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The monodontids--narwhals, Monodon monoceros, and belugas, Delphinapterus leucas--are found in much of the Arctic and in some subarctic areas. They are hunted by indigenous subsistence users. In the past, some populations were substantially reduced by commercial hunting and culling; more recently, some populations have declined due to uncontrolled subsistence hunting and environmental degradation. Monodontids are impacted increasingly by human activities in the Arctic including ship and boat traffic, industrial development, icebreaking, seismic surveys, competition with fisheries, and alteration of habitat due to climate change. Since comprehensive reviews in the 1990's, substantial new information has become available on both species and on changes to their habitat as a result of human activities and climate change. Thus NAMMCO and partners undertook an updated review in 2017. The review recognized 21 extant beluga stocks, 1 extirpated beluga stock, and 12 stocks of narwhals. The available information on each stock regarding population size, depletion level, current and past removals, and trends in abundance was reviewed to determine status. Concern was expressed where the lack of information prevented reliable assessment, removals were thought to be unsustainable, or the population was deemed at risk of declining even without direct removals by hunting. Beluga stocks of greatest concern are the small stocks in Ungava Bay (possibly extirpated), Cook Inlet (ca 300), St. Lawrence Estuary (ca 900), and Cumberland Sound (ca 1,100), and the stocks with uncertainty in Eastern Hudson Bay and the Barents-Kara-Laptev Seas. Narwhal stocks of greatest concern are those in Melville Bay and East Greenland., Introduction The family Monodontidae is comprised of the narwhal, Monodon monoceros, and the beluga or white whale, Delphinapterus leucas (Rice, 1998). These two species are found in much of the [...]

Aerial surveys were completed to estimate northwest Atlantic grey seal (Halichoerus grypus) pup production in eastern Canada during December 2020 to February 2021. These surveys underestimate pup production if animals are born after the surveys are flown or if pups leave the breeding site before it is surveyed. Past assessments have modelled the distribution of births to correct this bias by fitting the proportion of animals in different morphometrically defined stages of fixed duration to a gamma or Weibull distribution (Myers Birth Distribution [MBD] Model). A new Bayesian modelling approach was developed and compared with the MBD model to examine how this approach impacts our understanding of the timing of births. Assuming that animals are weaned at 20 days of age, the model was also applied to determine the proportion of animals that were weaned and thus available to harvesters at different colonies. The MBD and Bayesian models showed similar estimates when applied to the data rich dataset acquired on Sable Island. At other breeding sites, the Bayesian model tended to estimate a slightly shorter period of births compared to the MBD model, resulting in a higher estimated proportion of animals born on the aerial survey date, and thus a smaller adjustment of counts. The weaning date estimated with the Bayesian model showed a general trend starting off the Nova Scotia coast then moving into the Gulf of St. Lawrence. The model estimated that 50% of the grey seal pups were weaned by January 6, 2021 on the southwestern Nova Scotia Islands, and on January 24 in the southern Gulf. Application of the Bayesian model to staging data acquired at several colonies in previous years showed that the date when 50% of the pups are weaned has advanced by approximately one day each year since the early 2000s in the Gulf. This trend was less clear outside the Gulf, but the timing of births in 2021 was also estimated to be earlier than in previous years. The Bayesian model provides an approach to consider several sources of uncertainty not previously taken into account. These include uncertainty associated with the date of first birth, the development stage duration, and variability in classification of stages by the various observers. By updating priors, the model can make use of new information as it is collected. The use of the Bayesian model should lead to improved estimates of population size. [ABSTRACT FROM AUTHOR]

Belugas from the Hudson Bay-Strait Complex are harvested by hunters from Nunavik and Nunavut communities. In past studies, a genetic mixture analysis (GMA) was used to determine the contribution of animals from the Western Hudson Bay (WHB) and Eastern Hudson Bay (EHB) populations to harvests in the different management units. The population definition of WHB and EHB relied on short haplotypes from the mitochondrial (mt) DNA control region. However, studies with long haplotypes have shown that four populations could be identified in the Hudson Bay-Strait Complex. Here, we aim to 1) revisit the definition of populations within this area by resequencing and comparing short and long haplotypes for the mtDNA control region of 2 861 belugas, and 2) update the relative contribution of the newly-defined reference groups in management units using a GMA. Long haplotypes confirmed the existence of four previously defined populations, WHB, EHB, James Bay (JAM), and Cumberland Sound (CSB). They also allowed for the identification of a fifth population in the Belcher Islands (BEL). For the second objective, we tested the validity of the five populations using a leave-one-out approach and observed a high rate of erroneous assignments between EHB and BEL populations. Misassignments were due to shared genetic matrilineages and possible admixture during summer. Assignments were improved when EHB and BEL populations were combined in as a single reference named BEL-EHB stock. The GMA with the four new reference groups (WHB, JAM, CSB populations and BEL-EHB stock) led to higher proportions of the BEL-EHB stock in the fall harvest in Hudson Strait (5.6%) and Northeastern Hudson Bay (14.9%), and year-round in Sanikiluaq (3.3 to 61.2%), compared to previous studies using only two reference groups. Changes in reference groups, and not resequencing, likely caused most of the variation in the proportional estimate of the BEL-EHB stock in management units. Results from this study have increased the accuracy of the proportional contribution from reference groups to the harvest by the Nunavik and Nunavut (Sanikiluaq) communities. [ABSTRACT FROM AUTHOR]

Belugas from the James Bay population (JAM) and Belcher Islands-Eastern Hudson Bay (BEL-EHB) stock are harvested by hunters from all Nunavik communities and the Nunavut community of Sanikiluaq. In 2020-2021, a total of 366 belugas were reported harvested by Nunavik hunters, including 41 animals harvested in the Long Island area. From those, an estimated 139 BEL-EHB animals were harvested. Another 19 BEL-EHB animals were harvested in Sanikiluaq. A population model fitted to a time series of 8 aerial survey estimates using Bayesian methods and taking into account removals by harvesters provided a 2021 abundance estimate of 16,700 belugas in James Bay and a range of 2,900-3,200 belugas in eastern Hudson Bay, depending on model assumptions. The James Bay population has levelled off since the last assessment, whereas the BEL-EHB stock is currently declining at a rate of 2.5% per year. A harvest of 190 belugas per year in James Bay, would result in a 50% probability of decline in the JAM population after 5 years. The Potential Biological Removal (PBR) for this population is 296 belugas. If a Precautionary Approach framework was used to manage beluga in James Bay, a range of 170-173 belugas could be harvested annually. For the BEL-EHB stock, two model runs were completed and harvests were evaluated against two benchmarks or thresholds over time frames of 5 and 10 years. Depending on model assumptions, benchmarks and timeframes, harvests should not exceed levels of 0-70 BEL-EHB belugas annually for the stock to remain above the benchmark abundance estimate. The PBR for this stock is 5 animals. Over a 50-year time period, if the annual harvest of beluga from the BEL-EHB stocks stays within 20-25 animals annually, then there is a high probability of staying above the precautionary reference level. [ABSTRACT FROM AUTHOR]

In a recent review of the status of the Northwest Atlantic harp seal population, model fit to aerial survey estimates of pup production and annual reproductive rates was poor compared to previous assessments indicating underlying problems relating to model assumptions and/or structure. In this study, a new hierarchical Bayesian state-space model was fitted to the same data on pup production, annual fecundity, human removals, and environmental conditions used in the previous assessment to produce annual estimates of pup production and total abundance from 1952-2019. Data on age structure based upon random samples were also included, and the process model incorporated environmental stochasticity and several other improvements. The new model estimates were similar to the previous model through 1990 but then diverged, indicating that the population peaked in 1997 at 6.6 million animals, almost a decade earlier than modelled in previous assessments. After a period of decline due to high catches and poor ice conditions, the new model provides an abundance estimate of 4.7 (95% Credibility Interval (CI) 3.7-5.7) million in 2019, compared to an estimate of 7.6 (95% CI 6.6-8.8) million in the last assessment. The lower estimates of recent abundance reflect higher and more variable juvenile mortality after 2000 due to a combination of density-dependent and density independent factors operating on juvenile survival. The new model also suggests a decline in equilibrium abundance (K) levels from 7.6 (95% CI=7.4 to 7.8) million Northwest Atlantic harp seals prior to 2000 to 6.8 (95% CI=6.7 to 6.9) million animals post-2000. [ABSTRACT FROM AUTHOR]

The St. Lawrence Estuary (SLE) beluga population has been surveyed repeatedly via photographic and visual aerial surveys to evaluate its abundance and trends following similar survey designs since 1988. Published abundance indices from both types of surveys up to 2014 were corrected for availability bias only, using a fixed correction factor. The present study presents results from recently-conducted photographic strip-transect (four surveys, in 2019), and visual line-transect surveys (16 surveys, in 2015, 2016, 2018, 2019, 2020, 2021, and 2022) of the SLE beluga population, as well as a re-analysis of past surveys conducted since 1990 using newly-estimated survey-specific correction factors for both availability (photographic and visual) and perception biases (visual surveys only). The latest photographic survey in 2019 resulted in a total average abundance estimate of 2,119 whales (SE = 267). The latest visual survey in 2022 resulted in a total abundance estimate of 1,257 whales (SE = 400). The 2022 visual survey has the lowest abundance estimate of all visual surveys conducted since 2001. Mean abundance estimates from visual surveys were consistently higher than for photographic surveys once fully corrected for both availability and perception biases. In past survey analyses, no perception bias correction factors were applied due to lack of data, but their use in the present study yielded fully corrected abundance estimates which are 1.5 to 2 times greater than the abundance indices corrected only for availability. While past analyses were adequate to produce abundance indices for this population, the current study represents a major step forward not only for an improved precision and accuracy of abundance estimates for the SLE beluga population but also for understanding the caveats associated with different methodological and analytical approaches to aerial surveys. [ABSTRACT FROM AUTHOR]

In absence of adequate data, abundance estimates for St. Lawrence Estuary (SLE) beluga obtained from visual surveys have been corrected for availability bias using factors developed for photographic surveys. Not accounting for the longer detection time associated with visual surveys will lead to an overestimation of beluga abundance relative to indices obtained from photographic surveys. This study offers a comprehensive analysis of the relative influence of multiple methodological, environmental and behavioural factors on availability bias estimates for both photographic and visual surveys using detailed dive profiles from 27 SLE beluga. As expected, availability estimates were systematically higher for visual surveys than for photographic surveys for which time-in-view is instantaneous. However, for photographic surveys the change in methodology for estimating availability from an approach based on group visibility to one where the detailed diving patterns of individuals were logged, led to a 26--42% decrease in mean availability estimates. Our results confirmed that dives are longer when animals are inside compared to outside areas of high density (AHD), consistent with the prediction that these areas are used for behaviour like foraging. They also indicate that while some of the behavioural or environmental factors such as latent processes associated with the zone used may have a notable effect on availability, survey design (photographic or visual), characteristics of survey platforms, and observer searching patterns may be the most influential factors on availability bias. We conclude that previous estimates of SLE beluga abundance from photographic surveys were likely biased downward by an overestimation of beluga availability, and by not considering the uneven distribution of beluga among different zones with specific but undefined underlying processes. [ABSTRACT FROM AUTHOR]

Harvests of the Eastern Hudson Bay (EHB) summer stock are limited by a management plan that ends in 2020. This document updates the status of the stock using new harvest (up until 2019) and genetics data (up until 2018). The analyses indicate that the overall proportions of EHB beluga in the Hudson Strait harvest were 11.7% in spring and 29.1% in fall; for Ungava Bay the proportion was 6% in spring. In northeastern Hudson Bay fall harvest the proportion was 44.5%. Limited sample size from the Ungava Bay fall and northeastern Hudson Bay spring harvests precluded the breakdown by season for these regions. The population model produced a median abundance estimate of 3,300 animals in 2019, a slight decrease from the previous estimate of 3,400 animals in 2014 (rounded to the nearest 100). The annual Sustainable Yield, which maintains a stable population (50% probability of decline), was 58 belugas for 5 years or 62 animals if evaluated over 10 years. The Potential Biological Removal is 14 animals per year assuming a recovery factor of 0.25. [ABSTRACT FROM AUTHOR]

Harp seals require pack ice as a platform for resting, to give birth and nurse their young. They are also subject to commercial and subsistence harvesting. We examined the status of the Northwest Atlantic harp seal population using a three parameter population model that fits to estimates of pup production and reproductive rates, and incorporates information on annual catches in Canada and Greenland (including by-catch and struck and lost), and unusual pup mortality due to poor ice conditions. After applying the model formulation used during previous assessments, the fit to the reproductive data and aerial survey data was poor. Using an alternative formulation where adult mortality was fixed and juvenile mortality estimated, and a Comprehensive Environmental Index used to vary the population carrying capacity, improved the model fit to the data. Based upon a population model that included pup production estimates up to 2017, annual estimates of age-specific reproductive rates, removals and ice related mortality up to 2019, the harp seal population appears to have been relatively stable since the mid-1990s, but has been increasing in recent years likely due to higher reproductive rates and lower removals. The model estimated a pup production of 1,039,000 (95% CI 927,000 - 1,100,000) animals and a total population size of 6.8 (95% CI 5.8 - 8.0) million animals in 2017. Projecting forward to 2019, the model estimated that the population increased to 7.6 (95% CI 6.6 - 8.8) million harp seals. Climate change is having an impact on ice-cover, particularly in the Gulf of St Lawrence, but even the northeast Newfoundland area is expected to be ice-free by the end of the century. This will have a negative impact on harp seals unless new areas for pupping are found to the north of current whelping areas. [ABSTRACT FROM AUTHOR]

Cumberland Sound (CS) beluga (Delphinapterus leucas) are genetically differentiated and spatially segregated from other beluga populations, remaining in CS year-round. Under the Species at Risk Act the population is listed as Threatened. A survey in 2014 estimated approximately 1,150 (CV = 0.216) belugas in this population. A new series of visual and photographic surveys were flown during July and August 2017. The visual survey covered a larger area of CS than previous surveys, based on input from the Pangnirtung Hunters and Trappers Association, and was divided into three strata. The photographic survey provided full coverage of Clearwater Fiord, where CS beluga congregate in summer. Visual surveys of each of the three CS strata were flown twice, and analysed as a 600 m strip transect survey adjusted for perception and availability bias. The availability bias adjustment factor was calculated from whales equipped with satellite tags in 2006-2008 and was based on time spent in the upper 0-5 m for the visual survey (Ca = 2.54; CV = 0.050). Perception bias was calculated using duplicate sightings from the primary and secondary observers during the 2017 survey (Cp = 1.05; CV = 0.077). The photographic survey of Clearwater Fiord was conducted once during the first survey and four times during the second survey (using a weighted-CV average for the abundance estimate for the second survey) and adjusted to account for availability bias by evaluating the time spent in the 0-1 m or 0-2 m bin depending on beluga visibility (Ca = 4.46; CV = 0.117 and Ca = 2.06, CV = 0.056, respectively). The fully adjusted estimate for the two surveys of the entire area was 1,749 (CV = 0.423) and 1,379 (CV = 0.043) whales in Clearwater Fiord. This resulted in an average 2017 survey abundance estimate of 1,381 (CV = 0.043; 95% CI = 1,270-1,502) belugas, respectively. A model incorporating the 2017 and four previous survey estimates (1990-2014), along with harvest statistics from 1960-2017, was then fit using Bayesian inference to provide updated estimates of abundance and potential impacts of different harvest scenarios. The population model produced an estimated median abundance of 1,090 (CV = 0.207, 95% CI = 617-1,864) beluga in 2018. The model estimated 96% probability of stock decline in 10 years with the current annual quota (41) and a 0%, 25%, and 50% probability of population decline with harvests of 0, 14, and 20 beluga, respectively. PBR was calculated using reproductive rates of 0.04 (assumed for cetaceans) and 0.03 (estimated from the model) and varied from one to three animals, with a TALC of one to two whales. [ABSTRACT FROM AUTHOR]

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