Edible river fish-derived extended-spectrum ß-lactamase (ESBL)-producing Enterobacterales harboring transferable plasmids encoding bla CTX-M-15, bla CTX-M-27, and bla CTX-M-55.

Transmission of extended-spectrum ß-lactamase (ESBL) genes has increased the global prevalence of ESBL-producing bacteria, especially in developing countries. Human infection with these bacteria may be food-mediated but has not been fully elucidated. Therefore, we aimed to examine ESBL-producing bacteria in edible river fish and elucidate their potential for horizontal gene transfer. A total of 173 ESBL-producing Enterobacterales were isolated (Escherichia coli [n = 87], Klebsiella pneumoniae [n = 52], Enterobacter cloacae complex [n = 18], Citrobacter freundii complex [n = 14], Atlantibacter hermannii [n = 1] and Serratia fonticola [n = 1]) from 56 of 80 fish intestinal contents sampled. Among the bacterial bla CTX-M genotypes, bla CTX-M-55 was the most predominant, followed by bla CTX-M-15, bla CTX-M-27, and bla CTX-M-65. Furthermore, we found that ESBL-producing Enterobacterales were able to transfer their bla CTX-M genes to E. coli. In summary, our results suggest that ESBL-producing Enterobacterales transfer bla CTX-M to indigenous gut E. coli in humans, following the consumption of contaminated fish.

Novel ultrasound assisted extraction and d-SPE clean-up for the analysis of multiple legacy and emerging organic contaminants in edible fish.

Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs), phthalate esters (PAEs) are pervasive environmental pollutants, posing threats to both ecosystems and human health. Although several analytical methods were developed for these compounds, they are not performed simultaneously. This study addresses the need for a sustainable, novel, analytical approach capable of simultaneously determining these diverse chemical classes in edible fish muscles. Employing ultrasound extraction coupled with dispersive solid-phase extraction (d-SPE) as a cleanup procedure, the method was compared to conventional techniques, revealing significant improvements. Analytical parameters were thoroughly assessed, and the innovative method demonstrated notable advantages, reducing extraction and purification times by approximately 74-80 % and solvent consumption by around 94-97 %. Applied to Mediterranean Sea fish samples, the results underscore the method's potential as a viable, sustainable alternative to traditional approaches, promising enhanced efficiency and reduced environmental impact.

Comprehensive characterization and prioritization of halogenated organic compounds in fish and their implications for exposure.

Fish are an important pollution indicator for biomonitoring of halogenated organic compounds (HOCs) in aquatic environments, and HOCs in fish may pose health threats to consumers. This study performed nontarget and comprehensive analyses of HOCs in fish from an e-waste recycling zone by gas chromatography-high-resolution mass spectrometry, and further prioritized their human exposure risks. A total of 1652 formulas of HOCs were found in the fish, of which 1222, 117, and 313 were organochlorines, organobromines, and organochlorine-bromines, respectively. The total concentrations of HOCs were 15.4-18.7 µg/g (wet weight), and organobromines were the predominant (14.1-16.8 µg/g). Of the HOCs, 41 % were elucidated with tentative structures and divided into 13 groups. The estimated total daily exposures of HOCs via dietary consumption of the fish for local adult residents were 3082-3744 ng/kg bw/day. The total exposures were dominated by several groups of HOCs with the following contribution order: polyhalogenated biphenyls and their derivatives > polyhalogenated diphenyl ethers > halo- (H-)alkanes/olefines > H-benzenes > H-dioxins > H-polycyclic aromatic hydrocarbons > H-phenols. The comprehensive characterization and prioritization results provide an overview of the species and distributions of HOCs in edible fish, and propose an inventory of crucial HOCs associated with high exposure risks.

First insights into per-and polyfluoroalkyl substance contamination in edible fish species of the Indus water system of Pakistan.

Per- and polyfluoroalkyl substances (PFASs) are a group of emerging contaminants, that have a wide range of applications in industrial and commercial products. The direct discharge of untreated industrial and domestic wastewater into freshwater bodies is a common practice in developing countries, which are the main contributors to PFASs in the aquatic environment. The situation is further worsened due to poor wastewater treatment facilities and weak enforcement of environmental regulations in countries like Pakistan. The current study was designed to assess PFASs contamination in muscle tissues of edible fish species from major tributaries of the Indus System, including Head Panjnad (HP), Head Trimmu (HT), Chashma Barrage (CB), Head Blloki (HB) and Head Qadirabad (HQ). The analysis of target PFAS was performed using ultrahigh-performance liquid chromatography coupled with a quadrupole Orbitrap high-resolution mass spectrometry. The highest levels of ∑17PFASs were observed in S. seenghala, C. mirigala from HB, and C. mirigala from HQ with a mean value of 45.4 ng g-1, 43.7 ng g-1, and 40.8 ng g-1, respectively. Overall, the compositional profile of fish samples was predominated by long-chain PFASs such as PFOA, PFOS, PFHpS, and PFDS. The accumulation of PFASs in fish species is dependent on the physiochemical properties of PFASs, characteristics of the aquatic environment, and fish species. Significant associations of PFASs with isotopic composition (p < 0.05), feeding habits (p < 0.05), and zones (p < 0.05) indicate that dietary proxies could be an important predictor of PFASs distribution among species. The C7-C10 PFASs exhibited bio-accumulative tendency with an accumulation factor ranging from 0.5 to 3.4. However, none of the fish samples had sufficiently high levels of PFOS to cause human health risk (HR < 1). For future studies, it is s recommended to conduct seasonal monitoring and the bioaccumulation pattern along trophic levels of both legacy and emerging PFASs.

Does eating fish cause cancer? A case study metal(loid)s accumulation in mackerel and sardine tissues from Iskenderun Bay, Türkiye.

Due to the increasing harmful effects of metal(loid)s over time, it has become important in environmental studies carried out to increase environmental awareness. It is important to investigate the cumulative presence of metal(loid)s in nature, their interactions with each other and risks posed by fish consumption for human health. Total concentrations of As, Cd, Cu, Fe, Mn, Ni, Pb, and Zn were determined in muscle and gill tissues of horse mackerel (Trachurus trachurus) and sardine (Sardina pilchardus). Metal analyses were carried out using Inductively Coupled Plasma-Mass Spectroscopic (ICP-MS) methods. In both tissues, Fe and Zn concentrations were the highest and Cd, Cu and Pb concentrations were the lowest. The target hazard coefficient, estimated daily intake, target cancer risk, total target hazard coefficient, and hazard indices were calculated to assess the risks to an individual's health from consuming fish. Hazard index and total target hazard coefficient values calculated for each fish exceeded 1 but were very close to 1. Target cancer risk values of As and Ni were found to be 10-6 and 10-4 for Pb. These limit values indicate the need for regular monitoring of the region. In addition, the interactions between the metal(loid)s accumulated in the tissues were analyzed and a high correlation was found between As-Ni, which poses a risk to public health.

Consumption of commercially sold dried fish snack "Charales" contaminated with microplastics in Mexico.

Inadvertent human exposure to microplastics by the ingestion of microplastic-contaminated processed foods poses health risks and new preventative issues; nevertheless, investigations analyzing microplastic occurrences in commercially dried fish for direct human consumption are scarce. This study assessed the abundance and characteristics of microplastics in 25 commercially sold dried fish products (4 supermarkets, 3 street vendors, and 18 traditional agri-product farmers' markets) from two widely consumed and commercially important Chirostoma species (C. jordani and C. patzcuaro) in Mexico. Microplastics were detected in all the samples examined, with abundances ranging from 4.00 ± 0.94 to 55.33 ± 9.43 items g-1. C. jordani dried fish samples had higher mean microplastic abundance (15.17 ± 5.90 items g-1) than the C. patzcuaro dried fish samples (7.82 ± 2.90 items g-1); nevertheless, there was no statistically significant difference in microplastic concentrations between the samples. The most prevalent type of microplastic was fiber (67.55%), followed by fragment (29.18%), film (3.00%), and sphere (0.27%). Non-colored microplastics (67.35%) predominated, while microplastic sizes varied from 24 to 1670 µm, with sizes less than 500 µm (84%) being the most common. ATR-FTIR analysis revealed polyester, acrylonitrile butadiene styrene, polyvinyl alcohol, ethylene-propylene copolymer, nylon-6 (3), cellophane, and viscose in the dried fish samples. Overall, this study's findings are the first in Latin America to demonstrate microplastic contamination in dried fish for human consumption, underscoring the need for developing countermeasures to prevent plastic pollution in fish-caught regions and reduce the risks of human exposure to these micropollutants.

Metal pollution in freshwater fish: A key indicator of contamination and carcinogenic risk to public health.

Metals are micropollutants that cannot be degraded by microorganisms and are infiltrated into various environmental media, including both freshwater and marine water. Metals from polluted water are absorbed by many aquatic species, especially fish. Fish is a staple food in the diets of many regions in the world; hence, both the type and concentration of metals accumulated and transferred from contaminated water sources to fish must be determined and assessed. In this study, the heavy metal concentration was determined and assessed in fish collected from freshwater sources via published literature and Estimated Daily Intake (EDI), Target hazard quotient (THQ), and Carcinogenic Risk (CR) analyses, aiming to examine the metal pollution in freshwater fish. The fish was used as a bioindicator, and Geographic information system (GIS) was sued to map the polluted regions. The results confirmed that Pb was detected in fish sampled at 28 locations, Cr at 24 locations, Cu and Zn at 30 locations, with values Pb detected ranging from 0.0016 mg kg-1 to 44.3 mg kg-1, Cr detected ranging from 0.07 mg kg-1 to 27 mg kg-1, Cu detected ranging from 0.031 mg kg-1 to 35.54 mg kg-1, and Zn detected ranging from 0.242 mg kg-1 to 103.2 mg kg-1. The strongest positive associations were discovered between Cu-Zn (r = 0.74, p < 0.05) and Cr-Zn (r = 0.57, p < 0.05). Spatial distribution maps depicting the consumption of fish as food and its corresponding Pb and Cr intake revealed a higher incidence of both carcinogenic and non-carcinogenic health concerns attributed to Pb and Cr in the region with populations consuming the fish.

Bioaccumulation of Some Hazardous Heavy Metals in Three Edible Fishes Caught from Gorgan Bay, Caspian Sea.

A survey was conducted to evaluate heavy metal accumulation in edible fishes caught from Gorgan Bay, as a part of the Caspian Sea ecosystem. Fish samples including mullet, roach, and common carp were just randomly prepared from fishing locations in three different areas of Gorgan Bay including estuary, channel, and Miankale wetland twice the fishing seasons. A total of 135 samples were measured using an atomic absorption spectrometer to 4 heavy metals of arsenic (As), lead (Pb), cadmium (Cd), and copper (Cu) (a total of 540 metal samples). The highest accumulation of As was related to the mullet of estuary, and the lowest contamination was related to the mouth of the channel. In relation to Cd, the highest pollution in all three species related to the fishes caught from the estuary and the lowest accumulation related to the Miankaleh wetland. In the case of metal Pb, results showed the most contamination related to the Mullet caught from Miankaleh wetland and the lowest accumulation related to the roach of the mouth of the channel. In all three fish species, the highest contamination of Cu was in the estuary and the lowest was in the fish caught from Miankaleh wetland. In general, the highest accumulation belonged to all three species located in estuaries. The probable reason can be pouring river pollution to the bay more than wetlands and channel. Due to the enclosure of the Caspian Sea and consequently the Gulf of Gorgan, limiting the fishing times and points to the periods of least incoming pollutants is very helpful for public health, especially food hygiene and fishing from this ecologically sensitive and vulnerable basin.

Comparative Study of Intestinal Microbiota Composition of Six Edible Fish Species.

Intensive freshwater aquaculture in the Spring Valley, Israel, is implemented mainly in earthen fishponds and reservoirs that are stocked with a variety of edible fish species. Here we sampled six different healthy fish species from these intensive aquacultures. The fish were hybrid striped bass, European bass, red drum (all carnivores), hybrid tilapia, flathead grey mullet (both herbivores), and common carp (an omnivore). Significant differences were found among the intestinal microbiota of the six studied fish species. The microbiota composition diversity was strongly related to the trophic level of the fish, such that there was a significant difference between the carnivore and the herbivore species, while the omnivore species was not significantly different from either group. The most abundant genus in the majority of the fishes' intestinal microbiota was Cetobacterium. Furthermore, we found that beside Cetobacterium, a unique combination of taxa with relative abundance >10% characterized the intestine microbiota of each fish species: unclassified Mycoplasmataceae, Aeromonas, and Vibrio (hybrid striped bass); Turicibacter and Clostridiaceae 1 (European bass); Vibrio (red drum); ZOR0006-Firmicutes (hybrid tilapia); unclassified Mycoplasmataceae and unclassified Vibrionaceae (flathead grey mullet); and Aeromonas (common carp). We conclude that each fish species has a specific bacterial genera combination that characterizes it. Moreover, diet and the trophic level of the fish have a major influence on the gut microbiota of healthy fish that grow in intensive freshwater aquaculture.

A baseline study on the impact of nanoplastics on the portals of entry of xenobiotics in fish.

Mediterranean waters are particularly vulnerable to plastic pollution, with plastic particles concentrations comparable to those found in oceanic gyres. This work aimed to assess the impact of polymethylmethacrylate nanoplastics (PMMA-NPs) on the most important mucosal barriers of the gilthead seabream (Sparus aurata), a highly consumed fish species in the Mediterranean area. Fish were waterborne exposed to NPs (0.001-10 mg/L) for 24 and 96 h, and biochemical parameters associated with oxidative status (total oxidative status and total antioxidant capacity) and immune function (adenosine deaminase, ADA, acetylcholinesterase activity, AChE, and esterase activity, EA) were assessed in gills, intestine, and skin. In intestine, PMMA-NPs led to oxidative status alterations and decreased ADA and EA. In gills, PMMA-NPs induced EA decrease and AChE activity increase. Total protein values were significantly increased in skin. Overall, more alterations were observed in intestine, suggesting it may be one of the most affected tissues by exposure to NPs.

Taxon-toxicity study of fish to typical transition metals: Most sensitive species are edible fish.

Transition metals are widespread in aquatic environments and can be harmful when concentrations exceed thresholds. Especially for fish, an important component of the human diet, low concentrations of transition metals will directly affect their well-being. Different taxa are protected by unified water quality criteria (WQC) thresholds, which rarely consider the ecological status and economic value of different species. There is therefore an urgent need to study taxon-specific sensitivity. The present study established the species sensitivity distributions of nine typical transition metals (Cr, Mn, Fe, Ni, Cu, Zn, Ag, Cd and Hg) for protecting freshwater and seawater fish based on non-parametric kernel density estimation methods, and then derived their acute and chronic HC5-values. The results showed that Ag and Hg have the highest acute toxic potency to fish in freshwater as well as seawater. Compared with marine fish, freshwater fish were more tolerant to acute exposure to Cr, Fe, Ni and Zn, whilst being more sensitive to Ag and Cd. Moreover, edible fish are more sensitive than other fish to these metals in both freshwater and seawater, encouraging more protection of economically valuable fish that may potentially affect human health. The study provides a strong reference for future research on taxon-specific WQC for transition metals.

Nutritional, Texture, and Sensory Properties of composite biscuits produced from breadfruit and wheat flours enriched with edible fish meal.

This study aimed to develop biscuits with improved nutritional contents using edible fish meal from catfish as the source of macro- and micronutrient enrichment while trying to reduce the input of wheat flour in biscuit-making process. The biscuit was produced using edible fish meal (EFM: 0%-40%) from catfish, improved quality breadfruit (IQBF: 0%-60%), and wheat flours (WF: 0%-40%). Macro (crude protein, fat, fiber, ash, and carbohydrate)- and micro (calcium, magnesium, potassium, phosphorus, sodium, and iron)-nutrient contents of the biscuit were determined. The color (lightness-L*, redness-a*, and yellowness-b*), texture (hardness, springiness, and adhesiveness), and sensory (taste, texture, and overall acceptability) attributes of the biscuits were assessed using standard methods. Model characteristics of the responses were profiled, and numerical optimization technique was used to predict combination/blends that produce biscuits with desired nutritional contents. Moisture, crude protein, fat, fiber, and ash values were in the range of 3.50%-5.57%, 3.06%-15.52%, 13.62%-26.00%, 0.31%-1.40%, and 1.98%-5.32%, respectively. The iron, calcium, and phosphorus contents of the biscuit ranged from 103.85 to 201.30 mg/100 g, 100 to 754 mg/100 g, and 8 mg/100 g to 304 mg/100 g, respectively. Interaction between the models for WF and EFM was significant and this significantly affected the L* (36.37-51.90) and adhesiveness (0.01-0.29) values for color and texture, respectively. Similar observations were also noticed for most of the nutrients. The quadratic models selected for the nutrients were all significant (p < .05) and the adjusted R 2 ranged from 0.61 to 0.84 and 0.59 to 0.97 for the macro- and micronutrients, respectively. In conclusion, a biscuit from IQBF, WF, and EFM of 61.33, 0.07, and 38.60 with protein, fat, ash, iron, and calcium contents of 10.41%, 17.59%, 2.05%, 120.52 mg/100 g, and 500.00 mg/100 g, respectively, was produced.

Dietary intake of polycyclic aromatic hydrocarbons (PAHs) from coral reef fish in the Persian Gulf - Human health risk assessment.

The present study investigated accumulation of petrogenic polycyclic aromatic hydrocarbons (∑39PAHs) in the livers and muscles of three coral-reef fish (50 specimens) from the Persian Gulf, Kharg Island (Iran), specifically Lethrinus microdon (n = 18), Lutjanus argentimaculatus (n = 17), and Scomberomorus guttatus (n = 15). For all fish, PAHs originated mostly from petroleum and combustion sources. Concentrations of ∑39PAHs were 1004 ngg-1 freeze-dried weight (fdw) and 1390 ngg-1 fdw for liver and muscle, respectively. The biota-sediment accumulation factor of 20,181 and equivalent concentrations of ∑PAHs (liver) were highest for L. argentimaculatus. Most of the abundant PAHs identified were low molecular weight (LMW-PAH) (liver > muscle) with 2-3 aromatic ring. Results for the human health risk assessment concluded the probability of PAHs intake via fish consumption was considerable in this area (lifetime cancer risk (ILCR) > 1 × 10-5; hazard quotients (HQs) > 1; hazard index (HI) ≈6; the excess cancer risk (ECR) > 1 × 10-6) and, therefore, comprehensive management and long-term monitoring is needed.

Plastics occurrence in the gastrointestinal tract of Zeus faber and Lepidopus caudatus from the Tyrrhenian Sea.

The present study investigates the occurrence of plastic pollution in two commercially important marine teleosts (Zeus faber and Lepidopus caudatus) from the northern coasts of Sicily (Tyrrhenian Sea). Plastics occurrence in the gastrointestinal tract was higher in Lepidopus caudatus (78.1%) than Zeus faber (51.4%). Debris characterization, carried out by micro-Raman spectroscopy, allowed identified the main types of found polymers as: polypropylene (PP), polyamide (PA), nylon and, to a lesser extent, polyethylene (PE). Of the two fish species studied, the silver scabbardfish appeared to be the more vulnerable to plastic ingestion. Our study represents a starting point that may pave the way for future investigation of the fate, accumulation and transfer of plastic debris to upper trophic levels, to verify their potential toxicity and to better understand strategies to mitigate this phenomenon.

High arsenic and low lead concentrations in fish and reptiles from Taim wetlands, a Ramsar site in southern Brazil.

The pollution caused by heavy metals and metalloids represent an emerging threat to wetlands worldwide. Herein we examined the concentrations of arsenic (As) and lead (Pb) in fish and aquatic/semi-aquatic reptiles from Taim wetlands, a Ramsar site located at the southernmost Brazilian coastal plain. A total of 82 individuals from six fish and three reptile species from varied trophic levels were analysed through furnace graphite atomic absorption spectrophotometry. Mean As concentrations (µg·g-1 dry weight) were markedly high, ranging from 13.06 ±â€¯3.18 to 19.4 ±â€¯4.04 in fish and 3.51 ±â€¯2.36 to 19.00 ±â€¯10.45 in reptiles. Mean Pb concentrations were low, ranging from 0.00067 ±â€¯0.00060 to 0.0040 ±â€¯0.00045 in fishes and 0.00103 ±â€¯0.0011 to 0.0271 ±â€¯0.0353 in reptiles. The highest As mean level was detected in the herbivore-insectivore fish Astyanax aff. fasciatus, a species of low trophic level among the analysed taxa. The highest Pb mean level was found in the broad-snouted caiman Caiman latirostris, the highest trophic level species analysed. The present study warns for the contamination of As especially in edible fish, which constitute a threat to the communities that use this resource in systems connected to Taim wetlands. As concentrations in reptiles were also higher than those reported in previous studies concerning the groups herein addressed. It is possible that the high As burdens found in the analysed species could be attributed to the use of fertilizers and pesticides in extensive irrigated rice areas located in Taim wetlands surroundings, but natural sources cannot be dismissed.

Marine litter in stomach content of small pelagic fishes from the Adriatic Sea: sardines (Sardina pilchardus) and anchovies (Engraulis encrasicolus).

Marine litter impacts oceans and affects marine organisms, representing a potential threat for natural stocks of pelagic fish species located at the first levels of the marine food webs. In 2013-2014, on a seasonal basis, marine litter and microplastics in stomach contents from Sardinia pilchardus and Engraulis encrasicolus were evaluated. Selected species are plankitivores of great ecological and commercial importance in the Adriatic Sea. Collected data were correlated to possible factors able to affect ingested levels as well as species, season of sampling, biometry and sex of animals. Almost all tested samples (80 organisms for each species) contained marine litter (over 90% of samples from both species) and also microplastics; while any meso- or macroplastics were recorded. On average, recorded items were as follows: 4.63 (S. plichardus) and 1.25 (E. encrasicolus) per individual. Sardines evidenced a higher number of microplastics characterised by a smaller size than those recorded in anchovies. For sardines, sex, Gastro Somatic Index and sampling season showed negligible effects on the number of ingested litter; conversely, anchovies showed differences related with both sex of animals and dominant colour of ingested materials with prevalence for black and blue colours.

Distributions and compositional patterns of polycyclic aromatic hydrocarbons (PAHs) and their derivatives in three edible fishes from Kharg coral Island, Persian Gulf, Iran.

This is the first report on bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) and their derivatives (oxygen, nitrogen, sulfur, hydroxyl, carbonyl and methyl-containing PAHs) in three edible marine fishes, namely Lutjanus argentimaculatus, Lethrinus microdon and Scomberomorus guttatus, from Kharg Island, Persian Gulf, Iran. The concentrations (ng g-1dw) of Σ39PAHs resulted significantly higher in fish liver than muscle, with the PAH composition pattern dominated by low molecular weight compounds (naphthalene, alkyl-naphthalenes and phenanthrene). The highest mean concentrations of ∑9 oxygenated and ∑15 hydroxylated PAHs (ng g-1dw) were found ound in L. microdon and L. argentimaculatus, respectively, while the lowest values in S. guttatus. Additionally, the highest mean concentrations of Σ5 carbonylic PAHs (ng g-1dw) were found in L. argentimaculatus, followed by L. microdon. The PAHs levels and distribution in fish liver and muscle were dependent on both the Kow of PAHs congeners and fish lipid contents. Overall, the present findings provide important baseline data for further research on the ecotoxicity of PAHs in aquatic organisms, and consequent implications for human health.

Pharmaceuticals in grocery market fish fillets by gas chromatography-mass spectrometry.

Occurrences of pharmaceuticals are evident in aquatic organisms. A reproducible gas chromatography-mass spectrometry (GC-MS) method using selected ion monitoring (SIM) has been used to determine the anti-histamine diphenhydramine (DPH), anti-anxiety diazepam (DZP), anti-seizure carbamazepine (CZP) drugs and their metabolites in grocery stores fish that were homogenized, extracted, pre-concentrated, cleaned up, and examined. Identifications of the compounds in extracts were obtained by comparing similar mass spectral features and retention properties with standards. Among nine frequently detected drugs, only DPH and DZP were observed and ranged from 0.61 to 6.21 and 1.99 to 16.57 ng/g, respectively, in fourteen fish species. These concentration values were lower than the environmental fish. Mean spike recoveries of analytes exceeded 75% with relative standard deviations (RSD)<10%. The statistically-derived method detection limits (MDLs) for nine compounds ranged from 0.13 to 5.56 ng/g. Average surrogate recoveries were 80-85% with 4-9% RSD.

Methyl mercury concentrations in edible fish and shellfish from Dunedin, and other regions around the South Island, New Zealand.

Methyl mercury (MeHg) concentrations were determined in edible fish and shellfish available in local markets in Dunedin, New Zealand. While most of the fish species were sourced in Dunedin, some specimens of fish were also collected from waters off Picton, around Stewart Island and also off-shore of the South Island in the Puysegur and Subantarctic regions. The concentrations of MeHg were analysed in 25 different fish species and shellfish (103 muscle tissue samples). Total mercury (HgT) levels were also analysed in a few (n=12) selected fish samples. Most of the Hg was in the form of MeHg (≥ 96%). Higher MeHg concentrations were found in fish at higher trophic levels, particularly in predatory fish species such as ling, school shark, spiny dogfish and albacore tuna. Concentrations of MeHg in all samples ranged from 0.002 to 2.515 µg MeHg/g.