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A retrospective study of admission data of 401 West Indian manatees (Trichechus manatus latirostris) presented to the David A. Straz Jr. Manatee Critical Care Center at ZooTampa at Lowry Park (ZooTampa) for rehabilitation from August 1991 through October 2017. Causes of admittance, location of rescue, gender, and age class were all recorded for each manatee admitted. Admittance categories as defined by the Florida Fish and Wildlife Conservation Commission (FWC) included watercraft collisions, natural causes, entanglement, entrapment, orphaned calves, captive born, mothers of rescued calves, calves of rescued mothers, human, and other. The admitted population was primarily from the southwest and northwest coasts and related waterways of Florida. The gender difference was relatively equivocal (54% female) while the adults comprised 79% of the admissions. The overall total admissions increased steadily over the study period as did the admissions for each individual categories of admission. Watercraft collisions and natural causes combined were 71% of all admissions for the entire study period and are the dominant causes of admission. Watercraft collisions are more likely to occur during May through October, whereas natural causes of admittance are more likely to occur between December and March. Rehabilitated manatees may reduce overall manatee mortality and can provide insight into population-based health concerns if evaluated appropriately. Future efforts can incorporate physical examination findings, hematology, biochemistry profiles, and ancillary diagnostic testing to continue to improve the individual welfare of this marine mammal in its natural range. Admissions data could also potentially serve the wider conservation and recovery efforts if it is proven that the data obtained is at least as informative as that obtained by the carcass salvage program. Limited conservation resources could then be re-directed as new challenges arise with the expanding population and potentially expanding range of this species.

The Amazonian manatee (Trichechus inunguis), a vulnerable species native to the Amazon River Basin, is threatened by habitat loss, illegal hunting, and pollution. Rehabilitation centers rescue, rear, and release manatees negatively impacted by human activities. Factors characterizing the survival of rescued manatees at these rehabilitation centers remain unclear. We analyzed data from 54 rescued manatees at a rehabilitation center in the Peruvian Amazon, assessing factors hypothesized to be predictors of the probability of survival during the rehabilitation process. We found that initial weight at intake and the rate of weight gain while at the center were significantly associated with a higher probability of survival. Intestinal obstruction, often linked to inappropriate diets prior to rescue, was the leading cause of death while in rehabilitation (13 of 54 individuals; 24%). Early intervention to transport orphaned calves to rescue centers and equipping local authorities with resources for short‐term care until transportation is possible could improve rescue outcomes. The Amazonian manatee (Trichechus inunguis) faces threats like habitat loss, illegal hunting, and pollution. Our analysis of 54 rescued manatees in a Peruvian Amazon rehabilitation center revealed that initial weight and rate of weight gain significantly influenced survival during rehabilitation, while intestinal obstruction, often from prior inappropriate diets, was the leading cause of death. Early intervention and better resources for local authorities could enhance rescue outcomes.

Animals adopt various behavioral strategies to meet their biological needs, often adjusting their activity cycles. While some species restrict their activities to specific periods within the 24-hour light and dark cycle, others are cathemeral, showing flexible activity patterns that include both day and night. This study investigates the cathemeral activity of Amazonian manatees (Trichechus inunguis) in Anavilhanas National Park, Brazil, with a focus on their nocturnal behavior and ecological adaptability. Using thermal cameras, we recorded nocturnal feeding for the first time, highlighting the manatees’ flexibility beyond the typical diurnal–nocturnal cycle. Our findings reveal that manatees adjust their feeding strategies according to seasonal vegetation availability and water levels. Specifically, they feed at night on the riparian plant maracarãna (Coccoloba densifrons), which is only accessible during the flood season. This nocturnal behavior likely helps minimize predation risk and enhances foraging efficiency. These insights significantly improve our understanding of manatee ecological behavior in the Amazon, demonstrating their adaptability to environmental changes. The study underscores the importance of considering cathemeral activity in conservation strategies to ensure the ongoing protection of Amazonian manatees against environmental and human pressures.

Chromosomal painting in manatees has clarified questions about the rapid evolution of sirenians within the Paenungulata clade. Further cytogenetic studies in Afrotherian species may provide information about their evolutionary dynamics, revealing important insights into the ancestral karyotype in the clade representatives. The karyotype of Trichechus inunguis (TIN, Amazonian manatee) was investigated by chromosome painting, using probes from Trichechus manatus latirostris (TML, Florida manatee) to analyze the homeologies between these sirenians. A high similarity was found between these species, with 31 homologous segments in TIN, nineteen of which are whole autosomes, besides the X and Y sex chromosomes. Four chromosomes from TML (4, 6, 8, and 9) resulted in two hybridization signals, totaling eight acrocentrics in the TIN karyotype. This study confirmed in TIN the chromosomal associations of Homo sapiens (HSA) shared in Afrotheria, such as the 5/21 synteny, and in the Paenungulata clade with the syntenies HSA 2/3, 8/22, and 18/19, in addition to the absence of HSA 4/8 common in eutherian ancestral karyotype (EAK). TIN shares more conserved chromosomal signals with the Paenungulata Ancestral Karyotype (APK, 2n = 58) than Procavia capensis (Hyracoidea), Loxodonta africana (Proboscidea) and TML (Sirenia), where TML presents less conserved signals with APK, demonstrating that its karyotype is the most derived among the representatives of Paenungulata. The chromosomal changes that evolved from APK to the T. manatus and T. inunguis karyotypes (7 and 4 changes, respectively) are more substantial within the Trichechus genus compared to other paenungulates. Among these species, T. inunguis presents conserved traits of APK in the American manatee genus. Consequently, the karyotype of T. manatus is more derived than that of T. inunguis.

In this paper, we present a review of the current knowledge related to the cognitive abilities of the manatee, with a focus on the Antillean manatee in situ and ex situ. Following a biocentric approach, we consider the animals’ ecology, perception and sociality and we introduce future perspectives on their cognition. Scientific literature on the cognitive abilities of Antillean manatees’ is limited and mainly linked to medical training and veterinary manipulations. To perceive and to interact with their social and natural environment (e.g. social interactions, foraging and traveling), manatees use visual, acoustic and tactile modalities that may be involved in a large range of cognitive abilities. Research on stimuli perception in manatees is scarce; however, these animals demonstrate abilities to learn and appear to show long-term memory. For example, to mate and/or to forage manatees travel at medium and large geographical scales; without doubt their movements entail the use of a set of stimuli and learning processes. Furthermore, their social skills (e.g. social organization, tactile and acoustic communications) are also poorly understood although their social interactions appear to be more complex than previously thought. Finally, as for many animals, temperament/personality may play a key role during their interactions with conspecifics and the environment. These aspects on manatee behavior and cognition are important for management and conservation purposes and help us understand the evolution of these marine mammals.

We analysed 23 years of data on strandings of the Antillean manatee Trichechus manatus manatus in Belize, documented by the Belize Marine Mammal Stranding Network, to examine the threats to this population. A total of 451 stranding incidents were reported, of which 376 (83.4%) cases were verified. A total of 286 (63.4%) of the incidents occurred within Belize District, where the number of strandings has almost tripled since 2009. Watercraft collisions accounted for the highest number of strandings, with 131 confirmed cases, and is the leading cause of anthropogenic mortality for this population. Collision with watercraft is an emerging and major threat to manatees in Belize, and is correlated with increases in human activity, in particular associated with tourism. This finding of high levels of manatee deaths in Belize is consistent with trends previously reported for manatees in Florida and Puerto Rico. This work can provide guidance to detect and address similar patterns of mortality in other Antillean manatee populations across the species' range. There is a need for greater awareness of the threats facing the species and its habitat, for stakeholder partnerships to address these threats, implementation of legislation for the protection of manatees, and consistent enforcement of regulations to protect this population. Boating regulations, such as no-wake zones within areas of high manatee presence, as well as regulation of tourism boating activities, need to be implemented to reduce the threats to the species.

Better understanding human–wildlife interactions and their links with management can help improve the design of wildlife protection zones. One example is the problem of wildlife collisions with vehicles or human-built structures (e.g., power lines, wind farms). In fact, collisions between marine wildlife and watercraft are among the major threats faced by several endangered species of marine mammals. Natural resource managers are therefore interested in finding cost-effective solutions to mitigate these threats. We combined abundance estimators with encounter rate theory to estimate relative lethal collision risk of the Florida manatee (Trichechus manatus latirostris) from watercraft. We first modelled seasonal abundance of watercraft and manatees using a Bayesian analysis of aerial survey count data. We then modelled relative lethal collision risk in space and across seasons. Finally, we applied decision analysis and Linear Integer Programming to determine the optimal design of speed zones in terms of relative risk to manatees and costs to waterway users. We used a Pareto efficient frontier approach to evaluate the performance of alternative zones, which included additional practical considerations (e.g., spatial aggregation of speed zones) in relation to the optimal zone configurations. Under the various relationships for probability of death given strike speed that we considered, the current speed zones reduced the relative lethal collision risk by an average of 51.5% to 70.0% compared to the scenario in which all speed regulations were removed (i.e., the no-protection scenario). We identified optimal zones and near-optimal zones with additional management considerations that improved upon the current zones in terms of cost or relative risk. Policy implications. Our analytical framework combines encounter rate theory and decision analysis to quantify the effectiveness of speed zones in protecting manatees while accounting for uncertainty. Our approach can be used to optimize the design of protection zones intended to reduce conflicts between human waterborne activity and marine mammals. This framework could be extended to address many other problems of human–wildlife interactions, such as the optimal placement of wind farms to minimize collisions with wildlife or the optimal allocation of ranger effort to mitigate poaching threats.

Estimates of age-specific survival probabilities are needed for age-structured population models and to inform conservation decisions. However, determining the age of individuals in wildlife populations is often problematic. We present a hidden Markov model for estimating age-specific survival from capture–recapture or capture–recapture–recovery data when age is unknown and indicators of age, such as size and growth layer counts, are imprecise. The model is evaluated through simulations, and its implementation is illustrated with maximum likelihood and Bayesian approaches in commonly used software. The model is then applied to genetic capture–recapture data of Florida manatees to estimate age- and time-variant survival probabilities. The approach is broadly applicable to studies aiming to quantify age-specific effects of environmental change and management actions on population dynamics, including studies that rely on minimally invasive methods such as genetic and photo identification.

The Greater Caribbean manatee faces significant conservation challenges due to a lack of demographic data in low-visibility habitats. To address this, we present a refined automated manatee counting method pipeline integrating deep learning-based call detection with unsupervised individual counting. We resolved significant computational bottlenecks by implementing an offline feature extraction strategy, bypassing a 13-h processing lag for 43,031 audio samples. To mitigate overfitting in imbalanced bioacoustic datasets, non-parametric bootstrap resampling was employed to generate 100,000 balanced spectrograms. Benchmarking revealed that transfer learning via a VGG-16 backbone achieved a mean 10-fold cross-validation accuracy of 98.92% (±0.08%) and an F1-score of 98.08% for genuine vocalizations. Following detection, individual counting utilized k-means clustering on prioritized music information retrieval descriptors—spectral bandwidth, centroid, and roll-off—to resolve distinct acoustic signatures. This framework identified three individuals with a silhouette coefficient of 79.20%, demonstrating superior cohesion over previous benchmarks. These results confirm the automatic manatee count method as a robust, scalable framework for generating the scientific evidence required for regional conservation policies.

We evaluated the potential of using convolutional neural networks in classifying spectrograms of Antillean manatee (Trichechus manatus manatus) vocalizations. Spectrograms using binary, linear and logarithmic amplitude formats were considered. Two deep convolutional neural networks (DCNN) architectures were tested: linear (fixed filter size) and pyramidal (incremental filter size). Six experiments were devised for testing the accuracy obtained for each spectrogram representation and architecture combination. Results show that binary spectrograms with both linear and pyramidal architectures with dropout provide a classification rate of 94–99% on the training and 92–98% on the testing set, respectively. The pyramidal network presents a shorter training and inference time. Results from the convolutional neural networks (CNN) are substantially better when compared with a signal processing fast Fourier transform (FFT)-based harmonic search approach in terms of accuracy and F1 Score. Taken together, these results prove the validity of using spectrograms and using DCNNs for manatee vocalization classification. These results can be used to improve future software and hardware implementations for the estimation of the manatee population in Panama.