Four seasons abundance changes of Zalophus californianus californianus (Lesson 1828), Allen, 1880, in the Gulf of California, Mexico

Maravilla-Chávez, Martín Octavio; Zavala-González, Alfredo; Ortega‐Rubio, Alfredo

doi:10.1590/s1516-89132006000100013

Cited by 6 publications

(11 citation statements)

References 7 publications

(3 reference statements)

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“…Large numbers of female strandings may reflect differences in the structure of the population, as well as differences in aggregation patterns during bloom periods. Adult females on San Miguel Island and in the Gulf of California comprised at least 45% of the annual resident population (Francis and Heath 1991, Maravilla‐Chavez et al 2006). During the breeding season females spend at least 50% of their time at sea traveling to and from feeding grounds, while adult males spend little or no time foraging at sea (Francis and Heath 1991).…”

Section: Discussionmentioning

confidence: 99%

Demographics and spatio‐temporal signature of the biotoxin domoic acid in California sea lion (Zalophus californianus) stranding records

Bejarano¹,

Gulland²,

Goldstein³

et al. 2008

Marine Mammal Science

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California sea lions (Zalophus californianus) in otherwise good nutritional condition have been consistently affected by the marine biotoxin domoic acid since the late 1990s. In this study we evaluated the temporal and spatial stranding patterns of suspected and confirmed cases of domoic acid intoxicated sea lions from 1998 to 2006, using records of strandings along the California coast obtained from members of the California Marine Mammal Stranding Network. The majority of domoic acid cases were adult females (47%–82% of the total annual domoic acid cases), a contrast to strandings that were not related to domoic acid, which were generally dominated by juveniles and pups. Exposure to this biotoxin led to a 6.67‐fold increase in adult female strandings in 2000, and a 5.44‐fold increase in adult female deaths in 2006, relative to strandings and deaths of adult female not affected by domoic acid. Domoic acid cases have occurred annually since 1998 (except for 1999) between April and August, with clusters centered primarily at Pismo Beach (San Luis Obispo County), as well as at other beaches in San Luis Obispo, Monterey, Santa Cruz, Santa Barbara, Orange, and San Diego counties. The larger ecological and population level implications of increased domoic acid strandings and deaths, particularly among adult female sea lions, warrant further attention and need to be investigated.

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Section: Discussionmentioning

confidence: 99%

Demographics and spatio‐temporal signature of the biotoxin domoic acid in California sea lion (Zalophus californianus) stranding records

Bejarano¹,

Gulland²,

Goldstein³

et al. 2008

Marine Mammal Science

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“…total counts), as a consistent parameter that can be also used to estimate pinniped abundance 18,19,40 , especially if some perception and availability biases are accounted for 58,59 . For this, we used all counts available in the literature 16,18,19,21,59,60 and new, reported here for the first time. The main challenge for estimating the population size of California sea lions and its multi-decadal trend in the Gulf of California was that there is only one breeding season, in 2016, for which there are available counts of animals in all of the 13 reproductive colonies, an effort of this study for which we implemented both visual and drone-based counts.…”

Section: Methodsmentioning

confidence: 99%

The demographic decline of a sea lion population followed multi-decadal sea surface warming

Adame

Elorriaga‐Verplancken

Beier

et al. 2020

Sci Rep

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the population growth of top predators depends largely on environmental conditions suitable for aggregating sufficient and high-quality prey. We reconstructed numerically the size of a resident population of California sea lions in the Gulf of California during 1978-2019 and its relation with multi-decadal sea surface temperature anomalies. This is the first multi-decadal examination of the sea surface temperature of the Gulf of California and of one of its major predators. A three-decade sustained warming explained the population's trend accounting for 92% of the variance, including a 65% decline between 1991 and 2019. Long-term warming conditions started in the late 80s, followed by the population's decline from 43,834 animals (range 34,080-58,274) in 1991 to only 15,291 (range 11,861-20,316) in 2019. The models suggested a century-scale optimum sea surface habitat occurring in mildly temperate waters, from 0.18 to 0.39 °C above the 100-year mean. The mechanistic links of this relation are still untested, but apparent diversification of pelagic fish catches suggests a reduction of high quality prey. We propose this population should be considered vulnerable to any disturbance that could add to the negative effects of the current warm sea surface conditions in the Gulf of California. The physical structure of oceanic habitats often determines, through a multi-step process, the success of animal populations 1. Sea surface temperature and its variability is widely known to affect oceanic top predators such as pinnipeds, through bottom-up mechanisms 2-4. Abrupt or sustained changes of sea surface temperature affect the abundance and diversity of plankton communities 5 , pelagic fishes 6 , and ultimately marine mammals 7,8. The latter typically respond with alterations in foraging habits 9,10 , key physiological processes 11,12 , reproductive success, or survival 4. Although many marine mammal populations can withstand and recover from short-term sea surface warming conditions (e.g. El Niño) 13 , sustained positive environmental trends at a multi-decadal scale typically cause important shifts in the base of marine ecosystems 14 , and arguably the diversity of potential prey. These shifts could lead to the decline of some marine mammal populations as the conditions move away from the optimum habitat to which the species have adapted 15. In the Gulf of California (hereafter "the gulf "), there is a resident population of California sea lions (Zalophus californianus) 16 genetically isolated from the other populations of the Northeast Pacific Ocean 17. Although a ~ 20% reduction of this population during the 1990s has been proposed based on partial counts spanning 1997-2004 18,19 , its total size and temporal trend, as well as the historical environmental context, remain unknown. A recent review mentioned that the population decreased 44% between 1979 and 2016, based on unpublished data 20. Negative interaction with fisheries, and a temporal decline of the Pacific sardine (Sardinops sagax) in the early 1990s, as a resul...

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“…Una vez aplicados los factores de corrección se estimaron 8.598 crías y un total aproximado de 24.062 y 31.159 individuos, que en promedio representan el 11,6% de la población total estimada en 2005. Otros autores indican que en su distribución en México, principalmente en el Golfo de California existen hasta 40 loberas, 13 de carácter reproductivo, 18 no reproductivas y 9 temporales, dentro de estas últimas se encuentra localizada la Roca Tortuga en Mazatlán, Sinaloa (Maravilla-Chávez et al, 2006).…”

Section: Introductionunclassified

“…La migración invernal del lobo marino, es un aspecto relevante del comportamiento de esta especie es su ciclo migratorio, descrito como variaciones estacionales en el número de individuos. La migración de machos adultos de California hacia aguas del norte de Estados Unidos y sur de Canadá ha sido documentada desde la década de los sesenta (Maravilla-Chávez et al, 2006). La proporción de machos relativo al número de hembras aumenta considerablemente durante el invierno, observándose una población de machos sub-adultos 5,6 veces mayor en comparación con el verano, mientras que la proporción de hembras disminuye 4,6 veces (Aurioles-Gamboa et al, 2010).…”

Section: Introductionunclassified

“…Por otro lado, Maravilla-Chávez et al (2006) reportaron censos de nueve colonias reproductivas y una temporal en el Golfo de California concluyendo que durante la primavera y el verano los números poblacionales alcanzan su máximo para esta región, correspondiendo al periodo reproductivo y post-reproductivo. En todas las colonias del Golfo de California el número de individuos disminuyó considerablemente excepto en la lobera Los Islotes (Tabla 1), que es la misma que censaron Aurioles-Gamboa (1983), quien reporta una proporción mayor de machos con respecto a las hembras durante el invierno y un segundo máximo de abundancia durante la misma temporada.…”

Section: Introductionunclassified

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Un Biomodelo Turístico en El Pacifico Mexicano: Características Biológicas Y Ambientales Asociadas a La Actividad Sustentable Del Lobo Marino Zalophus Californianus (Lesson 1828)

Díaz-Maestre¹,

Zatarain²,

Roldán-Clarà³

et al. 2019

Biotempo

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El objetivo principal de esta revisión e investigación fue analizar las características biológicas y ambientales en donde se desarrolla el turismo en torno al lobo marino de California Zalophus californianus (Lesson, 1828) en la Bahía de Mazatlán, México. El lobo marino de California, de acuerdo a estudios recientes habita en las costas del noroeste mexicano durante los meses de noviembre a mayo (6 meses). En este periodo, alrededor de 35.531 turistas visitan a este animal acuático en su hábitat natural, a solo 2 km de la costa. Esta actividad económica genera un ingreso anual por servicios turísticos de $11,425,120.00 M.N ($626,517.24 USD) que ofrecen el ecoturismo del lobo marino como atractivo rentable en la bahía conocida como la Perla del Pacífico Mexicano. En la Bahía de Mazatlán, este mamífero marino, goza de un lugar privilegiado en el malecón, donde existe un monumento destacando su importancia en el puerto. Este animal es la únicaespecie de pinnípedo residente en el Golfo de California, con un registro aproximado de 40 colonias. Asimismo, existe una lobera temporal en una formación rocosa llamada Roca Tortuga (RT) en las coordenadas geográficas 23°11’13.15”N y 106°26’45.68” O en los meses de invierno y primavera. Estudios recientes, realizaron 245 censos de lobos marinos en Roca Tortuga durante el invierno de 2006 y la primavera de 2013 por una empresa local de ecoturismo. Se observaron lobos marinos en el sitio de estudio desde septiembre hasta mayo-junio, pero con variaciones interanuales en su abundancia. En las temporadas invernales de 2011-2012 y 2012-2013 se registraron anomalías en su abundancia, con una visitación mínima durante 2012. Se determinaron los factores ambientales más importantes: la temperatura del agua muestra variaciones estacionales, con valores máximos de julio a septiembre (30 ºC) y mínimos en diciembre (19ºC). La alimentación de este mamífero está basada en sardinas Sardinops sagax caeruleus (Girard, 1854), macarela del Pacífico Scomber japonicus Houttuyn, 1782 y merluza Merluccius sp. Rafinesque, 1810. La población temporal del lobo marino de California que visita las aguas costeras y que se agrega durante el invierno y primavera en Roca Tortuga, en las costas del Pacífico Mexicano, es considerado en este trabajo como un biomodelo de estudio en el sector turístico de naturaleza como actividad lucrativa. Este recurso marino es vulnerable tanto a cambios en las condiciones ambientales, particularmente aquellos que afectan la productividad local, como a los impactos asociados a actividades humanas como la pesca y el turismo que lo visita en RT, siendo éstas sus principales amenazas.

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Four seasons abundance changes of Zalophus californianus californianus (Lesson 1828), Allen, 1880, in the Gulf of California, Mexico

Abstract: ABSTRACT

Cited by 6 publications

References 7 publications

Demographics and spatio‐temporal signature of the biotoxin domoic acid in California sea lion (Zalophus californianus) stranding records

Demographics and spatio‐temporal signature of the biotoxin domoic acid in California sea lion (Zalophus californianus) stranding records

The demographic decline of a sea lion population followed multi-decadal sea surface warming

Un Biomodelo Turístico en El Pacifico Mexicano: Características Biológicas Y Ambientales Asociadas a La Actividad Sustentable Del Lobo Marino Zalophus Californianus (Lesson 1828)

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