Skinny dolphins: Can poor body condition explain population decline in Indo-Pacific humpback dolphins (Sousa chinensis)?

Indo-Pacific humpback dolphins (IPHDs) who form resident populations along the Chinese coastline are facing a wide range of anthropogenic disturbances including intense fishing and some populations have been shown to experience a severe decline. Body condition is thought to be a good indicator of health since it is linked to survival and reproductive success. In order to better understand population trends, we investigated whether the body condition of IPHDs is poorer in populations whose status is alarming than in other populations. UAV flights were conducted from 2022 to 2023 in four locations (i.e., Sanniang Bay, Leizhou Bay, Jiangmen, and Lingding Bay) in the northern South China Sea. Body ratios were calculated using the body length and widths of IPHDs and were used to analyze differences among seasons, locations, and demographic parameters. A PCA was then used to obtain a detailed picture of the body condition composition of dolphins at each location. Results showed that dolphins from Leizhou Bay and Jiangmen were in better body condition than those from Sanniang Bay and Lingding Bay. Since populations inhabiting Sanniang Bay and Lingding Bay have been shown to experience a sharp decline, it can be hypothesized that poor body condition may have played a role in such a trend. Further investigations of the factors impacting IPHDs' body condition are needed, including monitoring of prey density, contaminant concentration, stress levels, and impacts of human activities on dolphins' behavior. In addition, the creation of a robust scoring method would allow for regular monitoring of IPHDs' body condition to inform conservation measures.

A Quantitative Assessment of Trainers-Dolphins' Interactions in the Absence of Food Reward.

All the studies that have considered the motivation of the dolphins to interact with their trainers as a possible welfare indicator have been carried out in facilities where the trainer-dolphin interactions (TDIs) sessions were reinforced with food. Therefore, in these specific circumstances, it was difficult to separate the motivation of the dolphins interacting with the trainers from the food drive. The current study aims to assess the interaction between the trainers and the dolphins in the absence of food rewards. The research was carried out at The Dolphin Reef (Eilat, Israel), a facility where the interaction between the trainers and 14 bottlenose dolphins of different sex and age classes did not involve food rewards. A total of 531 TDIs were recorded, with dolphins participating in 94.5% of the sessions and an average of three dolphins per session. The dolphins participated in a higher number and more frequently in the TDIs when toys were provided by the trainers. Diel and seasonal differences were also observed, with the dolphins participating more during the morning sessions and the neutral season. The latency of response of the dolphins to the presence of the trainers on the platform or in the water, whether or not advertised by the trainers' signal ("call" or "no-call"), was very short (usually less than 1 min), and the dolphins often anticipated the beginning of the sessions by arriving at the trainers' location before or upon the caretakers' arrival (96% of the time). Individual differences in the participation in the TDIs were also recorded, which might be linked to both the dolphin's health/welfare status or their personality. The current study shows that the separation of the TDIs from the food reward allows for a better understanding of the willingness of dolphins under human care to interact with their trainers. In addition, the results presented in this paper show that such TDIs are an important part of these dolphins' lives, which suggests that these interactions might be an additional tool to improve the animals' social environment and monitor their welfare.

Ranging pattern development of a declining delphinid population: A potential cascade effect of vessel activities.

It is generally accepted that vessel activity causes various behavioral responses of cetaceans and undermines individual fitness. Whether or how it can lead to a demographic response of populations remains rarely examined. In the northern Beibu Gulf, China, vessel activities have sharply increased in the past two decades, while abnormal demographic dynamics was recently noted for the resident Indo-Pacific humpback dolphins. The present study first examined the humpback dolphins' utilization distribution (UD) from 2003 to 2019. Habitat suitability was then modeled with the sighting data collected before the most recent population reduction. Finally, we tried to disentangle the anthropogenic driver of dolphin demography by cross-referring the spatiotemporal development of dolphins' UD, vessel activities, and habitat suitability. Our results showed that the dolphins' UD shrank substantially during the port expansion in the early 2010s, and we suggest that the consequential increase in vessel activities might impose extra marine stressors on the resident humpback dolphins. To reduce the boat interaction, the dolphins steadily shifted their core area to a less suitable area in the east during 2015-2017, when unnaturally low survivals were recorded. Afterward, the dolphin core area partially shifted back to the more suitable area in the west, which corresponded to the improving dolphin survival in 2018. Our finding suggested that the vessel activity may be responsible for the dolphin displacement, while staying in the less suitable area may further lead to a more severe and acute demographic consequence on the population. The underlying and indirect impact of vessel activities as disclosed by the present study is particularly important for port management, marine planning, and conservation practice regarding coastal cetaceans, especially for those resident and endangered populations inhabiting the urbanized coastal areas.

Reliability of caretakers' ratings of captive bottlenose dolphins (Tursiops truncatus) and finless porpoises' (Neophocaena asiaeorientalis sp.) behavioral style for welfare monitoring.

Qualitative ratings are increasingly used to assess animal welfare. We investigated the associations between daily caretakers' ratings of individuals' behavioral style, behavior during free time, participation during training sessions, and environmental variables in captive Yangtze finless porpoises, East-Asian finless porpoises, and bottlenose dolphins. Associations between caretakers' ratings and behavior were found, including social swimming, fast swimming, play, interaction with humans, and agonistic and socio-sexual interactions. Ratings were also associated with participation during training sessions and food intake. Social separation, transport to a new pool, high visitors' density, and holding of a sick conspecific were associated with ratings indicating a deteriorated human-animal relationship, a lower interest/fear of the environment, and/or a higher social cohesion depending on the group. Through principal component analyses, new variables that represented both caretakers' ratings and behavior and that could be used for an easier interpretation of the data for welfare monitoring within each group were extracted. Caretaker ratings and behavior should be used as a complement to previously validated indicators to detect changes in welfare state and understand the potential causes of these changes.

Changes in the Dog's and Cat's Behaviors, as Reported by the Owners, before and during the Lockdown in China.

Considering the effects that the COVID-19 pandemic had and still has on human psychological health, it is expected that it might also affect household dogs' and cats' welfare. The current study explores the behavioral changes in dogs and cats before (BL) and during the lockdown (DL), as reported by their owners in China. Besides demographic parameters, variables related to the daily management of dogs and cats were analyzed in relation to behavioral problems, stress-related behaviors, and anxiety-related behaviors before and during the lockdown. A total of 261 questionnaires were collected. In general, behavioral problems and stress-related behaviors in dogs (p < 0.001) and cats (p < 0.001) decreased DL compared to BL, while anxiety-related behaviors in cats did not show any differences between the two periods considered. On the other hand, anxiety-related behaviors were more frequent in dogs DL (36.3%) compared to BL (35%), which were associated with reduced frequency of play activities with the owners (p = 0.016) and altered sleeping habits (p < 0.01). During the lockdown, dogs' and cats' daily routines and management (feeding and sleeping habits, dogs' walks, dogs' and cats' play activities, litter box management, and cats' lifestyle) experienced changes, but they were not associated with any behavioral issues. On the other hand, the behavioral issues considered for dogs and cats were more frequent BL, which were influenced by the daily management of the pets. The current study showed how critical the attention the owners can provide to the pets could be, to improve their companion animals' welfare. Therefore, it is important to provide pet owners with behavioral management support both during particularly difficult periods such as a lockdown and during regular daily routines.

Chinese College Students' Attitudes towards Animal Welfare.

Understanding the attitude of stakeholders towards animals is critical for the development and improvement of animal welfare in a country. College students from veterinary, animal, and life sciences majors represent future key stakeholders that will interact with professionals from animal industries. Therefore, it is critical to understand these college students' attitudes towards animals and their knowledge about animal welfare. The present survey aimed to investigate Chinese college students' concerns towards different animal classes (i.e., pets, farm, laboratory, and wild animals) through the animal Sentient and Five Freedoms models. Chinese college students from different majors (i.e., related to animal sciences or not) scored very well in their attitude towards both the animal Sentient and Five Freedoms models, with differences depending on the animal class considered. Pets (dogs and cats) had better consideration for both animal Sentient and Five Freedoms models, followed by wild animals, while farm and laboratory animals were less considered. Veterinary science major students showed the strongest differences in attitudes depending on the animal classes considered compared to other majors. Furthermore, respondents showed better attitude scoring if they currently owned or had owned animals, had participated in animal welfare courses, or in laboratory work that involved animals. When compared to previous studies, our results suggest a general improvement of Chinese college students' attitudes towards animals.

Behavioural Diversity Study in Bottlenose Dolphin (Tursiops truncatus) Groups and Its Implications for Welfare Assessments.

In the recent past, animal welfare studies have tried to determine the best animal welfare measures and indicators. Expression of behavioural diversity is considered a potential positive welfare indicator, and to the authors' knowledge, it has not been validated nor studied in cetaceans. For the first time, a behavioural diversity study on bottlenose dolphins (Tursiops truncatus) groups was conducted at six European facilities. The study was carried out by the animal care staff, biologists and veterinarians and included 54 dolphins housed in several group compositions at the different participating facilities. The goal of our study was to analyse behavioural diversity in bottlenose dolphins at the group level to investigate how particular factors might impact the diversity of behaviours within the group and to discuss its implications for dolphin welfare assessments. Eight factors (i.e., "observer location", "number of individuals", "age class", "sex", "social grouping", "presence/absence of leading male", "presence/absence of visitors" and "enrichment provision") impacted the behavioural diversity of the observed groups, while no significant impact of the factors "time of day" and "activity before/after observation" could be found. Our study showed the feasibility of this kind of approach for cetaceans under professional care and the relevance to considering this parameter in dolphin welfare studies, despite certain limitations that warrant further research.

The Click Production of Captive Yangtze Finless Porpoises (Neophocaena asiaeorientalis asiaorientalis) Is Influenced by Social and Environmental Factors.

Yangtze finless porpoises use high-frequency clicks to navigate, forage, and communicate. The way in which click production may vary depending on social or environmental context has never been investigated. A group of five captive Yangtze finless porpoises was monitored for one year, and 107 h of audio recordings was collected under different conditions. Using a MATLAB-generated interface, we extracted click density (i.e., number of clicks per minute) from these recordings and analyzed its variation depending on the context. As expected, click density increased as the number of animals present increased. The click density did not exhibit diurnal variations but did have seasonal variations, with click density being highest in summer and fall. Yangtze finless porpoises produced more clicks when socially separated than when not (136% more), during training/feeding sessions than outside of such sessions (312% more), when enrichment was provided (265% more on average), and when noisy events occurred rather than when no unusual event occurred (22% more). The click density decreased when many visitors were present in the facility (up to 35% less). These results show that Yangtze finless porpoises modulate their click production depending on the context and suggest that their echolocation activity and their emotional state may be linked to these changes. Such context-dependent variations also indicate the potential usefulness of monitoring acoustical activity as part of a welfare assessment tool in this species. Additionally, the click density variation found in captivity could be useful for understanding click rate variations of wild populations that are hardly visible.

Contextual impacts on individual and synchronous breathing rate variations in three captive odontocete groups.

Breathing rates are often collected both in the wild and in captivity to inform on cetaceans' internal state. However, few studies have investigated the effect of various factors on this breathing rate. We investigated the variations of individual and synchronous breathing rates depending on individual features (species, sex, age), displayed behavior, social parameters (social grouping), and environmental parameters (diurnal variation, presence of enrichment, unusual events, and presence of visitors in three groups of captive odontocetes (Yangtze finless porpoises, Neophocaena asiaeorentalis asiaeorientalis, East-Asian finless porpoises, Neophocaena asiaeorentalis sunameri, bottlenose dolphins, Tursiops truncatus). Both individual and synchronous breathing rates were the highest when animals engaged in energetic or social behaviors. Individual breathing rate decreased but synchronous breathing rate increased with the presence of enrichment. Both rates increased during unusual events (e.g., pool cleaning, presence of a diver in the pool, noise, transport) and when public was present for Yangtze finless porpoises. Finally, synchronous breathing rate increased for Yangtze finless porpoises when experiencing social separation. We suggest that individual and synchronous breathing rates are useful parameters to measure, both in wild and captive animals, to obtain information on their arousal/stress state. However, these rates should be interpreted with caution and should be used together with other parameters to allow more accurate inferences.

Body Contacts and Social Interactions in Captive Odontocetes Are Influenced by the Context: An Implication for Welfare Assessment.

Research on the welfare of captive odontocetes has increased in recent years, but has been mostly focused on bottlenose dolphins (Tursiops truncatus). Few studies investigated potential welfare indicators using quantitative data linked to a range of conditions or stimuli that are thought to impact the animals' emotional state. Since odontocetes are social animals that engage in various social interactions, these interactions might inform us on their welfare state. We investigated pectoral contact laterality and the effect of the context on several social behaviors in three groups of captive odontocetes (Yangtze finless porpoises, YFPs: Neophocaena asiaeorientalis asiaeorientalis; East-Asian finless porpoises, EAFPs: N. a. sunameri, and bottlenose dolphins, BDs). Animals exhibited patterns depending on the time of the day for most of the social behaviors we analyzed; social separation was associated with lower rates of social behaviors for the two analyzed groups (YFPs and BDs), the accessibility to several pools was associated with higher rates of social behaviors for BDs. The effect of enrichment, disturbances and public presence was less clear and strongly depended on the group, the type of enrichment and disturbance. Our results confirm that captive odontocetes' social behaviors are influenced by the context, and that, depending on the group, some of them, such as pectoral contacts, other body contacts, agonistic interactions or social play exhibit consistent patterns across contexts. Monitoring these behaviors might be useful to adapt the captive management to each species and group. The different responses among the three studied groups confirm that species and groups react differently to a stimulus and therefore, management decisions should be species/group specific. We recommend that more studies should be conducted to validate our findings in other groups of odontocetes under human care.

Swimming features in captive odontocetes: Indicative of animals' emotional state?

Captive welfare studies in odontocete species have been mostly conducted on bottlenose dolphins (Tursiops truncatus) while the welfare of many other species' -including endangered species- remains poorly studied. More research is needed to find and validate potential indicators of welfare for each species and even for each group. Since captive odontocetes spend most of their time swimming, their swimming features are interesting to study in relation to their welfare state. We first analysed the circular swimming direction bias in three groups of captive odontocetes (Yangtze finless porpoises: Neophocaena asiaeorientalis asiaeorientalis; East-Asian finless porpoises: N. a. sunameri; and bottlenose dolphins, Tursiops truncatus). Second, we studied the effect of environmental and social factors (i.e., time of the day, delay to training, enrichment, potential perturbation, social grouping, public presence and housing pool) on circular swimming, fast swimming, group swimming, synchronous swimming and contact swimming in the three groups. Yangtze finless porpoises exhibited a clockwise swimming bias while East-Asian finless porpoises and bottlenose dolphins swam significantly more in the counter-clockwise direction. Each studied factor significantly impacted the animals' swimming behaviour slightly differently depending on the group. However, some patterns were common for the three groups: animals seemed to be more active in the morning than at noon and in the afternoon, and enrichment seemed to decrease circular swimming, fast swimming and social swimming (i.e., synchronous, contact and group swimming), while potential perturbations (e.g., pool cleaning, noise) seemed to increase it. In addition, behaviour differed for Yangtze finless porpoises and bottlenose dolphins right before the training or when other animals were being trained, suggesting an anticipation of this event or an excited/frustrated state in this context. Social separation also impacted these animals' swimming behaviour with less group swimming but more circular swimming, synchronous swimming and fast swimming when separated. The housing pool had an impact on bottlenose dolphins' behaviour with more circular swimming, more fast swimming and less group swimming when having access to a larger space. The effect of the presence of public was unclear and requires further investigation. From our results, we propose that circular swimming, synchronous swimming and contact swimming could be useful to monitor animals' emotional state, but that additional parameters should be added (e.g., swimming speed) since these behaviours can be expressed both in quiet and relaxed contexts and in stressful ones. In addition, fast swimming can be a useful indicator of stress for porpoises but might be more ambiguous for bottlenose dolphins that engage in intense social play bouts for instance. Finally, group swimming might be a good behaviour to monitor when wanting to investigate reactions to various conditions or events that can potentially be stressful. We suggest that further research should be conducted on other groups of odontocetes to validate our findings.

Environmental changes and anthropogenic factors modulate social play in captive bottlenose dolphins (Tursiops truncatus).

Social play varies among species and individuals and changes in frequency and duration during ontogeny. This type of play is modulated by environmental changes (e.g., resource availability). In captivity, cetaceans and their environment are managed by humans, and training sessions and/or public presentations punctuate the day as well as other frequent or occasional events. There is a lack of research on the effects of environmental events that occur in captivity and might affect dolphins' behavior. We studied the context in which nine bottlenose dolphins (Tursiops truncatus) played socially and the events that could potentially impact this social interaction. The dolphins' social play behavior was significantly more frequent and lasted longer in the morning than in the afternoon and was present before and after interactions with their trainers with a non-significant tendency to be more frequent before and after a training session than a public presentation. In an experimental paradigm using familiar environmental enrichment, our results demonstrated that environmental enrichment tended to increase social play duration whereas temporary noisy construction work around the pool and display of agonistic behaviors by members of the group significantly decreased it. These results contribute to better understand the social play distribution in captive bottlenose dolphins and the impact of different events within their daily lives. Since play decreases or disappears when animals are facing unfavorable conditions, the evaluation of social play may relate to the animals' current well-being. We suggest that social play has potential to become an indicator of bottlenose dolphins' current welfare state.