Growth and reproduction of female short-beaked common dolphins, Delphinus delphis, in the eastern tropical Pacific

2007 ◽  
Vol 85 (1) ◽  
pp. 108-121 ◽  
Author(s):  
K. Danil ◽  
S.J. Chivers
Keyword(s):  
Life History ◽  
Sexual Maturity ◽  
Large Scale ◽  
Life History Strategy ◽  
Maximum Size ◽  
Tropical Pacific ◽  
Lactation Period ◽  
Eastern Tropical Pacific ◽  
Delphinus Delphis ◽  
Common Dolphins

We characterize the life-history strategy of female short-beaked common dolphins ( Delphinus delphis L., 1758) inhabiting the eastern tropical Pacific by estimating several growth and reproductive parameters. Reproductive condition (n = 700) and age (n = 405) were determined for animals sampled from those incidentally killed in the yellowfin tuna ( Thunnus albacares (Bonnaterre, 1788)) purse-seine fishery between 1975 and 1993. Females averaged 160.4 cm at age 2 years, 186.5 cm at attainment of sexual maturity, and 197.2 cm at asymptotic length. The estimated age at attainment of sexual maturity was 7.9 years and the oldest animal in the study was 25 years. Calving occurred throughout the year, with females producing a calf approximately every 2.1 years after a gestation period of approximately 11.4 months, an average lactation period of 16.5 months, and an average resting period of 2.8 months. A relatively high percentage (30.4%) of lactating females were simultaneously pregnant, which effectively shortens the average calving interval. No clear evidence of senescence was found. Estimated lengths at birth, 2 years of age, attainment of sexual maturity, and maximum size were greater than those reported for the temperate North Pacific population, indicating that large-scale geographic variation in life history occurs for this species, which likely reflects population-specific adaptations to the tropical and temperate habitats that they occupy.

scholarly journals Extreme lifespan of the human fish ( Proteus anguinus ): a challenge for ageing mechanisms

2010 ◽  
Vol 7 (1) ◽  
pp. 105-107 ◽  
Author(s):  
Yann Voituron ◽  
Michelle de Fraipont ◽  
Julien Issartel ◽  
Olivier Guillaume ◽  
Jean Clobert
Keyword(s):  
Life History ◽  
Sexual Maturity ◽  
Antioxidant Activities ◽  
Life History Strategy ◽  
Basal Metabolism ◽  
Maximum Lifespan ◽  
Oxidative Damages ◽  
Large Size ◽  
Proteus Anguinus ◽  
Ageing Processes

Theories of extreme lifespan evolution in vertebrates commonly implicate large size and predator-free environments together with physiological characteristics like low metabolism and high protection against oxidative damages. Here, we show that the ‘human fish’ (olm, Proteus anguinus ), a small cave salamander (weighing 15–20 g), has evolved an extreme life-history strategy with a predicted maximum lifespan of over 100 years, an adult average lifespan of 68.5 years, an age at sexual maturity of 15.6 years and lays, on average, 35 eggs every 12.5 years. Surprisingly, neither its basal metabolism nor antioxidant activities explain why this animal sits as an outlier in the amphibian size/longevity relationship. This species thus raises questions regarding ageing processes and constitutes a promising model for discovering mechanisms preventing senescence in vertebrates.

scholarly journals Too risky to settle: avian community structure changes in response to perceived predation risk on adults and offspring

2013 ◽  
Vol 280 (1764) ◽  
pp. 20130762 ◽  
Author(s):  
Fangyuan Hua ◽  
Robert J. Fletcher ◽  
Kathryn E. Sieving ◽  
Robert M. Dorazio
Keyword(s):  
Life History ◽  
Natural History ◽  
Predation Risk ◽  
Large Scale ◽  
Life History Theory ◽  
Life History Strategy ◽  
Bird Community ◽  
Breeding Bird ◽  
Potential Force ◽  
Perceived Predation Risk

Predation risk is widely hypothesized as an important force structuring communities, but this potential force is rarely tested experimentally, particularly in terrestrial vertebrate communities. How animals respond to predation risk is generally considered predictable from species life-history and natural-history traits, but rigorous tests of these predictions remain scarce. We report on a large-scale playback experiment with a forest bird community that addresses two questions: (i) does perceived predation risk shape the richness and composition of a breeding bird community? And (ii) can species life-history and natural-history traits predict prey community responses to different types of predation risk? On 9 ha plots, we manipulated cues of three avian predators that preferentially prey on either adult birds or offspring, or both, throughout the breeding season. We found that increased perception of predation risk led to generally negative responses in the abundance, occurrence and/or detection probability of most prey species, which in turn reduced the species richness and shifted the composition of the breeding bird community. Species-level responses were largely predicted from the key natural-history trait of body size, but we did not find support for the life-history theory prediction of the relationship between species' slow/fast life-history strategy and their response to predation risk.

Behaviour of free-ranging short-beaked common dolphins (Delphinus delphis) in Gulf St Vincent, South Australia

2013 ◽  
Vol 61 (4) ◽  
pp. 291 ◽  
Author(s):  
Nicole E. Filby ◽  
Mike Bossley ◽  
Karen A. Stockin
Keyword(s):  
Group Size ◽  
Water Depth ◽  
Large Scale ◽  
South Australia ◽  
Population Level ◽  
Common Dolphin ◽  
Time Data ◽  
Fishing Activity ◽  
Delphinus Delphis ◽  
Common Dolphins

Common dolphins are subject to large-scale fishing activity and tourism operations in South Australia; however, there is a paucity of data on this species. Understanding the behaviour of a population can contribute greatly to our knowledge of a species and how to manage potential population-level threats. This paper describes the behaviour of short-beaked common dolphins (Delphinus delphis) in Australian waters for the first time. Data were collected from 109 independent dolphin groups during boat-based surveys conducted in Gulf St Vincent, South Australia, between September 2005 and May 2008. Activity budgets were used to assess behaviour of common dolphins in relation to diel patterns, season, water depth, sea surface temperature (SST), group size and composition. Foraging (33.9%) and resting (2.8%) were the most and least frequently observed behaviours, respectively. Travelling (33.0%), socialising (20.2%) and milling (10.1%) accounted for the remainder of the activity budget. Diurnal differences were detected, with foraging (59.5%) and socialising (31.8%) groups most frequently observed from 10.00 to 11.59 hours. Behaviour did not vary seasonally or with water depth, SST, group size or composition. Behaviour varied significantly between single- and multispecies aggregations. Foraging was more frequent in multispecies aggregations, as 78.4% of all foraging behaviour observed for common dolphins occurred in the presence of other species. Multispecies aggregations were most frequently observed with flesh-footed shearwaters (Puffinus carneipes), which were present during 29.4% of common dolphin encounters. Behaviour varied significantly during aggregations with shearwaters, as 62.2% of foraging groups occurred in the presence of shearwaters. Resting, milling or socialising was rarely observed in the presence of any other species, indicating that the primary mechanism for aggregations is likely prey-related.

scholarly journals Environmental harshness is associated with lower investment in collective actions

2019 ◽  
Author(s):  
N. Lettinga ◽  
P.O. Jacquet ◽  
J-B. André ◽  
N. Baumard ◽  
C. Chevallier
Keyword(s):  
Life History ◽  
Structural Equation ◽  
Large Scale ◽  
Structural Equation Models ◽  
Life History Strategy ◽  
World Values Survey ◽  
Collective Actions ◽  
The World ◽  
European Values ◽  
European Values Study

AbstractAlthough humans cooperate universally, there is variability across individuals, times and cultures in the amount of resources people invest in cooperative activities. The origins of such variability are not known but recent work highlights that variations in environmental harshness may play a key role. A growing body of experimental work in evolutionary psychology suggests that humans adapt to their specific environment by calibrating their life-history strategy. In this paper, we apply structural equation models to test the association between current and childhood environmental harshness, life-history strategy and adult cooperation in two large-scale datasets (the World Values Survey and the European Values Study). The present study replicates existing research linking a harsher environment (both in adulthood and in childhood) with a modulated reproduction-maintenance trade-off and extends these findings to the domain of collective actions. Specifically, we find that a harsher environment (both in adulthood and in childhood) is associated with decreased involvement in collective action and that this association is mediated by individuals’ life-history strategy.

scholarly journals The Eastern Tropical Pacific Marine Corridor (CMAR): The Emergence of a Voluntary Regional Cooperation Mechanism for the Conservation and Sustainable Use of Marine Biodiversity Within a Fragmented Regional Ocean Governance Landscape

2021 ◽  
Vol 8 ◽  
Author(s):  
Sarah Ryan Enright ◽  
Ricardo Meneses-Orellana ◽  
Inti Keith
Keyword(s):  
Large Scale ◽  
Regional Cooperation ◽  
Sustainable Use ◽  
Tropical Pacific ◽  
Marine Biodiversity ◽  
Eastern Tropical Pacific ◽  
Anthropogenic Pressures ◽  
Governance Framework ◽  
Ocean Governance ◽  
Cooperation Mechanism

The San Jose Declaration formally established the Eastern Tropical Pacific Marine Corridor (CMAR) in 2004, a voluntary regional cooperation mechanism created by the coastal States of Ecuador, Costa Rica, Colombia, and Panama in response to anthropogenic pressures in the Eastern Tropical Pacific, one of the most productive and biodiverse oceans in the world. This article will explain how, in the absence of a coherent, overarching regional ocean governance framework, these four coastal States came together to create a regional cooperation mechanism for the conservation and sustainable use of marine biodiversity in the Eastern Tropical Pacific. The key normative features of CMAR will be examined, as well as legal and governance challenges, such as its non-binding nature, large scale, limited sectoral engagement, and insufficient resources. The analysis will be couched within a discussion of the wider regional ocean governance framework, which remains fragmented, with gaps and overlaps in terms of membership, mandates and geographic coverage. Possibilities for integration, and the potential impact of a new treaty protecting biodiversity beyond national jurisdiction (BBNJ), will also be considered.

scholarly journals Seasonal and interannual variations in the distributions of tuna-associated dolphins in the eastern tropical Pacific Ocean

2019 ◽  
Vol 20 (1) ◽  
pp. 67-79
Author(s):  
Paul C. Fielder ◽  
Cleridy E. Lennert-Cody
Keyword(s):  
Pacific Ocean ◽  
Tropical Pacific ◽  
La Niña ◽  
Niche Separation ◽  
Common Dolphin ◽  
Cold Tongue ◽  
Tropical Pacific Ocean ◽  
Eastern Tropical Pacific ◽  
La Nina ◽  
Common Dolphins

Seasonal and interannual (El Niño–La Niña) variations in dolphin distributions in the eastern tropical Pacific Ocean have not been quantified, inspite of an extensive research vessel database. Fisheries observer data from the yellowfin tuna purse-seine fishery, collected year-round from 1986through 2015, were used to construct a binned spatiotemporal dataset of the presence/absence of spotted, spinner and common dolphin schools bymonth and 1° area. Distribution patterns were predicted from generalised additive logistic regression models applied to the binned data, with dynamicpredictors of surface temperature and salinity, thermocline depth and a stratification index. The dolphin taxa, especially common dolphins, showsome niche separation in relation to these variables. Predicted distributions for each taxon showed seasonal and interannual differences. Spottedand spinner dolphins responded to changes in the position and size of the eastern Pacific warm pool and avoided the equatorial cold tongue inSeptember–October and during La Niña. Common dolphins responded to seasonal and interannual changes in the Costa Rica Dome, the cold tongue,and the coastal upwelling habitat along Baja California, Peru and Ecuador. These predicted temporal variations are consistent with changes inpreferred habitat driven by environmental variability.

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