Mike O. Hammill, G. Stenson, T. Doniol-Valcroze, Shelley L. C. Lang
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.
{"title":"Application of the Precautionary Approach to the Management of Marine Mammals in northern Canada","authors":"Mike O. Hammill, G. Stenson, T. Doniol-Valcroze, Shelley L. C. Lang","doi":"10.7557/3.7413","DOIUrl":"https://doi.org/10.7557/3.7413","url":null,"abstract":"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. ","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"24 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141807332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tanguy Sandré, J. Vanderlinden, Jeanne-Marie Gherardi, Zhiwei Zhu, F. Wickson
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.
{"title":"Addressing epistemic injustices in species at risk assessments through improved credibility and legitimacy: case study of narwhal management in Ittoqqortoormiit","authors":"Tanguy Sandré, J. Vanderlinden, Jeanne-Marie Gherardi, Zhiwei Zhu, F. Wickson","doi":"10.7557/3.7371","DOIUrl":"https://doi.org/10.7557/3.7371","url":null,"abstract":"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.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"36 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141349292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The last extensive (pan-Arctic) review on knowledge available on the bearded seal (Erignathus barbatus) was conducted by Cameron et al. in 2010. As bearded seals are hunted off Svalbard and Greenland but no stock assessments are available, NAMMCO requested a status review, and if possible, an assessment of the species in its area. This literature review attempts to summarise the knowledge that has become available post 2010, with a focus on the Atlantic Arctic. A large amount of information has become available on the behaviour of the bearded seal, with hearing, vocalisation, haul-out behaviour and movement patterns (through satelitte tagging), and their phenology, being well studied. A database of baseline blood parameters is slowly being built but is still limited. New data on distribution has emerged from PAM studies and non-targeted surveys. Abundance estimates are missing for Svalbard, but partial estimates have become available for the North Water Polynya in 2009 and 2014. Additionally, observations of bearded seals from aerial line-transect surveys are available for several areas of Greenland but have not been analysed. More information has become available on the impact of anthropogenic stressors, such as climate change and other related environmental changes, although demographic impacts of changes are missing. Catch data exists for both Svalbard and Greenland, but for the latter the data needs to be thoroughly validated. In summary, information on stock structure as well as local and global abundance estimates, which are both important to assess the sustainability of current catches, are still missing. However other lines of evidence can inform the delineation of management areas and the results of a pan-arctic genetic study should become available shortly. There is survey data available from Greenland that could be used to generate local abundance estimates, the analysis of which should be prioritised.
{"title":"Bearded seals in the Atlantic Arctic: review of post 2010 knowledge available for informing stock assessments","authors":"Nicolai Scherdin, Jana Djukarić, G. Desportes","doi":"10.7557/3.6883","DOIUrl":"https://doi.org/10.7557/3.6883","url":null,"abstract":"The last extensive (pan-Arctic) review on knowledge available on the bearded seal (Erignathus barbatus) was conducted by Cameron et al. in 2010. As bearded seals are hunted off Svalbard and Greenland but no stock assessments are available, NAMMCO requested a status review, and if possible, an assessment of the species in its area. This literature review attempts to summarise the knowledge that has become available post 2010, with a focus on the Atlantic Arctic. A large amount of information has become available on the behaviour of the bearded seal, with hearing, vocalisation, haul-out behaviour and movement patterns (through satelitte tagging), and their phenology, being well studied. A database of baseline blood parameters is slowly being built but is still limited. New data on distribution has emerged from PAM studies and non-targeted surveys. Abundance estimates are missing for Svalbard, but partial estimates have become available for the North Water Polynya in 2009 and 2014. Additionally, observations of bearded seals from aerial line-transect surveys are available for several areas of Greenland but have not been analysed. More information has become available on the impact of anthropogenic stressors, such as climate change and other related environmental changes, although demographic impacts of changes are missing. Catch data exists for both Svalbard and Greenland, but for the latter the data needs to be thoroughly validated. In summary, information on stock structure as well as local and global abundance estimates, which are both important to assess the sustainability of current catches, are still missing. However other lines of evidence can inform the delineation of management areas and the results of a pan-arctic genetic study should become available shortly. There is survey data available from Greenland that could be used to generate local abundance estimates, the analysis of which should be prioritised.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42197018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abundance estimation of narwhals is usually done with either visual or photographic aerial surveys. The basic estimation for both methods is detection of whales at the surface, and to obtain fully corrected abundance estimates, the at-surface detections need to be corrected for the proportion of whales that, at any given time, is available to be detected at the surface. The surfacing time or ‘availability correction factor’ is obtained from whales instrumented with dive recorders, that either relay concatenated information on the proportion of time spent at different depth intervals to satellites, or from recovered instruments that collect complete dive profiles, measured at high frequency. Concatenated data binned in depth histograms from Satellite-Linked-Time-Depth-Recorders (SLTDR) falls in two categories, where those that correct the zero depth values with information from the saltwater switch provide larger and apparently more accurate surfacing times, than those collected from instruments that does not correct the zero depth readings. The erroneous detection of near-surface pressure values is likely due to slow response of pressure transducers made from temperature sensitive materials. The high frequency sampling from AcousondeTM recorders documents erroneous surface detections, and adjustments of the dive profiles are needed to obtain realistic near-surface values. Any reconstruction of dive profiles and near-surface values apparently involves some level of corrections and it is recommended, for development of availability correction factors for aerial surveys, that data from zero-adjusted SLTDRs or TDR instruments are used. The mean estimate of surface time from 7 SLTDRs was 29% (CV=0.05). One SLTDR, with steel pressure transducer and zero-adjustments, that was retrieved from the whale, provided a particular long-record (83 days) of reliable high-resolution data. The surface time for this sample was 31%, when calculated as the sum of all depth readings at or above 2 m. The mean of 144 hourly depth readings during 06:00-18:00, and including dives above 3m, was 27.36% (CV=0.8) for 12 days overlapping with the usual timing of aerial surveys. Accurate estimation of smaller depth bins (e.g. 0-1 m) should, even with high resolution instruments, be used with caution when estimating availability bias.
{"title":"On the availability bias in narwhal abundance estimates","authors":"M. Heide‐Jørgensen, J. Lage","doi":"10.7557/3.6518","DOIUrl":"https://doi.org/10.7557/3.6518","url":null,"abstract":"Abundance estimation of narwhals is usually done with either visual or photographic aerial surveys. The basic estimation for both methods is detection of whales at the surface, and to obtain fully corrected abundance estimates, the at-surface detections need to be corrected for the proportion of whales that, at any given time, is available to be detected at the surface. The surfacing time or ‘availability correction factor’ is obtained from whales instrumented with dive recorders, that either relay concatenated information on the proportion of time spent at different depth intervals to satellites, or from recovered instruments that collect complete dive profiles, measured at high frequency. Concatenated data binned in depth histograms from Satellite-Linked-Time-Depth-Recorders (SLTDR) falls in two categories, where those that correct the zero depth values with information from the saltwater switch provide larger and apparently more accurate surfacing times, than those collected from instruments that does not correct the zero depth readings. The erroneous detection of near-surface pressure values is likely due to slow response of pressure transducers made from temperature sensitive materials. The high frequency sampling from AcousondeTM recorders documents erroneous surface detections, and adjustments of the dive profiles are needed to obtain realistic near-surface values. Any reconstruction of dive profiles and near-surface values apparently involves some level of corrections and it is recommended, for development of availability correction factors for aerial surveys, that data from zero-adjusted SLTDRs or TDR instruments are used. The mean estimate of surface time from 7 SLTDRs was 29% (CV=0.05). One SLTDR, with steel pressure transducer and zero-adjustments, that was retrieved from the whale, provided a particular long-record (83 days) of reliable high-resolution data. The surface time for this sample was 31%, when calculated as the sum of all depth readings at or above 2 m. The mean of 144 hourly depth readings during 06:00-18:00, and including dives above 3m, was 27.36% (CV=0.8) for 12 days overlapping with the usual timing of aerial surveys. Accurate estimation of smaller depth bins (e.g. 0-1 m) should, even with high resolution instruments, be used with caution when estimating availability bias.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44625788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Regular harbour seal (Phoca vitulina) population censuses are necessary to monitor fluctuations in the population size and to inform seal management. In this paper, the status of the Icelandic harbour seal population is presented, along with trends in the population over a 40-year period. In total, 13 full aerial censuses were carried out during the moulting season (July-August) between 1980 and 2020. The most recent census from 2020 yielded an estimate of 10,319 (CI 95%= 6,733-13,906) animals, indicating that the population is 69.04% smaller than when systematic monitoring of the population commenced in 1980 (33,327 seals). The observed decrease puts the population on the national red list for threatened populations. Trend analyses indicate that most of the decline occurred during the first decade, when the population decreased about 50% concurrently with large human induced removals of harbour seals. After that point, the population decline slowed down but continued, and currently the population seems to fluctuate around a stable minimum level. The sensitive conservation status of the population underlines the need to assess and sustainably manage current threats to the population, including human induced removals, anthropogenic disturbance, and various environmental factors such as contaminants, climate change and fluctuation in prey availability. Furthermore, it is urgent to continue regular censuses and to increase monitoring of population demographic factors.
{"title":"The Icelandic harbour seal (Phoca vitulina) population: trends over 40 years (1980–2020) and current threats to the population.","authors":"S. M. Granquist","doi":"10.7557/3.6328","DOIUrl":"https://doi.org/10.7557/3.6328","url":null,"abstract":"Regular harbour seal (Phoca vitulina) population censuses are necessary to monitor fluctuations in the population size and to inform seal management. In this paper, the status of the Icelandic harbour seal population is presented, along with trends in the population over a 40-year period. In total, 13 full aerial censuses were carried out during the moulting season (July-August) between 1980 and 2020. The most recent census from 2020 yielded an estimate of 10,319 (CI 95%= 6,733-13,906) animals, indicating that the population is 69.04% smaller than when systematic monitoring of the population commenced in 1980 (33,327 seals). The observed decrease puts the population on the national red list for threatened populations. Trend analyses indicate that most of the decline occurred during the first decade, when the population decreased about 50% concurrently with large human induced removals of harbour seals. After that point, the population decline slowed down but continued, and currently the population seems to fluctuate around a stable minimum level. The sensitive conservation status of the population underlines the need to assess and sustainably manage current threats to the population, including human induced removals, anthropogenic disturbance, and various environmental factors such as contaminants, climate change and fluctuation in prey availability. Furthermore, it is urgent to continue regular censuses and to increase monitoring of population demographic factors.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44122697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Székely, Kristina M. Cammen, Morten Tange Olsen
Marine mammals in the North Atlantic have experienced severe depletions due to overexploitation. While some species and populations have now recovered, there are numerous other anthropogenic activities impacting their North Atlantic ecosystem. Studying marine mammals is often associated with logistical challenges, and many species have an elusive nature, resulting in substantial knowledge gaps on the distribution, abundance and diversity of marine mammals in the North Atlantic. Environmental DNA (eDNA) is an emerging tool in biodiversity monitoring and has successfully been demonstrated to complement traditional monitoring methods for a wide range of marine taxonomic groups. The promising potential of seawater eDNA is owe to advances within an array of molecular methods used to extract, detect and/or sequence the genetic material of marine organisms from a single seawater sample. We present a literature review of eDNA studies of marine mammals and discuss the potential applications and practical challenges of eDNA in marine mammal research, management and conservation. Environmental DNA has already been introduced to a wide range of applications within marine mammal science, from detection of endangered species to population genetic assessments. Furthermore, eDNA has the power to capture other biologically important species in the marine ecosystem and food web, which could facilitate insight into the spatiotemporal variation of different marine communities in a changing environment. With methodological and technological standardization, eDNA based approaches have a promising potential to be integrated into regular monitoring practices and management strategies.
{"title":"Needles in an ocean haystack: using environmental DNA to study marine mammals in the North Atlantic","authors":"D. Székely, Kristina M. Cammen, Morten Tange Olsen","doi":"10.7557/3.6482","DOIUrl":"https://doi.org/10.7557/3.6482","url":null,"abstract":"Marine mammals in the North Atlantic have experienced severe depletions due to overexploitation. While some species and populations have now recovered, there are numerous other anthropogenic activities impacting their North Atlantic ecosystem. Studying marine mammals is often associated with logistical challenges, and many species have an elusive nature, resulting in substantial knowledge gaps on the distribution, abundance and diversity of marine mammals in the North Atlantic. Environmental DNA (eDNA) is an emerging tool in biodiversity monitoring and has successfully been demonstrated to complement traditional monitoring methods for a wide range of marine taxonomic groups. The promising potential of seawater eDNA is owe to advances within an array of molecular methods used to extract, detect and/or sequence the genetic material of marine organisms from a single seawater sample. \u0000We present a literature review of eDNA studies of marine mammals and discuss the potential applications and practical challenges of eDNA in marine mammal research, management and conservation. \u0000Environmental DNA has already been introduced to a wide range of applications within marine mammal science, from detection of endangered species to population genetic assessments. Furthermore, eDNA has the power to capture other biologically important species in the marine ecosystem and food web, which could facilitate insight into the spatiotemporal variation of different marine communities in a changing environment. With methodological and technological standardization, eDNA based approaches have a promising potential to be integrated into regular monitoring practices and management strategies.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48479820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The common minke whale (Balaenoptera acutorostrata acutorostrata) is a migratory species, and the summer period is generally characterized by intensive feeding and consequently seasonal fattening at high latitudes. The fat deposited is stored as energy reserves for overwintering at lower latitudes where feeding is supposed to be greatly reduced. It is therefore expected that their body condition on the summer feeding grounds will reflect foraging success during their most intensive feeding period and thus indicate how well the high latitude ecosystems can support the populations. During the commercial catch operations on feeding grounds in Norwegian waters, body condition data (blubber thickness and girth) have been collected from 13 937 common minke whales caught during the period 1993-2020. To investigate associations between body condition and area usage in minke whales, we applied three statistical approaches: regressions, canonical correlations, and spatiotemporal effect estimations. The analyses revealed a significant negative trend in blubber thickness from 1993 until 2015. After 2015, the trend was reversed, and blubber thickness values increased significantly. It has previously been suggested that there may be a link between the decreased minke whale blubber thickness and the abundance of the Northeast Arctic cod (Gadus morhua) stock which increased to a record high level between 2006 and 2013. Recruitment to the cod stock in more recent years has been low with a subsequent and continuous decrease in the total stock after 2013 to a current level which is presumably approximately 60% of the 2013 level. Interestingly, the observed common minke whale body condition was at its lowest in 2015, after which it has increased. This may support a connection between cod abundance and common minke whale body condition.
{"title":"Recent trends in temporal and geographical variation in blubber thickness of common Minke whales (Balaenoptera acutorostrata acutorostrata) in the Northeast Atlantic","authors":"H. Solvang, T. Haug, N. Øien","doi":"10.7557/3.6308","DOIUrl":"https://doi.org/10.7557/3.6308","url":null,"abstract":"The common minke whale (Balaenoptera acutorostrata acutorostrata) is a migratory species, and the summer period is generally characterized by intensive feeding and consequently seasonal fattening at high latitudes. The fat deposited is stored as energy reserves for overwintering at lower latitudes where feeding is supposed to be greatly reduced. It is therefore expected that their body condition on the summer feeding grounds will reflect foraging success during their most intensive feeding period and thus indicate how well the high latitude ecosystems can support the populations. During the commercial catch operations on feeding grounds in Norwegian waters, body condition data (blubber thickness and girth) have been collected from 13 937 common minke whales caught during the period 1993-2020. To investigate associations between body condition and area usage in minke whales, we applied three statistical approaches: regressions, canonical correlations, and spatiotemporal effect estimations. The analyses revealed a significant negative trend in blubber thickness from 1993 until 2015. After 2015, the trend was reversed, and blubber thickness values increased significantly. It has previously been suggested that there may be a link between the decreased minke whale blubber thickness and the abundance of the Northeast Arctic cod (Gadus morhua) stock which increased to a record high level between 2006 and 2013. Recruitment to the cod stock in more recent years has been low with a subsequent and continuous decrease in the total stock after 2013 to a current level which is presumably approximately 60% of the 2013 level. Interestingly, the observed common minke whale body condition was at its lowest in 2015, after which it has increased. This may support a connection between cod abundance and common minke whale body condition.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46383861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Stenson, J. Gosselin, J. Lawson, A. Buren, P. Goulet, Shelley L. C. Lang, K. Nilssen, M. Hammill
Photographic and visual aerial surveys were conducted off Newfoundland and Labrador (”the Front”), and in the Gulf of St. Lawrence (“Gulf”) in March 2017 to estimate pup production of Northwest Atlantic harp seals (Pagophilus groenlandicus). Traditionally, harp seals pup (whelp) in three general areas; the southern Gulf of St. Lawrence, the northern Gulf of St. Lawrence, and off the east coast of Newfoundland and Labrador. After extensive reconnaissance, four whelping areas were identified: one in each of the southern and northern Gulf, and two at the Front. We estimated a total pup production in 2017 of 746,500 (SE=89,900, CV=12%), the lowest since 1994. Most (96%) pups were born at the Front (714,600 pups, SE=89,700). Very few pups were born in the southern Gulf (18,300, SE=1,500) and no whelping concentrations were observed prior to March 5, approximately one week later than previously observed. This is far lower than the 2012 survey estimate of 115,500 (SE=15,100) for the same area. Pup production in the northern Gulf was also lower than in previous years, at 13,600 (SE=3,000). The timing of births in the southern Gulf was much later than normal in 2017, and unusually early pupping at the Front suggests that some females from the Gulf herd may have moved to the Front to whelp due to a lack of ice suitable for pupping (i.e., thin first year) in the Gulf. Harp seals whelp in large concentrations. While one large whelping concentration formed at the Front, approximately 15% of the pupping at the Front occurred in small, dispersed groups which formed later than observed in previous years. Given the unusual ice conditions, distribution of whelping seals, and timing of pupping, assessing the results of the 2017 surveys relative to other estimates of pup production in the Northwest Atlantic is challenging and indicates the ongoing difficulties of assessing a population that is being impacted by climate change.
{"title":"Pup production of Harp Seals in the Northwest Atlantic in 2017 during a time of ecosystem change","authors":"G. Stenson, J. Gosselin, J. Lawson, A. Buren, P. Goulet, Shelley L. C. Lang, K. Nilssen, M. Hammill","doi":"10.7557/3.6214","DOIUrl":"https://doi.org/10.7557/3.6214","url":null,"abstract":"Photographic and visual aerial surveys were conducted off Newfoundland and Labrador (”the Front”), and in the Gulf of St. Lawrence (“Gulf”) in March 2017 to estimate pup production of Northwest Atlantic harp seals (Pagophilus groenlandicus). Traditionally, harp seals pup (whelp) in three general areas; the southern Gulf of St. Lawrence, the northern Gulf of St. Lawrence, and off the east coast of Newfoundland and Labrador. After extensive reconnaissance, four whelping areas were identified: one in each of the southern and northern Gulf, and two at the Front. We estimated a total pup production in 2017 of 746,500 (SE=89,900, CV=12%), the lowest since 1994. Most (96%) pups were born at the Front (714,600 pups, SE=89,700). Very few pups were born in the southern Gulf (18,300, SE=1,500) and no whelping concentrations were observed prior to March 5, approximately one week later than previously observed. This is far lower than the 2012 survey estimate of 115,500 (SE=15,100) for the same area. Pup production in the northern Gulf was also lower than in previous years, at 13,600 (SE=3,000). The timing of births in the southern Gulf was much later than normal in 2017, and unusually early pupping at the Front suggests that some females from the Gulf herd may have moved to the Front to whelp due to a lack of ice suitable for pupping (i.e., thin first year) in the Gulf. Harp seals whelp in large concentrations. While one large whelping concentration formed at the Front, approximately 15% of the pupping at the Front occurred in small, dispersed groups which formed later than observed in previous years. Given the unusual ice conditions, distribution of whelping seals, and timing of pupping, assessing the results of the 2017 surveys relative to other estimates of pup production in the Northwest Atlantic is challenging and indicates the ongoing difficulties of assessing a population that is being impacted by climate change.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44583864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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