16 research outputs found
Allocating Harvests among Polar Bear Stocks in the Beaufort Sea
Recognition that polar bears are shared by hunters in Canada and Alaska prompted development of the âPolar Bear Management Agreement for the Southern Beaufort Sea.â Under this Agreement, the harvest of polar bears from the southern Beaufort Sea (SBS) is shared between Inupiat hunters of Alaska and Inuvialuit hunters of Canada. Quotas for each jurisdiction are to be reviewed annually in light of the best available scientific information. Ideal implementation of the Agreement has been hampered by the inability to quantify geographic overlap among bears from adjacent populations. We applied new analytical procedures to a more extensive radiotelemetry data set than has previously been available to quantify that overlap and thereby improve the efficacy of the Agreement. We constructed a grid over the eastern Chukchi Sea and Beaufort Sea and used twodimensional kernel smoothing to assign probabilities to the distributions of all instrumented bears. A cluster analysis of radio relocation data identified three relatively discrete groups or âpopulationsâ of polar bears: the SBS, Chukchi Sea (CS), and northern Beaufort Sea (NBS) populations. With kernel smoothing, we calculated relative probabilities of occurrence for individual members of each population in each cell of our grid. We estimated the uncertainty in probabilities by bootstrapping. Availability of polar bears from each population varied geographically. Near Barrow, Alaska, 50% of harvested bears are from the CS population and 50% from the SBS population. Nearly 99% of the bears taken by Kaktovik hunters are from the SBS. At Tuktoyaktuk, Northwest Territories, Canada, 50% are from the SBS and 50% from the NBS population. We displayed the occurrence of bears from each population as probabilities for each cell in our grid and as maps with contour lines delineating changes in relative probability. This new analytical approach will greatly improve the accuracy of allocating harvest quotas among hunting communities and jurisdictions while assuring that harvests remain within the bounds of sustainable yield.La reconnaissance du fait que lâours polaire est chassĂ© tant au Canada quâen Alaska a initiĂ© la crĂ©ation de lâ«Accord de gestion de lâours polaire dans le sud de la mer de Beaufort». En vertu de cet accord, le prĂ©lĂšvement de lâours polaire du sud de la mer de Beaufort est partagĂ© entre les chasseurs inupiat de lâAlaska et les chasseurs inuvialuit du Canada. Les quotas pour chaque territoire de compĂ©tence doivent ĂȘtre rĂ©visĂ©s sur une base annuelle Ă la lumiĂšre de la meilleure information scientifique disponible. Une parfaite mise en oeuvre de lâaccord a Ă©tĂ© rendue difficile en raison de lâimpossibilitĂ© de quantifier le chevauchement gĂ©ographique des populations dâours voisines. En vue de quantifier ce chevauchement et dâamĂ©liorer ainsi lâefficacitĂ© de lâaccord, on a appliquĂ© de nouvelles procĂ©dures analytiques Ă un plus vaste ensemble de donnĂ©es tĂ©lĂ©mĂ©triques quâon nâavait pu le faire auparavant. On a construit une grille recouvrant lâest de la mer des Tchouktches et la mer de Beaufort, et on a utilisĂ© une mĂ©thode de lissage bidimensionnel par noyaux afin dâassigner des probabilitĂ©s aux distributions de tous les ours appareillĂ©s. Une analyse de groupage des donnĂ©es de dĂ©placement obtenues par radiocommunication a rĂ©vĂ©lĂ© trois groupes relativement distincts ou «populations» dâours polaires, soit celles du sud de la mer de Beaufort (SMB), de la mer des Tchouktches (MT) et du nord de la mer de Beaufort (NMB). En recourant Ă la mĂ©thode de lissage par noyaux, on a calculĂ© les probabilitĂ©s relatives de prĂ©sence des membres individuels de chaque population dans chacune des mailles de notre grille. On a Ă©valuĂ© lâincertitude dans les probabilitĂ©s par la mĂ©thode de bootstrapping. La disponibilitĂ© dâours polaires au sein de chacune des populations variait gĂ©ographiquement. PrĂšs de Barrow en Alaska, 50 % des ours prĂ©levĂ©s viennent de la population MT, et 50 %, de la population SMB. PrĂšs de 99 % des ours abattus par les chasseurs de Kaktovik proviennent de la SMB. Ă Tuktoyaktuk, dans les Territoires du Nord-Ouest au Canada, 50 % des prises proviennent de la population SMB et 50 % de celle de la NMB. On a reprĂ©sentĂ© la prĂ©sence des ours de chaque population sous la forme de probabilitĂ©s pour chaque maille de notre grille et sous celle de cartes avec courbes de niveau dĂ©limitant les changements dans la probabilitĂ© relative. Cette nouvelle approche analytique va grandement amĂ©liorer la justesse de lâattribution des quotas de prĂ©lĂšvement parmi les communautĂ©s de chasseurs et les territoires dont ils relĂšvent, tout en garantissant que les prĂ©lĂšvements restent dans les limites dâun rendement durable
Climate change threatens the world's marine protected areas
Marine protected areas (MPAs) are a primary management tool for mitigating threats to marine biodiversity 1,2 . MPAs and the species they protect, however, are increasingly being impacted by climate change. Here we show that, despite local protections, the warming associated with continued business-as-usual emissions (RCP8.5) 3 will likely result in further habitat and species losses throughout low-latitude and tropical MPAs 4,5 . With continued business-as-usual emissions, mean sea-surface temperatures within MPAs are projected to increase 0.035 °C per year and warm an additional 2.8 °C by 2100. Under these conditions, the time of emergence (the year when sea-surface temperature and oxygen concentration exceed natural variability) is mid-century in 42% of 309 no-take marine reserves. Moreover, projected warming rates and the existing 'community thermal safety margin' (the inherent buffer against warming based on the thermal sensitivity of constituent species) both vary among ecoregions and with latitude. The community thermal safety margin will be exceeded by 2050 in the tropics and by 2150 for many higher latitude MPAs. Importantly, the spatial distribution of emergence is stressor-specific. Hence, rearranging MPAs to minimize exposure to one stressor could well increase exposure to another. Continued business-as-usual emissions will likely disrupt many marine ecosystems, reducing the benefits of MPAs
Relating polar bears killed, human presence, and ice conditions in Svalbard 1987â2019
Conflicts between humans and polar bears have been predicted to increase as
polar bear prime habitat, sea ice, is decreasing. In Svalbard, a strict protection and
control schemes have secured near complete records of bears killed and found
dead since 1987. We analyzed the trend in the number of kills and related this to
human visitation to the archipelago. We found a slight decrease in the number of
kills in the period 1987-2019, and a decrease in per capita number of kills when
monthly kills were compared to the monthly number of visitors disembarking in
the main settlement. We then used a discrete choice resource selection model to
assess whether polar bear kill events are related to attributes of the kill sites and
environmental conditions at the time. We divided Svalbard in four sectors, North,
East, South, and West, and monthly average ice cover was calculated in 25-km
rings around Svalbard, rings that were further delineated by the four sectors. We
found that the odds of a kill was greater along the shoreline, and that the odds
would be reduced by 50% when moving only 900 m from the shoreline when all
sectors were included. Distance from other covariates like settlements, trapperâs
cabins, and landing sites for tourists did for the most part not have a significant
impact on the odds of a kill. Sectorwise, ice cover had no significant impact on
the odds for a kill. The decreasing trend in kills of polar bears might partly be
explained by the success of strict protection and management regimes of
Svalbard wilderness
Bayesian networks to predict data mining algorithm behavior in ubiquitous computing environments
The growing demand of data mining services for ubiquitous computing environments necessitates deployment of appropriate mechanisms that make use of circumstantial factors to adapt the data mining behavior. Despite the efforts and results so far for efficient parameter tuning, incorporating dynamically changing context information on the parameter setting decision is lacking in the present work. Thus, Bayesian networks are used to learn, in possible situations the effects of data mining algorithm parameters on the final model obtained. Based on this knowledge, we propose to infer future algorithm configurations appropriate for situations. Instantiation of the approach for association rules is also shown in the paper and the feasibility of the approach is validated by the experimentation