Cetaceans are potentially at risk of poor welfare due to the animals’ natural reliance on sound and the persistent nature of anthropogenic noise, especially in the wild. Industrial, commercial, and recreational human activity has expanded across the seas, resulting in a propagation of sound with varying frequency characteristics. In many countries, current regulations are based on the potential to induce hearing loss; however, a more nuanced approach is needed when shaping regulations, due to other non-hearing loss effects including activation of the stress response, acoustic masking, frequency shifts, alterations in behavior, and decreased foraging. Cetaceans in managed-care settings share the same acoustic characteristics as their wild counterparts, but face different environmental parameters. There have been steps to integrate work on welfare in the wild and in managed-care contexts, and the domain of acoustics offers the opportunity to inform and connect information from both managed-care settings and the wild. Studies of subjects in managed-care give controls not available to wild studies, yet because of the conservation implications, wild studies on welfare impacts of the acoustic environment on cetaceans have largely been the focus, rather than those in captive settings. A deep integration of wild and managed-care-based acoustic welfare research can complement discovery in both domains, as captive studies can provide greater experimental control, while the more comprehensive domain of wild noise studies can help determine the gaps in managed-care based acoustic welfare science. We advocate for a new paradigm in anthropogenic noise research, recognizing the value that both wild and managed-care research plays in illustrating how noise pollution affects welfare including physiology, behavior, and cognition.

The effects of anthropogenic noise continue to threaten marine fauna, yet the impacts of human-produced sound on the broad aspects of cognition in marine mammals remain relatively understudied. The shutdown of non-essential activities due to the COVID-19-related anthropause created an opportunity to determine if reducing levels of oceanic anthropogenic noise on cetaceans affected processes of sensitization and habituation for common human-made sounds in an experimental setting. Dolphins at Dolphin Quest Bermuda were presented with three noises related to human activities (cruise ship, personal watercraft, and Navy low-frequency active sonar) both in 2018 and again during the anthropause in 2021 via an underwater speaker. We found that decreased anthropogenic noise levels altered dolphin responses to noise playbacks. The dolphins spent significantly more time looking towards the playback source, but less time producing burst pulse and echolocation bouts in 2021. The dolphins looked towards the cruise ship sound source significantly more in 2021 than 2018. These data highlight that different sounds may incur different habituation and sensitization profiles and suggest that pauses in anthropogenic noise production may affect future responses to noise stimuli as dolphins dishabituate to sounds over time.

Attention is a process that guides organisms to engage in goal-directed behavior, such as seeking food when hungry. However, attention is subject to distraction, which can impact the execution of these behaviors. The ocean is full of auditory stimuli that are potentially distracting. Bottlenose dolphins (Tursiops spp.), who rely on sound as their primary sensory and communicative modality, have been shown to be impacted by noise, especially anthropogenic noise. In our study, we assessed whether louder background noise, including both natural and anthropogenic noise, was associated with worse performance on two common cognitive tasks. Using previously recorded cognitive task data, we collected information on how long it took dolphins to make a choice, how many times they considered each alternative, whether they succeeded at the trial, and the root-mean-squared amplitude of the background noise across three frequency bands while they were making a choice. In both datasets, longer choice times and more oscillations between alternatives were associated with louder noise in the highest frequency band, which mostly consists of social sounds produced by nearby dolphins. Worse performance was also associated with this higher frequency band in one of the datasets. Results were mixed for low and middle frequency bands. Our results suggest that social sounds may be more distracting than vessel noise for dolphins in San Diego Bay, though these data are correlational and should be further investigated. Future experiments should manipulate the types and magnitudes of noise that are most distracting across additional types and difficulties of cognitive tasks. This would further shed light on both welfare considerations and comparative cognition.

Dishabituation; Sensitization effect; Habituation effect; Sensitization process; The Dual-Process Theory Sensitizationis a term that applies to both an effect and a process. The sensitization effect...

Marine mammals act as sentinels of environmental well-being with economic and human health implications. For decades, investigators have used invasive methods to gather biological samples from whales and dolphins for health monitoring. Traditionally, delphinid species are rounded up onto boats or corralled and held while numerous samples are collected. Drones or Uncrewed Aircraft Systems (UASs) equipped to capture respiratory vapors (blow) became an alternative to more invasive traditional sampling methods. While commercial off-the-shelf rotary wing UASs have been used to collect samples from free-ranging baleen whales and killer whales (Orcinus orca), smaller cetaceans, such as delphinids, present a greater challenge for sample collection via UASs. The use of standard commercial drones may result in inaccurate data or insufficient collection as rotary blades create blow downwash and introduce high noise levels into the environment. However, a fixed-wing capable UAS equipped with a siphon may enable accurate testing of population genetics, hormonal levels, pathogen loads, and microbiological contaminants. The objective of this project was to evaluate the feasibility of a custom fixed-wing UAS, PHASM (Passive Health Assessment of Sea Mammals), to fly over bottlenose dolphins (Tursiops truncatus) without causing strong behavioral responses while attempting to collect respiratory vapor samples using its siphon system. While attempting blow collection by PHASM, we evaluated swim path deviations and look responses of six dolphins (n = 6) housed at Dolphin Quest Hawaii across 10 trial days. Further, we tested for habituation of effects by testing for significance across trial day by dolphin. Between Control and PHASM treatment, the dolphins exhibited no significant differences in look responses across spatial zones corresponding to drone pass-overs (Zone 1: z = -2.492, p = 0.061; Zone 2: z = -1.699, p = 0.324). Dolphins deviated slightly more post-approach by PHASM than during the Control trials (z = -3.006, p = 0.014). Additionally, we managed to obtain respiratory vapor collection over the last three flight trial days. This is the first ever successful collection of respiratory vapors by a fixed-wing UAS without significant behavioral response, which marks a new technological milestone for health assessment that avoids major disruption of small cetaceans’ lives.