DEVELOPMENT OF DISPERSAL, MOVEMENT PATTERNS, AND HAUL‐OUT USE BY PUP AND JUVENILE STELLER SEA LIONS (<i>EUMETOPIAS JUBATUS</i>) IN ALASKA

Raum-Suryan, Kimberly L.; Rehberg, Michael J.; Pendleton, Grey W.; Pitcher, Kenneth W.; Gelatt, Thomas S.

doi:10.1111/j.1748-7692.2004.tb01195.x

Cited by 105 publications

(138 citation statements)

References 76 publications

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“…Male Steller sea lions more often make longrange movements as juveniles than as adults (Raum-Suryan et al 2004), yet survival costs of dispersal are highest for this age-class (Table 5). Juveniles have greater mass-specific energy demands than adults due to higher growth rates and smaller body size, such that dispersing while young may be particularly risky.…”

Section: Sex Effectsmentioning

confidence: 99%

Cohort effects and spatial variation in age-specific survival of Steller sea lions from southeastern Alaska

et al. 2011

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Pitcher. 2011. Cohort effects and spatial variation in age-specific survival of Steller sea lions from southeastern Alaska.Ecosphere 2(10):111. doi:10.1890/ES11-00215.1Abstract. Information concerning mechanistic processes underlying changes in vital rates and ultimately population growth rate is required to monitor impacts of environmental change on wildlife. We estimated age-specific survival and examined factors influencing survival for a threatened population of Steller sea lions (Eumetopias jubatus) in southeastern Alaska. We used mark-recapture models and data from 1,995 individuals marked at approximately one month of age at four of five rookeries in southeastern Alaska, and resighted from Oregon to the Bering Sea. Average annual survival probability for females was 0.64 for pups and 0.77 for yearlings, and increased from 0.91 to 0.96 from age 3-7 yrs. Annual survival probability of males averaged 0.60 for pups and 0.88 by 7 yrs, resulting in probability of survival to age 7, 33% lower for males compared to females. Pups from northern southeastern Alaska (including an area of low summer population size but rapid growth) were twice as likely to survive to age 7 compared to pups from southern rookeries (including a large, historical, stable rookery). Effects of early conditions on future fitness were observed as (1) environmental conditions in the birth year equally affected first-and secondyear survival, and (2) effects of body mass at approximately one month of age were still apparent at 7 yrs. Survival from 0-2 yrs varied among five cohorts by a maximum absolute difference of 0.12. We observed survival costs for long-distance dispersal for males, particularly as juveniles. However, survival was higher for non-pups that dispersed to northern southeastern Alaska, suggesting that moving to an area with greater productivity, greater safety, or lower population size may alleviate a poor start and provide a mechanism for spatial structure for sea lion populations.

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Section: Sex Effectsmentioning

confidence: 99%

Cohort effects and spatial variation in age-specific survival of Steller sea lions from southeastern Alaska

et al. 2011

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“…However, telemetry data on Steller sea lions have been collected at only a few sites and for a relatively small number of juveniles and adult females, and provides an incomplete picture of seasonal changes in distribution because tag deployment and duration of attachment is influenced by the timing of moult (Raum-Suryan et al 2004, Pitcher et al 2005. Given the evidence of site and season-specific foraging (Loughlin et al 1998, Raum-Suryan et al 2002, Gende & Sigler 2006, ecological signals relevant to identifying sea lion habitat may be obscured if telemetry data are combined from different sites or generalized from a single season.…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

A novel presence-only validation technique for improved Steller sea lion Eumetopias jubatus critical habitat descriptions

Gregr

Trites²

2008

Mar. Ecol. Prog. Ser.

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We used published information about foraging behaviour, terrestrial resting sites, bathymetry and seasonal ocean climate to develop hypotheses relating life-history traits and physical variables to the at-sea habitat of a wide-ranging marine predator, the Steller sea lion Eumetopias jubatus. We used these hypotheses to develop a series of habitat models predicting the probability of sea lions occurring within a 3 × 3 km 2 grid in the Gulf of Alaska and the Bering Sea. We compared these deductive model predictions with opportunistic at-sea observations of sea lions (presence-only data) using (1) a likelihood approach in a small area where effort was assumed to be uniformly distributed and (2) an adjusted skewness (Sk adj ) test that evaluated the distribution of the predicted values associated with true presence observations. We found that the Sk adj statistic was comparable to the likelihood test when using pseudo-absence data, but it was more powerful for assessing the relative performance of the different predictive spatial models across the entire study area. The habitat maps we produced for adult female sea lions using the deductive modelling approach captured a higher proportion of presence observations than the current habitat model (critical habitat) used by fisheries managers since 1993 to manage Steller sea lions. Such improved predictions of habitat are necessary to effectively design, implement and evaluate fishery mitigation measures. The deductive approach we propose is suitable for modelling the habitat use of other age and sex classes, and for integrating these age/sex-class-specific models into a revised definition of critical habitat for Steller sea lions. The skewness test provides a means of comparing the relative performance of such models, using presence-only data. The approach can be readily applied to other central-place foragers. KEY WORDS: Steller sea lion · Critical habitat · Endangered species · Ecosystem management · Habitat model · Skewness · Bering Sea · Gulf of Alaska Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 365: [247][248][249][250][251][252][253][254][255][256][257][258][259][260][261] 2008 These studies have been effective primarily because the extent of the telemetry data matched the foraging range of the species under investigation. However, telemetry data on Steller sea lions have been collected at only a few sites and for a relatively small number of juveniles and adult females, and provides an incomplete picture of seasonal changes in distribution because tag deployment and duration of attachment is influenced by the timing of moult (Raum-Suryan et al. 2004, Pitcher et al. 2005. Given the evidence of site and season-specific foraging (Loughlin et al. 1998, Raum-Suryan et al. 2002, Gende & Sigler 2006, ecological signals relevant to identifying sea lion habitat may be obscured if telemetry data are combined from different sites or generalized from a single season. Consequently, combined telemetry data may no...

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“…Sea lions were captured using the underwater dive capture technique and moved to a larger boat for immobilization and processing (ADFG, Anchorage, unpubl. ;Raum-Suryan et al 2004). The combination of tag(s) that each sea lion received was scaled such that the smaller animals were not burdened by multiple or bulky tags.…”

Section: Methodsmentioning

confidence: 99%

“…For example, seasonal directed migrations of thousands of kilometers made by southern elephant seals (Mirounga leonina) across the open ocean can be effectively tracked with satellite telemetry . In contrast, juvenile Steller sea lions (Eumetopias jubatus) often conduct short trips (<15 km) in coastal regions (Raum-Suryan et al 2004). At these scales the precision of data provided by conventional satellite telemetry (Stewart et al 1989, RaumSuryan et al 2004) is insufficient to fully understand the relationships between individual movements and the features encountered on these smaller scale foraging trips.…”

Section: Introductionmentioning

confidence: 99%

“…Recent Steller sea lion telemetry research efforts have focused on the behavior of juvenile animals (Loughlin et al 2003, Raum-Suryan et al 2004, partly because of the logistic challenges in capturing adults (Loughlin 1998, Andrews et al 2002, but primarily because of the importance of reduced juvenile survival in influencing the dramatic decline in population numbers (Pascual and Adkison 1994, York 1994, Trites and Larkin 1996. Here we describe the techniques that we applied to actively track juvenile Steller sea lions from a boat during the winter and spring of [2003][2004] in Southeast Alaska.…”

Section: Introductionmentioning

confidence: 99%

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Techniques for real-time, active tracking of sea lions

Lea

Wilson²

2006

Sea Lions of the World

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The movements of otariids at sea are generally studied by satellite telemetry. At fine scales (1-20 km), however, the level of precision provided by this technique (± mean 1.5-19 km) may be insufficient to accurately reconstruct the track of an individual and/or integrate such movement data with habitat and environmental features. An alternative technique is the boat-based active tracking of individuals by very high frequency (VHF) or acoustic telemetry. By following an individual equipped with transmitters, detailed observations of habitat use, predator occurrence, social context, behavioral state, and prey availability may be integrated to provide a real-time context in which to place the animals' movements. For species such as the Steller sea lion (Eumetopias jubatus), which are difficult to recapture, such techniques enable the collection of much needed contextual information. Here we describe the methods we applied to actively track Steller sea lions. Twenty-one juveniles were captured in Southeast Alaska during October 2003 and February 2004. They were fitted with a variety of VHF, satellite, and/or acoustic tags and were tracked through the winter and spring of [2003][2004]. The use of ship-based VHF telemetry in conjunction with real time navigation plotting software was highly successful and provided 37 fine-scale tracks of coastal and pelagic 1 Current

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DEVELOPMENT OF DISPERSAL, MOVEMENT PATTERNS, AND HAUL‐OUT USE BY PUP AND JUVENILE STELLER SEA LIONS (EUMETOPIAS JUBATUS) IN ALASKA

Cited by 105 publications

References 76 publications

Cohort effects and spatial variation in age-specific survival of Steller sea lions from southeastern Alaska

Cohort effects and spatial variation in age-specific survival of Steller sea lions from southeastern Alaska

A novel presence-only validation technique for improved Steller sea lion Eumetopias jubatus critical habitat descriptions

Techniques for real-time, active tracking of sea lions

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