Does lack of knowledge lead to misperceptions? Disentangling the factors modulating public knowledge about and perceptions towards sharks

Identifying sources of variability in public perceptions and attitudes toward sharks can assist managers and conservationists with developing effective strategies to raise awareness and support for the conservation of threatened shark species. This study examined the effect of several demographic, economic and socioenvironmental factors on the quality of knowledge about and perceptions toward sharks in two contrasting scenarios from northeastern Brazil: a shark hazardous coastal region and a marine protected insular area. Ordered logistic regression models were built using Likert data collected with a self-administered questionnaire survey (N = 1094). A clear relationship between education, knowledge and perceptions was found, with low education level and knowledge of sharks resulting in more negative perceptions toward these species. Prejudice toward sharks stemmed as a potentially limiting factor because the positive effects of other variables such as affinity for nature and specific knowledge about sharks were superseded by the effects of negative prejudice. Other practical factors such as age, economic level, and gender, also influenced respondent’s knowledge and perceptions and could provide a guidance for optimizing socioenvironmental gains relative to public engagement efforts. Results also suggested that populations inhabiting regions with high shark bite incidence likely require distinct outreach methods because some factors underlying knowledge and perception dynamics exhibited structural differences in their effects when compared to the trends observed in a marine protected area. Altogether, public perceptions and attitudes toward sharks could be feasibly enhanced with educational development and nature experiencing strategies. Moreover, disseminating shark-specific knowledge across the society might catalyze support for the conservation of these species in a cost-effective way. This study provides a Frontiers in potentially useful socioenvironmental framework to deal with the human dimensions of shark management and to strengthen conservation policies aimed at promoting societal compliance with pro-environmental values, which is crucial to endow shark populations with effective protection from anthropogenic threats.info:eu-repo/semantics/publishedVersio

Trophic-mediated pelagic habitat structuring and partitioning by sympatric elasmobranchs

Funding provided by the TRIATLAS project through the European Union’s Horizon 2020 Research and Innovation Programme (grant No. 817578), the Conselho Nacional de Desenvolvimento Cientı́fico e Tecnológico - CNPq (478070/2008-0, 482557/2011-7), the Fundação Grupo Boticário (0760/2007.2), the Save Our Seas Foundation (66/2008), and the Fundação para a Ciência e Tecnologia – FCT (UIDB/04292/2020; UIDP/04292/2020), is deeply acknowledged. Scholarships granted by the FACEPE foundation to NPAB and by CNPq to BCLM (140567/2012-7) are also acknowledged. We acknowledge the Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio), the Brazilian Navy (SECIRM) and the Conselho Nacional de Desenvolvimento Cientı́fico e Tecnológico (CNPq) through the Pró-Arquipélago Program (557183/2009-0; 562062/20102-6; 405460/2012-0; 442884/2015-0) for providing precious logistic support.Pelagic elasmobranchs are key elements of oceanic ecosystems and must be preserved if marine trophic networks are to be kept in balance. Yet, they face intense fishing pressure that has been threatening their populations worldwide. Ensuring proper conservation management of these taxa depends on a better understanding of the strategies they use to explore the pelagic realm and their contributions to trophic web structuring across the ocean column. This study aimed at examining relationships between vertical habitat use and trophic attributes among six sympatric pelagic elasmobranchs using satellite transmitting tags in the western equatorial South Atlantic Ocean. The vertical movements of 35 elasmobranch individuals were tracked during an overall total of 1911 days. Clear relationships between species’ feeding habits, maximum diving depths, and proportion of time spent either in epipelagic or in surface waters were evidenced by Bayesian generalized linear mixed models and multivariate analysis. Filter-feeders made most use of deep waters from the mesopelagic and bathypelagic and shifted their diving depths in phase with diel vertical migrations of the deep scattering layer, i.e., shallower during the night and deeper during the day. Specialists exhibited distinct diving patterns in epipelagic and mesopelagic waters across the diel period which are potentially indicative of habitat partitioning, whereas generalists were more surface-oriented but also explored deeper waters compared to specialists. The trophic level also seemed to influence elasmobranch maximum diving depths, which tended to become shallower as species’ trophic level increased. These results corroborate previous evidence of widespread vertical habitat partitioning among sympatric pelagic predators and depict a trophicmediated structuring of the pelagic environment where top-down control may be exerted at different depths by distinct species. Further research is yet required to understand the role of elasmobranch vertical movements in structuring pelagic habitats as well as to guide ecosystem-based fisheries management aimed at reducing species susceptibility to fishing gear and at preserving the structure and functionality of marine trophic networks.info:eu-repo/semantics/publishedVersio

Reply to: Shark mortality cannot be assessed by fishery overlap alone

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Reply to: Caution over the use of ecological big data for conservation

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Reproductive aspects of the oceanic whitetip shark, Carcharhinus longimanus (Elasmobranchii: Carcharhinidae), in the equatorial and southwestern Atlantic Ocean

The present study sought to study the reproductive biology of the oceanic whitetip shark, Carcharhinus longimanus, in the equatorial and southwestern Atlantic Ocean. A total of 234 specimens were collected as bycatch during pelagic longline fisheries targeting tunas and swordfish, between December 2003 and December 2010. The fishing area was located between latitudes 10N and 35S and longitudes 3E and 40W. Of the 234 individuals sampled, 118 were females (with sizes ranging from 81 to 227 cm TL, total length) and 116 males (ranging from 80 to 242 cm TL). The reproductive stages of the females were classed as immature, mature, preovulatory and pregnant, while males were divided into immature, maturing and mature. The size at maturity for females was estimated at 170.0 cm TL, while that for males was between 170.0 and 190.0 cm TL. Ovarian fecundity ranged from 1 to 10 follicles and uterine fecundity from 1 to 10 embryos. The reproductive cycle of this species is most likely biennial, with parturition occurring once every two years.info:eu-repo/semantics/publishedVersio

The effect of light attractor color in pelagic longline fisheries

Improving the selectivity of the fishing gear is one of the most promising methods to mitigate deleterious impacts of longline fisheries upon bycatch species. Light lures have recently become widespread in epipelagic longline fisheries since they increase the catch rates of valuable target species such as swordfish and tunas. Yet, little is known about their effect upon the incidence of bycatch. Here, we compared the catchability of target and bycatch species in a pelagic longline fishery targeting swordfish and tunas equipped with light attractors with three different colors to ascertain if any of the light attractor colors would enhance the selectivity of the fishing gear. A total of 3488 individuals were caught across 57 fishing sets. The proportion of target species to bycatch species was high (58–65 %) in each color treatment. Overall, green attractors (peak wavelength at 525 nm) exhibited the highest catch rates of target species, but they were also responsible for the highest incidence of bycatch, rendering 73 % and 82 % of the blue shark and sea turtle catch, respectively. Blue (peak wavelength at 465 nm) and white attractors caught significantly less individuals of both target and bycatch species. Further, significant interactions between light attractor color and the intensity of lunar illumination were observed for most species analyzed. Differences in the catchability of bycatch such as blue sharks and white marlins across attractor color treatments were more conspicuous at high lunar illumination levels (i.e. full moon periods), when white attractors rendered the lowest catch of these taxa. In contrast, the catchability of target species such as swordfish, yellowfin tuna and albacore showed greater differences between treatments at low illumination levels (i.e. new moon periods). The observed differences in the performance of the three light attractor colors across the lunar cycle might provide an opportunity to mitigate bycatch incidence in longline fisheries. Yet, further research is required to fully understand the combined effects of light lures and lunar illumination on the behavioral responses of pelagic species.info:eu-repo/semantics/publishedVersio

Catch rates and size composition of blue sharks (

Distribution and relative abundance of blue sharks (Prionace glauca) in the southwestern Atlantic Ocean was modeled based on catch-per-unit-effort (CPUE) per 1000 hooks and length frequencies of blue sharks caught by the Brazilian pelagic tuna longline fleet. As a measure of relative abundance, CPUE of blue sharks caught in 58 238 fishing sets by the Brazilian pelagic tuna longline fleet (national and chartered), from 1978 to 2009, was standardized by a Generalized Linear Model (GLM) using three different approaches: i) a negative binomial error structure (log link); ii) the traditional delta lognormal model; and iii) the Tweedie distribution, recently proposed to adjust models with a high proportion of zeros. A cluster analysis using the K-means method was used to identify target species and incorporate it as a factor into the GLM. Cluster analysis grouped the data into six different fishing clusters according to the percentage of target species. Target factor (cluster) was the most important factor explaining the variance in all three CPUE models. The Tweedie model showed a relatively better fit compared to the other models. Blue shark nominal and standardized CPUE showed a relatively stable trend from 1978 to 1995. From 1995 onwards, however, there was an increasing trend in the standardized CPUE, up to a maximum value in 2008. In general, nominal CPUE and standardized CPUE tracked well up until 2000, after which standardized CPUE’s values were at a noticeably lower level than nominal CPUE. Length frequency data were analyzed for 11 932 blue sharks measured as part of the Brazilian onboard observer program operating on the pelagic tuna longline fleet between 2006 and 2008, with sizes ranging from 91 to 224 cm fork length. Overall, blue shark size data showed clear spatial and seasonal distributions for males and females in the southwestern Atlantic Ocean, with juveniles predominantly concentrated in the most southerly latitudes

Population genetics reveals global and regional history of the apex predator Galeocerdo cuvier (carcharhiniformes) with comments on mitigating shark attacks in north-eastern Brazil

The knowledge of the population structure of a given species is of great importance for its conservation and for the management of its fishing exploitation, especially for sharks. The tiger shark (Galeocerdo cuvier Péron&Lesueur, 1822) is an apex predator species that is currently listed as “Near Threatened” on the International Union for the Conservation of Nature's (IUCN) Red List of Threatened Species. In this study, the tiger shark's genetic structure in the Metropolitan Region of Recife (MRR) and oceanic archipelago of Fernando de Noronha (FN) was investigated based on one mitochondrial and two nuclear DNA markers. In addition, sequenced data from other geographic sites were added into the mitochondrial analysis. The data showed moderate-to-high genetic diversity, and it is consistent with good resilience of G. cuvier in ecological terms. The structuring tests reinforced a global distinction of the species in two lineages, one being from the Indo-Pacific and the other from the North Atlantic. Also, this analysis showed the close relationship between tiger sharks from Indo-Pacific and South-eastern coast of Brazil. The Bayesian and AMOVA tests indicated that tiger sharks from FN and MRR are genetically similar, forming a cohesive population. These analyses support live specimen translocations from beaches (where the attacks occur) to distant marine areas given we detected a historical cohesive population occurring between those beaches from MRR and FN Islands where the sharks migrate. This research is the first that has validated individual translocations as a green strategy in South-western Atlantic.info:eu-repo/semantics/publishedVersio

Public support for conservation may decay with increasing residence time in suboptimal marine protected areas

Marine Protected Areas (MPAs) are potentially effective conservation and management instruments yet they often produce socioeconomic conflicts which may challenge their success. Knowledge and perceptions about environmental subjects among MPA residents were examined to identify possible effects of conservation policies upon local communities. Sharks were used as a proxy for wildlife given their local relevance and socioenvironmental context. Self-administered questionnaires were used to collect data from 134 randomly-selected residents of Fernando de Noronha (FEN), Brazil. Affinity towards nature tended to decrease among people>44 years old, whereas>10 years residents were more associated with negative feelings about sharks. Homogeneity in knowledge was noticed but perceptions decreased conspicuously across residence time-classes. Only 33% of respondents reported unarguable MPA benefits to local welfare, while several problems pertaining to infrastructure, management and resources were mentioned. These results are worrisome because they might translate into growing frustration along with residence time, which could potentially jeopardize the success of conservation policies. Wildlife conservation and at least partial improvements to welfare being positively signalized by a relevant proportion of respondents suggest an encouraging potential for relationship improvement between MPAs and stakeholders. Nonetheless, the long-term sustainability of inhabited MPAs could depend on properly integrating human users and ensuring their support and compliance, which must be considered while designing management strategies. Given the prestige of FEN in the South Atlantic and worldwide, it is important that this MPA delivers successful, sustainable outcomes that can be representative of efficient conservation trajectories to be replicated elsewhere.info:eu-repo/semantics/publishedVersio