Search

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understanding their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Significant vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps towards incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasising the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements

Fish movements are fundamental to their ecology and survival. Understanding the causes and consequences of the spatial behaviour of fish is of high relevance as it provides critical knowledge for conservation purposes. Skate (Rajidae) populations face an unprecedented global decline due to overfishing. In this study, we used acoustic telemetry to track the movements of nine individuals of the near threatened thornback skate (Raja clavata) around the Cíes Islands, a small marine protected area in the northwest of the Iberian Peninsula. Our results demonstrate the significant impacts of biotic and abiotic drivers on the spatial behaviour of R. clavata. Overall residency inside the study array was low (0.073), differed between sexes (higher for females) and over the course of the year (peaking in summer). The analysis of the direction of the excursions performed by R. clavata individuals revealed high consistency in the exit and entry areas and a strong connectivity with inshore waters connecting with the Ría de Vigo, as compared with offshore waters connecting with the open ocean. Finally, the activity space of R. clavata also varied over the time of the year with a peak in summer. This study provides an important baseline information for understanding the spatial behaviour of R. clavata that can serve as a starting point for planning future conservation actions or studies

Understanding population dynamics, movements, and fishing mortality is critical to establish effective shark conservation measures across international boundaries in the ocean. There are few survival and dispersal estimates of juveniles of oceanic shark species in the North Atlantic despite it being one of the most fished regions in the world. Here we provide estimates of dispersal, survival, and proportion of fishing mortality in the North Atlantic for two threatened oceanic sharks: the blue shark (Prionace glauca) and the shortfin mako shark (Isurus oxyrinchus). Our results are based on multi-event models applied to tag-recovery data of 700 blue sharks and 132 shortfin makos tagged over a decade. A total of 60 blue sharks (8.57% of tagged) and 30 makos (22.73%) were recovered by the longline fishery between 2009 and 2017. Tag-reporting rate (percentage of returned information when a tagged shark was caught) was estimated to be high (0.794 ± 0.232 SE). Mean annual survival, as predicted from the models, was higher for blue shark (0.835 ± 0.040 SE) than for shortfin mako (0.618 ± 0.189 SE). Models predicted that fishing caused more than a half of total mortality in the study area for both species (0.576 ± 0.209), and more than a third of tagged individuals dispersed from the study area permanently (0.359 ± 0.073). Our findings, focused mainly on juveniles from oceanic areas, contribute to a better understanding of shark population dynamics in the North Atlantic and highlight the need for further conservation measures for both blue shark and shortfin mako, such as implementing efficient bycatch mitigation measures and static/dynamic time–area closures in the open ocean

Individual variation in almost any trait is a common feature of aquatic species. Despite being crucial to understand both ecological (e.g. demographic change) and evolutionary processes (e.g. fishing-induced evolution), individual variation in behavior remains understudied, and often overlooked in fish conservation and ecology studies. Here, we investigated the existence and covariation of spatial behavioral traits at multiple levels within a population of the endangered undulate skate, Raja undulata, in a small marine protected area in Galicia, NW Spain. We used tracking data of 197 individuals across four years to explore long-term movement strategies (e.g. seasonal residents, continuous residents and individuals expressing site fidelity) based on presence/absence patterns in the study area, and fine-scale behavioral patterns (e.g. activity, space use) based on high-resolution positions. Then, we used Bayesian multivariate mixed-effects models to investigate consistency at the individual level in spatial behavior, and covariation between long-term movement strategies and short term behavioral traits. We show that multiple movement strategies coexist in the studied population. In our preliminary analysis, 45.5% of individuals were seasonal residents, followed by individuals expressing site fidelity, and thus returning to the site after an extended absence (28.9%). Continuous residents were the least common (25.6%). Furthermore, we found consistent individual variation in fine-scale spatial behavior which reinforces the idea that individual variation in behavior may be common in aquatic species. Our results suggest that in order to enhance the resilience of the species, the conservation of different behavioral types should be taken into account when designing and managing marine protected areas

Shark populations have suffered dramatic declines across the world as a result of overfishing. Marine protected areas (MPAs) can help restore overfished populations; however, their effectiveness largely relies on understanding the ecology of the targeted species. This study investigated the spatial ecology of the intensely harvested but understudied small spotted catshark (Scyliorhinus canicula) through acoustic telemetry in the Cíes Islands, a small MPA in the north-west of the Iberian Peninsula. There were significant effects of diel, seasonal cycles, biotic (sex and total length) and abiotic (bottom sea temperature) variables on the spatial behaviour of S. canicula. The mean residency index was low (0.27) and movement patterns suggested a strong connection with inshore waters. While the probability of presence in the study area was mainly driven by sex (i.e. greater for females), a drastic increase in activity was observed at night (compared with daytime hours). The activity space decreased with larger body sizes. Warmer waters were related to higher activity levels and larger activity spaces. This study provides essential knowledge of the spatial behaviour of S. canicula, with significant implications for the conservation and management of this species. The results indicate that small MPAs may fail to protect the whole range of movements of S. canicula, but suggest a larger protection potential for females. To be effective for S. canicula conservation, MPAs should be appropriately sized and designed for the ranging behaviour of the target species in order to provide total protection. Temporal restrictions on fishing at night mirroring the peak activity pattern of S. canicula could be implemented to limit the probability of its capture

The smalltooth sand tiger shark Odontaspis ferox (Risso, 1810) appears to have an extensive and fragmented distribution in tropical and warm-temperate worldwide oceans. One female of O. ferox was caught and released by a small-scale fishery vessel in Ría de Arousa (Northwest of Spain), subsequently stranded still alive on the coast (42°33’18.4"N 8°49’18.3"O) after a few hours. The individual (336 cm total length, weight ~ 300 kg) was identified based on a collection of features including the characteristic dentition, body morphology and by molecular assignment. This is the first confirmed record of O. ferox in Galician waters. This finding complements the knowledge of the geographic distribution and occurrence of this rare and sparse species in the Northeastern Atlantic

Shark populations have suffered dramatic declines across the world as a result of overfish- ing. Marine protected areas (MPAs) can help restore overfished populations; however, their effectiveness largely relies on understanding the ecology of the targeted species. This study investigated the spatial ecology of the intensely harvested but understudied small spotted cat- shark (Scyliorhinus canicula) through acoustic telemetry in the C´ıes Islands, a small MPA in the northwest of the Iberian Peninsula. There were significant effects of diel, seasonal cycles, biotic (sex and total length) and abiotic (bottom sea temperature) variables on the spatial ecology of S. canicula. The mean residency index was low (0.27) and movement patterns suggested a strong connection with inshore waters. While the probability of presence in the study area was mainly driven by sex (i.e. greater for females), a drastic increase in activity was observed at night (compared to day hours). Activity space decreased with larger body sizes. Warmer waters were related to higher activity levels and larger activity spaces. This study offers an essential foundation for comprehending key aspects of the behaviour of S. canicula, with significant im- plications for the conservation and management of this species. The present findings suggest the failure of small MPAs to efficiently protect the whole range of movements of S. canicula, however, they show their ability to offer protection for part of the population (i.e. females). Finally, this work reveals temporal instances when S. canicula are at its maximum vulnerability and the conservation benefits that this species could gain from the implementation of temporal fishing restrictions. To be effective for S. canicula conservation, MPAs should be appropriately sized and designed for the ranging behaviour of the target species for total protection. Temporal restrictions of fishing at night time mirroring the peak activity pattern of S. canicula could be i

Understanding functional connectivity of threatened species must provide critical information for an effective management and conservation spatial planning. In this study, we use a non-lethal novel combination of acoustic telemetry and stable isotope analysis (SIA) on a “Near threatened” elasmobranch, Raja undulata, to test that the isotopic niche width is dependent of behavioural patterns in relation to the space use within a marine protected area. Acoustic telemetry records of a local population of R. undulata within waters of a national park in NW Spain revealed a seasonal aggregation during summer. Yet, our results also evidenced that up to 32.65% of the studied individuals can be classified as resident based on their residency patterns. Resident skates showed narrower isotopic niche width than seasonal summer visitors, as these individuals were likely exposed to a limited variety of habitats and resources. Conversely, seasonal visitors showed wider isotopic niche widths, where females have larger isotopic niches, indicative of greater diversity of resources use from different environments. Therefore, we hypothesize that seasonal visitors play an important role connecting different habitats, and even populations, along the coast particularly through dispersing patterns of females. This study provides valuable insights into the spatial and resource ecology of Raja undulata and their role in the functional connectivity of the coastal ecosystem, key information for the management of marine protected areas

[EN] In the present work, key aspects of the biology and ecology of the shortfin mako were studied. Feeding habits, analysed in two ocean basins, indicated that pelagic fish and cephalopods were the main prey items. In the South Pacific Ocean, a marked sexual segregation was found, with females being more common in the SE region; this was also the area with a higher abundance of juveniles and of late-stage pregnant females. In the North Atlantic Ocean, large-scale horizontal movements (including trans-Atlantic migrations) were identified and diel vertical behaviour patterns described. Importantly, individuals that performed wider movements away from the tagging location were less at risk from surface longline fishing. Using tagging and recapture data that spanned a ten-year period, survival, dispersal, and fishing mortality rates for both mako and blue sharks were estimated. The presence of plastics and hooks was also observed for both species, in two studied ocean basins. Finally, bycatch rates for other internationally protected shark species that are commonly caught using surface longlines was estimated based on direct observations, which were several times higher than the official reported data. The results presented here are especially relevant for improving the management measures focused on pelagic sharks, [ES] En el presente trabajo se estudiaron diferentes aspectos importantes de la biología y ecología del marrajo azul. Los hábitos alimentarios analizados en dos cuencas oceánicas indicaron que los peces y los cefalópodos pelágicos fueron las presas mayoritarias. Se constató una marcada segregación sexual en el Pacífico, además de un área de agrupación de juveniles hacia la que parecen viajar las hembras preñadas. En el Atlántico se identificaron los movimientos horizontales a gran escala y se estudió el comportamiento vertical diario, observando que aquellos ejemplares que realizan mayores desplazamientos están en un menor riesgo frente a la pesca industrial. Se estimaron, gracias al marcado y recaptura de diez años, tasas supervivencia, dispersión y mortalidad por pesca tanto de marrajos como la especie acompañante, la tintorera. La presencia de plásticos y anzuelos viejos fue constatada para ambas especies, en dos océanos estudiados. Finalmente, la captura incidental de otras especies de tiburones protegidos internacionalmente que acompañan a esta especie en la pesquería, fue extrapolada en base a observaciones directas, llegando a estimaciones de descarte que son varias decenas de veces los datos oficiales reportados. Los resultados aquí expuestos son especialmente relevantes para la optimización de los sistemas de gestión enfocados al marrajo azul y otras especies de tiburones oceánicos

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements. Vertical habitat use by sharks, rays, and skates varies globally and has implications for their conservation and management.

The Iberian hare (Lepus granatensis Rosenhauer, 1856) has the western distribution limit in the south of the dorsal galega. This work provides new data on the status of the species over 16 years of sampling. Indices of relative abundance of Iberian hare were determined in the dorsal galega through night censuses carried out in each season. During the years 2006-2020, a total of 2,500 km was gone down along forest tracks in the Suido and Faro de Avión mountain ranges, spread over 196 days. The relative abundance for the hare ranged between 0.07 and 0.30 ind/km for the Faro de Avión with an average of 0.18 ± 0.06 ind/km, and between 0.02 and 0.22 ind/km for the Suido, with an average of 0.07 ± 0.06 ind/km. The monitoring along the years of the studied population supports scientific decision-making for conservation and hunting management purposes., La liebre ibérica (Lepus granatensis Rosenhauer, 1856) tiene su límite de distribución occidental al sur de la dorsal galega. En el presente trabajo se aportan nuevos datos sobre la situación de esta especie tras 16 años de muestreos. Se calcularon los índices de abundancia relativa de liebre ibérica en la dorsal galega mediante censos nocturnos realizados estacionalmente. En los años 2006-2020 se recorrieron un total de 2.500 km por pistas forestales en las sierras de Suído y Faro de Avión, con un total de 196 jornadas de trabajo. La abundancia relativa de liebre ibérica osciló entre 0,07 y 0,30 ind/km para Faro de Avión, con una media de 0,18 ± 0,06 ind/km, y entre 0,02 y 0,22 ind/km para Suído con una media de 0,07 ± 0,06 ind/km. El trabajo realizado ha permitido el seguimiento continuo de la población de liebres durante estos años, lo que facilitará la toma de decisiones eficientes en cuanto a su conservación y gestión.

Discard reduction is a cornerstone of the European Common Fisheries Policy. The discard ban policy, which aims to reduce fisheries discards, is particularly challenging for small-scale fisheries. Demonstrating high survival rates of discarded individuals may provide flexibility to the application of the discard ban through the so-called survival exemption. Here we used acoustic telemetry and mark-recapture data to estimate discard survival of coastal elasmobranch species at multiple temporal scales. We focused on four species targeted by the small-scale fishery in Galicia (NW Spain), one of the most important fishing regions in Europe: Scyliorhinus canicula, Raja undulata, Raja clavata and Raja brachyura. The overall survival rate was 90% on the short term and 85.7% on the long term, but it varied among species. Survival rates of R. clavata and S. canicula on the short term were 70% and 100%, respectively, and 66.7% and 92.9% on the long term, respectively. All the individuals of R. brachyura and R. undulata survived on the long term. Our results are critical to support the application of survival exemption in small scale fisheries

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements

Global abundances of oceanic pelagic sharks have declined due to overfishing. Internationally protected shark species remain at risk due to indiscriminate bycatch in longline fisheries with under-reported catches affecting reliability of population assessments for management. However, the scale of under-reporting remains poorly understood. Here we use detailed shark species catch data in a global fishing hotspot to show that the discards of three globally or regionally ‘Endangered’ or ‘Critically Endangered’ species (bigeye thresher Alopias superciliosus; oceanic whitetip Carcharhinus longimanus; smooth hammerhead Sphyrna zygaena) are potentially under-reported on a large scale: the total discards made by a single observed vessel in April–June 2018 in the eastern tropical Atlantic exceeded by 1.3–11.0 times the discards reported officially for these species Atlantic-wide for all of 2018. Scaling up observed catches (discards) of a single vessel to potential discards made by a single nation's fleet in the region, we estimate a mean annual total of 1526.2 t (±1 S.D. range: 415.3–2637.0 t), which exceeds by 89.2 times (±1 S.D. range: 24.3–154.2 times) the official reported discards for these three species. Without reducing bycatch mortality, which at present appears obscured by substantial under-reporting, Atlantic populations remain at serious risk

The site fidelity of ballan wrasse Labrus bergylta was studied using photo‐identification and external tagging. Five male individuals were observed to defend the same small territory composed of a few rocks during several reproductive seasons spanning 2 to 15 years. These results provide one of the strongest indications of long‐term very fine‐scale site fidelity in marine fishes

The global lockdown to mitigate COVID-19 pandemic health risks has altered human interactions with nature. Here, we report immediate impacts of changes in human activities on wildlife and environmental threats during the early lockdown months of 2020, based on 877 qualitative reports and 332 quantitative assessments from 89 different studies. Hundreds of reports of unusual species observations from around the world suggest that animals quickly responded to the reductions in human presence. However, negative effects of lockdown on conservation also emerged, as confinement resulted in some park officials being unable to perform conservation, restoration and enforcement tasks, resulting in local increases in illegal activities such as hunting. Overall, there is a complex mixture of positive and negative effects of the pandemic lockdown on nature, all of which have the potential to lead to cascading responses which in turn impact wildlife and nature conservation. While the net effect of the lockdown will need to be assessed over years as data becomes available and persistent effects emerge, immediate responses were detected across the world. Thus, initial qualitative and quantitative data arising from this serendipitous global quasi-experimental perturbation highlights the dual role that humans play in threatening and protecting species and ecosystems. Pathways to favorably tilt this delicate balance include reducing impacts and increasing conservation effectiveness.

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Magozzi, S., Thorrold, S. R., Houghton, L., Bendall, V. A., Hetherington, S., Mucientes, G., Natanson, L. J., Queiroz, N., Santos, M. N., & Trueman, C. N. Compound-specific stable isotope analysis of amino acids in pelagic shark vertebrae reveals baseline, trophic, and physiological effects on bulk protein isotope records. Frontiers in Marine Science, 8, (2021): 673016, https://doi.org/10.3389/fmars.2021.673016., Variations in stable carbon and nitrogen isotope compositions in incremental tissues of pelagic sharks can be used to infer aspects of their spatial and trophic ecology across life-histories. Interpretations from bulk tissue isotopic compositions are complicated, however, because multiple processes influence these values, including variations in primary producer isotope ratios and consumer diets and physiological processing of metabolites. Here we challenge inferences about shark tropho-spatial ecology drawn from bulk tissue isotope data using data for amino acids. Stable isotope compositions of individual amino acids can partition the isotopic variance in bulk tissue into components associated with primary production on the one hand, and diet and physiology on the other. The carbon framework of essential amino acids (EAAs) can be synthesised de novo only by plants, fungi and bacteria and must be acquired by consumers through the diet. Consequently, the carbon isotopic composition of EAAs in consumers reflects that of primary producers in the location of feeding, whereas that of non-essential amino acids (non-EAAs) is additionally influenced by trophic fractionation and isotope dynamics of metabolic processing. We determined isotope chronologies from vertebrae of individual blue sharks and porbeagles from the North Atlantic. We measured carbon and nitrogen isotope compositions in bulk collagen and carbon isotope compositions of amino acids. Despite variability among individuals, common ontogenetic patterns in bulk isotope compositions were seen in both species. However, while life-history movement inferences from bulk analyses for blue sharks were supported by carbon isotope data from essential amino acids, inferences for porbeagles were not, implying that the observed trends in bulk protein isotope compositions in porbeagles have a trophic or physiological explanation, or are suprious effects. We explored variations in carbon isotope compositions of non-essential a, The internship of SM at the Woods Hole Oceanographic Institution was funded by the School of Ocean and Earth Science at University of Southampton. Stable isotope analyses were paid by CT and ST research budgets and SM Ph.D. and placement funding.

Spatial ecology and behaviour of a species are essential to assess its vulnerability to environmental and anthropogenic stressors and consequently to develop eJcient management strategies. Elasmobranchs, as k-strategy species, are particularly vulnerable to exploitation, especially in coastal areas where they are subject to a broad range of anthropogenic stressors. It has been shown that species-speciOc knowledge is crucial to successfully implement conservation and management measures, especially for species that are subject to overexploitation and where rapidly changing environmental conditions present an additional challenge. Yet, species-speciOc conservation management has proven to be challenging, due to insuJcient information on their biology and ecology. In our study we used a VPS acoustic telemetry array to identify biological drivers for presence, space use and activity of the endangered undulate skate, Raja undulata, within a marine protected area (MPA) in the southern Galician coast (NW Spain) and to assess the effect of temperature on their movement and behaviour. Movement and behaviour were mainly driven by diel and seasonal patterns. Skates used more space and were more active during night-time as compared to daytime. Their presence in the study area peaked during summer and sea temperature had only a negligible effect on activity. Our work represents an important contribution to the understanding of the ecology of this endangered, yet commercially important elasmobranch species in Europe and provides insights for management and conservation strategies.