herbivorous fish to the CTX-producing microalgae Gambierdiscus polynesiensis. Juvenile Naso brevirostris were fed a gel-food embedded with microalgae for 16 weeks (89 cells g-1 fish daily, 0.4 μg CTX3C equiv kg-1 fish). CTXs in muscle tissue were detectable after 2 weeks at levels above the threshold for human intoxication (1.2 ± 0.2 μg CTX3C equiv kg-1). Although tissue CTX concentrations stabilized after 8 weeks (∼3 ± 0.5 μg CTX3C equiv kg-1), muscle toxin burden (total μg CTX in muscle tissue) continued to increase linearly through the end of the experiment (16 weeks). Toxin accumulation was therefore continuous, yet masked by somatic growth dilution. The observed CTX concentrations, accumulation rates, and general absence of behavioural signs of intoxication are consistent with field observations and indicate that this method of dietary exposure may be used to develop predictive models of tissue-specific CTX uptake, metabolism and depuration. Results also imply that slow-growing fish may accumulate higher CTX flesh concentrations than fast-growing fish, which has important implications for global seafood safety.
... In French Polynesia, regulations prohibit the sale of all moray eels [57]. In New Caledonia, G. javanicus is considered by some experts as highly risky, regardless of its size, and should be banned [58]. In Australia, the largest center of fish distribution (Sydney Fish Market) rejected G. javanicus and fish from high-risk regions (Kiribati and Marshall Islands) [59]. ...
Moray eels (Gymnothorax species) from tropical waters have long been known to be high-risk species, and the consumption of particularly the viscera or ungutted eels can result in severe ciguatera (known as Gymnothorax or moray eel poisoning), characterized by prominent neurological features. In this review, the main objective was to describe the risk and severity of ciguatera caused by eating moray eels in different parts of the world. Moray eels can accumulate very high ciguatoxin (CTX) levels in the flesh and particularly the liver. Therefore, even the smaller ones can be toxic and the consumption of an average portion (particularly liver) can result in severe or fatal ciguatera. Moray eels (particularly when ungutted) must never be served in gatherings since they can cause mass poisoning because of their large sizes and high CTX levels. Apart from regulatory measures restricting or excluding access, the public should be repeatedly warned to avoid eating moray eels.
... Economic impacts have been evaluated in other world regions, such as Tahiti [280], Rarotonga in the southern Cook Islands [281], Canada [282,283], Pacific locations [183], and Puerto Rico [13]. CFP has been associated with reduced fishery productivity [183,279,280], government restrictions on the sale of potentially ciguatoxic fish [190,[284][285][286][287], medical costs [281,283,288], lost worker productivity [280], reduced tourism and recreational fishing [183,279], and the costs of public health programs to monitor and manage the risk of CFP [276,289,290]. These impacts vary according to contextual factors, such as the availability of processed food, CTX prevalence, fishery dependence, social customs, and demographic trends [179,236,291,292]. ...
Ciguatera Fish Poisoning (CFP) is the most frequently reported seafood-toxin illness in the world. It causes substantial human health, social, and economic impacts. The illness produces a complex array of gastrointestinal, neurological and neuropsychological, and cardiovascular symptoms, which may last days, weeks, or months. This paper is a general review of CFP including the human health effects of exposure to ciguatoxins (CTXs), diagnosis, human pathophysiology of CFP, treatment, detection of CTXs in fish, epidemiology of the illness, global dimensions, prevention, future directions, and recommendations for clinicians and patients. It updates and expands upon the previous review of CFP published by Friedman et al. (2008) and addresses new insights and relevant emerging global themes such as climate and environmental change, international market issues, and socioeconomic impacts of CFP. It also provides a proposed universal case definition for CFP designed to account for the variability in symptom presentation across different geographic regions. Information that is important but unchanged since the previous review has been reiterated. This article is intended for a broad audience, including resource and fishery managers, commercial and recreational fishers, public health officials, medical professionals, and other interested parties.
Most studies involving Pacific reef fishes use underwater visual censusing techniques to estimate their biomass and stock. This requires to know the length-weight relationships of all the species censused. Currently, only a small proportion of these relationships (15.4%) are available for reef fish species in the Pacific area. In the present article we propose length-weight relationships at four organisation levels: species, genera, families and morphological groups. A data base of 53,800 specimens belonging to 788 species from New Caledonia were used to estimate the relationships for 396 species, 185 genera, 75 families. At the genus level, the length-weight relationships cover 76% of the Pacific reef species and the coverage is nearly 85 % at the family level. A study of the morphology of 1,100 specimens belonging to 311 species allowed to define 30 morphological groups, for which length-weight relationships were then estimated using 32,551 specimens belonging to these species. Using 3 classes of body thickness, a second clustering of these species defined 20 groups allowing length-weight relationships to be estimated from 2D pictures. These relationships allow to estimate weight from length data for most of the species not covered by the relationships at the species, genus or family level. The error levels increase from the species (average error 9.4%) to the family level (13.5%), the morphological groups yielding errors equivalent to those from the family level equations (13.2%). Agraphical analysis of the coefficients from 396 length-weight relationships suggests that there are physical limits to fish shapes.
The Peacock gouper (Cephalopholis argus) was introduced to Hawai‘i in 1956 to establish a new fishery. It has become abundant, but the fishery failed due to concerns about ciguatera fish poisoning, a neurological disease in humans caused by ingestion of fish containing ciguatoxin. The aim of this study was to provide better understanding of geographic patterns of ciguatoxicity in C. argus and of the correlation of toxicity with morphometric characters of this species, with the goal to assess the possibility of a safe fishery. Overall, 18.2% of C. argus specimens from sites around O‘ahu and Hawai‘i Island contained ciguatoxin in concentrations potentially harmful to humans. This was higher than the rate of occurrence in Hawaiian reef fishes in general, and on the scale of ciguatoxicity in species banned from sale in fish markets. Toxicity was high around both analyzed islands. However, toxic individuals were significantly less common around O‘ahu than around Hawai‘i Island (8% versus 24%). Regular geographic patterns in toxicity within islands (e.g., gradients along coastlines) were not present, and variability in toxicity within each sample site was high. Toxicity was significantly but weakly positively correlated with C. argus length but not with fish condition (measured by length at weight). In conclusion, high prevalence of toxic individuals, variability in toxicity on all analyzed spatial scales, and low explanatory power of morphometric characters make the avoidance of ciguatoxic C. argus individuals difficult. A safe fishery for this species in Hawai‘i therefore does not appear feasible at present.
Marine pelagic diazotrophic cyanobacteria of the genus Trichodesmium (Oscillatoriales) are widespread throughout the tropics and subtropics, and are particularly common in the waters of New Caledonia. Blooms of Trichodesmium are suspected to be a potential source of toxins in the ciguatera food chain and were previously reported to contain several types of paralyzing toxins. The toxicity of water-soluble extracts of Trichodesmium spp. were analyzed by mouse bioassay and Neuroblastoma assay and their toxic compounds characterized using liquid chromatography coupled with tandem mass spectrometry techniques. Here, we report the first identification of palytoxin and one of its derivatives, 42-hydroxy-palytoxin, in field samples of Trichodesmium collected in the New Caledonian lagoon. The possible role played by Trichodesmium blooms in the development of clupeotoxism, this human intoxication following the ingestion of plankton-eating fish and classically associated with Ostreopsis blooms, is also discussed.
Anthropogenically-derived increases in atmospheric greenhouse gas concentrations have been implicated in recent climate change, and are projected to substantially impact the climate on a global scale in the future. For marine and freshwater systems, increasing concentrations of greenhouse gases are expected to increase surface temperatures, lower pH, and cause changes to vertical mixing, upwelling, precipitation, and evaporation patterns. The potential consequences of these changes for harmful algal blooms (HABs) have received relatively little attention and are not well understood. Given the apparent increase in HABs around the world and the potential for greater problems as a result of climate change and ocean acidification, substantial research is needed to evaluate the direct and indirect associations between HABs, climate change, ocean acidification, and human health. This research will require a multidisciplinary approach utilizing expertise in climatology, oceanography, biology, epidemiology, and other disciplines. We review the interactions between selected patterns of large-scale climate variability and climate change, oceanic conditions, and harmful algae.
Emerging environmental pressures resulting from climate change and globalization challenge the capacity of health information systems (HIS) in the Pacific to inform future policy and public health interventions. Ciguatera, a globally common marine food-borne illness, is used here to illustrate specific HIS challenges in the Pacific and how these might be overcome proactively to meet the changing surveillance needs resulting from environmental change.
We review and highlight inefficiencies in the reactive nature of existing HIS in the Pacific to collect, collate, and communicate ciguatera fish poisoning data currently used to inform public health intervention. Further, we review the capacity of existing HIS to respond to new data needs associated with shifts in ciguatera disease burden likely to result from coral reef habitat disruption.
Improved knowledge on the ecological drivers of ciguatera prevalence at local and regional levels is needed, combined with enhanced surveillance techniques and data management systems, to capture environmental drivers as well as health outcomes data.
The capacity of public HIS to detect and prevent future outbreaks is largely dependent on the future development of governance strategies that promote proactive surveillance and health action. Accordingly, we present an innovative framework from which to stimulate scientific debate on how this might be achieved by using existing larger scale data sets and multidisciplinary collaborations.
Bibliography p. 101-118; Job number added acc. to DOCREP assignment
Ciguatera fish poisoning (ciguatera), a common poisoning caused by fish ingestion, is reviewed in the Western Atlantic and the Caribbean waters. It is endemic from Florida coasts (northern limit) to Martinique Island (southern limit), with outbreaks occurring from time to time. In the Caribbean, ciguatera causes a polymorphic syndrome with gastrointestinal, cardiovascular, and neurological signs and symptoms. Neurological and muscular dysfunctions can be treated by intravenous injection of D-mannitol. The lipid-soluble toxins involved are ciguatoxins that are likely produced by the dinoflagellate Gambierdiscus toxicus. G. toxicus strains are endemic in the Caribbean Sea and in theWestern Atlantic. Although it is likely that blooms of G. toxicus are ingested by herbivorous fishes, they are not implicated in ciguatera in the Caribbean. Rather, large carnivores (barracudas, jacks, snappers, groupers), consumers of smaller benthic fish, are often involved in ciguatera. Fish toxicity depends on fishing area and depth, fish size and tissues, and climatic disturbances. Ciguatoxins have been isolated and purified from Caribbean fish species. The structure of two epimers, C-CTX-1 and C-CTX-2 from horse-eye jack, comprise 14 trans-fused ether-linked rings and a hemiketal in terminal ring. Caribbean ciguatoxins are mainly detected in the laboratory by chicken, mouse, mosquito, or cell bioassays, and by analytical HPLC/tandem mass spectrometry down to parts per billion (ppb). A ciguatera management plan that integrates epidemiology, treatment, and a simple method of detection is required to ensure the protection of consumers.
Ciguatera is a tropical disease caused by seafood poisoning, for which the duration of symptoms remains to be determined. The objectives of this prospective study were to determine the prevalence of symptoms at different time points and to identify factors associated with chronic symptoms observed in adults suffering from this disease. At the time of onset, we observed a dose-response relationship including a strong association between the delay of appearance of symptoms and a severity index (P < 0.001). Our results confirmed the key role of fish organs in the risk of contracting a more severe form of ciguatera. In the chronic stage, only the severity score based on information recorded in the acute phase is related to the persistence of symptoms (P < 0.001). Our findings suggest that several symptoms observed in the acute phase of the disease are still experienced 15 days after onset. This supports previous observations based on isolated case reports.
We present a retrospective study of 129 medical files concerning seafood poisonings (SFPs) registered at the central hospital of Tahiti (French Polynesia) between 1999 and 2005. Even if during that period most of the described cases (96%) concerned the ichtyosarcotoxism ciguatera, it is interesting to note that we also registered three other SFPs: tetrodotoxism, carchatoxism and lyngbyatoxism due to the consumption of tetraodon/diodon species, sharks or sea turtles, respectively. In ciguatera, cardiovascular symptoms were the primary criteria of severity with bradycardia and hypotension observed at 75% and 43%, respectively. Neurological manifestations (such as cerebellar syndrome, language troubles, diplopia or polyradiculoneuritis), trouble and/or loss of consciousness and dyspnoea were secondary criteria of severity. Body temperature was reported under 36.5 degrees C in 48 of 80 documented files. This observation, which has not previously been described in humans, may be related to possible central effects of the ingested toxin. The last remark concerns two extremely severe cases of ciguatera fish poisoning in which physicians had suspected an inflammatory neuropathy called the Guillain-Barré syndrome (GBS). Even if it is premature to conclude any correlation between the intoxication and the appearance of GBS, it is interesting to note that in both pathologies, morphological disturbances of nerve fibres have been reported.
We present a retrospective study of 129 medical files concerning seafood poisonings (SFPs) registered at the central hospital of Tahiti (French Polynesia) between 1999 and 2005. Even if during that period most of the described cases (96%) concerned the ichtyosarcotoxism ciguatera, it is interesting to note that we also registered three other SFPs: tetrodotoxism, carchatoxism and lyngbyatoxism due to the consumption of tetraodon/diodon species, sharks or sea turtles,
respectively. In ciguatera, cardiovascular symptoms were the primary criteria of severity with bradycardia and hypotension observed at 75% and 43%, respectively. Neurological manifestations (such as cerebellar syndrome, language troubles, diplopia or polyradiculoneuritis), trouble and/or loss of consciousness and dyspnoea were secondary criteria of severity. Body temperature was reported under 36.5 1C in 48 of 80 documented files. This observation, which has not previously been described in humans, may be related to possible central effects of the ingested toxin. The last remark concerns two extremely severe cases of ciguatera fish poisoning in which physicians had suspected an inflammatory neuropathy called the Guillain–Barre´ syndrome (GBS). Even if it is premature to conclude any correlation between the intoxication and the appearance of GBS, it is interesting to note that in both pathologies, morphological disturbances of nerve fibres have been reported.
The Peacock gouper (Cephalopholis argus) was introduced to Hawai'i in 1956 to establish a new fishery. It has become abundant, but the fishery failed due to concerns about ciguatera fish poisoning, a neurological disease in humans caused by ingestion of fish containing ciguatoxin. The aim of this Study was to provide better understanding of geographic patterns of ciguatoxicity in C. argus and of the correlation of toxicity with morphometric characters of this species, with the goal to assess the possibility of a safe fishery. Overall, 18.2% of C. argus specimens from sites around O'ahu and Hawai'i Island contained ciguatoxin in concentrations potentially harmful to humans. This was higher than the rate of occurrence in Hawaiian reef fishes in general, and on the scale of ciguatoxicity in species banned from sale in fish markets. Toxicity was high around both analyzed islands. However, toxic individuals were significantly less common around O'ahu than around Hawai'i Island (8% versus 24%). Regular geographic patterns in toxicity within islands (e.g., gradients along coastlines) were not present, and variability in toxicity within each sample site was high. Toxicity was significantly but weakly positively correlated with C. argus length but not with fish condition (measured by length at weight). In conclusion, high prevalence of toxic individuals, variability in toxicity on all analyzed spatial scales, and low explanatory power of morphometric characters make the avoidance of ciguatoxic C. argus individuals difficult. A safe fishery for this species ill Hawai'i therefore does not appear feasible at present.
Experiments were designed to see whether a dinoflagellate, Diplopsalis sp. nov, found in a toxic sample of detritus collected from a ciguatera-endemic area is the cause of ciguatera.
The dinoflagellate in the detritus was separated from other materials by means of sedimentation and sieving through sieves of various mesh sizes. Bioassay of the dinoflagellaterich samples thus obtained proved that the toxicity of each sample was proportionally related to the number of the dinoflagellate cells in the sample. Subsequent extraction of the dinoflagellate sample followed by fractionation of the extracts with solvents afforded two major toxins; a diethyl ether soluble toxin and an acetone precipitable toxin. The former toxin was judged to be identical, or closely related, to ciguatoxin, a major toxin in ciguatera, on the basis of various column and thin layer chromatographic properties. A close similarity was also observed between the acetone precipitable toxin and maitotoxin, a secondary toxin isolated from ciguateric surgeonfish.
Judging from these results, it was concluded that Diplopsalis sp. nov is very likely to be the cause of ciguatera.
Following the previous discovery of a new toxic dinoflagellate Gambierdiscus toxicus as the most likely cause of ciguatera, an ecological survey was undertaken on this organism around Tahiti Island and in the Gambier Islands of French Polynesia. In the survey the epiphytic nature of the dinoflagellate was disclosed and a rapid assay method was established by taking advantage of this living patten. The method consisted of shaking off of the organisms from the appropriate substrative algae and subsequent microscopic counting of the cells. The population of the organism was found much higher in the Gambier Islands than around Tahiti, even though there were marked regionalities in both survey areas. The distribution map prepared by the survey not only agreed well with the results of the past surveys but gave a more quantitiative and clearer picture of the ciguatera-endemicity of the areas.
In addition to increased seafood consumption and tourism, recent studies link global climate change with an apparent increasing incidence of the Marine Seafood Toxin diseases. However, the epidemiology of the human diseases caused by the harmful marine phytoplankton is still in its infancy. In general, the epidemiology of these diseases has consisted of case reports of acute illness, sometimes as epidemic outbreaks, associated with the ingestion of suspicious seafood. Furthermore, even these outbreaks are highly under-reported, especially in poorer countries and in traditionally non-endemic areas. True incidence data are not available due to the lack of disease and exposure biomarkers in humans, as well as the global lack of routine exposure and disease surveillance. Without true incidence data to establish background population rates, it is impossible to evaluate the impact of Global Change or the apparent increasing incidence (1,2). Using Ciguatera as an example, general principles of the epidemiology of these diseases will be presented. The issue of disease surveillance as an essential component in the epidemiologic study and public health control of the marine seafood toxin diseases in human populations will be discussed. Recommendations will be made for epidemiologic study and public health control of the marine seafood toxin diseases in human populations. Background
A total of 551 specimens of 48 species of potentially ciguatoxic fishes from Enewetak and 256 specimens of 23 species from Bikini, Marshall Islands, were tested for ciguatoxin by feeding liver or liver and viscera from these fishes to mongooses at 10% body weight (except for sharks, when only muscle tissue was used). The fishes are representatives of the following families: Orectolobidae, Carcharhinidae, Dasyatidae, Muraenidae, Holocentridae, Sphyraenidae, Mugilidae, Serranidae, Lutjanidae, Lethrinidae, Carangidae, Scombridae, Labridae, Scaridae, Acanthuridae, and Balistidae. The species selected were all ones for which toxicity can be expected, including the worst offenders from reports of ciguatera throughout Oceania; only moderate to large-sized adults were tested. In all, 37.3% of the fishes from Enewetak and 19.7% from Bikini gave a positive reaction for ciguatoxin. Because liver and other viscera are more toxic than muscle, the percentage of positive reactions at the level which might cause illness in humans eating only the flesh of these fishes collectively would drop to 16.2 for Enewetak and 1.4 for Bikini. This level of toxicity is not regarded as high for Pacific islands, in general. Because ciguatoxin is acquired through feeding, the food habits of these fishes were investigated. Most of the highly toxic species, including seven of the eight causing severe illness or death in the test animals (Lycodontis javanicus, Cephalopholis argus, Epinephelus hoedtii, E. microdon, Plectropomus leopardus, Aprion virescens, and Lutjanus bohar) are primarily piscivorous.
The categories of fish poisoning as proposed by Halstead and Lively (1954) are revised. An attempt is made to document what appear to be the established phenomena of ciguatera, an illness of occasional occurrence following the ingestion of various tropical reef and inshore fishes and possibly certain echinoids and gastropods. The toxin appears to be cumulative and the most toxic fishes, generally, are large piscivorous types like barracuda, jacks, and groupers. Plankton-feeding fishes have not been implicated in ciguatera. Herbivorous and detritus-feeding fishes and mollusk-feeders may be poisonous. Fishes causing ciguatera are not found universally over large areas, but are localized, often in small sectors. A region once poisonous may lose its poisonous fishes and vice versa. Previous theories of the cause of ciguatera are discussed, and a new hypothesis is presented. In this, it is assumed that a benthic organism, most likely a blue-green alga, is the source of the toxin. This organism would seem to be one of the first growing in normal ecological succession in tropic seas. The localization of poisonous fishes is explained in terms of availability of new substratum for marine growth. Recommendations are made for further reasearch on ciguatera.
The central Pacific Ocean has arguably more ciguatera poisoning than any other place on earth. Here we tested two competing hypotheses that outline the primary causes of ciguatera outbreaks: (1) the ‘new surface hypothesis’ and (2) the ‘climate oscillation hypothesis’. Our findings indicated that in Rarotonga, from 1994 to 2010, the annual incidence of ciguatera poisoning ranged from 204 to 1,058 per 10,000 population per year. We found that the widest reefs of Rarotonga elicited the most cases of ciguatera poisoning, but found no relationship between ciguatera outbreaks and reef exposure. We also found strong correlations between cases of ciguatera poisoning and (i) the positive phase of the Pacific Decadal Oscillation, (ii) El Niño years, and (iii) periods with frequent disturbances. Yet, most disturbances occurred during the above-mentioned climate phases. This study links the two supposedly, mutually exclusive hypotheses. Moreover, as predicted by the ‘climate oscillation hypothesis’, the Pacific Ocean is now, in 2010, experiencing a negative phase of the Pacific Decadal Oscillation, and Rarotonga is reporting few cases of ciguatera poisoning.
From 2001 to 2005, numerous cases of seafood poisonings were reported in a tribe from Lifou (Loyalty Islands Province, New Caledonia) of which 35 were thoroughly examined. Observations outlined by the epidemiological and clinical data (including severity and rapid onset of certain symptoms following consumption of either giant clams (Tridacna spp.) or grazing and molluscivorous fish together with the apparent inefficacy of traditional remedies, were not in favour of a classical Ciguatera Fish Poisoning (CFP) outbreak. From 2005 onwards, an environmental offshore survey of the affected area was conducted. Screening of the damaged coral area revealed the presence of large populations of cyanobacteria identified as Hydrocoleum Kützing, but the absence of Gambierdiscus spp., the well-known dinoflagellate causative agent of CFP. In vivo and in vitro toxicological studies of extracts obtained from cyanobacteria and giant clams, strongly suggested the co-occurrence of ciguatoxin-like, anatoxin-like and paralytic shellfish toxins in these samples.
These new findings shed new light on the complexity of the CFP symptomatology and treatment and also on the diversity and origin of the CFP toxins. Furthermore they provide new evidence of the overall variability of seafood poisonings following the ingestion of different sea products living in a marine environment where significant harmful populations of microalgae and cyanobacteria coexist.
This is the first report on the involvement of cyanobacteria in CFP-like outbreaks following the consumption of giant clams or fish specimens. Consequently, it is recommended that CFP risk assessment programs now include monitoring of cyanobacteria besides the obvious screening of CFP-promoting dinoflagellates.
Ciguatera is a widespread ichthyosarcotoxism which causes gastrointestinal, neurological and cardiovascular disturbances. Investigations conducted by ORSTOM in 1992 highlighted a prevalence of 25% in the adult population of Noumea, New Caledonia. The main objective of our study was to estimate the prevalence of ciguatera and the persistence of symptoms by sex and by ethnicity among adult patients of a nurse clinic in Noumea in 2005.Investigations were conducted from 1st January to 15th June 2005. During this period, 559 patients were included: 165 males and 394 females. Among them, 37.8% were poisoned at least once in their life. This rate was independent of gender and ethnicity, but was significantly higher in age groups above 40 years. Neurological signs were more frequent (>80%) than gastrointestinal (<50%) and cardiac signs (<15%). Symptoms presented no difference between ethnic or gender groups, even for subjective signs. Most of poisonings were due to carnivorous fishes, but quite all species living in the lagoon were quoted. Symptoms persisted more than one year for 34% of the population, in both Melanesians and Caucasians.This study shows a significant increase of ciguatera prevalence, and its chronicity for 1/5 of European cases.
Coastal fisheries in Pacific island countries are characterised by a strong predominance of catches for subsistence purposes which involves mainly finfish and is difficult to quantify. In 1997–1998, a consumer survey conducted in the Northern Province of New Caledonia (Southwest Pacific Ocean) made it possible to indirectly estimate subsistence fishing production. Catch from subsistence fishing did not result in a significant change of the exploitation potential. The catch composition of subsistence fishing differed significantly from commercial fishing, with a higher proportion of species less vulnerable to exploitation. Interpretation of the consumer typology highlighted the importance of factors such as ethnic group and geographical location in explaining eating habits and therefore, indirectly, fishing behaviours. These results suggest that this fish consumption survey could assist in the design of subsistence fisheries monitoring programmes.
Resumen
Esta guía de campo incluye los principales grupos de recursos pesqueros de la costa septentrional de Sur América: macroalgas, gastrópodos, bivalvos, cefalópodos, estomatópodos, camarones, langostas, cangrejos, tiburones, peces batoídeos, peces óseos y tortugas marinas. La obra comienza con una descripción detallada de los límites, caracteres geofísicos, oceanográficos y ecológicos del área, localización y caracterización de los principales fondos de pesca, especies predominantes en cada hábitat y métodos de pesca utilizados. El tratamiento de cada uno de los grupos incluye una explicación de la terminología y las medidas utilizadas, una guía para la identificación de las familias presentes en el área, y la presentación más detallada de las familias y especies consideradas de interés para la pesca, incluyendo nomenclatura científica, nombres FAO propuestos para uso regional, una o varias ilustraciones, indicación de caracteres diagnósticos, y notas sobre distribución geográfica, hábitat y pesca. Sigue un índice alfabético de todos los nombres utilizados. La guía es profusamente ilustrada con dibujos en blanco y negro y con 320 fotografías en colores.
Marine pelagic cyanobacteria Trichodesmium are widespread in the New Caledonia lagoon. Blooms of these Oscillatoriales are suspected to be a potential source of toxins in the ciguatera food chain and were previously reported to contain certain types of paralysing toxins. In the present study, toxicity experiments were conducted on lipid- and water-soluble extracts of freeze-dried samples of these cyanobacteria. Lipid-soluble fractions revealed a ciguatoxin-like activity in both in vivo (mouse bioassay) and in vitro (mouse neuroblastoma cells assay and receptor binding assay using tritiated brevetoxin-3) assays. The water-soluble fractions tested on mice exhibited neurotoxicity with paralytic symptoms. These toxicities have also been observed with benthic filamentous cyanobacteria within the Oscillatoriales order, also collected in New Caledonia. This study provides an unprecedented evidence of the toxicity of Trichodesmium species from the New Caledonia lagoon. This survey also demonstrates the possible role of these cyanobacteria in ciguatera fish poisoning.
Ciguatera is a food poisoning identified as the principal risk factor in the consumption of tropical fish in Oceania. The syndrome, which follows ingestion of ciguatoxin-contaminated ciguateric fishes, is characterised by an array of gastrointestinal and neurological features. In this report we examine forensic samples associated with a human fatality using a 3H-brevetoxin binding assay and reversed-phase HPLC/MS and HPLC/MS/MS. Three Pacific ciguatoxins (P-CTX) were detected in the implicated fish flesh sample by LC-MS/MS, implicating multiple P-CTXs in the fatal case. Additionally, ciguatoxin was identified in a liver sample obtained at post-mortem. The level of ciguatoxin detected (0.14 ppb P-CTX-1 equivalents by binding assay) indicated that at least 10% of the ingested P-CTX-1 remained in the human liver 6 days after the toxic fish was consumed. This study confirms the potential of tropical reef fish to accumulate sufficient P-CTX to be lethal to humans, especially if the liver and viscera are consumed as part of the meal.
Ciguatera fish poisoning is a seafood-borne illness caused by consumption of fish that have accumulated lipid-soluble ciguatoxins. In the United States, ciguatera is responsible for the highest reported incidence of food-borne illness outbreaks attributed to finfish, and it is reported to hold this distinction globally. Ciguatoxins traverse the marine food web from primary producers, Gambierdiscus spp., to commonly consumed fish in tropical and subtropical regions of the world. Ciguatoxins comprise 12 known congeners among Caribbean and tropical Atlantic fish and 29 reported congeners among Pacific fish. Expanding trade in fisheries from ciguatera-endemic regions contributes to wider distribution and increasing frequency of disease among seafood consumers in non-endemic regions. Ciguatoxins produce a complex array of gastrointestinal, neurological and cardiological symptoms. Treatment options are very limited and supportive in nature. Information derived from the study of ciguatera outbreaks has improved clinical recognition, confirmation, and timely treatment. Such studies are equally important for the differentiation of ciguatoxin profiles in fish from one region to the next, the determination of toxicity thresholds in humans, and the formulation of safety limits. Analytical information from case and outbreak investigations was used to derive Pacific and Caribbean ciguatoxin threshold contamination rates for adverse effects in seafood consumers. To these threshold estimates 10-fold safety factors were applied to address individual human risk factors; uncertainty in the amount of fish consumed; and analytical accuracy. The studies may serve as the basis for industry and consumer advisory levels of 0.10ppb C-CTX-1 equivalent toxicity in fish from the tropical Atlantic, Gulf of Mexico, Caribbean, and 0.01ppb P-CTX-1 equivalent toxicity in fish from Pacific regions.
The most detailed dataset of ciguatera intensity is that produced by the South Pacific Epidemiological and Health Information Service (SPEHIS) of the Secretariat of the Pacific Community. The SPEHIS fish poisoning database has been previously analysed yielding statistically significant correlations between the Southern Oscillation Index (SOI) and ciguatera case numbers in several countries raising concerns this affliction will increase as oceans warm. Mapping of the SPEHIS records and other data hints at ciguatera not only being restricted to warm waters but that the Indo-Pacific Warm Pool, a body of water that remains hot throughout much of the year, may inhibit ciguatera prevalence. A qualitative assessment of ciguatera intensity and sea surface temperature (SST) behaviour within the EEZ of selected South Pacific nations supported the notion that ciguatera intensity was highest when SST was between an upper and lower limit. Many more climate and SST indices beyond the SOI are now available, including some that measure the abovementioned phenomenon of oceanic warm pools. Statistically significant, positive and negative cross-correlations were obtained between time series of annual ciguatera case rates from the SPEHIS dataset and the Pacific Warm Pool Index and several ENSO related indices which had been lagged for up to 2 years before the ciguatera time series. This further supports the possibility that when considering the impact of climate change on ciguatera, one has to consider two thresholds, namely waters that remain warm enough for a long enough period can lead to ciguatera and that extended periods where the water remains too hot may depress ciguatera case rates. Such a model would complicate projections of the effects of climate change upon ciguatera beyond that of a simple relationship where increased SST may cause more ciguatera.
A referee analysis method for the detection and quantification of Pacific ciguatoxins in fish flesh has recently been established by the public health analytical laboratory for the State of Queensland, Australia. Fifty-six fish samples were analysed, which included 10 fillets purchased as negative controls. P-CTX-1 was identified in 27 samples, and P-CTX-2 and P-CTX-3 were found in 26 of those samples. The range of P-CTX-1 concentrations was 0.04-11.4 microg/kg fish flesh; coefficient of variation from 90 replicate analyses was 7.4%. A liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) method utilising a rapid methanol extraction and clean-up is reliable and reproducible, with the detection limit at 0.03 microg/kg fish flesh. Some matrix effects are evident, with fish oil content a likely signal suppression factor. Species identification of samples by DNA sequence analysis revealed some evidence of fish substitution or inadvertent misidentification, which may have implications for the management and prevention of ciguatera poisoning. Blinded inspection of case notes from suspect ciguatera poisoning cases showed that reporting of ciguatera-related paraesthesias was highly predictable for the presence of ciguatoxins in analysed fish, with 13 of 14 expected cases having consumed fish that contained P-CTX-1 (p<0.001, Fishers Exact Test).
Okinawa being located in the subtropical region has the highest incidence of ciguatera in Japan. Officially, 33 outbreaks involving 103 patients have been reported between 1997 and 2006. The implicated species were Variola louti, Lutjanus bohar, Lutjanus monostigma, Epinephelus fuscoguttatus, unidentified Lutjanus sp., Plectropomus areolatus, Oplegnathus punctatus, Epinephelus polyphekadion, Caranx ignobilis and moray eel. Toxicities of the leftover meals, as determined by mouse bioassays, ranged from 0.025 to 0.8 MU/g or above (equivalent to 0.175-5.6 ngCTX1B/g). We collected 612 specimens of fish belonging to L. monostigma, L. bohar, Lutjanus argentimaculatus, Lutjanus russellii, V. louti, Variola albimarginata, and E. fuscoguttatus from the coasts around Okinawa and examined the toxicity of the flesh by the mouse bioassay. The rate of toxic fish was as follows: L. monostigma: 32.3%, L. bohar: 11.9%, V. louti: 14.3%, E. fuscoguttatus: 20.8%. Only one out of 36 samples of V. albimarginata and two of 74 samples of L. russellii were found toxic. None of the 35 samples of L. argentimaculatus was toxic. Nor the L. bohar samples weighing less than 4 kg were toxic. In all toxic samples, CTX1B was detected by LC/MS analysis but CTX3C and 51-hydroxyCTX3C were not.
Based on epidemiological data available through long-term monitoring surveys conducted by both the Public Health Directorate and the Louis Malardé Institute, ciguatera is highly endemic in French Polynesia, most notably in Raivavae (Australes) which appears as a hot spot of ciguatera with an average incidence rate of 140 cases/10,000 population for the period 2007-2008. In order to document the ciguatera risk associated with Raivavae lagoon, algal and toxin-based field monitoring programs were conducted in this island from April 2007 to May 2008. Practically, the distribution, abundance and toxicity of Gambierdiscus populations, along with the toxicity levels in 160 fish distributed within 25 distinct species, were assessed in various sampling locations. Herbivores such as Scarids (parrotfish) and Acanthurids (unicornfish) were rated as high-risk species based on receptor-binding assay toxicity data. A map of the risk stratification within the Raivavae lagoon was also produced, which indicates that locations where both natural and man-made disturbances have occurred remained the most susceptible to CFP incidents. Our findings also suggest that, locally, the traditional knowledge about ciguatera may not be scientifically complete but is functionally correct. Community education resulted in self-regulating behaviour towards avoidance of high-risk fish species and fishing locations.
Clinical observations on ciguatera were collected between 1964 and 1977 on 3,009 patients from several South Pacific island groups. Patients generally presented with neurologic symptoms such as parasthesia, vertigo, and ataxia, in addition to gastrointestinal symptoms such as diarrhea, abdominal pain, nausea, and vomiting. Patients with this illness usually became symptomatic less than 24 hours after ingestion of the fish and most patients (76.8%) developed symptoms in less than 12 hours. Significant differences in certain symptoms were noted between Melanesian and Polynesian ethnic groups, suggesting a susceptibility difference, or a difference in the nature of the toxin found in different areas of the Pacific. Being poisoned multiple times appeared to result in a clinically more severe illness than disease observed in patients experiencing ciguatera for the first time.
Ciguatoxicity of barracuda (Sphyraena barracuda) head, viscera and flesh tissues has been determined in 219 specimens caught along the southwest coast of Puerto Rico from March 1985 through May 1987. Twenty-nine percent of these specimens were toxic. Monthly frequencies of ciguatoxic barracuda showed an apparent seasonal variability, with peak values (60-70% toxic fish) in the late winter-early spring (January-May) and fall (August-November). Minimal frequencies (0-10% toxic fish) were observed during June-July and December. The most frequently toxic tissues in poisonous animals were the viscera and head. Viscera tissue was the only toxic tissue found in 31% of the poisonous fish assayed, and this tissue was poisonous in all toxic fish. In no case was a poisonous specimen found to have toxic flesh alone. Marked temporal variation in frequency of ciguatoxicity suggests that ciguatera toxins, at least in their active form, are not accumulated in barracuda tissues for extended periods of time. Variability in barracuda ciguatoxicity may reflect fluctuations in the toxicity of smaller reef fish prey, seasonal fluctuations in toxic benthic dinoflagellates and/or changes in the ability of the barracuda to detoxify ingested poisons or their precursors.
Ciguatera is an important form of human poisoning caused by the consumption of seafood. The disease is characterised by gastrointestinal, neurological and cardiovascular disturbances. In cases of severe toxicity, paralysis, coma and death may occur. There is no immunity, and the toxins are cumulative. Symptoms may persist for months or years, or recur periodically. The epidemiology of ciguatera is complex and of central importance to the management and future use of marine resources. Ciguatera is an important medical entity in tropical and subtropical Pacific and Indian Ocean regions, and in the tropical Caribbean. As reef fish are increasingly exported to other areas, it has become a world health problem. The disease is under-reported and often misdiagnosed. Lipid-soluble, polyether toxins known as ciguatoxins accumulated in the muscles of certain subtropical and tropical marine finfish cause ciguatera. Ciguatoxins arise from biotransformation in the fish of less polar ciguatoxins (gambiertoxins) produced by Gambierdiscus toxicus, a marine dinoflagellate that lives on macroalgae, usually attached to dead coral. The toxins and their metabolites are concentrated in the food chain when carnivorous fish prey on smaller herbivorous fish. Humans are exposed at the end of the food chain. More than 400 species of fish can be vectors of ciguatoxins, but generally only a relatively small number of species are regularly incriminated in ciguatera. Ciguateric fish look, taste and smell normal, and detection of toxins in fish remains a problem. More than 20 precursor gambiertoxins and ciguatoxins have been identified in G. toxicus and in herbivorous and carnivorous fish. The toxins become more polar as they undergo oxidative metabolism and pass up the food chain. The main Pacific ciguatoxin (P-CTX-1) causes ciguatera at levels=0.1 microg/kg in the flesh of carnivorous fish. The main Caribbean ciguatoxin (C-CTX-1) is less polar and 10-fold less toxic than P-CTX-1. Ciguatoxins activate sodium ion (Na ) channels, causing cell membrane excitability and instability. Worldwide coral bleaching is now well documented, and there is a strong association between global warming and the bleaching and death of coral. This, together with natural environmental factors such as earthquakes and hurricanes, and man-made factors such as tourism, dock construction, sewage and eutrophication, may create more favourable environments for G. toxicus. While low levels of G. toxicus are found throughout tropical and subtropical waters, the presence of bloom numbers is unpredictable and patchy. Only certain genetic strains produce ciguatoxins, and environmental triggers for increasing toxin production are unknown.
Ciguatera Fish Poisoning (CFP) is a tropical syndrome well known in remote archipelagos where the population is still dependent on fish resources. In order to assess the ciguatera risk in two islands of French Polynesia, Tubuai (Australes) and Nuku Hiva (Marquesas), a study was carried out on both Gambierdiscus populations as well as on various fish species using the receptor-binding assay (RBA) to detect and quantify ciguatoxins. Relationship between RBA data and size or weight of fish was evaluated, and when only few individuals for a particular species were available the trophic level was used to help comparisons between studied areas. According to epidemiological data, toxic versus safe areas were explored and compared in both islands. In Tubuai Island, Gambierdiscus cells were surprisingly absent in the north area, considered as a toxic area, but almost 94% of fishes were classified as RBA+. In contrast, the south area, supposed to be safe, was evolving to be a risky area because of the presence of Gambierdiscus cells and 74% of fishes being RBA+. In Nuku Hiva Island, Gambierdiscus cells were present in the toxic areas, Anaho, Taiohae and Taipivei, with two toxic blooms in Anaho Bay, but none in Terre Déserte, the fishing area of this island. With RBA data, fishes were analyzed to be RBA+ at a high percentage in Anaho and Taiohae, higher than in Taipivei and Terre Déserte areas. In general, our findings were congruent with epidemiological data and the knowledge of local people only for risky fish species.
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