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

Adame, Karen; Elorriaga‐Verplancken, Fernando R.; Beier, Emilio; Acevedo‐Whitehouse, Karina; Pardo, Mario A.

doi:10.1101/2020.03.09.984716

Cited by 2 publications

(3 citation statements)

References 52 publications

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“…In the central region, the growth rate has remained relatively low (1%) and the decline has been continuous since 1978, reducing the population to a level that may represent a threat to the species’ persistence. Not all reproductive colonies were included in our analysis; however, previous studies examining all colonies have reported the same trend (Szteren, Aurioles‐Gamboa & Gerber, 2006; Adame et al, 2020). Meanwhile, the population in the southern region increased steadily during the same period.…”

Section: Discussionmentioning

confidence: 91%

“…Considering the climatology of the entire GoC for the period from 1920 to 2018, Adame et al (2020) argue that positive SST anomalies began to be registered around 1990, about the same time that the California sea lion population in the GoC began to decrease. They propose that the increase in the SST has resulted in a diversification of pelagic fish catches by fisheries, which suggests a reduction in high‐quality prey for California sea lions.…”

Section: Discussionmentioning

confidence: 99%

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Effect of environmental variables on the number of births at California sea lion (Zalophus californianus) rookeries throughout the Gulf of California, Mexico

Pelayo‐González

Hernández‐Camacho

Aurioles‐Gamboa

et al. 2021

Aquatic Conservation

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1. The 13 California sea lion breeding colonies in the Gulf of California (GoC), Mexico are each characterized by different population growth trends, including a variable number of births. Despite being located in a highly productive marine area, both the species' population and the number of births have declined significantly over the past few decades.2. The goal of this study was to assess the effects of certain environmental variables on the number of births at colonies in three regions (northern, central and southern) of the GoC (1995GoC ( -2018. Data on diet, small pelagic fish catches by fisheries, the density of small pelagic fish schools, remotely sampled values of sea surface temperature and chlorophyll-a concentration and El Niño Southern Oscillation events were collected in order to evaluate whether these variables had an effect on the number of births using correlations and generalized linear models.3. No significant relationships were found between the environmental variables and the number of births. However, the number of births decreased when the sea surface temperature anomalies exceeded 1 C in the northern and central regions of the GoC. Although no significant relationships were found between the small pelagic fish catches and the number of births, positive trends were observed between sardine catches and the number of births during certain periods in the central region. A positive correlation between the density of small pelagic fish schools and the number of births suggests a possible relationship between prey availability and reproductive success in the central region. 4. A Programme of Action for the Conservation of the Species should be promoted by the Federal Government and carried out in order to implement specific management actions. Specifically, surveillance efforts should increase, fishing gear conversion plans should be established and sea lion exclusion devices should be introduced, among other measures.

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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Effect of environmental variables on the number of births at California sea lion (Zalophus californianus) rookeries throughout the Gulf of California, Mexico

Pelayo‐González

Hernández‐Camacho

Aurioles‐Gamboa

et al. 2021

Aquatic Conservation

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“…Although otariid reproductive males do not forage during the reproductive season, they require sufficient accumulation of fat stores before the season to energetically sustain this stressful period ( Campagna et al 1988 ; Pavés et al 2005 ). Therefore, adverse environmental conditions associated with higher SST and decline in prey items could lead to poor storage of fat reserves and early departure of males from reproductive colonies ( Sydeman and Allen 1999 ; Adame et al 2020 ). This reduction in reproductive male density could potentially facilitate intromission of SASL into the fur seal colony, increasing the number of agonistic interactions.…”

Section: Discussionmentioning

confidence: 99%

Lower marine productivity increases agonistic interactions between sea lions and fur seals in Northern Pacific Patagonia

et al. 2022

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Interspecific interactions are key drivers of individual and population level fitness in a wide range of animals. However, in marine ecosystems, it is relatively unknown which biotic and abiotic factors impact behavioral interactions between competing species. We assessed the impact of weather, marine productivity and population structure on the behavioral agonistic interactions between South American fur seals (SAFS), Arctocephalus australis, and South American sea lions (SASL), Otaria byronia, in a breeding colony of SAFS. We hypothesized that agonistic interactions between SAFSs and SASLs respond to biotic and abiotic factors such as SAFS population structure, marine productivity and weather. We found that SASL and SAFS interactions almost always resulted in negative impacts on the social structure or reproductive success of the SAFS colony. SASL adult males initiated stampedes of SAFS and/or abducted and predated SAFS pups. Adult SAFS males abundance and severe weather events were negatively correlated with agonistic interactions between species. However, proxies for lower marine productivity such as higher sea surface temperature and lower catches of demerso-pelagic fish were the most important predictors of more frequent agonistic interactions between SAFS and SASL. Under the current scenario of decline in marine biomass due to global climate change and overfishing, agonistic interactions between competing marine predators could increase and exacerbate the negative impacts of environmental change in these species.

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

Cited by 2 publications

References 52 publications

Effect of environmental variables on the number of births at California sea lion (Zalophus californianus) rookeries throughout the Gulf of California, Mexico

Effect of environmental variables on the number of births at California sea lion (Zalophus californianus) rookeries throughout the Gulf of California, Mexico

Lower marine productivity increases agonistic interactions between sea lions and fur seals in Northern Pacific Patagonia

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