1
|
Vivier F, Wells RS, Hill MC, Yano KM, Bradford AL, Leunissen EM, Pacini A, Booth CG, Rocho‐Levine J, Currie JJ, Patton PT, Bejder L. Quantifying the age structure of free-ranging delphinid populations: Testing the accuracy of Unoccupied Aerial System photogrammetry. Ecol Evol 2023; 13:e10082. [PMID: 37384246 PMCID: PMC10293808 DOI: 10.1002/ece3.10082] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 04/13/2023] [Accepted: 04/25/2023] [Indexed: 06/30/2023] Open
Abstract
Understanding the population health status of long-lived and slow-reproducing species is critical for their management. However, it can take decades with traditional monitoring techniques to detect population-level changes in demographic parameters. Early detection of the effects of environmental and anthropogenic stressors on vital rates would aid in forecasting changes in population dynamics and therefore inform management efforts. Changes in vital rates strongly correlate with deviations in population growth, highlighting the need for novel approaches that can provide early warning signs of population decline (e.g., changes in age structure). We tested a novel and frequentist approach, using Unoccupied Aerial System (UAS) photogrammetry, to assess the population age structure of small delphinids. First, we measured the precision and accuracy of UAS photogrammetry in estimating total body length (TL) of trained bottlenose dolphins (Tursiops truncatus). Using a log-transformed linear model, we estimated TL using the blowhole to dorsal fin distance (BHDF) for surfacing animals. To test the performance of UAS photogrammetry to age-classify individuals, we then used length measurements from a 35-year dataset from a free-ranging bottlenose dolphin community to simulate UAS estimates of BHDF and TL. We tested five age classifiers and determined where young individuals (<10 years) were assigned when misclassified. Finally, we tested whether UAS-simulated BHDF only or the associated TL estimates provided better classifications. TL of surfacing dolphins was overestimated by 3.3% ±3.1% based on UAS-estimated BHDF. Our age classifiers performed best in predicting age-class when using broader and fewer (two and three) age-class bins with ~80% and ~72% assignment performance, respectively. Overall, 72.5%-93% of the individuals were correctly classified within 2 years of their actual age-class bin. Similar classification performances were obtained using both proxies. UAS photogrammetry is a non-invasive, inexpensive, and effective method to estimate TL and age-class of free-swimming dolphins. UAS photogrammetry can facilitate the detection of early signs of population changes, which can provide important insights for timely management decisions.
Collapse
Affiliation(s)
- Fabien Vivier
- Marine Mammal Research ProgramHawaiʻi Institute of Marine BiologyUniversity of Hawaiʻi at MānoaMānoaHawaiʻiUSA
| | - Randall S. Wells
- Chicago Zoological Society's Sarasota Dolphin Research Programc/o Mote Marine LaboratorySarasotaFloridaUSA
| | - Marie C. Hill
- Cooperative Institute for Marine and Atmospheric ResearchResearch Corporation of the University of HawaiʻiHonoluluHawaiʻiUSA
- Pacific Islands Fisheries Science CenterNOAA FisheriesHonoluluHawaiʻiUSA
| | - Kymberly M. Yano
- Cooperative Institute for Marine and Atmospheric ResearchResearch Corporation of the University of HawaiʻiHonoluluHawaiʻiUSA
- Pacific Islands Fisheries Science CenterNOAA FisheriesHonoluluHawaiʻiUSA
| | - Amanda L. Bradford
- Pacific Islands Fisheries Science CenterNOAA FisheriesHonoluluHawaiʻiUSA
| | - Eva M. Leunissen
- Department of Marine ScienceUniversity of OtagoDunedinNew Zealand
| | - Aude Pacini
- Marine Mammal Research ProgramHawaiʻi Institute of Marine BiologyUniversity of Hawaiʻi at MānoaMānoaHawaiʻiUSA
| | - Cormac G. Booth
- SMRU ConsultingScottish Oceans InstituteUniversity of St AndrewsSt AndrewsUK
| | | | - Jens J. Currie
- Marine Mammal Research ProgramHawaiʻi Institute of Marine BiologyUniversity of Hawaiʻi at MānoaMānoaHawaiʻiUSA
- Pacific Whale FoundationWailukuHawaiʻiUSA
| | - Philip T. Patton
- Marine Mammal Research ProgramHawaiʻi Institute of Marine BiologyUniversity of Hawaiʻi at MānoaMānoaHawaiʻiUSA
| | - Lars Bejder
- Marine Mammal Research ProgramHawaiʻi Institute of Marine BiologyUniversity of Hawaiʻi at MānoaMānoaHawaiʻiUSA
- ZoophysiologyDepartment of BioscienceAarhus UniversityAarhusDenmark
| |
Collapse
|
2
|
Distribution and habitat partitioning of cetaceans (Mammalia: Cetartiodactyla) in the Bohol Sea, Philippines. JOURNAL OF ASIA-PACIFIC BIODIVERSITY 2022. [DOI: 10.1016/j.japb.2022.05.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
|
3
|
Quintana Martín-Montalvo B, Hoarau L, Deffes O, Delaspre S, Delfour F, Landes AE. Dolphin Watching and Compliance to Guidelines Affect Spinner Dolphins' ( Stenella longirostris) Behaviour in Reunion Island. Animals (Basel) 2021; 11:ani11092674. [PMID: 34573639 PMCID: PMC8470298 DOI: 10.3390/ani11092674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/25/2021] [Accepted: 09/08/2021] [Indexed: 11/30/2022] Open
Abstract
Simple Summary Whale and dolphin watching have expanded worldwide, with their impacts on cetaceans over the short and long terms being widely reported. In Reunion Island, the activity has rapidly developed, notably around a resident spinner dolphin population, which can be seen year-round. Focal follows revealed that the dolphins are less likely to begin socialising or resting and more likely to remain travelling or milling in the presence of dolphin-watching vessels. The dolphins’ avoidance reactions increased when tourist vessels were numerous or in non-compliance with the regulations. The cumulative effect of such behavioural responses likely impacts the dolphins at the population level, highlighting the need for enforcing adaptive and efficient dolphin-watching management measures to ensure the welfare and preservation of the resident spinner dolphins of Reunion Island. Abstract Marine wildlife tourism has rapidly developed in Reunion Island, due to a large demand for interactions with a resident population of spinner dolphins (Stenella longirostris). The presence of dolphin-watching vessels close to dolphin groups can cause short-term impacts on their behaviour; cumulative incidences likely result in deleterious long-term impacts on the population. Using scan sampling, we collected behavioural data on spinner dolphins to evaluate the short-term effects of dolphin watching on their behaviour. The dolphins were less likely to begin socialising or diving while travelling and more likely to stay travelling and milling in the presence of vessels. Additionally, activity budgets for resting and socialising decreased simultaneously with increased travelling and milling. Avoidance responses significantly increased with an increase in the number of vessels and non-compliance with the local dolphin-watching guidelines. These behavioural responses are likely to have energetic costs for the dolphins, which may lead to decreased survival and reproductive success at individual and population levels. More restrictive regulations, increased surveillance and animal-based measures are key tools to adapt the conservation efforts in Reunion Island. Further studies on the island’s resident dolphin populations are necessary to ensure the continuity of dolphin-watching activities in a sustainable manner.
Collapse
Affiliation(s)
- Belén Quintana Martín-Montalvo
- Centre d’Etude et Découverte des Tortues Marines (CEDTM), 97424 Piton Saint Leu, France; (O.D.); (S.D.); (A.-E.L.)
- Correspondence:
| | - Ludovic Hoarau
- UMR ENTROPIE, Université de La Réunion, IRD, CNRS, IFREMER, UNC, CEDEX 9, 97744 Saint Denis, France;
| | - Ophélie Deffes
- Centre d’Etude et Découverte des Tortues Marines (CEDTM), 97424 Piton Saint Leu, France; (O.D.); (S.D.); (A.-E.L.)
- Faculté des Sciences et Techniques, Université Jean Monnet, 42100 Saint-Etienne, France
| | - Sylvain Delaspre
- Centre d’Etude et Découverte des Tortues Marines (CEDTM), 97424 Piton Saint Leu, France; (O.D.); (S.D.); (A.-E.L.)
| | | | - Anne-Emmanuelle Landes
- Centre d’Etude et Découverte des Tortues Marines (CEDTM), 97424 Piton Saint Leu, France; (O.D.); (S.D.); (A.-E.L.)
| |
Collapse
|
4
|
Fumagalli M, Cesario A, Costa M, Notarbartolo di Sciara G, Harraway J, Slooten E. Population ecology and the management of whale watching operations on a data-deficient dolphin population. Ecol Evol 2019; 9:10442-10456. [PMID: 31624559 PMCID: PMC6787854 DOI: 10.1002/ece3.5565] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 04/27/2019] [Accepted: 07/22/2019] [Indexed: 11/10/2022] Open
Abstract
Whale watching is a popular commercial activity, producing socio-ecological benefits but also potential long-term effects on the targeted cetacean population. This industry is currently developing in data-deficient contexts in a largely unregulated fashion. Management schemes should adopt precaution and be informed by the relevant literature, but would be more effective if the assessment of the target population vulnerability, biological impacts, and management implications was drawn from site-specific data.This paper focuses on a reef-associated, data-deficient population of spinner dolphins in the Egyptian Red Sea. In Satayah Reef, new information on population size and dynamic parameters were documented using visual observation and photo-identification-based capture-recapture methods (Cormack-Jolly-Seber time-since-marking model).Dolphins occurred on 98% of the survey days. Average school size was 66 individuals (±42.1 SE), with most groups including calves. The population was equally divided into recurrent and transient individuals. An "emigration + mortality" model best described residence at the site. Five recurrent males (5% of the Satayah population) provided connectivity between this and the geographically close population of Samadai Reef.Average annual survival probability was 0.83 (±0.06 SE) in the year following first capture and 0.99 (±0.06 SE) for recurrent individuals. Mean yearly population sizes ranged 143-207 individuals.The study had the power to detect a 30% decline in the population, but not the rate of change in abundance estimated from the data (r = 0.018 ± 0.04), which would have required a 3- to 5-times longer study. Synthesis and application: These findings advance the assessment of the Satayah population's intrinsic vulnerability and have three major management applications: (a) the delineation of management units; (b) the identification of key indicators for future impact monitoring and assessment; and (c) realistic estimates of the statistical power for trend detection. Based on our results, we recommend supporting future research, devising site-specific time-area closure plans, and integrating them in a regional scheme. Approaches employed in this case study can inform the management of whale watching industries targeting other data-deficient populations.
Collapse
Affiliation(s)
- Maddalena Fumagalli
- Department of ZoologyUniversity of OtagoDunedinNew Zealand
- Tethys Research InstituteMilanoItaly
| | - Amina Cesario
- Tethys Research InstituteMilanoItaly
- The Swire Institute of Marine ScienceUniversity of Hong KongHong Kong SARChina
| | - Marina Costa
- Tethys Research InstituteMilanoItaly
- South Atlantic Environmental Research Institute (SAERI)StanleyFalkland Islands
| | | | - John Harraway
- Department of Mathematics and StatisticsUniversity of OtagoDunedinNew Zealand
| | | |
Collapse
|
5
|
Tyne JA, Christiansen F, Heenehan HL, Johnston DW, Bejder L. Chronic exposure of Hawaii Island spinner dolphins ( Stenella longirostris) to human activities. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171506. [PMID: 30473795 PMCID: PMC6227997 DOI: 10.1098/rsos.171506] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 09/24/2018] [Indexed: 06/09/2023]
Abstract
Habitat selection is strongly influenced by spatial variations in habitat quality and predation risk. Repeated exposure of wildlife to anthropogenic activities in important habitats may affect habitat selection, leading to negative biological consequences. We quantified the cumulative human exposure of a small, genetically isolated and behaviourally constrained spinner dolphin (Stenella longirostris) population, off Hawaii Island, and exposure effects on their daytime cumulative activity budget. Dolphins were exposed to human activities within 100 m for 82.7% of the daytime, with a median duration of 10 min between exposure events. Individual dolphins spent on average 61.7% (s.d. = 6.5) of their daytime resting. Of their total rest time, greater than 90% occurred inside sheltered bays. Despite high levels of human exposure, we did not observe an effect on dolphin resting behaviour. The short intervals between exposure events probably prevent dolphins from returning to a natural resting state before the next event. Consequently, 'control' observations may represent a resting behaviour of a more vigilant nature. Chronic levels of exposure to human activities could lead to rest deprivation, displacement from preferred resting habitats and ultimately negative population level effects. These results have implications for new proposed legislation aiming to reduce dolphin exposure to human activities.
Collapse
Affiliation(s)
- Julian A. Tyne
- Aquatic Megafauna Research Unit, School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, Western Australia, Australia
| | - Fredrik Christiansen
- Aquatic Megafauna Research Unit, School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, Western Australia, Australia
| | - Heather L. Heenehan
- Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University Marine Lab, 135 Duke Marine Lab Road, Beaufort, NC, USA
| | - David W. Johnston
- Aquatic Megafauna Research Unit, School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, Western Australia, Australia
- Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University Marine Lab, 135 Duke Marine Lab Road, Beaufort, NC, USA
| | - Lars Bejder
- Aquatic Megafauna Research Unit, School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, Western Australia, Australia
- Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University Marine Lab, 135 Duke Marine Lab Road, Beaufort, NC, USA
- Marine Mammal Research Program, Hawaii Institute of Marine Biology, University of Hawaii, Hawaii, HI, USA
| |
Collapse
|
6
|
Fumagalli M, Cesario A, Costa M, Harraway J, Notarbartolo di Sciara G, Slooten E. Behavioural responses of spinner dolphins to human interactions. ROYAL SOCIETY OPEN SCIENCE 2018; 5:172044. [PMID: 29765660 PMCID: PMC5936925 DOI: 10.1098/rsos.172044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 03/20/2018] [Indexed: 05/10/2023]
Abstract
There is increasing evidence that whale and dolphin watching activities have detrimental effects on targeted cetacean populations. In Egypt, spinner dolphins regularly occur in the resting areas of Samadai, Satayah and Qubbat'Isa reefs. In-water human interactions with dolphins are regulated with a time-area closure system at Samadai, unregulated at Satayah and non-existent at Qubbat'Isa. This provided an ideal experimental setting to advance our understanding of the effects of tourism on a species highly sensitive to disturbances. Our study confirmed that the intensity and duration of interactions, and therefore, dolphin exposure to tourism, differed among the study sites. Compared with the Qubbat'Isa control site, behavioural reactions to boats and swimmers at the two tourism sites suggested that dolphin rest was disrupted, especially around the middle of the day and especially at Satayah, where dolphin tourism is unregulated. Our results indicate also that the dolphin protection measures at Samadai reduce the level of disturbance. We recommend that similar measures be implemented at other dolphin tourism locations, and that no new operations be initiated until the long-term impacts on dolphin populations are better understood. Our experience emphasizes the need to adopt precautionary approaches in research and management of whale and dolphin watching.
Collapse
Affiliation(s)
- Maddalena Fumagalli
- Department of Zoology, University of Otago, 340 Great King Street, Dunedin 9054, New Zealand
- Tethys Research Institute, Viale G.B. Gadio 2, Milano 20121, Italy
- Author for correspondence: Maddalena Fumagalli e-mail:
| | - Amina Cesario
- Tethys Research Institute, Viale G.B. Gadio 2, Milano 20121, Italy
- The Swire Institute of Marine Science, University of Hong Kong, Pokfulam Road, Hong Kong SAR, People's Republic of China
| | - Marina Costa
- Tethys Research Institute, Viale G.B. Gadio 2, Milano 20121, Italy
- South Atlantic Environmental Research Institute (SAERI), Stanley Cottage, Falkland Islands
| | - John Harraway
- Department of Mathematics and Statistics, University of Otago, 730 Cumberland Street, Dunedin 9016, New Zealand
| | | | - Elisabeth Slooten
- Department of Zoology, University of Otago, 340 Great King Street, Dunedin 9054, New Zealand
| |
Collapse
|