NAMMCO Scientific Publications

Application of the Precautionary Approach to the Management of Marine Mammals in northern Canada

Mike O. Hammill, Garry B. Stenson, Thomas Doniol-Valcroze, Shelley L. C. Lang — Wed, 24 Jul 2024 00:00:00 +0200

Canada is committed to managing its resources using a Precautionary Approach (PA). However, when applying this approach to Arctic marine mammals, the Government of Canada must also respect the land claims agreements it has signed with Canada’s Inuit. Under these agreements the co-management boards are responsible for wildlife management within the land claim area. In addition to protecting the rights of hunters to harvest, the land claims agreements also call for the development of management systems that respect the principles of conservation and ensure sustainability of the resource, potentially resulting in a management paradox. We present criteria by which the status of a population can be assessed, and an appropriate PA framework applied. If sufficient data are available to understand the population dynamics of a given stock (i.e., a Data Rich situation), management decisions can be based upon an appropriate population model with quantitatively estimated reference levels. In cases where the population dynamics are poorly understood (i.e., Data Poor), a more conservative approach, referred to as the Potential Biological Removal (PBR) should be used to provide advice on sustainable harvest levels. Generally, only the most recent estimate of abundance is used in the PBR calculation which may ignore other data. We propose that if sufficient data are available to fit a population model, while still not sufficient to be considered Data Rich, the modelled estimate of current abundance can be used for a more robust PBR estimate. We also review guidelines for the choice of the recovery factor which is part of the PBR calculation. The apparent management paradox can be addressed within the context of a Management Procedure or Management Strategy Evaluation where Indigenous Knowledge and Western Science can contribute to setting management objectives, decision rules and appropriate time-frames that can be evaluated within a simulation environment.

Estimates of Pinniped abundance in the North Atlantic of relevance to NAMMCO

Marina Metic, Maria Garagouni — Wed, 18 Dec 2024 00:00:00 +0100

No abstract

Large decline in hooded seal (Cystophora cristata) pup production off of northeastern Newfoundland in 2012 and 2017

Charmain Hamilton, Pierre Goulet, Shelley Lang, Arnaud Mosnier, Garry Stenson — Wed, 18 Dec 2024 00:00:00 +0100

Accurate data on population abundance is needed to monitor trends through time, especially for species that are commercially harvested or vulnerable to climate change related impacts. Hooded seals (Cystophora cristata) in the Northwest Atlantic whelp on drifting sea ice in three areas: Davis Strait, the southern Gulf of St. Lawrence and off of northeastern Newfoundland (“Front”), Canada, with the majority of whelping (>90%) occurring at the Front. They are harvested in Canada and Greenland but have not been assessed since 2005. Aerial surveys for harp seals (Pagophilus groenlandicus) took place at the Front in 2012 and 2017. These surveys also captured the vast majority of hooded seal whelping patches in these years and so were used to estimate hooded seal pup production at the Front. Pup production was estimated from photo (2012 and 2017) and visual (2017 only) line-transect surveys. Staging data from 2004, 2005 and 2017 were used to correct these estimates for the proportion of pups not born on the survey days, resulting in total pup production estimates of 41,129 (SE = 7,374) and 39,021 (SE = 18,334) pups in 2012 and 2017, respectively. This is a large decrease from the previous estimate, being 38% and 36%, respectively, of the pup production estimated on the Front in 2005. Extensive reconnaissance that failed to locate whelping hooded seals in Davis Strait (2024) or outside the traditional whelping area at the Front (2012, 2017), along with low sea-ice coverage in the Gulf of St. Lawrence makes it unlikely that significant whelping was redistributed to other areas. The large decline in pup production after 2005 mirrors a similar decline and continued low level of pup production for hooded seals in the Greenland Sea that occurred between 1997 and 2005/07. Although the cause of the decline in the Northwest Atlantic is unknown, it is possible that negative impacts of ecosystem change on female fecundity and juvenile survival, as has been documented for harp seals in the Northwest Atlantic, are also impacting hooded seals.

Addressing epistemic injustices in species at risk assessments through improved credibility and legitimacy: case study of narwhal management in Ittoqqortoormiit

Thu, 13 Jun 2024 00:00:00 +0200

The regulation of seal and whale hunting in Kalaallit Nunaat (Greenland) belongs to the Naalakkersuisut (National Government), which is notably informed by the work of the Scientific Committee (SC) of the North Atlantic Marine Mammal Commission (NAMMCO). Since 2004, quotas were set in Kalaallit Nunaat to regulate hunting practices and promote ecologically sustainable harvesting. In South East Greenland, the SC's recommendations for the closure of the narwhal (Monodon monoceros or qialuar) hunt since 2019 has met both national disagreement and local resistance due to a desire to preserve the long-standing relation with narwhals organised around hunting, which is strongly intertwined within place-based communities’ experiences. The situation requires further attention to deploy an informed dialogue in the light of both available literature and local narratives capturing knowledge and values which are underrepresented within scientific discussions, as are social sciences. Grounded in repetitive and long-standing research fieldwork in Ittoqqortoormiit, and extensive qualitative data collection from 2019 to 2023, the article shows that community members express strong attachment and concern towards narwhal hunting together with the social, economic and cultural importance of mattak (narwhal skin). Local narratives also suggest that the resistance against limitations on narwhal hunting is not to be understood only as a conservatism that aims to preserve traditional hunting practices or about sustaining economic incomes for hunters, but in a significant way as protest against epistemic injustices, resulting from a feeling of being systematically unheard, distrusted and uninvolved in decision-making processes. Together with the expression of concern and attachment for narwhal hunting, the tensions between scientific knowledge and local value and knowledge were reiterated while shared concern for the preservation of the species is affirmed. We show that legitimacy and credibility of the scientific evidence and species management are contested. Ultimately, we ascertain the situation of epistemic injustices and raise the need to shift towards decolonial practices to open the possibility for the emergence of a fair and respectful dialogue that would support narwhal preservation, through securing hunters' material living conditions, community food security, and ensuring consideration and respect is given to individual and collective immaterial dimensions associated with narwhal.

Bowhead whales spend more time in waters with colder sea surface temperatures

Manh Cuong Ngo, Susanne Ditlevsen, Mads Peter Heide-Jørgensen — Wed, 18 Dec 2024 00:00:00 +0100

Marine mammals are under potential threats due to rapid ocean warming. Such threats may be especially challenging for the bowhead whale (Balaena mysticetus), an endemic arctic cetacean, because it is limited in how much further north it can go. To explore the effects of global warming on this species, data from 84 bowhead whales in Baffin Bay – West Greenland tagged with satellite linked radio transmitters during the 11 years between 2001 and 2011 were analysed. With this time series, it is possible to investigate the effect of increasing temperature of preferred water mass temperature and temperature at depth where most bowhead feeding occurs through sea surface temperature (SST) on bowhead whale behaviour. We used daily positions and daily SST to develop seasonal Tweedie generalised linear mixed models to model the duration that bowhead whales spend in 20 x 20 km cells as a function of SST. The model was fitted on a much finer spatial and temporal scale than in previous studies, thus enabling a more detailed understanding of behaviour relative to water temperature. Our study demonstrates that bowhead whales spend more time in water with colder surface temperatures, suggesting that as waters continue to warm, bowheads may move further north, potentially reducing their overall available habitat.

Distribution and habitat use of deep-diving cetaceans in the central and north-eastern North Atlantic

Thu, 19 Dec 2024 00:00:00 +0100

Major changes in the distribution of some cetaceans have been observed coincident with changing oceanography of the North Atlantic in the last 30 years. This study aimed to improve understanding of the underlying ecological drivers of any changes in deep-diving cetacean distribution. We used data from two series of summer surveys (in Iceland-Faroes and Norway) to model density of sperm (Physeter macrocephalus), long-finned pilot (Globicephala melas) and northern bottlenose (Hyperoodon ampullatus) whales as a function of static (relief), physical, and biological oceanographic covariates using GAMs. The best models, based on a robust model selection framework, were used to predict distribution. The study period was divided into two periods, 1987‑1989 and 1998-2015, based on environmental changes in the area and data availability. The common covariates that best explained these three species’ distributions (in both periods) were bathymetric variables and SST. The selected dynamic temperature-related covariates for sperm and pilot whales were for spring, but for bottlenose whales were for summer. Summer relationships were also found for the three species for the other dynamic variables, except spring chlorophyll-a for bottlenose whales. The difference in seasonal relationships for bottlenose whales may be related to a previously suggested north-south summer migration. As expected, the predicted high-use areas for all three species were deep waters, with some overlap among them in the central Norwegian Sea, and the Central North Atlantic, including the Irminger Sea. Differences in distribution likely reflect differences in prey. Changes in distribution between the two periods appear more as a range expansion than a shift, which could result from an increase in suitable habitat due to warming waters. This new knowledge will help improve understanding of how these species may respond over this wide area to a changing environment and inform their conservation.

Preface

Naima El bani Altuna, Maria Garagouni — Fri, 20 Dec 2024 00:00:00 +0100

Previous, current and future monitoring and management of common minke whales in Norway

Thu, 21 Nov 2024 00:00:00 +0100

An account of the historical, current and possible future management of common minke whales in Norway is presented. The current management is based on an approach very similar to the International Whaling Commission’s Revised Management Procedure (RMP) and requires historical and current catch statistics, together with new abundance estimates with associated variance estimates every six years. The abundance estimates are based on visual sampling online-transect sighting surveys with two independent observer platforms. These surveys are no longer economically viable with the current limited commercial harvest. Alternative methods for obtaining abundance estimates are discussed, including a simpler sighting survey design and genetic mark-recapture methods. The RMP requires Implementation Reviews desirably every six years, which take into account all new information available. The associated simulation trials are very technical and complex, and few experts have the insight to run these simulation tests. Simpler alternatives to the current Implementation Reviews are discussed. The objective is to develop more economically viable methods for abundance estimation and a simpler procedure for catch limit calculation without compromising the sustainability of the harvest. Any new procedure for abundance estimation and catch limit calculations will be submitted to the International Whaling Commission Scientific Committee for discussion.