A spatial hierarchical model for abundance of three ice-associated seal species in the eastern Bering Sea

Hoef, Jay M. Ver; Cameron, Michael F.; Boveng, Peter L.; London, Josh M.; Moreland, Erin E.

doi:10.1016/j.stamet.2013.03.001

Cited by 39 publications

(53 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results are somewhat contradictory to those discovered by Simpkins et al (2003), which showed that bearded seals off of St. Lawrence Island preferred sea ice cover between 70 and 90 % and tended to avoid areas with greater than 90 % cover. However, a more recent study showed that bearded seals seem to be a more ''interior'' seal species and were typically found on sea ice cover between 25 and 100 % (Ver Hoef et al 2013). Our results support the more recent findings; however, sea ice concentration in this study is measured at 12.5 km resolution and averaged over a 20 km radius.…”

Section: Discussionsupporting

confidence: 87%

Year-round acoustic detection of bearded seals (Erignathus barbatus) in the Beaufort Sea relative to changing environmental conditions, 2008–2010

et al. 2013

Self Cite

View full text Add to dashboard Cite

192 Hz. Spectrograms of acoustic data were examined for characteristic patterns of bearded seal vocalizations. For each recorder, the number of hours per day with vocalizations was compared with in situ water temperature and satellite-derived daily sea ice concentrations. At all sites, bearded seals were vocally active yearround. Call activity escalated with the formation of pack ice in the winter and the peak occurred in the spring, coinciding with mating season and preceding breakup of the sea ice. There was a change in the timing of seasonal sea ice formation and retreat between the two consecutive years that was reflected in the timing of peak bearded seal call activity. This study provides new information on fall and winter bearded seal vocal behavior and the relationship between year-round vocal activity and changes in annual sea ice coverage and in situ water temperature.

show abstract

Section: Discussionsupporting

confidence: 87%

Year-round acoustic detection of bearded seals (Erignathus barbatus) in the Beaufort Sea relative to changing environmental conditions, 2008–2010

et al. 2013

Self Cite

View full text Add to dashboard Cite

show abstract

“…For instance, our seal density estimates compared favourably to results from 2006 helicopter transect surveys over a 279 880‐km 2 subset of our study area (Ver Hoef et al . ), where densities were estimated as 0·22 bearded seals km −2 (95% CI 0·12–0·61), 0·22 ribbon seals km −2 (95% CI 0·13–0·68) and 0·84 spotted seals km −2 (95% CI 0·49–2·83). In addition to the actual numbers, the relationships between abundance and underlying landscape and environmental covariates may also be of interest.…”

Section: Discussionmentioning

confidence: 99%

“…Ver Hoef et al . ), possibly due to the uncharacteristically high levels of ice in the Bering Sea in 2012. We plan to build upon this modelling framework to arrive at more definitive estimates of seal abundance and covariate relationships in the near future.…”

Section: Discussionmentioning

confidence: 99%

Estimating multispecies abundance using automated detection systems: ice‐associated seals in the Bering Sea

et al. 2013

View full text Add to dashboard Cite

Summary1. Automated detection systems employing advanced technology (e.g. infrared imagery, auditory recording systems, pattern recognition software) are compelling tools for gathering animal abundance and distribution data since investigators can often collect data more efficiently and reduce animal disturbance relative to surveys using human observers. 2. Even with these improvements, analysing animal abundance with advanced technology can be challenging because of potential for incomplete detection, false positives and species misidentification. We argue that double sampling with an independent sampling method can provide the critical information needed to account for such errors.3. We present a hierarchical modelling framework for jointly analysing automated detection and double sampling data obtained during animal population surveys. Under our framework, observed counts in different sampling units are conceptualized as having arisen from a thinned log-Gaussian Cox process subject to spatial autocorrelation (where thinning accounts for incomplete detection). For multispecies surveys, our approach handles incomplete species observations owing to (i) structural uncertainties (e.g. in cases where the automatic detection data do not provide species observations) and (ii) species misclassification; the latter requires auxiliary information on the misclassification process. 4. As an example of combining an automated detection system and a double sampling procedure, we consider the problem of estimating animal abundance from aerial surveys that use infrared imagery to detect animals, and independent, high-resolution digital photography to provide information on species composition and thermal detection accuracy. We illustrate our approach by analysing simulated data and data from a survey of four iceassociated seal species in the eastern Bering Sea. 5. Our analysis indicated reasonable performance of our hierarchical modelling approach, but suggested a need to balance model complexity with the richness of the data set. For example, highly parameterized models can lead to spuriously high predictions of abundance in areas that are not sampled, especially when there are large gaps in spatial coverage. 6. We recommend that ecologists employ double sampling when enumerating animal populations with automated detection systems to estimate and correct for detection errors. Combining multiple data sets within a hierarchical modelling framework provides a powerful approach for analysing animal abundance over large spatial domains.

show abstract

“…It is possible that more hauled-out seals may have been encountered had the aerial surveys been conducted mid-day as recommended by Lake et al (1997), and if more frequent surveys were conducted within and between seasons. We, therefore, recommend that future surveys in the area take into account the time of the aerial surveys and adopt standardized, quantitative methods for design or model-based estimates such as those used by Southwell (2005), Conn et al (2013), andver Hoef et al (2014).…”

Section: Discussionmentioning

confidence: 99%

Aerial surveys for pack-ice seals along the Ingrid Christensen and Princess Astrid Coasts, East Antarctica

Kumar¹,

Johnson²

2014

J. Threat. Taxa

View full text Add to dashboard Cite

A spatial hierarchical model for abundance of three ice-associated seal species in the eastern Bering Sea

Cited by 39 publications

References 12 publications

Year-round acoustic detection of bearded seals (Erignathus barbatus) in the Beaufort Sea relative to changing environmental conditions, 2008–2010

Year-round acoustic detection of bearded seals (Erignathus barbatus) in the Beaufort Sea relative to changing environmental conditions, 2008–2010

Estimating multispecies abundance using automated detection systems: ice‐associated seals in the Bering Sea

Aerial surveys for pack-ice seals along the Ingrid Christensen and Princess Astrid Coasts, East Antarctica

Contact Info

Product

Resources

About