Shark Consumption Research Articles

Using SMS surveys to understand songbird ownership and shark product consumption in Indonesia

AbstractThe unsustainable use of wildlife increases the risk of species extinction. In biodiversity-rich Indonesia, information on the scale of wildlife use is limited and requires further study. To address this, we explored the potential of text messaging (short message service; SMS) surveys to investigate levels and spatial patterns of domestic wildlife use, using songbird keeping and shark consumption as case studies because of their widespread occurrence in all 34 Indonesian provinces. We sent 340,000 messages for each survey during October–November 2018 and incentivized responses with a mobile data package as reward. We obtained survey response rates of 1.4% (songbird ownership) and 1.5% (shark consumption). Our results revealed an estimated 175.7 million songbirds being kept by 35% (80.4–86.6 million) of the Indonesian population and 33.5 million people (14% of the Indonesian population) to have consumed shark products in their lifetime. We identified hotspots of songbird ownership in several provinces in Java, corroborating previous findings, and new ones in the North Sumatra province, for example. The provinces of Maluku, Aceh and East Nusa Tenggara had the highest numbers of reported shark consumers per 1,000 people. Responses indicated a wide variety of shark products being consumed, highlighting the need for in-depth research to understand the explanatory factors behind these practices. These findings demonstrate the potential of SMS surveys to be a cost-effective approach for conducting large-scale studies on wildlife consumption patterns over a short period of time.

Bioaccumulation of cd and hg in Muscle of Juvenile Pacific Sharpnose Shark Rhizoprionodon longurio from the SE Gulf of California.

In this study, the concentrations of Cd and Hg were measured in muscle of juvenile individuals at an importan fishing ground in southeastern Gulf of California to assess the health risk to human consumers considering elemental levels and rate of shark consumption in NW Mexico. Twenty-eight individuals were sampled in September 2019. Quantification of Hg was made by cold vapor-atomic absorption spectrophotometry, analyses of Cd were made by graphite furnace atomic absorption spectrophotometry. In general, average Hg (1.27µg g-1 dry weight) concentrations were higher than Cd (0.059). In comparison to results of Cd and Hg in muscle of several species of genus Rhizoprionodon sp., our reported concentrations were comparable. Maximum permissible limits (Cd 0.5 and Hg 0.5µg g-1 wet weight) in fish products for human consumption were not exceeded. Health risk assessment to shark consumers indicated that Hg is of more concern than Cd but no hazards exist.

Framing Effects on Attitudes and Intentions Toward Shark Meat Consumption in Lima, Peru

Peru has one of the major shark fisheries in the world. Moreover, shark meat consumption is popular and the main commercially exploited species are considered threatened. Recent studies have found high mislabeling rates and high concentrations of methylmercury in shark meat. The purpose of this study is to explore the effectiveness of different framing messages in persuading fish consumers to avoid shark meat consumption and promote sustainable fish (“popular fish”) consumption. Specifically: To what extent do intrinsic and extrinsic risk messages differ in terms of deterring the intention to eat shark meat and promoting the consumption of popular fish, in the presence or absence of an efficacy message about mislabeling of shark meat? The three message frames were: intrinsic (sharks have mercury), extrinsic (sharks are threatened), and efficacy (sharks are mislabeled). The experiment had a factorial design of 2 × 2 × 2 (present vs. absent for each message). Participants (n = 285), surveyed through an online questionnaire, were assigned to one of eight experimental conditions. Participants then completed a survey regarding their intentions and attitudes toward shark meat and popular fish consumption. Attitudes and intentions toward consuming shark meat were discouraged in all experimental conditions. Moreover, the mislabeling message did not reduce participants' perceived response efficacy (how effective the recommendations for dealing with the problem are), but enhanced it. This study suggests that not all consumers' attitudes about sharks are negative or that a negative attitude does not affect shark consumption in an adverse way. More research targeting different audiences is needed to determine the optimal approach for promoting sustainable seafood that is also healthy for consumers.

A Global Review of Cadmium, Mercury, and Selenium in Sharks: Geographical Patterns, Baseline Levels and Human Health Implications

Globally, there is concern about the concentrations of some metals and metalloids in sharks and the associated impacts to themselves and to human consumers. Concentrations of Hg, Cd, and Se reported in muscle, liver and fins of sharks from all the world were reviewed to define geographical patterns of elemental distribution, to model the baseline concentrations of the three elements, and to assess potential human health risk. Published information corresponded to 102 sites that belong to thirteen FAO Major Fishing Areas. The majority of the sites corresponded to the Atlantic (39 sites), followed by the Pacific Ocean (37). Statistical analysis indicated significant differences of elemental concentrations among all FAO regions and oceans. The 5% baseline levels, estimated with a cumulative frequency distribution method for each element were: for Hg, 0.129 μg g−1 in muscle, 0.147 μg g−1 in liver; for Cd, 0.517 μg g−1 in muscle, 0.290 μg g−1 in liver; for Se, 0.105 μg g−1 in muscle, 0.218 μg g−1 in liver. These baseline leves are equivalent to the 5th percentile on a normal distribution. Levels of Cd, Hg and Se in muscle of sharks were above maximum permissible limits (Cd, 0.5; Hg, 1.0; Se, 1.0 μg g−1; Nauen in FAO Fish Circ 764:1–102, 1983; CEC in Off J Eur Union 364:5–24, 2006) for human consumption in 6, 49 and 25% of the reports, respectively. Considering all the studies, hazard quotients (it indicates the risk during the lifetime of an individual different to cancer if value is above one) were Cd (0.10 ± 0.18), Se (0.11 ± 0.10) and Hg (2.05 ± 2.69); i.e. only average Hg values are of concern. The concentrations of Hg and Se in muscle of sharks from the Mediterranean were statistically different from all other oceans. In shark species with more reports, baseline levels (µg g−1 wet weight) of Hg in muscle were: for P. glauca from the Pacific Southeast (0.048), for I. oxyrinchus from the Pacific Southeast (0.034), and for S. lewini from the Pacific Eastern Central (0.55). The balance of Hg and Se molar concentrations (it is used to assess the benefit or risk to the combined occurrence of Hg and Se) in muscle of sharks was assessed through the Se health benefit value (HBVSe), positive results indicate that shark consumption is beneficial to humans. In general, HBVSe was positive (3.06 ± 13.84). According to FAO Fishing areas, negative HBVSe values corresponded to Mediterranean and Black Sea (− 48.37), Atlantic Northwest (− 5.54), Pacific Eastern Central (− 0.97), and Atlantic Southwest (− 0.21); nevertheless, HBVSe values in sharks from Mediterranean and Black Sea, and Atlantic Northwest corresponded to only one species. Overall, similar elemental concentrations were found in some FAO regions of the southern hemisphere. Baseline values of Hg were in the same magnitude order as the low atmospheric deposition flux. Under the approach of the hazard quotient, Hg is of concern because values were above one in almost half of the studies. More information related to Hg and Se in muscle of sharks is required in some FAO regions (Indian Ocean Eastern, Pacific Northeast and Pacific Southeast) to estimate HBVSe.

Mercury concentrations and trophic relations in sharks of the Pacific Ocean of Colombia

Sharks are fished for human consumption in Colombia, and fins are exported illegally to international markets. The goal was to identify differences in total mercury (THg) concentrations in fins and muscles of shark species seized in the Buenaventura port (Colombian Pacific), and to assess potential human health risks related to shark consumption. Seven species were considered in this study: Pelagic Thresher (Alopias pelagicus), Pacific Smalltail Shark (Carcharhinus cerdale), Brown Smoothhound (Mustelus henlei), Sicklefin Smoothhound (Mustelus lunulatus), Scalloped Bonnethead (Sphyrna corona), Scalloped Hammerhead (Sphyrna lewini), and Bonnethead Shark (Sphyrna tiburo), and THg was analyzed in shark tissues. 24% muscle samples concentrations were above international recommended limits for human consumption, especially for A. pelagicus and S. lewini. Stable isotopes (δ13C and δ15N) analysis showed a foraging overlapping in coastal habitats, where overfishing usually occurs. This study provides useful scientific information to develop management plans for sharks in Colombia and neighboring countries.

Concentrations and stable isotopes of mercury in sharks of the Galapagos Marine Reserve: Human health concerns and feeding patterns

The human ingestion of mercury (Hg) from sea food is of big concern worldwide due to adverse health effects, and more specifically if shark consumption constitutes a regular part of the human diet. In this study, the total mercury (THg) concentration in muscle tissue were determined in six sympatric shark species found in a fishing vessel seized in the Galapagos Marine Reserve in 2017. The THg concentrations in shark muscle samples (n = 73) varied from 0.73 mg kg-1 in bigeye thresher sharks (Alopias superciliosus) to 8.29 mg kg-1 in silky sharks (Carcharhinus falciformis). A typical pattern of Hg bioaccumulation was observed for all shark species, with significant correlation between THg concentration and shark size for bigeye thresher sharks, pelagic thresher sharks (Alopias pelagicus) and silky sharks. Regarding human health concerns, the THg mean concentration exceeded the maximum weekly intake fish serving in all the studied species. Mass-Dependent Fractionation (MDF, δ202Hg values) and Mass-Independent Fractionation (MIF, Δ199Hg values) of Hg in whitetip sharks (Carcharhinus longimanus) and silky sharks, ranged from 0.70‰ to 1.08‰, and from 1.97‰ to 2.89‰, respectively. These high values suggest that both species are feeding in the epipelagic zone (i.e. upper 200 m of the water column). While, blue sharks (Prionace glauca), scalloped hammerhead sharks (Shyrna lewini) and thresher sharks were characterized by lower Δ199Hg and δ202Hg values, indicating that these species may focus their foraging behavior on prey of mesopelagic zone (i.e. between 200 and 1000 m depth). In conclusion, the determination of THg concentration provides straight-forward evidence of the human health risks associated with shark consumption, while mercury isotopic compositions constitute a powerful tool to trace the foraging strategies of these marine predators. CapsuleA double approach combining Hg concentrations with stable isotopes ratios allowed to assess ontogeny in common shark species in the area of the Galapagos Marine Reserve and the human health risks concern associated to their consumption.

Would ending shark meat consumption in Australia contribute to the conservation of white sharks in South Africa?

South African white sharks have disappeared from one of the world's aggregation ‘hot spots’. This has led to speculation that unsustainable fishing of smaller shark species may have displaced white sharks by removing their primary food source. Most of the catch from these fisheries is exported to Australia to supply the domestic ‘fish and chips’ market so a link has been made between the disappearance of South Africa's white sharks and shark consumption in Australia. As cooked seafood is not properly labelled in Australia, consumers cannot readily distinguish between sustainable and non-sustainable seafood. Hence, a highly promoted campaign was recently initiated to encourage Australians to stop eating ‘fish and chips’ and as such save South Africa's white sharks. However, most of the consumed shark in Australia is sourced from sustainable domestic fisheries and encouraging Australian consumers to stop eating ‘fish and chips’ would not help South African white sharks as it would simply displace the issue. It would not address any South African sustainability concerns and would negatively impact a legitimate and sustainable Australian industry. Instead, we encourage the South African government to establish and enforce a governance system for sustainably managing sharks and the Australian government to legislate and enforce the accurate labelling of all types of seafood.

An evaluation of the public's Knowledge, Attitudes and Practices (KAP) in Trinidad and Tobago regarding sharks and shark consumption.

There is a global lack of data concerning shark consumption trends, consumer attitudes, and public knowledge regarding sharks. This is the case in Trinidad and Tobago, where shark is a popular culinary delicacy. A Knowledge, Attitudes, and Practices (KAP) survey was conducted in Trinidad and Tobago. Six hundred and seven questionnaires were administered. Univariate and stepwise multivariate logistic regressions were performed to test the association between KAP and demographic categories. The response rate was 93.4% with 567 questionnaires returned (473 from Trinidad and 94 from Tobago). Two hundred and seventeen (38.3%) participants were knowledgeable, 422 (74.4%) displayed attitudes in favour of shark conservation and sustainable use, and 270 (47.6%) displayed practices promoting shark conservation and sustainable use. Island (AOR = 2.81, CI = 1.78, 4.46) and tertiary education (AOR = 2.31, CI = 1.20, 4.46) significantly influenced knowledge level. Gender (AOR = 1.50, CI = 1.02, 2.20) and island (AOR = 0.56, CI = 0.35, 0.90) significantly influenced attitude. Gender (COR = 1.59, CI = 1.14, 2.22) was significantly associated with practices. Over 70% of respondents ate shark, and 54.7% ate shark infrequently enough to avoid risks from heavy metal toxicity. Our results may be useful to develop public awareness and practice improvement initiatives in order to improve KAP regarding shark meat consumption.

First concurrent assessment of elemental- and organic-contaminant loads in skin biopsies of whale sharks from Djibouti

The Gulf of Tadjoura (Djibouti) is an important site where the whale shark (Rhincodon typus Smith, 1828) aggregates seasonally. Because of the proximity to the port of Djibouti that is located along one of the busiest shipping areas in the world, whale sharks are potentially exposed to relatively high levels of trace elements and organochlorines. To assess their contamination status, concentrations of 15 trace elements, DDTs and PCBs were concurrently assessed for the first time in skin biopsies of 20 whale sharks. Additionally, 12 zooplankton samples were collected and analyzed for trace elements content. Concentration of As, Cu, Zn and Se were higher than in previous studies on this species. Whale shark samples exceeded the maximum allowable limits for foodstuffs for Cr, Pb Se, Cd and Zn. Results from this study suggests that Cr, Ni and Mo may biomagnify in this species. With regard to PCBs, the predominant congener were Tetra-CB, accounting for 41% of total PCBs and Penta-CB for 23%, while for DDTs, the predominant metabolite was DDE contributing for 51% of total compounds. The maximum residue limit for DDTs and for the ind-PCBs in fish set by U.S. EPA and by the EU regulation, respectively, was exceeded in 62% of whale sharks. Moreover, the p,p′DDE/ΣDDT ratios were higher than the critical value of 0.6, indicating possible recent inputs of technical DDTs in the area. This study suggests some concerns for the contamination status of whale sharks in Djibouti and, since major threats for this species include bycatch and illegal fisheries, highlights some level of risk from the exposure to elemental- and organic-contaminant via shark consumption.

Historical Shark Meat Consumption and Trade Trends in a Global Richness Hotspot

Shark catches have increased worldwide, threatening the survival of several species. This study describes historical trends concerning shark consumption and commercialization by artisanal fishers in northeastern Brazil. Semi-structured questionnaires were applied and respondents pointed out that sharks used to be locally regarded as low-quality fish in the past and rejected by fish consumers, with low fisher consumption frequency. However, this has changed in recent decades, as a total of 95.4% (n=62) of the questionnaire respondents reported currently consuming shark meat, while 61.5% (n=40) highlighted its high quality. In addition, most interviewees (90.8%; n=59) reported decreasing numbers of sharks caught over time, following worldwide trends, leading to decreased fisher access to shark meat. Because of this, most respondents (70.7%, n=46) now consider it more advantageous to sell the sharks they catch than to consume them. In addition, the local commercialization of these fish is currently based on immature coastal species (<1 m). Thus, economic and biological studies on local shark populations are suggested in order to preserve local fisher culture and ensure food security for artisanal fisher communities and a long-term sustainable fishery and conservation of exploited species.

Molecular Identification of Shark Meat From Local Markets in Southern Brazil Based on DNA Barcoding: Evidence for Mislabeling and Trade of Endangered Species.

Elasmobranchs, the group of cartilaginous fishes that include sharks and rays, are especially vulnerable to overfishing due to low fecundity and late sexual maturation. A significant number of elasmobranch species are currently overexploited or threatened by fisheries activities. Additionally, several recent reports have indicated that there has been a reduction in regional elasmobranch population sizes. Brazil is an important player in elasmobranch fisheries and one of the largest importers of shark meat. However, carcasses entering the shark meat market have usually had their fins and head removed, which poses a challenge to reliable species identification based on the morphology of captured individuals. This is further complicated by the fact that the internal Brazilian market trades several different elasmobranch species under a common popular name: “cação.” The use of such imprecise nomenclature, even among governmental agencies, is problematic for both controlling the negative effects of shark consumption and informing the consumer about the origins of the product. In this study, we used DNA barcoding (mtDNA, COI gene) to identify, at the species level, “cação” samples available in local markets from Southern Brazil. We collected 63 samples traded as “cação,” which we found to correspond to 20 different species. These included two teleost species: Xiphias gladius (n = 1) and Genidens barbus (n = 6), and 18 species from seven elasmobranch orders (Carcharhiniformes, n = 42; Squaliformes, n = 3; Squatiniformes, n = 2; Rhinopristiformes, n = 4; Myliobatiformes, n = 3; Rajiformes, n = 1; and Torpediniformes, n = 1). The most common species in our sample were Prionace glauca (n = 15) and Sphyrna lewini (n = 14), while all other species were represented by four samples or less. Considering IUCN criteria, 47% of the elasmobranch species found are threatened at the global level, while 53% are threatened and 47% are critically endangered in Brazil. These results underline that labeling the meat of any shark species as “cação” is problematic for monitoring catch allocations from the fishing industry and discourages consumer engagement in conservationist practices through informed decision-making.

The associations between blood mercury levels and shark meat intake among workers in Gyeongsangbuk-do

BackgroundShark meat is used as sacrificial food in Gyeongsangbuk-do, and is a major source of dietary mercury. This study aimed to evaluate the effects of shark meat intake or the ritual of Jesa on blood mercury levels within workers living in Gyeongsangbuk-do.MethodsThis study was conducted from September 2016 to October 2016 in two cities of Gyeongsangbuk-do. To compare the differences between urban and rural areas, two workplaces each in Daegu as the urban area and Yeongcheon as the rural area were selected. General characteristics and characteristics related to shark meat consumption of the workers were acquired by personal interviews during their health examination. Blood mercury concentrations were analyzed by the gold amalgamation method using a direct mercury analyzer (DMA-80; Milestone Inc., Shelton, CT, USA).ResultsThe shark consumption group had a higher blood mercury concentration than the non-consumption group. The levels of blood mercury increased with the frequency, annual intake, as well as most recent date of shark meat consumption. Moreover, the levels of mercury in blood increased according to the annual frequency of participation in Jesa (times per year) and the annual frequency of shark meat consumption during Jesa (times per year).ConclusionsShark meat intake and the ritual of Jesa contributed to an increase in the blood mercury levels of workers in Gyeongsangbuk-do. Therefore, it is necessary to evaluate dietary exposure, occupational as well as other factors that may influence blood mercury concentrations in workers during their health examination, particularly in regions with high mercury exposures.

Trace element concentrations in muscle tissue of milk shark, (Rhizoprionodon acutus) from the Persian Gulf

We analyze the heavy metals concentrations in muscle samples of milk shark (Rhizoprionodon acutus) from Persian Gulf. The metals distribution was Zn>Cu>Pb>Cd>Hg. No statistical differences were observed among size or weight by sex (p<0.05). Metals concentrations in the population de R. acutus from Larak and Lavan islands are homogeneous along the coastal study area. Our study suggest that the results reflect the natural contents of trace metals in this species, and the health risk associated to milk shark consumption in Persian Gulf is relatively low.

Influence of bioaccessibility of total mercury, methyl-mercury and selenium on the risk/benefit associated to the consumption of raw and cooked blue shark (Prionace glauca)

This study aimed to identify the benefit and risk associated with raw and cooked blue shark consumption taking into account the bioaccessibility of Se, Hg and MeHg, by using in vitro digestion method. Selenium, Hg and MeHg levels were higher in cooked samples, particularly in grilled blue shark. Whereas Se bioaccessibility was above 83% in grilled samples, Hg and MeHg bioaccessibility was lower in grilled samples with values near 50%. In addition, all Se-Health Beneficial Values were negative and the molar MeHg:Se ratios were higher than one. The risk-benefit assessment yielded a maximum consumption of one yearly meal for raw or cooked blue shark, thus emphasizing the need to recommend the consumption of a wider variety of seafood species in a balanced and healthy diet.