Demographic analysis of sperm whales using matrix population models

Chiquet, Ross A.; Ma, Bao‐Qing; Ackleh, Azmy S.; Pal, Nabendu; Sidorovskaia, Natalia A.

doi:10.1016/j.ecolmodel.2012.09.023

Cited by 19 publications

(33 citation statements)

References 14 publications

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“…A shipping route with a relatively low volume of traffic does traverse the study area; however, to our knowledge there have been no reports of ships striking sperm whales in this area. To what extent pressures such as ship strike and entanglement may affect this sperm whale population is not known: however, the cumulative effect of multiple threatening processes could be highly significant in a vulnerable population that has low rates of recruitment and high sensitivity to individual mortality (Chiquet et al 2013).…”

Section: Discussionmentioning

confidence: 99%

“…As in elephants, which have a similar social structure, a loss of older females from these units may have fragmented these associations and caused a loss of cultural knowledge such as predator evasion tactics and the location of occasional feeding grounds (Whitehead 2003, McComb et al 2011. Removal of matriarchs from social groups may serve to reduce female fitness and affect the population more broadly, as the demography of sperm whales is most sensitive to mortality of adult females (Chiquet et al 2013).…”

Section: Discussionmentioning

confidence: 99%

“…Sperm whale bulls reach physical maturity at age 17 to 20; however, they do not appear to effectively participate in reproduction until they are in their late twenties, when they begin to attend breeding grounds (Best 1979). These life history traits underpin the fragility of sperm whale populations and are responsible for their low intrinsic rate of increase (Whitehead 2003, Chiquet et al 2013. Additionally, it appears that populations of sperm whales and other odontocetes may be inherently less resilient to exploitation than mysticetes with similar life history characteristics, due to behavioural and social traits (Wade et al 2012), and that this has been compounded by sex-biased hunting (Whitehead et al 1997).…”

Section: Discussionmentioning

confidence: 99%

“…Demographic analysis has shown that sperm whale populations are potentially so fragile that they could experience decline with even a slight decrease in adult survivorship and could face extinction with the occurrence of a major stochastic event (Chiquet et al 2013). Female sperm whales usually have their first calf at age 10 (Rice 1989) and then reproduce every 4 to 6 yr (Best et al 1984).…”

Section: Discussionmentioning

confidence: 99%

“…In the 25+ yr since sperm whaling Physeter macrocephalus operations became uneconomical or were closed down following the 1986 moratorium, ex ploited sperm whale stocks can be expected to have shown a trend towards recovery at their theoretical growth rate of 1 to 1.1% (Whitehead 2003, Chiquet et al 2013). Due to their wide distribution (Rice 1989) and relatively large global population size (Whitehead 2002), it is often assumed by management agencies that sperm whale populations are likely to be recovering in lieu of data to suggest otherwise.…”

Section: Introductionmentioning

confidence: 99%

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No evidence for recovery in the population of sperm whale bulls off Western Australia, 30 years post-whaling

Carroll¹,

Hedley²,

Bannister³

et al. 2014

Endang. Species. Res.

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The global sperm whale Physeter macrocephalus population has been protected from large-scale commercial whaling for > 25 yr, yet there is no clear evidence of recovery in any heavily exploited stock. This may indicate that whaling has long-term demographic effects on this species or that other endogenous or exogenous processes are inhibiting population growth. This study investigates the status of mature sperm bulls off Albany, Western Australia, a population reduced through whaling by 74% between 1955 and 1978. We conducted an aerial survey designed as far as possible to provide an index of abundance comparable with that derived from the whale 'spotter' planes employed by the Albany whaling company from 1968 to 1978, using the number of sperm bulls seen on each morning flight as a comparative index between bulls seen historically and in 2009. The mean number of sperm bulls seen on transect in 2009 was 2.43 (95% percentile interval [0.96, 6.08]); this increased to 3.38 (95% percentile interval [1.30, 7.60]) when sightings off transect were included. Both 2009 point estimates were lower than the mean (± SE) number seen in any of the years between 1968 and 1978, which ranged from 6.30 (±1.18) in 1976 to 12.45 (±1.83) in 1968. The lack of recovery in the population of bull sperm whales off Albany, despite full protection, is of concern and adds weight to the growing body of evidence that suggests that sperm whales may not be recovering effectively from past exploitation.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

No evidence for recovery in the population of sperm whale bulls off Western Australia, 30 years post-whaling

Carroll¹,

Hedley²,

Bannister³

et al. 2014

Endang. Species. Res.

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Australian sperm whales from different whaling stocks belong to the same population

Day

Power

Gales³

et al. 2021

Aquatic Conservation

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Understanding the factors driving population structure in marine mammals is needed to evaluate the impacts of previous exploitation, current anthropogenic threats, conservation status, and success of population recovery efforts. Sperm whales are characterized by a worldwide distribution, low genetic diversity, complex patterns of social and genetic structure that differ significantly within and between ocean basins, and a long history of being commercially whaled. In Australia, sperm whales from the (International Whaling Commission assigned) southern hemisphere ‘Division 5’ stock were very heavily exploited by whaling. The present study assessed the potential effects of whaling on the genetic diversity of sperm whales in Australia and the population genetic structure of these whales within a global context. A combination of historical and contemporary sperm whale samples (n = 157) were analysed across six regions, from south‐eastern Australia (‘Division 6’ stock in the Pacific Ocean) to south‐western Australia (‘Division 5’ stock in the Indian Ocean). Sperm whales sampled from the ‘Division 5’ and ‘Division 6’ stocks belong to the same population based on nuclear and mitochondrial DNA (mtDNA) analyses. Four novel sperm whale mtDNA haplotypes were identified in animals from Australian waters. Levels of genetic diversity were low in Australian sperm whales but were similar to those previously reported for populations in the Indian and Pacific Oceans. Given the genetic distinctiveness of sperm whales in Australian waters from other regions in the Pacific and Indian Oceans, and the lack of recovery in population numbers, further scientific studies are needed to increase our understanding of population dynamics and the effectiveness of threat management strategies in this species.

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Analysis of lethal and sublethal impacts of environmental disasters on sperm whales using stochastic modeling

Ackleh

Chiquet

et al. 2017

Ecotoxicology

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Mathematical models are essential for combining data from multiple sources to quantify population endpoints. This is especially true for species, such as marine mammals, for which data on vital rates are difficult to obtain. Since the effects of an environmental disaster are not fixed, we develop time-varying (nonautonomous) matrix population models that account for the eventual recovery of the environment to the pre-disaster state. We use these models to investigate how lethal and sublethal impacts (in the form of reductions in the survival and fecundity, respectively) affect the population’s recovery process. We explore two scenarios of the environmental recovery process and include the effect of demographic stochasticity. Our results provide insights into the relationship between the magnitude of the disaster, the duration of the disaster, and the probability that the population recovers to pre-disaster levels or a biologically relevant threshold level. To illustrate this modeling methodology, we provide an application to a sperm whale population. This application was motivated by the 2010 Deepwater Horizon oil rig explosion in the Gulf of Mexico that has impacted a wide variety of species populations including oysters, fish, corals, and whales.

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Demographic analysis of sperm whales using matrix population models

Cited by 19 publications

References 14 publications

No evidence for recovery in the population of sperm whale bulls off Western Australia, 30 years post-whaling

No evidence for recovery in the population of sperm whale bulls off Western Australia, 30 years post-whaling

Australian sperm whales from different whaling stocks belong to the same population

Analysis of lethal and sublethal impacts of environmental disasters on sperm whales using stochastic modeling

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