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Research evaluating marine mammal welfare and opportunities for advancements in the care of species housed in a professional facility have rapidly increased in the past decade. While topics, such as comfortable housing, adequate social opportunities, stimulating enrichment, and a high standard of medical care, have continued to receive attention from managers and scientists, there is a lack of established acoustic consideration for monitoring the welfare of these animals. Marine mammals rely on sound production and reception for navigation and communication. Regulations governing anthropogenic sound production in our oceans have been put in place by many countries around the world, largely based on the results of research with managed and trained animals, due to the potential negative impacts that unrestricted noise can have on marine mammals. However, there has not been an established best practice for the acoustic welfare monitoring of marine mammals in professional care. By monitoring animal hearing and vocal behavior, a more holistic view of animal welfare can be achieved through the early detection of anthropogenic sound sources, the acoustic behavior of the animals, and even the features of the calls. In this review, the practice of monitoring cetacean acoustic welfare through behavioral hearing tests and auditory evoked potentials (AEPs), passive acoustic monitoring, such as the Welfare Acoustic Monitoring System (WAMS), as well as ideas for using advanced technologies for utilizing vocal biomarkers of health are introduced and reviewed as opportunities for integration into marine mammal welfare plans.

The SEA LIFE Trust Beluga Whale Sanctuary (BWS) has been in operation for over five years and serves as a unique case study to evaluate the effectiveness of marine sanctuaries for cetaceans. While cetacean sanctuaries are often regarded as a middle-ground solution between captivity and release, evidence from the BWS highlights complexities in adapting cetaceans to these environments. Despite initial assumptions that natural conditions would inherently improve welfare, the belugas at the BWS spent the majority of the operational period (92.6%) in a conventional indoor pool, due to health and welfare concerns. Repeated delays, challenges in acclimatization, and distress-related conditions observed during periods in the bay suggest that natural environments alone may not guarantee improved welfare. Additionally, the lack of publicly accessible data on health and welfare outcomes hinders comprehensive evaluation of the sanctuary’s success and raises questions about transparency and evidence-based practices. This review underscores the need for refined sanctuary models, improved infrastructure, and structured adaptation programs tailored to species and individual cetaceans. It highlights the importance of robust planning, ongoing research, and transparency to meet the ambitious goals of marine sanctuaries in the best interests of the well-being of cetaceans under human care. These considerations also raise concerns about the decision to relocate captive cetaceans to marine sanctuaries, as the available evidence suggests that such environments may not inherently guarantee better welfare outcomes.

Cognitive enrichment for professionally managed species has become more prevalent in recent years in both zoological and research settings and has been encouraged as a means of welfare enhancement. However, the task’s difficulty must be specifically tailored as it can impact the successful nature of the sessions, as tasks that are too simple or difficult may not be perceived as enriching by the animals. While pinnipeds are common in zoos, aquariums, and research facilities, few studies have explored the use of cognitively challenging enrichment in this species, and the level of difficulty and presence of failure on animal success and engagement in this type of session has not been assessed. In this study, gameplay strategies during computerized enrichment sessions were evaluated before and after a game that introduced failure, or the loss of opportunity to complete a level for a reward after an incorrect movement. Interest in participation during the session, measured as the latency without contact, was also tested as a proxy for this enrichment’s effect on welfare. When incorrect movements resulted in a short pause and removed the opportunity to finish individual levels for a reward, all three sea lions tested significantly reduced the amount of time spent on each of several strategies they employed, but significantly increased the number of button presses per strategy, suggesting the animals focused on more precise movements as their proficiency improved. Two sea lions also showed a significant decline in latency without contact following the introduction of failure in the form of a single opportunity to complete a task for a reward after previously having unlimited opportunities, while one maintained a low latency without contact across both test conditions. The results suggest that more cognitively challenging tasks incorporating failure did not cause a reduction in gameplay performance and session interest in sea lions. Individual variation was also noted in strategy use, emphasizing the importance of evaluating the individual in terms of enrichment provision.

In this review we highlight the relevance of biodiversity that inhabit coastal lagoons, emphasizing how species functions foster processes and services associated with this ecosystem. We identified 26 ecosystem services underpinned by ecological functions performed by bacteria and other microbial organisms, zooplankton, polychaetae worms, mollusks, macro-crustaceans, fishes, birds, and aquatic mammals. These groups present high functional redundancy but perform complementary functions that result in distinct ecosystem processes. Because coastal lagoons are located in the interface between freshwater, marine and terrestrial ecosystems, the ecosystem services provided by the biodiversity surpass the lagoon itself and benefit society in a wider spatial and historical context. The species loss in coastal lagoons due to multiple human-driven impacts affects the ecosystem functioning, influencing negatively the provision of all categories of services (i.e., supporting, regulating, provisioning and cultural). Because animals’ assemblages have unequal spatial and temporal distribution in coastal lagoons, it is necessary to adopt ecosystem-level management plans to protect habitat heterogeneity and its biodiversity, ensuring the provision of services for human well-being to multi-actors in the coastal zone.

When about 125 dolphins were stranded on a beach in Cape Cod, Mass., the International Fund for Animal Welfare (IFAW) worked with community members to save over 100 of them.

Despite a long-documented history of severe harmful algal blooms (HABs) in New England coastal waters, corresponding HAB-associated marine mammal mortality events in this region are far less frequent or severe relative to other regions where HABs are common. This long-term survey of the HAB toxins saxitoxin (STX) and domoic acid (DA) demonstrates significant and widespread exposure of these toxins in New England marine mammals, across multiple geographic, temporal and taxonomic groups. Overall, 19% of the 458 animals tested positive for one or more toxins, with 15% and 7% testing positive for STX and DA, respectively. 74% of the 23 different species analyzed demonstrated evidence of toxin exposure. STX was most prevalent in Maine coastal waters, most frequently detected in common dolphins ( Delphinus delphis ), and most often detected during July and October. DA was most prevalent in animals sampled in offshore locations and in bycaught animals, and most frequently detected in mysticetes, with humpback whales ( Megaptera novaeangliae ) testing positive at the highest rates. Feces and urine appeared to be the sample matrices most useful for determining the presence of toxins in an exposed animal, with feces samples having the highest concentrations of STX or DA. No relationship was found between the bloom season of toxin-producing phytoplankton and toxin detection rates, however STX was more likely to be present in July and October. No relationship between marine mammal dietary preference and frequency of toxin detection was observed. These findings are an important part of a framework for assessing future marine mammal morbidity and mortality events, as well as monitoring ecosystem health using marine mammals as sentinel organisms for predicting coastal ocean changes.

Euthanasia may be necessary for stranded cetaceans to alleviate suffering, achievable through properly applied ballistics causing rapid insensibility and death. Despite widespread use, understanding of appropriate equipment relative to anatomical variation remains limited. We conducted experimental ballistics trials using cetacean cadavers to examine cranial trauma from five projectile types. A .308 calibre rifle with two deforming and three non-deforming projectiles was tested on 30 cadavers across four odontocete species (six per projectile type). Post-mortem computed tomography (PMCT) and dissection evaluated ballistics trauma. PMCT analysis assessed calvarium damage across 8 quadrants, summarized into four sectors. Marked caudoventral (brainstem) fractures were used as a conservative proxy indicator for likely instant insensibility. Generalized linear mixed models evaluated projectile type, brain sector, and species effects on fracture severity and fragmentation. Only 17 (56.7%) cadavers exhibited marked brainstem fractures. Non-deforming full metal jacket and hydrostatic projectiles caused significantly less severe fractures than other projectiles. Deforming and non-deforming monolithic projectiles produced brainstem-disrupting fractures in common, striped, and dusky dolphins. Monolithic projectiles appear more effective for bottlenose dolphins. Preliminary findings indicate deforming or monolithic projectiles were associated with a higher frequency of brainstem-associated osseous fractures in the cadavers studied. However, increased sample sizes with the addition of soft tissue damage quantification, are required to better elucidate species-specific equipment selection.

This study examines the alignment between whale-watching experiences and tourist expectations in three different destinations. Whale-watching is a global tourist activity, with locations such as the Canary Islands (Spain) and the Azores (Portugal) in Macaronesia rapidly becoming prime spots for these marine activities. Those locations attract a significant number of tourists with varying recreational interests and diverse perceptions of each destination and its natural resources, including marine wildlife megafauna species that can be seen. While often marketed as sustainable tourism, the ecological impacts of whale-watching are a matter of concern. Evolving whale-watching practices may reinforce or diminish the effectiveness of conservation and environmental education efforts. In this regard, exploring whale watchers’ expectatives, preferences, previous experiences, level of satisfaction, and environmental information may help to assess better practices and sustainable tourism initiatives. This study employed a multidisciplinary approach, incorporating a series of questionnaires that explored whale watchers’ expectations and overall satisfaction before and after sea trips in the Tenerife and El Hierro Islands (Canary Islands, Spain), as well as in São Miguel (Azores, Portugal). The findings highlight differences across three study cases: El Hierro attracted more experienced and oriented tourists, while Tenerife and São Miguel received more generalist visitors. Satisfaction was closely linked to the number of cetacean sightings. Many participants who did not mention specific species expressed open preferences such as wanting to “see everything” or “whatever is possible”, reflecting limited prior knowledge. The study highlights the importance of tailoring whale-watching strategies to tourist profiles by enhancing communication, adjusting group sizes and vessel types, and reinforcing conservation messaging to ensure both positive experiences and long-term ecological sustainability.

Accredited zoological facilities are committed to fully understanding the behavioral, mental, and physical needs of each species to continuously improve the welfare of the animals under their professional care and detect when welfare has diminished. In order to accomplish this goal, internally consistent and externally valid indicators of animal welfare are necessary to advance our understanding of the current welfare status of individual animals. Historically, efforts have focused on monitoring visible or observable signs of poor health or problem behavior, but lack of signs or problems does not necessarily demonstrate that an individual animal is thriving. The current study examined fecal hormone metabolite levels and behavior for two species of bottlenose dolphins ( Tursiops truncatus and Tursiops aduncus ) from 25 different accredited zoological facilities. At the time of the study, all facilities were accredited by the Alliance of Marine Mammal Parks and Aquariums and/or the Association of Zoos and Aquariums. This was part of the multi-institutional study ‘Towards understanding of the welfare of cetaceans in zoos and aquariums” commonly referred to as the Cetacean Welfare Study. Behavioral diversity was calculated using the Shannon Diversity Index on species-appropriate behavioral events. Behavioral diversity was compared to the fecal metabolites of cortisol, aldosterone, and the ratio of cortisol to dehydroepiandrosterone (DHEA) as well as the stereotypic behavior of route tracing. Similar to previous studies on other species, there was a significant inverse relationship between behavioral diversity and both fecal cortisol metabolites and route tracing. Additionally, a significant inverse relationship also exists between behavioral diversity and the ratio of fecal cortisol to DHEA metabolites. Behavioral diversity and fecal aldosterone metabolites were not associated. Additional research is still needed to validate behavioral diversity as an indicator of positive animal welfare for bottlenose dolphins and across species. However, based on current results, facilities could utilize behavioral diversity combined with other measures of welfare to more comprehensively evaluate the welfare of bottlenose dolphins.

Cetaceans are long-lived, social species that are valued as ambassadors inspiring the public to engage in conservation action. Under professional care, they are critical partners with the scientific community to understanding the biology, behavior, physiology, health, and welfare requirements of this taxonomic group. The Cetacean Welfare Study was a highly collaborative research effort among zoos and aquariums accredited by the Alliance for Marine Mammal Parks and Aquariums and/or the Association of Zoos & Aquariums that provided important empirical and comparative information on the care and management of cetaceans. The goal was to identify factors that were related to the welfare of bottlenose dolphins and to develop reference intervals and values for common and novel indicators of health and welfare for common bottlenose dolphins ( Tursiops truncatus ), Indo-Pacific bottlenose dolphins ( Tursiops aduncus ), beluga whales ( Delphinapterus leucas ), and Pacific white-sided dolphins ( Lagenorhynchus obliquidens ). Data were collected from cetaceans at 43 accredited zoos and aquariums in seven countries in 2018 and 2019. This overview presents a summary of findings from the initial research articles that resulted from the study titled “Towards understanding the welfare of cetaceans in zoos and aquariums.” With multiple related objectives, animal-based metrics were used to advance frameworks of clinical care and target key conditions that were associated with good welfare of cetaceans in zoo and aquarium environments. As a result of this collaboration, species-specific reference intervals and values for blood variables and fecal hormone metabolites were developed and are freely available in an iOS application called ZooPhysioTrak. The results suggested that environmental enrichment programs and social management factors were more strongly related to behaviors likely indicative of positive welfare than habitat characteristics for common and Indo-Pacific bottlenose dolphins. These findings can be widely applied to optimize care and future science-based welfare practice.