The influence of repressive legislation on the structure of a social media network

Social media have been widely used to organize citizen movements. In 2012, 75% university and college students in Quebec, Canada, participated in mass protests against an increase in tuition fees, mainly organized using social media. To reduce public disruption, the government introduced special legislation designed to impede protest organization. Here, we show that the legislation changed the behaviour of social media users but not the overall structure of their social network on Twitter. Thus, users were still able to spread information to efficiently organize demonstrations using their social network. This natural experiment shows the power of social media in political mobilization, as well as behavioural flexibility in information flow over a large number of individuals.Comment: 4 pages, 4 figures, submitted to EP

Computer-Assisted Photo-Identification of Narwhals

Although the narwhal (Monodon monoceros) is economically and culturally important to northern residents, sound management of this species is impaired by large gaps in knowledge. Research on this species has been limited partly by the cost of the methods used, and partly because some of these methods are invasive and therefore condemned by Inuit communities. Photo-identification, a non-invasive, inexpensive, and easy-to-use method recently developed for narwhals, uses photographs of natural marks to identify individuals. Its main drawback is the extended time required to process photographs. We developed a computer program to accelerate the identification process and thus mitigate the main drawback of photo-identification. This program uses the locations of notches on the dorsal ridge to compare a new image to each individual in a catalogue and lists those individuals in decreasing order of similarity. We tested consistency in user assignment of dorsal ridge features and the accuracy of the program by comparing sets of known individuals. While assignment errors were common, the program ranked the true match within the first 10% of the catalogue 78% of the time. The program accelerates the matching process by 1.2 to 4.1 times for catalogues ranging in size from 40 to 500 individuals, and the degree of acceleration increases with the size of the catalogue. This program could also be applied to the beluga whale (Delphinapterus leucas), another important northern species.Bien que le narval (Monodon monoceros) soit une espèce exploitée d’importance économique et culturelle pour les résidents du Nord, la gestion efficace de cette espèce est affaiblie par des lacunes importantes en matière de connaissance de l’espèce. La quantité de recherche sur le narval est limitée par le coût des méthodes utilisées et par le fait que certaines de ces méthodes sont invasives, ce qui est désapprouvé par les communautés inuites. La photo-identification, soit une méthode non-invasive, peu coûteuse et facile d’utilisation, a été récemment mise au point pour le narval. Cette méthode utilise des photographies de marques naturelles pour identifier les individus. Toutefois, le plus grand défaut de cette méthode est qu’elle requiert beaucoup de temps pour comparer les photographies. Nous avons mis au point un programme informatique dans le but d’accélérer le processus d’identification et donc remédier au principal inconvénient de la photo-identification. Ce programme utilise l’emplacement des entailles dans la crête dorsale des narvals pour comparer une nouvelle image à celles d’un catalogue et les ordonne en ordre décroissant selon leur similarité. Nous avons testé la constance de l’utilisateur lorsqu’il attribue les caractéristiques de la crête dorsale et l’exactitude du programme en comparant des photographies d’individus précédemment identifiés. Bien que les erreurs de l’utilisateur soient fréquentes, le programme classe le bon individu parmi le premier 10 % des individus du catalogue, et ce 78 % du temps. Ce nouveau programme permet alors un meilleur rendement du processus d’identification de 1,2 à 4,1 fois plus rapide que sans l’assistance d’un programme pour un catalogue comprenant de 40 à 500 individus. Par ailleurs, plus le catalogue est grand, plus le degré d’accélération augmente. Ce programme informatique pourrait aussi être appliqué au béluga (Delphinapterus leucas), une autre espèce d’importance pour les résidents du Nord

Vocal sequences in narwhals (Monodon monoceros)

Sequences are indicative of signal complexity in vocal communication. While vocal sequences are well-described in birds and terrestrial mammals, the extent to which marine mammals use them is less well understood. This study documents the first known examples of sequence use in the narwhal (Monodon monoceros), a gregarious Arctic cetacean. Eight female narwhals were fitted with animal-borne recording devices, resulting in one of the largest datasets of narwhal acoustic behaviour to date. A combination of visual and quantitative classification procedures was used to test whether subjectively defined vocalization patterns were organized into sequences. Next, acoustic characteristics were analyzed to assess whether sequences could disclose group or individual identity. Finally, generalized linear models was used to investigate the behavioural context under which sequences were produced. Two types of sequences, consisting of “paired” patterns and “burst pulse series,” were identified. Sequences of burst pulse series were typically produced in periods of high vocal activity, whereas the opposite was true for sequences of paired patterns, suggesting different functions for each. These findings extend the set of odontocetes which are known to use vocal sequences. Inquiry into vocal sequences in other understudied marine mammals may provide further insights into the evolution of vocal communication.Publisher PDFPeer reviewe

Local Passive Acoustic Monitoring of Narwhal Presence in the Canadian Arctic: A Pilot Project

Long-term community-based monitoring of narwhals (Monodon monoceros) is needed because narwhals are important to local Inuit and are facing changes in their environment. We examined the suitability of passive acoustic recording for monitoring narwhals, using data gathered in the Canadian Arctic from an autonomous acoustic recorder (Repulse Bay, 2006) and a hand-held digital recorder (Koluktoo Bay, 2006 – 08). We found a relationship between the number of narwhals observed passing a fixed point and the number of calls heard. In addition, we found that an automated call detector could isolate segments of recording containing narwhal vocalizations over long recording periods containing non-target sound, thus decreasing the time spent on the analysis. Collectively, these results suggest that combining passive acoustic sampling with an automated call detector offers a useful approach for local monitoring of the presence and relative abundance of narwhals.La nécessité d’avoir un programme communautaire de surveillance à long terme des narvals (Monodon monoceros) s’avère évidente étant donné que les narvals revêtent de l’importance aux yeux des Inuits de la région et que leur environ­nement est en pleine évolution. Nous explorons la pertinence d’un programme de surveillance par acoustique passive pour les populations de narvals à partir de données récoltées dans l’Arctique canadien à l’aide d’une enregistreuse autonome (Repulse Bay, 2006) et d’une enregistreuse portable (Koluktoo Bay, 2006 – 2008). Grâce à des enregistrements accompagnés d’obser­vations sur le terrain, nous avons trouvé une corrélation entre le nombre de vocalisations entendues et le nombre de narvals observés. L’utilisation d’un détecteur automatique de vocalisations de narvals a permis d’isoler des segments d’enregis­trements contenant des vocalisations de narvals sur de longues périodes d’enregistrement contenant des sons non-ciblés, et ainsi diminuer le temps d’analyse. Ces résultats suggèrent que la combinaison de surveillance acoustique passive avec l’utili­sation d’un détecteur automatique offre une approche utile pour la surveillance locale de la présence et de l’abondance relative des narvals

Détection des bélugas dans le détroit Cumberland Sound à l'aide de réseaux de neurones à convolution

This is an Accepted Manuscript of an article published by Taylor & Francis in Canadian Journal of Remote Sensing on March 29, 2021, available online: https://www.tandfonline.com/doi/10.1080/07038992.2021.1901221The Cumberland Sound Beluga is a threatened population of belugas and the assessment of the population is done by a manual review of aerial surveys. The time-consuming and labour-intensive nature of this job motivates the need for a computer automated process to monitor beluga populations. In this paper, we investigate convolutional neural networks to detect whether a section of an aerial survey image contains a beluga. We use data from the 2014 and 2017 aerial surveys of the Cumberland Sound, conducted by the Fisheries and Oceans Canada to simulate two scenarios: 1) when one annotates part of a survey and uses it to train a pipeline to annotate the remainder and 2) when one uses annotations from a survey to train a pipeline to annotate another survey from another time period. We experimented with a number of different architectures and found that an ensemble of 10 CNN models that leverage Squeeze-Excitation and Residual blocks performed best. We evaluated scenarios 1) and 2) by training on the 2014 and 2017 surveys respectively. In both scenarios, the performance on 1) is higher than 2) due to the uncontrolled variables in the scenes, such as weather and surface conditions.Natural Sciences and Engineering Research Council of Canada (NSERC), Grants RGPIN-2017-04869, DGDND-2017-00078, RGPAS-2017-50794, and RGPIN-2019-06744 || University of Waterloo || Marine Environmental Observation Prediction and Response Networ

Migration, Dispersal, and Gene Flow of Harvested Aquatic Species in the Canadian Arctic

Migration occurs when key aspects of the life cycle such as growth, reproduction, or maintenance cannot all be completed in one location. The Arctic habitats are variable and Arctic species are often migratory. The predictable nature of migrations in both space and time allow Arctic people to harvest fishes and marine mammals. We describe migratory/dispersal behavior in four types of taxa from the Canadian Arctic: anadromous and freshwater fishes, marine fishes, marine invertebrates, and marine mammals. Patterns of migration are remarkably different between these groups, in particular between distances migrated, seasonal timing of migrations, and the degree of reproductive isolation. Migratory anadromous and freshwater fishes become adapted to specific locations resulting in complex life histories and intra- and inter-population variation. Marine mammals not only migrate longer distances but also appear to have distinct demographic populations over large scales. Marine fishes tend to be panmictic, probably due to the absence of barriers that would restrict gene flow. Migratory patterns also reflect feeding or rearing areas and/or winter refugia. Migratory patterns of harvested aquatic organisms in the Canadian north are extremely variable and have shaped the north in terms of harvest, communities, and culture

Abundance and species diversity hotspots of tracked marine predators across the North American Arctic

Aim: Climate change is altering marine ecosystems worldwide and is most pronounced in the Arctic. Economic development is increasing leading to more disturbances and pressures on Arctic wildlife. Identifying areas that support higher levels of predator abundance and biodiversity is important for the implementation of targeted conservation measures across the Arctic. Location: Primarily Canadian Arctic marine waters but also parts of the United States, Greenland and Russia. Methods: We compiled the largest data set of existing telemetry data for marine predators in the North American Arctic consisting of 1,283 individuals from 21 species. Data were arranged into four species groups: (a) cetaceans and pinnipeds, (b) polar bears Ursus maritimus (c) seabirds, and (d) fishes to address the following objectives: (a) to identify abundance hotspots for each species group in the summer–autumn and winter–spring; (b) to identify species diversity hotspots across all species groups and extent of overlap with exclusive economic zones; and (c) to perform a gap analysis that assesses amount of overlap between species diversity hotspots with existing protected areas. Results: Abundance and species diversity hotpots during summer–autumn and winter–spring were identified in Baffin Bay, Davis Strait, Hudson Bay, Hudson Strait, Amundsen Gulf, and the Beaufort, Chukchi and Bering seas both within and across species groups. Abundance and species diversity hotpots occurred within the continental slope in summer–autumn and offshore in areas of moving pack ice in winter–spring. Gap analysis revealed that the current level of conservation protection that overlaps species diversity hotspots is low covering only 5% (77,498 km 2 ) in summer–autumn and 7% (83,202 km 2 ) in winter–spring. Main conclusions: We identified several areas of potential importance for Arctic marine predators that could provide policymakers with a starting point for conservation measures given the multitude of threats facing the Arctic. These results are relevant to multilevel and multinational governance to protect this vulnerable ecosystem in our rapidly changing world

Marine mammal hotspots across the circumpolar Arctic

Aim: Identify hotspots and areas of high species richness for Arctic marine mammals. Location: Circumpolar Arctic. Methods: A total of 2115 biologging devices were deployed on marine mammals from 13 species in the Arctic from 2005 to 2019. Getis-Ord Gi* hotspots were calculated based on the number of individuals in grid cells for each species and for phyloge-netic groups (nine pinnipeds, three cetaceans, all species) and areas with high spe-cies richness were identified for summer (Jun-Nov), winter (Dec-May) and the entire year. Seasonal habitat differences among species’ hotspots were investigated using Principal Component Analysis. Results: Hotspots and areas with high species richness occurred within the Arctic continental-shelf seas and within the marginal ice zone, particularly in the “Arctic gateways” of the north Atlantic and Pacific oceans. Summer hotspots were generally found further north than winter hotspots, but there were exceptions to this pattern, including bowhead whales in the Greenland-Barents Seas and species with coastal distributions in Svalbard, Norway and East Greenland. Areas with high species rich-ness generally overlapped high-density hotspots. Large regional and seasonal dif-ferences in habitat features of hotspots were found among species but also within species from different regions. Gap analysis (discrepancy between hotspots and IUCN ranges) identified species and regions where more research is required. Main conclusions: This study identified important areas (and habitat types) for Arctic marine mammals using available biotelemetry data. The results herein serve as a benchmark to measure future distributional shifts. Expanded monitoring and teleme-try studies are needed on Arctic species to understand the impacts of climate change and concomitant ecosystem changes (synergistic effects of multiple stressors). While efforts should be made to fill knowledge gaps, including regional gaps and more com-plete sex and age coverage, hotspots identified herein can inform management ef-forts to mitigate the impacts of human activities and ecological changes, including creation of protected areas

Narwhal communication and grouping behaviour: a case study in social cetacean research and monitoring

Narwhals (Monodon monoceros) are gregarious, toothed whales restricted to the Arctic, where habitats are changing and shipping traffic is increasing. Challenges associated with the remoteness of narwhal populations and the general difficulty of studying deep diving mammals have resulted in a lack of knowledge of narwhal social behaviour, which can only be rectified with intensive, direct and systematic observations. I studied the grouping patterns and vocal behaviour of narwhals using non-invasive methods and developed new statistical tools to analyse the data. The field work was conducted at Bruce Head, a peninsula at the mouth of Koluktoo Bay, Nunavut, during the summers of 2006-2008. Shore-based observations were used to delineate narwhal groups by sex and age class. Narwhals travelled in clusters of 1–25 individuals of mixed sex and age class. Narwhals entered the bay in larger groups than they exited. The coloration of narwhal's backs on photographs was used to estimate their age and investigate their association with individuals of similar age. To analyse these data, I developed statistical methods that examine the distribution of observations in time and their associated characteristics. Using these methods, I found that narwhals form groups with individuals of similar age. The variability and the context of usage of narwhal calls were examined from underwater recordings. Some physical characteristics of narwhal whistles seemed behaviour-specific. Both whistles and pulsed calls might serve in individual- or group-recognition. Finally, given that there is a need for sustained, local monitoring of narwhals, I explored the potential of passive acoustic methods for narwhal monitoring. An automated detector was able to correctly identify narwhal calls in a 25-day continuous recording. There was a correlation between the number of calls manually detected in non-continuous recordings and the number of narwhals observed during the recordings. Non-invasive methods can provide valuable insight into the social organization, communication and movement patterns of large numbers of non-disturbed cetaceans.Le narval (Monodon monoceros) est un cétacé grégaire arctique dont l'habitat est en train de se modifier rapidement. Les difficultés reliées à l'accès en Arctique et à l'étude des cétacés en haute mer expliquent le manque d'information sur le comportement social des narvals. Dans le cadre de mes études doctorales j'ai étudié les groupes sociaux des narvals ainsi que leur communication vocale en utilisant des méthodes de récolte de données non invasives. De plus, j'ai développé des méthodes statistiques pour l'analyse de ces données. Le travail de terrain s'est déroulé au cours des étés 2006 à 2008 dans la baie Koluktoo, au Nunavut. À partir d'observations faites de la côte, la composition et la taille des groupes de narvals ont été compilées. Les narvals se déplaçaient en groupes de 1 à 25 individus d'âge et de sexe variés et entraient dans la baie en groupes plus nombreux que lorsqu'ils en sortaient. La coloration sur le dos des narvals pris en photo a servi à estimer leur âge et à évaluer la formation de groupe en fonction de ces âges. Pour analyser ces données, j'ai développé des méthodes statistiques qui évaluent la distribution d'observations réparties dans le temps ainsi que des caractéristiques associées à chacune des observations. Cette analyse m'a permis de conclure que les narvals forment des groupes avec des individus d'âges similaires. La variabilité et le contexte de l'utilisation des vocalisations émises par les narvals ont par la suite été étudiés à partir d'enregistrements acoustiques sous-marins. Ainsi, certaines caractéristiques acoustiques des vocalisations semblent associées spécifiquement à certains comportements. De plus, certaines de ces vocalisations pourraient être uniques à chaque groupe. Finalement, j'ai exploré la faisabilité d'un programme de surveillance acoustique à long terme pour les narvals. Les vocalisations des narvals ont été correctement détectées par un détecteur automatique appliqué à un enregistrement continu sur 25 jours. Le nombre de narvals observés visuellement et le nombre de vocalisations entendues durant ces enregistrements non continus étaient corrélés. Ces méthodes non invasives permettent d'étudier l'organisation sociale, la communication et les mouvements cétacés en grand nombre sans les perturber