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Abundance estimates and habitat preferences of bottlenose dolphins reveal the importance of two gulfs in South Australia.

ABSTRACT: Informed conservation management of marine mammals requires an understanding of population size and habitat preferences. In Australia, such data are needed for the assessment and mitigation of anthropogenic impacts, including fisheries interactions, coastal zone developments, oil and gas exploration and mining activities. Here, we present large-scale estimates of abundance, density and habitat preferences of southern Australian bottlenose dolphins (Tursiops sp.) over an area of 42,438km² within two gulfs of South Australia. Using double-observer platform aerial surveys over four strata and mark-recapture distance sampling analyses, we estimated 3,493 (CV?=?0.21; 95%CI?=?2,327-5,244) dolphins in summer/autumn, and 3,213 (CV?=?0.20; 95%CI?=?2,151-4,801) in winter/spring of 2011. Bottlenose dolphin abundance and density was higher in gulf waters across both seasons (0.09-0.24 dolphins/km²) compared to adjacent shelf waters (0.004-0.04 dolphins/km²). The high densities of bottlenose dolphins in the two gulfs highlight the importance of these gulfs as a habitat for the species. Habitat modelling associated bottlenose dolphins with shallow waters, flat seafloor topography, and higher sea surface temperatures (SSTs) in summer/autumn and lower SSTs in winter/spring. Spatial predictions showed high dolphin densities in northern and coastal gulf sections. Distributional data should inform management strategies, marine park planning and environmental assessments of potential anthropogenic threats to this protected species.

SUBMITTER: Bilgmann K

PROVIDER: S-EPMC6541621 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Abundance estimates and habitat preferences of bottlenose dolphins reveal the importance of two gulfs in South Australia.

Bilgmann Kerstin K Parra Guido J GJ Holmes Lauren L Peters Katharina J KJ Jonsen Ian D ID Möller Luciana M LM

Scientific reports 20190529 1

Informed conservation management of marine mammals requires an understanding of population size and habitat preferences. In Australia, such data are needed for the assessment and mitigation of anthropogenic impacts, including fisheries interactions, coastal zone developments, oil and gas exploration and mining activities. Here, we present large-scale estimates of abundance, density and habitat preferences of southern Australian bottlenose dolphins (Tursiops sp.) over an area of 42,438km<sup>2</s ...[more]

PMID: 31142765

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Project description:In recent decades, animal welfare science has evolved to utilize a multidisciplinary approach to assess the welfare of animals in accredited zoos and aquariums. Science-based animal welfare assessments have become an essential component of management programs and widespread application is expected by animal care professionals. Management practices for bottlenose dolphins in accredited facilities incorporate several programs that potentially impact animal welfare including environmental enrichment and animal training. Additionally, habitat characteristics, such as the dimensions of the habitat, have been proposed to affect welfare. While accredited facilities are required to meet high standards of care, habitat characteristics and management practices are not standardized across locations. Knowledge and subsequent application of these practices and habitat characteristics can enhance our understanding of factors associated with positive welfare. As part of a larger study of dolphin welfare titled "Towards understanding the welfare of cetaceans in zoos and aquariums" (colloquially called the Cetacean Welfare Study), survey data were collected from 86 bottlenose dolphins in 40 habitats at 38 facilities in seven countries. The major aims of this paper are to provide general descriptive information regarding dolphin management in accredited zoos and aquariums and to provide supplemental context to the other research published from the Cetacean Welfare Study data set. This paper provides a review of current habitat characteristics and management practices at those 38 accredited zoos and aquariums. These data enabled the identification and quantification of how cetacean management practices differed between participating facilities accredited by the Alliance for Marine Mammal Parks and Aquariums and the Association of Zoos & Aquariums. Variables were selected based on their potential association with welfare including the physical habitat, environmental enrichment, and training programs. The variables were also used for subsequent research in this collection of related papers to investigate important connections between potential indicators of welfare and habitat characteristics, environmental enrichment, and training programs.

Project description:The way an animal uses its habitat can serve as an indicator of habitat appropriateness for the species and individuals. Bottlenose dolphins (Tursiops truncatus and Tursiops aduncus) in accredited zoos and aquariums experience a range of habitat types and management programs that provide opportunities for dolphins to engage in species-appropriate behaviors and potentially influence their individual and group welfare. Data in the present study were collected as part of a larger study titled "Towards understanding the welfare of cetaceans in zoos and aquariums" (colloquially called the Cetacean Welfare Study). Non-invasive bio-logging devices (Movement Tags) recorded the diving behavior and vertical habitat movements of 60 bottlenose dolphins at 31 zoos and aquariums that were accredited by the Alliance for Marine Mammal Parks and Aquariums and/or the Association of Zoos & Aquariums. Bottlenose dolphins wore a Movement Tag one day per week for two five-week data collection periods. Demographic variables, environmental enrichment programs, training programs, and habitat characteristics were associated with habitat usage. Longer dive durations and use of the bottom third of the habitat were associated with higher enrichment program index values. Dolphins receiving new enrichment on a monthly/weekly schedule also used the bottom third of the habitat more often than those receiving new enrichment on a yearly/year+ schedule. Dolphins that were managed in a group that was split into smaller subgroups during the day and were reunited into one group at night spent less time in the top third of the habitat than those who remained in a single group with consistent members at all times. Dolphins that were managed as subgroups with rotating members but were never united as one group spent less time in the bottom third of the habitat than those who remained in a single group with consistent members at all times. Taken together, the results suggested that management practices, such as enrichment and training programs, played a greater role in how dolphins interacted with their environment relative to the physical characteristics of the habitat.

Project description:Accredited zoos and aquariums continually strive to ensure high levels of animal welfare for the animals under their professional care. Best management practices include conducting research to better understand factors that lead to optimal welfare and then turning findings into practice. The current study is part of the larger Cetacean Welfare Study or more formally, "Towards understanding the welfare of cetaceans in zoos and aquariums." Facilities participating in the study were accredited by the Alliance of Marine Mammal Parks and Aquariums and/or the Association of Zoos and Aquariums. Animal management factors and habitat characteristics were examined in relation to two potential indicators of welfare for common (Tursiops truncatus) and Indo-Pacific (Tursiops aduncus) bottlenose dolphins. Specifically, we examined environmental enrichment, animal training, and habitat characteristics that were significantly related to behavioral diversity and route tracing, a form of stereotypic behavior. Behavior was recorded from 47 animals at 25 facilities around the world. Overall, the rate of route tracing behavior observed during the study was very low and few animal management factors or habitat characteristics were found to be related to this behavior. One factor, enrichment diversity, had a significant positive relationship with route tracing and an inverse relationship with behavioral diversity. This finding may be a product of a response mounted by animal care specialists to the behavior as opposed to a cause. Animals that engaged in this behavior were likely provided more diverse enrichment in attempts to ameliorate the stereotypic behavior. However, multiple factors were found to significantly relate to behavioral diversity, a potential positive indicator of welfare for bottlenose dolphins. Dolphins that were trained on a predictable schedule had higher behavioral diversity than those on a semi-predictable schedule. There was a positive significant relationship between behavioral diversity and the number of habitats to which an animal had access, and a significant inverse relationship with the maximum depth of the habitat. Finally, animals that were split into groups and reunited or rotated between subgroups had higher behavioral diversity than animals managed in the same group. Information gained from the current study suggested that animal management techniques may be more important in ensuring good welfare for bottlenose dolphins than focusing on habitat size.

Dataset Information

Abundance estimates and habitat preferences of bottlenose dolphins reveal the importance of two gulfs in South Australia.

Publications

Abundance estimates and habitat preferences of bottlenose dolphins reveal the importance of two gulfs in South Australia.

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