Harbor seal (<i>Phoca vitulina richardii</i>) decline continues in the rapidly changing landscape of Glacier Bay National Park, Alaska 1992-2008

Womble, Jamie N.; Pendleton, Grey W.; Mathews, Elizabeth A.; Blundell, Gail M.; Bool, Natalie; Gende, Scott M.

doi:10.1111/j.1748-7692.2009.00360.x

Cited by 39 publications

(83 citation statements)

References 24 publications

(58 reference statements)

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“…After the grounding of Muir Glacier in the East Arm of Glacier Bay around 1993 (Hall et al, 1995), the glacier no longer produced icebergs that seals could use as resting sites (Mathews, 1995). Before the grounding of the glacier, more than 1300 seals were documented in Muir Inlet (Streveler, Estimates of harbor seal population (non-pups only) are derived from data collected at terrestrial haulout sites (see Mathews and Pendleton, 2006;Womble et al, 2010). Moose population estimates were derived from data collected on the Gustavus forelands winter range.…”

Section: Discussionmentioning

confidence: 99%

“…More recently, however, substantially fewer seals have been counted in the East Arm of Glacier Bay, with the primary haulout areas for seals restricted to Adams Inlet, McBride Inlet, and Wachusett Inlet (Womble et al, 2010). From 1992 to 2011, harbor seals at terrestrial sites in Glacier Bay declined at a rate of 9.3% per year (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…From 1992 to 2011, harbor seals at terrestrial sites in Glacier Bay declined at a rate of 9.3% per year (Fig. 3) (Mathews and Pendleton, 2006;Womble et al, 2010;J.N. Womble, unpubl.…”

Section: Discussionmentioning

confidence: 99%

“…Salmon also have colonized recently deglaciated watersheds in Glacier Bay (Milner et al, 2007). In addition, the spatial distribution of harbor seals (Phoca vitulina richardii) has changed over the past two decades, and the number of harbor seals in Glacier Bay has decreased substantially since 1992 (Mathews and Pendleton, 2006;Womble et al, 2010). Thus, the potential terrestrial and marine prey base of wolves in Glacier Bay has changed considerably over the past several decades.…”

Section: Introductionmentioning

confidence: 99%

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Linking Wolf Diet to Changes in Marine and Terrestrial Prey Abundance

Lafferty¹,

Belant²,

White³

et al. 2014

ARCTIC

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ABSTRACT. Since most wolf (Canis lupus) diet studies have been conducted in inland ecosystems, comparatively few data are available on diets of wolves in coastal systems. We investigated the diet of wolves in Glacier Bay, Alaska, from 12 May to 28 June in both 2010 and 2011. Although we identified 12 different prey species, including birds and small to medium-sized mammals, in wolf scats, moose (Alces alces) was the most frequent food item, observed in 80% of all scats. In contrast, a study conducted in 1993 in an area 37 km away found harbor seal (Phoca vitulina richardii) in 41% of wolf scats. Although we cannot account for differences in sampling design between the two studies, wolf diets may have changed between the two time periods.Key words: wolves, Canis lupus, diet, Glacier Bay, Alaska RÉSUMÉ. Puisque la plupart des études sur le régime alimentaire des loups (Canis lupus) ont été réalisées dans des écosystèmes situés à l'intérieur des terres, relativement peu de données existent sur le régime alimentaire des loups évoluant dans les environnements côtiers. Nous avons étudié l'alimentation des loups de Glacier Bay, en Alaska, du 12 mai au 28 juin 2010 et 2011. Bien que nous ayons retrouvé 12 proies différentes, y compris des espèces aviaires et des mammifères de taille petite ou de taille moyenne dans les déjections de loups, l'aliment le plus fréquemment rencontré, dans une mesure de 80 %, a été l'orignal, aussi appelé élan (Alces alces). Par contraste, une étude effectuée en 1993 dans une zone située à 37 kilomètres de distance a permis de découvrir du phoque commun (Phoca vitulina richardii) dans 41 % des déjections de loups. Bien que nous ne soyons pas en mesure de prendre en compte les différences d´échantillonnage entre les deux études, il est possible que le régime alimentaire des loups ait changé entre ces deux périodes.Mots clés : loups, Canis lupus, régime alimentaire, Glacier Bay, Alaska Révisé pour la revue Arctic par Nicole Giguère.Тезис. Большинство исследований рациона волка (Canis lupus) проводилось на внутриматериковых территориях, в то время как имеется сравнительно небольшое количество данных по рациону волка в прибрежных экосистемах. Ежегодно с 12 мая по 28 июня 2010-2011 гг. нашей группой проводились исследования рациона волков в бухте Глейшер-Бей, Аляска. Несмотря на то, что нами было определено 12 различных видов, используемых волками в качестве добычи, включая птиц, а также мелких и средних млекопитающих, останки лося (Alces alces) встречались в 80% экскрементов волков, указывая на то, что данный вид является наиболее частым пищевым объектом волка. В отличие от данных результатов, эксперимент, проведенный в 1993 г. на участке, удаленном от нашего на 37 км, обнаружил наличие останков тюленя (Phoca vitulina richardii) в 41% экскрементов волков. Несмотря на то, что мы не можем объяснить различия в выборке по каждому из исследований, их результаты указывают на то, что в период между двумя исследованиями в рационе волков могли произойти изменения.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…From 1992 to 2011, harbor seals at terrestrial sites in Glacier Bay declined at a rate of 9.3% per year (Fig. 3) (Mathews and Pendleton, 2006;Womble et al, 2010;J.N. Womble, unpubl.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Linking Wolf Diet to Changes in Marine and Terrestrial Prey Abundance

Lafferty¹,

Belant²,

White³

et al. 2014

ARCTIC

Self Cite

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“…The park is characterized by highly variable bathymetry containing multiple sill-basin complexes, which cause strong up welling and complex current systems with resulting high levels of primary and secondary productivity (Hooge & Hooge 2002). The high net community productivity (Reisdorph & Mathis 2014) supports large aggregations of marine mammals including sea otters Enhydra lutris (Bodkin et al 2007), Stellar sea lions Eumetopias jubatus (Mathews et al 2011), and harbor seals Phoca vitulina richardii (Womble et al 2010).…”

Section: Study Areamentioning

confidence: 99%

Factors affecting whale detection from large ships in Alaska with implications for whale avoidance

Williams¹,

Gende²,

Lukacs³

et al. 2016

Endang. Species. Res.

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Calibrating and adjusting counts of harbor seals in a tidewater glacier fjord to estimate abundance and trends 1992 to 2017

et al. 2020

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Long-term monitoring for understanding status and trend of species of conservation concern is undeniably valuable, yet monitoring methods often evolve over time due to the development of new technology, fluctuations in funding, logistical constraints, and innovations in sampling methods or analytical approaches. Consequently, valuable insights into annual or decadal-scale trends can be lost unless calibration between historical and current methods is developed. Glacier Bay National Park, in southeastern Alaska, hosts an important regional population of harbor seals, with the majority of seals pupping and molting on icebergs calved from a tidewater glacier in Johns Hopkins Inlet. Monitoring efforts to assess abundance and trends of harbor seals used counts of seals by shore-based observers from 1992 to 2002, but transitioned to aerial photographic surveys in 2007 through 2017. To produce a rigorous long-term evaluation of abundance and trends of harbor seals, we (1) conducted concurrent shore-based counts and aerial photographic surveys in 2007 and 2008; (2) developed an analytical calibration between the two monitoring methods; (3) developed a haul-out model to estimate the number of harbor seals in the water at the time of counts; and (4) estimated abundance and trends of harbor seals from 1992 to 2017 from the adjusted counts. Our calibration analysis revealed that during the pupping season in June, counts of harbor seals by observers from shore were consistently lower than counts from aerial surveys. During the molting season, counts by shore-based observers were only slightly less than aerial photographic surveys, and there was an interaction between survey method and season. After calibrating methods, we found important decadal-scale changes in trend. Over the 26-yr period (1992-2017), the estimated trend was negative; however, trends computed for rolling 10-yr time intervals showed steep and significant declines ending around 2011, with leveling off and possibly some subsequent recovery. The most recent shorter-term (2013-2017) trends are negative again, rivaling the steepest decreases over the 26-yr period. Our calibration between two monitoring methods improved continuity for long-term monitoring for a species of conservation concern by taking advantage of new sampling methods and innovations in analytical approaches.

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Harbor seal (Phoca vitulina richardii) decline continues in the rapidly changing landscape of Glacier Bay National Park, Alaska 1992-2008

Cited by 39 publications

References 24 publications

Linking Wolf Diet to Changes in Marine and Terrestrial Prey Abundance

Linking Wolf Diet to Changes in Marine and Terrestrial Prey Abundance

Factors affecting whale detection from large ships in Alaska with implications for whale avoidance

Calibrating and adjusting counts of harbor seals in a tidewater glacier fjord to estimate abundance and trends 1992 to 2017

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