Guadalupe Fur Seal Population Expansion and its Post-breeding Male Migration to the Gulf of Ulloa, México

Aurioles‐Gamboa, David; Pablo-Rodríguez, Nereyda; Rosas‐Hernández, Martha P.; Hernández‐Camacho, Claudia J.

doi:10.1201/9781315151588-7

Cited by 5 publications

(10 citation statements)

References 27 publications

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“…In February and March of 2013 and 2015, a massive stranding of starving sea lion pups named "unusual mortality event" was observed in the Pacific US westcoast (NOAA). This event also involved the Pacific of Baja California, California sea lion population that showed a decrease of pups and adult females in 2014(Elorriaga et al, 2015 and in the same region in 2015 it was registered an anomalous dispersion of Guadalupe fur seal to northern areas in California, Oregon and British Columbia (Canada) (Aurioles-Gamboa, Rodríguez, Rosas, & Hernández-Camacho, 2017). In 2015, a high number of Guadalupe fur seal juvenile and pups were found stranded along the coast of California (Aurioles-Gamboa et al 2017).…”

Section: Climatic Moderate Variability (2000-2010) Population Stabilmentioning

confidence: 98%

Review of California sea lion (Zalophus californianus) abundance, and population dynamics in the Gulf of California

Masper

2019

RBT

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The life history of California sea lion (Zalophus californianus) in the California Gulf is marked by a series of important events influencing and modifying its population growth, evolution and distribution. Despite the fact that the population has been studied since the 1950s, research has been have been rather punctual and fragmentary, before 2010, there are a very few censuses conducted simultaneously in all rookeries, which prevent obtaining information on key aspects of life cycle, population trend and potential threats. In the present work we conducted a thorough review encompassing the last 37 years of California sea lion life history and environment in the Gulf of California. This allowed an opportunity to focus on short- and long-term processes acting on the population and hopefully improve knowledge about the population trend and status and unveil some latent aspects hardly recognizable using a partial vision. We collected and analyzed data from different sources since the 1970s to 2018: published papers, master’s and doctoral thesis, in addition to technical reports. The data is organized in sections corresponding with crucial population life history events. Considering a long-time frame period the population could appear stable with zero growth due to the cyclic interannual fluctuation that could denote a certain dependence with climatic factors, not directly with El Niño event, but with sea surface temperature anomalies that determine a change in prey availability. However, many doubts persist about the incidence of different local environmental factors on gender and age, particularly related with juvenile recruitment and female survival rate. More information is required based on seasonal censuses, life cycle, regional environmental variation; statistical errors need to be assessed and monitoring methods should be standardized and must be considered to ascertain short- and long-term population and colony spatial-temporal patterns.

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Section: Climatic Moderate Variability (2000-2010) Population Stabilmentioning

confidence: 98%

Review of California sea lion (Zalophus californianus) abundance, and population dynamics in the Gulf of California

Masper

2019

RBT

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“…2c). While these positive changes bode well for the future of Guadalupe fur seals, notable drops in numbers from one year to the next and the volatile variability in counts in recent years at the San Benito Islands suggest they may be particularly vulnerable to shifts in the availability of prey caused by extreme climatic events such as occurred in 2014 (the Blob) and 2015 (El Niño) (Cavole et al 2016, Elorriaga-Verplancken et al 2016b, Aurioles-Gamboa et al 2017.…”

Section: Pvamentioning

confidence: 89%

“…The San Benito Islands colony can be considered the 'bedroom community' of the Guadalupe Island colo ny. It is essentially a resting place where large numbers of non-breeding animals born on Guadalupe Island stay between feeding trips (Aurioles-Gamboa et al 2017). A small number of pups are born here (< 30 pups; Table 1), but it is not yet large enough to be considered a breeding site.…”

Section: Pvamentioning

confidence: 99%

“…However, unusual numbers of fur seals of different age and sex classes stranded in recent years throughout parts of their former distribution and beyond (i.e. central California, Pacific coast of Mexico, Gulf of California, and Vancouver Island in British Columbia, Canada) (Villegas-Zurita et al 2015, Elorriaga-Verplancken et al 2016a, Aurioles-Gamboa et al 2017, Carretta et al 2017. Equally troublesome are the recent numbers of young seals that have stranded and died along the coasts of California and Baja California, as well as the dead adult and subadult fur seals that have washed ashore (Aurioles-Gamboa et al 2017, Carretta et al 2017.…”

Section: Introductionmentioning

confidence: 99%

“…It ex tended to the Baja California peninsula and affected organisms at all levels of the food web (Kintisch 2015). The adult and subadult male fur seals that stranded on the Baja California peninsula during the post-breeding migration were possibly using a new feeding ground in the Gulf of Ulloa (Aurioles-Gamboa et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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Population viability analysis of Guadalupe fur seals Arctocephalus townsendi

Hernández‐Camacho¹,

Trites²

2018

Endang. Species. Res.

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The Guadalupe fur seal Arctocephalus townsendi was intensively hunted and considered extinct by the end of the 1800s. However, small numbers (< 20 seals) were reported on Guadalupe Island (Mexico) in the mid-1950s and were observed at a second location (San Benito Islands, Mexico) in the late 1990s. Sporadic counts at these 2 sites have followed a relatively rapid increase in numbers, but considerable uncertainty remains about the long-term viability of this recovering species. We performed a population viability analysis using historic seal counts from Guadalupe Island and the San Benito Islands to predict the probability of each colony (and both colonies combined) going extinct under 3 critical population threshold scenarios (100, 500, and 1000 seals). Using a diffusion approximation model, we found that the growth rates of the 2 colonies were similar (10−11% yr −1) and that the population totaled ~41 000 individuals in 2017 (⎯ x = 40 614, 95% CI = 35 779−46 877). Guadalupe fur seals appear to be vulnerable to extreme climatic events. Of the 2 fur seal colonies, the San Benito Islands colony is less secure and is Endangered to Critically Endangered, depending on the quasi-extinction value used under the quantitative listing criteria established by the IUCN. In contrast, the Guadalupe Island colony and the 2 colonies combined meet the quantitative analysis criteria of Least Concern. Population viability analysis is an important component of assessing the status of wildlife populations and assisting nations and organizations in assigning appropriate categories of protection.

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