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McKeegan KA, Clayton K, Williams R, Ashe E, Reiss S, Mendez-Bye A, Janik VM, Goetz T, Zinkgraf M, Acevedo-Gutiérrez A. The effect of a startle-eliciting device on the foraging success of individual harbor seals (Phoca vitulina). Sci Rep 2024; 14:3719. [PMID: 38355948 PMCID: PMC10866881 DOI: 10.1038/s41598-024-54175-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 02/09/2024] [Indexed: 02/16/2024] Open
Abstract
Pinniped predation on commercially and ecologically important prey has been a source of conflict for centuries. In the Salish Sea, harbor seals (Phoca vitulina) are suspected of impeding the recovery of culturally and ecologically critical Pacific salmon (Oncorhynchus spp.). In Fall 2020, a novel deterrent called Targeted Acoustic Startle Technology (TAST) was deployed at Whatcom Creek to deter harbor seals from preying on fall runs of hatchery chum (O. keta) and Chinook (O. tshawytscha) salmon in Bellingham, Washington, USA. Field observations were conducted in 2020 to compare the presence and foraging success of individual harbor seals across sound exposure (TAST-on) and control (TAST-off) conditions. Observations conducted the previous (2019) and following (2021) years were used to compare the effects observed in 2020 to two control years. Using photo-identification, individual seals were associated with foraging successes across all 3 years of the study. Generalized linear mixed models showed a significant 45.6% reduction in the duration (min) individuals remained at the creek with TAST on, and a significant 43.8% reduction in the overall foraging success of individuals. However, the observed effect of TAST varied across individual seals. Seals that were observed regularly within one season were more likely to return the year after, regardless of TAST treatment. Generalized linear models showed interannual variation in the number of seals present and salmon consumed. However, the effect of TAST in 2020 was greater than the observed variation across years. Our analyses suggest TAST can be an effective tool for managing pinniped predation, although alternate strategies such as deploying TAST longer-term and using multi-unit setups to increase coverage could help strengthen its effects. Future studies should further examine the individual variability found in this study.
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Affiliation(s)
- Kathleen A McKeegan
- Biology Department, Western Washington University, Bellingham, WA, 98225, USA.
- Research and Recovery Program, Skagit River System Cooperative, P.O. Box 368, La Conner, WA, 98257-0368, USA.
| | - Kate Clayton
- Biology Department, Western Washington University, Bellingham, WA, 98225, USA
| | - Rob Williams
- Oceans Initiative, 117 E Louisa St. #135, Seattle, WA, 98102, USA
| | - Erin Ashe
- Oceans Initiative, 117 E Louisa St. #135, Seattle, WA, 98102, USA
| | - Stephanie Reiss
- Oceans Initiative, 117 E Louisa St. #135, Seattle, WA, 98102, USA
| | | | - Vincent M Janik
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, East Sands, St Andrews, Fife, KY16 8LB, UK
| | - Thomas Goetz
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, East Sands, St Andrews, Fife, KY16 8LB, UK
| | - Matthew Zinkgraf
- Biology Department, Western Washington University, Bellingham, WA, 98225, USA
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Götz T, Pacini AF, Nachtigall PE, Janik VM. The startle reflex in echolocating odontocetes: basic physiology and practical implications. ACTA ACUST UNITED AC 2020; 223:223/5/jeb208470. [PMID: 32165452 PMCID: PMC7075047 DOI: 10.1242/jeb.208470] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 01/24/2020] [Indexed: 11/29/2022]
Abstract
The acoustic startle reflex is an oligo-synaptic reflex arc elicited by rapid-onset sounds. Odontocetes evolved a range of specific auditory adaptations to aquatic hearing and echolocation, e.g. the ability to downregulate their auditory sensitivity when emitting clicks. However, it remains unclear whether these adaptations also led to changes of the startle reflex. We investigated reactions to startling sounds in two bottlenose dolphins (Tursiops truncatus) and one false killer whale (Pseudorca crassidens). Animals were exposed to 50 ms, 1/3 octave band noise pulses of varying levels at frequencies of 1, 10, 25 and 32 kHz while positioned in a hoop station. Startle responses were quantified by measuring rapid muscle contractions using a three-dimensional accelerometer attached to the dolphin. Startle magnitude increased exponentially with increasing received levels. Startle thresholds were frequency dependent and ranged from 131 dB at 32 kHz to 153 dB at 1 kHz (re. 1 µPa). Startle thresholds only exceeded masked auditory AEP thresholds of the animals by 47 dB but were ∼82 dB above published behavioural audiograms for these species. We also tested the effect of stimulus rise time on startle magnitude using a broadband noise pulse. Startle responses decreased with increasing rise times from 2 to 100 ms. Models suggested that rise times of 141–220 ms were necessary to completely mitigate startle responses. Our data showed that the startle reflex is conserved in odontocetes and follows similar principles as in terrestrial mammals. These principles should be considered when assessing and mitigating the effects of anthropogenic noise on marine mammals. Summary: The acoustic startle reflex is conserved in echolocating toothed whales and should be considered when predicting marine mammal responses to human-generated underwater noise.
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Affiliation(s)
- Thomas Götz
- Sea Mammal Research Unit, Scottish Oceans Institute, School of Biology, University of St Andrews, Fife KY16 8LB, UK
| | - Aude F Pacini
- Hawaii Institute of Marine Biology, University of Hawaii at Manoa, P.O. Box 1346, Kaneohe, Hawaii 96744, USA
| | - Paul E Nachtigall
- Hawaii Institute of Marine Biology, University of Hawaii at Manoa, P.O. Box 1346, Kaneohe, Hawaii 96744, USA
| | - Vincent M Janik
- Sea Mammal Research Unit, Scottish Oceans Institute, School of Biology, University of St Andrews, Fife KY16 8LB, UK
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Malone KM, Powell AC, Hua F, Sieving KE. Bluebirds perceive prey switching by Cooper’s hawks across an urban gradient and adjust reproductive effort. ECOSCIENCE 2017. [DOI: 10.1080/11956860.2017.1346449] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Kristen M. Malone
- Wildlife Ecology and Conservation Department, University of Florida, Gainesville, FL, USA
| | | | - Fangyuan Hua
- Conservation Science Group, Department of Zoology, University of Cambridge, Cambridge, UK
- State Key Laboratory of BioControl, College of Ecology and Evolution/School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Kathryn E. Sieving
- Wildlife Ecology and Conservation Department, University of Florida, Gainesville, FL, USA
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Mikkelsen L, Hermannsen L, Beedholm K, Madsen PT, Tougaard J. Simulated seal scarer sounds scare porpoises, but not seals: species-specific responses to 12 kHz deterrence sounds. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170286. [PMID: 28791155 PMCID: PMC5541550 DOI: 10.1098/rsos.170286] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 06/19/2017] [Indexed: 06/07/2023]
Abstract
Acoustic harassment devices (AHD) or 'seal scarers' are used extensively, not only to deter seals from fisheries, but also as mitigation tools to deter marine mammals from potentially harmful sound sources, such as offshore pile driving. To test the effectiveness of AHDs, we conducted two studies with similar experimental set-ups on two key species: harbour porpoises and harbour seals. We exposed animals to 500 ms tone bursts at 12 kHz simulating that of an AHD (Lofitech), but with reduced output levels (source peak-to-peak level of 165 dB re 1 µPa). Animals were localized with a theodolite before, during and after sound exposures. In total, 12 sound exposures were conducted to porpoises and 13 exposures to seals. Porpoises were found to exhibit avoidance reactions out to ranges of 525 m from the sound source. Contrary to this, seal observations increased during sound exposure within 100 m of the loudspeaker. We thereby demonstrate that porpoises and seals respond very differently to AHD sounds. This has important implications for application of AHDs in multi-species habitats, as sound levels required to deter less sensitive species (seals) can lead to excessive and unwanted large deterrence ranges on more sensitive species (porpoises).
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Affiliation(s)
| | - Line Hermannsen
- Department of Bioscience, Aarhus University, Roskilde, Denmark
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - Kristian Beedholm
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
| | | | - Jakob Tougaard
- Department of Bioscience, Aarhus University, Roskilde, Denmark
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Schakner ZA, Götz T, Janik VM, Blumstein DT. Can fear conditioning repel California sea lions from fishing activities? Anim Conserv 2017. [DOI: 10.1111/acv.12329] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Zachary A. Schakner
- Department of Ecology & Evolutionary Biology University of California Los Angeles Los Angeles CA 90095‐1606 USA
| | - Thomas Götz
- Sea Mammal Research Unit Scottish Oceans Institute University of St Andrews East Sands St Andrews Fife KY16 8LB UK
| | - Vincent M. Janik
- Sea Mammal Research Unit Scottish Oceans Institute University of St Andrews East Sands St Andrews Fife KY16 8LB UK
| | - Daniel T. Blumstein
- Department of Ecology & Evolutionary Biology University of California Los Angeles Los Angeles CA 90095‐1606 USA
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Götz T, Janik VM. The startle reflex in acoustic deterrence: an approach with universal applicability? Anim Conserv 2016. [DOI: 10.1111/acv.12295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- T. Götz
- Sea Mammal Research Unit; Scottish Oceans Institute; University of St Andrews; St Andrews UK
| | - V. M. Janik
- Sea Mammal Research Unit; Scottish Oceans Institute; University of St Andrews; St Andrews UK
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Trites AW, Spitz J. One-two punches to eliminate depredation by marine mammals on fish caught or raised for human consumption. Anim Conserv 2016. [DOI: 10.1111/acv.12291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- A. W. Trites
- Marine Mammal Research Unit; Institute for the Oceans and Fisheries; University of British Columbia; Vancouver BC Canada
| | - J. Spitz
- Observatoire PELAGIS, UMS 3462; Université de La Rochelle/CNRS; La Rochelle France
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