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• Sex-specific beluga body condition models account for size, age, location, and year. • Belugas from entrapment events can serve as thresholds for body condition indicators. • Spatial variability was detected and requires consideration in the use of indicators. • This study aims to develop blubber thickness and girth as body condition indicators. Monitoring marine protected areas requires simplifying complex marine ecosystems into a suite of indicators. The Tarium Niryutait Marine Protected Area (TN MPA), the first MPA in the Canadian Arctic is located in the Inuvialuit Settlement Region, NT and is selecting indicators for monitoring. Proposed health indicators for the TN MPA species of interest, the Eastern Beaufort Sea (EBS) beluga, include the body condition metrics blubber thickness and girth. Sex-specific body condition models for both metrics were developed to account for age, size, location, and timing of harvest from belugas harvested from 2000 to 2015. Models were tested to determine if the spatial variation is detected in the condition of belugas between the three areas of the TN MPA and between belugas harvested inside to outside of the TN MPA. Lastly, we assessed belugas from entrapment events to determine if indicator thresholds could be developed. Three of the indicators (girth male, girth female, blubber thickness male) contain both temporal and spatial factors, signalling the significant influence of year and harvest location on condition. Male belugas harvested from the western area of the TN MPA had smaller mean blubber thickness and girth compared to the other TN MPA areas, whereas there was no significant difference in female condition across the TN MPA. There was a significant difference inside and outside the TN MPA for all four indicators, with larger mean blubber thickness inside the TN MPA, females exhibiting larger mean girth and males exhibiting smaller mean girth inside the TN MPA. Indicators confirm that belugas from entrapment events had significantly lower body condition than belugas harvested during the summer and can serve as thresholds for condition indicators. This study provides guidance on the selection and use of condition indicators for their application in monitoring the TN MPA and demonstrates that careful consideration is required for indicator development and selection. [ABSTRACT FROM AUTHOR]

Abstract: Simulations testing the future impacts of harvest and climate change to the Hudson Bay marine ecosystem were created utilizing an existing Ecopath with Ecosim model (Hoover et al., 2013). Building on past simulations depicting known changes to the region, a suite of future scenarios was constructed to include a variety of climate change and harvest levels. Previously identified ecosystem shifts favoring pelagic species (zooplankton, planktivorous fish) over benthic species (benthos, benthic feeding fish), are further exaggerated under future climate scenarios. Environmental forcing was incorporated to mimic the declines in sea ice, and increases in temperature causing shifts in the food web from an ice algae–benthos–benthic fish pathway to a spring bloom–zooplankton–planktivorous fish dominated ecosystem. Future simulations indicate some stocks are unable to sustain current harvest levels until the end of the future simulations (2069), and may be extirpated (narwhal, eastern Hudson Bay beluga, polar bears, and walrus). Larger populations of marine mammals (ringed seals and western Hudson Bay beluga) are identified to increase in biomass even under extreme harvest and climate scenarios (a high future climate scenario coupled with a doubling in harvest rates). Harvest mortality is highlighted as an important stressor for some marine mammal stocks and should be investigated further when setting future harvest or conservation targets. [Copyright &y& Elsevier]

Abstract: An ecosystem model was created for the Hudson Bay region, Canada, for 1970–2009, aiming to identify ecosystem linkages while bringing together research from diverse sources. The model presented here in detail includes 40 functional groups. Using the Ecopath with Ecosim (EwE) modelling framework we are able to provide estimates for previously unknown parameters such as the biomass of fish species. In addition to providing a comprehensive overview of the trophic dynamics within the system, temporal simulations mimic the changes known to occur in the region. The model is fitted to catch data for the Hudson Bay region, along with environmental drivers (sea surface temperature and ice cover). Declines in sea ice and increases in the spring bloom facilitate a shift from benthic to pelagic pathways in lower trophic levels of the model. Polar bears, bearded seals and eastern Hudson Bay belugas demonstrate the greatest declines due to hunting mortality. Additional model scenarios testing the model sensitivity to hunting and environmental pressures indicate higher trophic level organisms (marine mammals) are more responsive to hunting pressures, while lower trophic levels (benthos, zooplankton) are primarily influenced by climate drivers. While marine mammals are the most well studied, the region lacks comprehensive assessments on fish and other mid trophic level organisms. This model captures many patterns present in the system, while identifying gaps in existing data for future research and provides the first step for future research simulating climate change and its impacts on the Hudson Bay ecosystem. [Copyright &y& Elsevier]