Preliminary assessment of persistent organic pollutants (POPs) in tissues of Risso's dolphin (Grampus griseus) specimens stranded along the Italian coasts.

Ecotoxicological and pathological research on Grampus griseus (Cuvier, 1812) (Risso's dolphins) is scarce both globally and in the Mediterranean Sea. This species has been classified as "Vulnerable" by the International Union for Conservation of Nature (IUCN) in the Mediterranean Sea. To evaluate the presence of "persistent organic pollutants" (POPs), especially organochlorine compounds (OCs), in the animals, chemical analyses were performed on tissues and organs of Risso's dolphin stranded along the Italian coasts between 1998 and 2021. Toxic contaminants such as hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs) were examined in the blubber, liver, muscle, and brain of 20 animals, and data was correlated with sex, age, and stranding locations.

Picturing donations: Do images influence conservation fundraising?

Many environmental organizations use photographic images to engage donors and supporters. While images play a role in fundraising, visual framing remains understudied in the environmental field. Few real-world experiments have examined which types of images result in higher donations to biodiversity conservation. We examined the role of images in conservation fundraising through a public experiment at Zoomarine, a marine park located in southern Portugal. Zoomarine runs a program called Dolphin Emotions where visitors pay to learn about dolphin biology and to interact with dolphins. We placed a donation box and a large informational poster about the Marine Megafauna Foundation, a conservation partner, in the lounge of the Dolphin Emotions program, which is open to participants and their families. The text on the poster, which solicited donations for the Marine Megafauna Foundation, was held constant, while four different image conditions were tested: dolphins, ocean wildlife, children, and people staring out from the poster (i.e., "watching eyes"). Each image condition was displayed for three days at a time and was on display for at least seven randomly assigned three-day periods over the course of 91 days. 20,944 visitors passed the donation box and the four poster conditions during this time and a total of € 952.40 was collected. The differences in mean donations in € per visitor per 3-day period were not statistically significant, F(3, 25) = 0.745, p = 0.54. Thus, we did not find that different images had a significant influence on donations to conservation. This may be due to our choice of visual frames or to the use of a donation box, which is a passive fundraising channel. Future research should examine how visual framing influences donations in other public settings and should test the influence of other visual frames on philanthropic behavior.

Assessment on the effectiveness of vessel-approach regulations to protect cetaceans in Australia: A review on behavioral impacts with case study on the threatened Burrunan dolphin (Tursiops australis).

Vessels cause considerable disturbance to cetaceans world-wide, with potential long-term impacts to population viability. Here we present a comprehensive review of vessel impacts to cetacean behavior in Australian waters (2003-2015), finding inadequate protections to be in place. The majority of these studies found trends of decreased animal travel and resting behavioral states as well as low compliance to regulations, and they recommended further regulatory action such as greater enforcement or monitoring, or passive management strategies. As a case study, we conducted the first field assessment of vessel compliance with the Wildlife (Marine Mammal) Regulations 2009 in Gippsland Lakes, Australia, and provide the first assessment of the endangered Gippsland Lakes Burrunan dolphin (Tursiops australis) population's behavioral ecology. Dolphin behavior and vessel regulation compliance data were collected during boat-based surveys of Gippsland Lakes from July 2017 to January 2018, with a total of 22 dolphin group sightings resulting in 477 five-minute point samples. 77% of dolphin sightings involved vessel interactions (within 400 m), and 56 regulation breaches were observed. These breaches were most severe in summer (mean = 4.54 breaches/hour). Vessels were found to alter dolphin behavior before, during, and after interactions and regulation breaches, including increased mating (mate guarding) and milling behavioral states, and increased 'fish catch', 'high leap' and 'tail slap' behavioral events. These behavioral changes may indicate masking of the dolphins' acoustic communication, disturbance of prey, increased dolphin transition behaviors, and/or induced stress and changes to group structure (including increased mate guarding). While our results provide evidence of short-term altered behavior, the potential for long-term effects on population dynamics for this threatened species is high. In the context of reported inadequate cetacean protection Australia-wide, our management recommendations include greater monitoring and enforcement, and the utilisation of adaptive management.

Using GIS and stakeholder involvement to innovate marine mammal bycatch risk assessment in data-limited fisheries.

Fisheries bycatch has been identified as the greatest threat to marine mammals worldwide. Characterizing the impacts of bycatch on marine mammals is challenging because it is difficult to both observe and quantify, particularly in small-scale fisheries where data on fishing effort and marine mammal abundance and distribution are often limited. The lack of risk frameworks that can integrate and visualize existing data have hindered the ability to describe and quantify bycatch risk. Here, we describe the design of a new geographic information systems tool built specifically for the analysis of bycatch in small-scale fisheries, called Bycatch Risk Assessment (ByRA). Using marine mammals in Malaysia and Vietnam as a test case, we applied ByRA to assess the risks posed to Irrawaddy dolphins (Orcaella brevirostris) and dugongs (Dugong dugon) by five small-scale fishing gear types (hook and line, nets, longlines, pots and traps, and trawls). ByRA leverages existing data on animal distributions, fisheries effort, and estimates of interaction rates by combining expert knowledge and spatial analyses of existing data to visualize and characterize bycatch risk. By identifying areas of bycatch concern while accounting for uncertainty using graphics, maps and summary tables, we demonstrate the importance of integrating available geospatial data in an accessible format that taps into local knowledge and can be corroborated by and communicated to stakeholders of data-limited fisheries. Our methodological approach aims to meet a critical need of fisheries managers: to identify emergent interaction patterns between fishing gears and marine mammals and support the development of management actions that can lead to sustainable fisheries and mitigate bycatch risk for species of conservation concern.

AUDITORY EVOKED POTENTIALS AND BEHAVIORAL CONSIDERATIONS WITH HEARING LOSS IN SMALL CETACEANS: APPLICATION AS A STANDARD DIAGNOSTIC TEST IN HEALTH ASSESSMENT.

The primary sense in odontocetes is hearing and a large portion of the odontocete brain is devoted to the auditory processing of echolocation signals. Hearing deficits in odontocetes potentially compromise the ability to forage, navigate, socialize, and evade predators. This presents a challenge to survival and reproduction in wild odontocetes and can affect the general welfare of odontocetes under human care. Currently, little empirical information on how odontocete behavior is affected by hearing loss exists. This study investigated hearing deficits in several species of stranded dolphins and age-related hearing deficits in dolphins kept under human care through auditory evoked potential (AEP) testing and evaluated whether individual behavior correlated with hearing impairment. Behavioral questionnaires for participating animals were completed by individuals with extensive knowledge of the animals' history and behavior. A chi-square analysis determined whether animals with hearing impairment demonstrated behaviors that differed significantly from those considered normal. All tested individuals under human care over 35 years of age had some degree of hearing loss, as did a large percentage of previously stranded animals. Individuals with hearing loss exhibited a range of behavioral changes, including delays in learning new behaviors, accepting novel enrichment, and habituating to new environments. Some individuals with profound hearing loss also displayed a change in vocalization rate in various situations. Findings within previously stranded animals suggest AEP studies should be conducted in all stranded individuals entering rehabilitation. It is further recommended that dolphins living under human care undergo hearing tests as part of their normal health assessments, with emphasis on aging individuals and animals that exhibit delayed learning, respond poorly to audible cues, or show atypical vocalization behavior.

A framework for the assessment of the spatial and temporal patterns of threatened coastal delphinids.

The massively accelerated biodiversity loss rate in the Anthropocene calls for an efficient and effective way to identify the spatial and temporal dynamics of endangered species. To this end, we developed a useful identification framework based on a case study of locally endangered Sousa chinensis by combining both LEK (local ecological knowledge) evaluation and regional boat-based survey methods. Our study investigated the basic ecological information of Sousa chinensis in the estuaries of eastern Guangdong that had previously been neglected, which could guide the future study and conservation. Based on the statistical testing of reported spatial and temporal dolphins sighting data from fishermen and the ecological monitoring analyses, including sighting rate, site fidelity and residence time estimations, some of the current Sousa chinensis units are likely to be geographically isolated and critically endangered, which calls for much greater conservation efforts. Given the accelerated population extinction rate and increasing budgetary constraints, our survey pattern can be applied in a timely and economically acceptable manner to the spatial and temporal assessment of other threatened coastal delphinids, particularly when population distributions are on a large scale and traditional sampling methods are difficult to implement.

Re-assessment of the Conservation Status of the Indo-Pacific Humpback Dolphin (Sousa chinensis) Using the IUCN Red List Criteria.

The IUCN Red List designation of the Indo-Pacific humpback dolphin (Sousa chinensis) is re-assessed in light of its newly recognized taxonomic status (it has recently been separated into three species) and findings that humpback dolphins along the coast of Bangladesh, and possibly eastern India, are phylogenetically distinct from other members of the Sousa genus. Sousa chinensis is found in Southeast/South Asia (in both the Indian and Pacific oceans), from at least the southeastern Bay of Bengal east to central China, and then south to the Indo-Malay Archipelago. There are no global population estimates, and the sum of available abundance estimates add up to about 5700 individuals, although only a portion of the range has been covered by surveys. This species occurs in shallow (<30m deep), coastal waters of the tropics and subtropics, and feeds mainly on small fishes. It has a similar reproductive biology to other large dolphins, occurs mostly in small groups, and generally has individual movements of about 50-200km(2). Major threats throughout the range include entanglement in fishing nets (primarily gillnets) and habitat destruction/degradation, although in some more industrialized areas, vessel traffic, and environmental contamination from organochlorines are also serious issues. Conservation management is largely lacking in most parts of the species' range, although there has been significant (though still inadequate) attention in some parts of China (e.g. Hong Kong and adjacent areas, and Taiwan). Much greater efforts are needed toward conservation of Indo-Pacific humpback dolphins to stop apparent declines, and to lower the species' extinction risk. Sousa chinensis meets the IUCN Red List requirements for Vulnerable (under criteria A4cd), with fisheries bycatch and habitat loss/degradation being the main pervasive threats.

Humpback Dolphins: A Brief Introduction to the Genus Sousa.

The delphinid genus Sousa has recently undergone a major revision, and currently contains four species, the Atlantic humpback (Sousa teuszii), Indian Ocean humpback (Sousa plumbea), Indo-Pacific humpback (Sousa chinensis), and Australian humpback (Sousa sahulensis) dolphins. Recent molecular evidence suggests that humpback dolphins in the Bay of Bengal may comprise a fifth species. These moderate-sized dolphin species are found in shallow (<30m), coastal waters of the eastern Atlantic, Indian, and western Pacific oceans. Abundance and trends have only been studied in a few areas, mostly in eastern Africa, China, and northern Australia. No global, empirically derived abundance estimates exist for any of the four species, but none appear to number more than about 20,000 individuals. Humpback dolphins feed mostly on small fishes, and sometimes shrimps; occur for the most part in small groups (mostly 12 or less); have limited nearshore movements; and in most parts of their range exhibit a fission/fusion type of social organization. Major threats that affect all the species are entanglement in fishing gear, and habitat degradation/destruction from various forms of coastal development. Impacts from vessel traffic (including behavioural disturbance and displacement, as well as mortality and morbidity from collisions with vessels) appear to be significant in most areas. Several other threats are apparently significant only in particular parts of the range of some species (e.g. high levels of organochlorine contaminants affecting Indo-Pacific humpback dolphins in Hong Kong). Direct hunting only occurs in limited areas and primarily on a small scale. Conservation actions so far have been limited, with most populations receiving little study and almost no management attention. Much more work is needed on humpback dolphin population status, threats, and how the major threats can be reduced or eliminated. Extinction risks for the four species and some populations are preliminarily re-assessed using the IUCN Red List criteria in the current volume. The results suggest that all four species in the genus are threatened at some level (suggested Red List status ranges from Vulnerable for S. chinensis and S. sahulensis to Critically Endangered for S. teuszii).

Re-assessment of the Conservation Status of the Atlantic Humpback Dolphin, Sousa teuszii (), Using the IUCN Red List Criteria.

The Atlantic humpback dolphin (Sousa teuszii) is an obligate shallow water dolphin that is endemic to the western coasts of Africa, ranging from Western Sahara to Angola. The species occurs exclusively in a limited number of near-shore habitats, a tendency that routinely exposes it to a suite of lethal and deleterious anthropogenic threats. These include habitat degradation, accidental capture in artisanal fishing nets, and hunting for use as food and bait. The species also competes with rapidly expanding human populations for coastal resources in some of the poorest countries on Earth. Data for most aspects of the species' ecology are sparse, but S. teuszii is considered by most qualified observers to be rare and greatly threatened. A lack of appropriate survey data precludes a quantitative assessment of population trends and status. Most populations for which any data are available are considered to be extremely small, numbering in the tens or low hundreds of individuals. The available published estimates suggest that the total population likely falls below 3000 individuals. Declines in abundance have been observed or are suspected for each population and will continue, given projected expansions of identified threats that affect most of the species' known range, and a corresponding lack of appropriate management actions. The apparent scale of threats, the presumed isolation of most populations, and a lack of directed conservation efforts in most areas suggest that the species qualifies for a listing of Critically Endangered (under criteria A3cd) on the IUCN Red List.

Assessment of the Conservation Status of the Indian Ocean Humpback Dolphin (Sousa plumbea) Using the IUCN Red List Criteria.

Indian Ocean humpback dolphins (Sousa plumbea) are obligate shallow-water dolphins that occur exclusively in the near-shore waters of the Indian Ocean, from South Africa to the Bay of Bengal. They have a narrow habitat preference, restricted distribution and do not appear very abundant across any part of their range. There is no estimate of total species abundance; all populations that have been quantitatively evaluated have been small in size, usually fewer than 200 individuals. Fishing, dredging, land reclamation, construction blasting, port and harbour construction, pollution, boat traffic and other coastal development activities all occur, or are concentrated within, humpback dolphin habitat and threaten their survival. Although data are far from sufficient to make a rigorous quantitative assessment of population trends for this species, the scale of threats is large enough over a significant enough portion of the range to suspect or infer a decline of at least 50% over three generations, which qualifies it for listing on the IUCN Red List as Endangered. The issue primarily responsible is incidental mortality in fisheries, but the loss and degradation of habitat is likely a contributing factor. None of the threats have been adequately addressed in any part of the species' range, even though threat levels are increasing virtually everywhere.

Behavioural effects of tourism on oceanic common dolphins, Delphinus sp., in New Zealand: the effects of Markov analysis variations and current tour operator compliance with regulations.

Common dolphins, Delphinus sp., are one of the marine mammal species tourism operations in New Zealand focus on. While effects of cetacean-watching activities have previously been examined in coastal regions in New Zealand, this study is the first to investigate effects of commercial tourism and recreational vessels on common dolphins in an open oceanic habitat. Observations from both an independent research vessel and aboard commercial tour vessels operating off the central and east coast Bay of Plenty, North Island, New Zealand were used to assess dolphin behaviour and record the level of compliance by permitted commercial tour operators and private recreational vessels with New Zealand regulations. Dolphin behaviour was assessed using two different approaches to Markov chain analysis in order to examine variation of responses of dolphins to vessels. Results showed that, regardless of the variance in Markov methods, dolphin foraging behaviour was significantly altered by boat interactions. Dolphins spent less time foraging during interactions and took significantly longer to return to foraging once disrupted by vessel presence. This research raises concerns about the potential disruption to feeding, a biologically critical behaviour. This may be particularly important in an open oceanic habitat, where prey resources are typically widely dispersed and unpredictable in abundance. Furthermore, because tourism in this region focuses on common dolphins transiting between adjacent coastal locations, the potential for cumulative effects could exacerbate the local effects demonstrated in this study. While the overall level of compliance by commercial operators was relatively high, non-compliance to the regulations was observed with time restriction, number or speed of vessels interacting with dolphins not being respected. Additionally, prohibited swimming with calves did occur. The effects shown in this study should be carefully considered within conservation management plans, in order to reduce the risk of detrimental effects on common dolphins within the region.

Compensating for the effects of site and equipment variation on delphinid species identification from their echolocation clicks.

A concern for applications of machine learning techniques to bioacoustics is whether or not classifiers learn the categories for which they were trained. Unfortunately, information such as characteristics of specific recording equipment or noise environments can also be learned. This question is examined in the context of identifying delphinid species by their echolocation clicks. To reduce the ambiguity between species classification performance and other confounding factors, species whose clicks can be readily distinguished were used in this study: Pacific white-sided and Risso's dolphins. A subset of data from autonomous acoustic recorders located at seven sites in the Southern California Bight collected between 2006 and 2012 was selected. Cepstral-based features were extracted for each echolocation click and Gaussian mixture models were used to classify groups of 100 clicks. One hundred Monte-Carlo three-fold experiments were conducted to examine classification performance where fold composition was determined by acoustic encounter, recorder characteristics, or recording site. The error rate increased from 6.1% when grouped by acoustic encounter to 18.1%, 46.2%, and 33.2% for grouping by equipment, equipment category, and site, respectively. A noise compensation technique reduced error for these grouping schemes to 2.7%, 4.4%, 6.7%, and 11.4%, respectively, a reduction in error rate of 56%-86%.

Cost of living dictates what whales, dolphins and porpoises eat: the importance of prey quality on predator foraging strategies.

Understanding the mechanisms that drive prey selection is a major challenge in foraging ecology. Most studies of foraging strategies have focused on behavioural costs, and have generally failed to recognize that differences in the quality of prey may be as important to predators as the costs of acquisition. Here, we tested whether there is a relationship between the quality of diets (kJ · g(-1)) consumed by cetaceans in the North Atlantic and their metabolic costs of living as estimated by indicators of muscle performance (mitochondrial density, n = 60, and lipid content, n = 37). We found that the cost of living of 11 cetacean species is tightly coupled with the quality of prey they consume. This relationship between diet quality and cost of living appears to be independent of phylogeny and body size, and runs counter to predictions that stem from the well-known scaling relationships between mass and metabolic rates. Our finding suggests that the quality of prey rather than the sheer quantity of food is a major determinant of foraging strategies employed by predators to meet their specific energy requirements. This predator-specific dependence on food quality appears to reflect the evolution of ecological strategies at a species level, and has implications for risk assessment associated with the consequences of changing the quality and quantities of prey available to top predators in marine ecosystems.

Behavioural responses of dusky dolphin groups (Lagenorhynchus obscurus) to tour vessels off Kaikoura, New Zealand.

BACKGROUND: Commercial viewing and swimming with dusky dolphins (Lagenorhynchus obscurus) near Kaikoura, New Zealand began in the late 1980s and researchers have previously described changes in vocalisation, aerial behaviour, and group spacing in the presence of vessels. This study was conducted to assess the current effects that tourism has on the activity budget of dusky dolphins to provide wildlife managers with information for current decision-making and facilitate development of quantitative criteria for management of this industry in the future. METHODOLOGY/PRINCIPAL FINDINGS: First-order time discrete Markov chain models were used to assess changes in the behavioural state of dusky dolphin pods targeted by tour vessels. Log-linear analysis was conducted on behavioural state transitions to determine whether the likelihood of dolphins moving from one behavioural state to another changed based on natural and anthropogenic factors. The best-fitting model determined by Akaike Information Criteria values included season, time of day, and vessel presence within 300 m. Interactions with vessels reduced the proportion of time dolphins spent resting in spring and summer and increased time spent milling in all seasons except autumn. Dolphins spent more time socialising in spring and summer, when conception occurs and calves are born, and the proportion of time spent resting was highest in summer. Resting decreased and traveling increased in the afternoon. CONCLUSIONS/SIGNIFICANCE: Responses to tour vessel traffic are similar to those described for dusky dolphins elsewhere. Disturbance linked to vessels may interrupt social interactions, carry energetic costs, or otherwise affect individual fitness. Research is needed to determine if increased milling is a result of acoustic masking of communication due to vessel noise, and to establish levels at which changes to behavioural budgets of dusky dolphins are likely to cause long-term harm. Threshold values from these studies would allow managers to set appropriate operational conditions based on quantifiable criteria.

Effects of tour boats on dolphin activity examined with sensitivity analysis of Markov chains.

In Patagonia, Argentina, watching dolphins, especially dusky dolphins (Lagenorhynchus obscurus), is a new tourist activity. Feeding time decreases and time to return to feeding after feeding is abandoned and time it takes a group of dolphins to feed increase in the presence of boats. Such effects on feeding behavior may exert energetic costs on dolphins and thus reduce an individual's survival and reproductive capacity or maybe associated with shifts in distribution. We sought to predict which behavioral changes modify the activity pattern of dolphins the most. We modeled behavioral sequences of dusky dolphins with Markov chains. We calculated transition probabilities from one activity to another and arranged them in a stochastic matrix model. The proportion of time dolphins dedicated to a given activity (activity budget) and the time it took a dolphin to resume that activity after it had been abandoned (recurrence time) were calculated. We used a sensitivity analysis of Markov chains to calculate the sensitivity of the time budget and the activity-resumption time to changes in behavioral transition probabilities. Feeding-time budget was most sensitive to changes in the probability of dolphins switching from traveling to feeding behavior and of maintaining feeding behavior. Thus, an increase in these probabilities would be associated with the largest reduction in the time dedicated to feeding. A reduction in the probability of changing from traveling to feeding would also be associated with the largest increases in the time it takes dolphins to resume feeding. To approach dolphins when they are traveling would not affect behavior less because presence of the boat may keep dolphins from returning to feeding. Our results may help operators of dolphin-watching vessels minimize negative effects on dolphins.

Total number and volume of Von Economo neurons in the cerebral cortex of cetaceans.

Von Economo neurons (VENs) are a type of large, layer V spindle-shaped neurons that were previously described in humans, great apes, elephants, and some large-brained cetaceans. Here we report the presence of Von Economo neurons in the anterior cingulate (ACC), anterior insular (AI), and frontopolar (FP) cortices of small odontocetes, including the bottlenose dolphin (Tursiops truncatus), the Risso's dolphin (Grampus griseus), and the beluga whale (Delphinapterus leucas). The total number and volume of VENs and the volume of neighboring layer V pyramidal neurons and layer VI fusiform neurons were obtained by using a design-based stereologic approach. Two humpback whale (Megaptera novaeangliae) brains were investigated for comparative purposes as representatives of the suborder Mysticeti. Our results show that the distribution of VENs in these cetacean species is comparable to that reported in humans, great apes, and elephants. The number of VENs in these cetaceans is also comparable to data available from great apes, and stereologic estimates indicate that VEN volume follows in these cetacean species a pattern similar to that in hominids, the VENs being larger than neighboring layer V pyramidal cells and conspicuously larger than fusiform neurons of layer VI. The fact that VENs are found in species representative of both cetacean suborders in addition to hominids and elephants suggests that these particular neurons have appeared convergently in phylogenetically unrelated groups of mammals possibly under the influence of comparable selective pressures that influenced specifically the evolution of cortical domains involved in complex cognitive and social/emotional processes.

'O father: where art thou?'--Paternity assessment in an open fission-fusion society of wild bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia.

Sexually mature male bottlenose dolphins in Shark Bay cooperate by pursuing distinct alliance strategies to monopolize females in reproductive condition. We present the results of a comprehensive study in a wild cetacean population to test whether male alliance membership is a prerequisite for reproductive success. We compared two methods for inferring paternity: both calculate a likelihood ratio, called the paternity index, between two opposing hypotheses, but they differ in the way that significance is applied to the data. The first method, a Bayesian approach commonly used in human paternity testing, appeared to be overly conservative for our data set, but would be less susceptible to assumptions if a larger number of microsatellite loci had been used. Using the second approach, the computer program cervus 2.0, we successfully assigned 11 paternities to nine males, and 17 paternities to 14 out of 139 sexually mature males at 95% and 80% confidence levels, respectively. It appears that being a member of a bottlenose dolphin alliance is not a prerequisite for paternity: two paternities were obtained by juvenile males (one at the 95%, the other at the 80% confidence level), suggesting that young males without alliance partners pursue different mating tactics to adults. Likelihood analyses showed that these two juvenile males were significantly more likely to be the true father of the offspring than to be their half-sibling (P < 0.05). Using paternity data at an 80% confidence level, we could show that reproductive success was significantly skewed within at least some stable first-order alliances (P < 0.01). Interestingly, there is powerful evidence that one mating was incestuous, with one calf apparently fathered by its mother's father (P < 0.01). Our study suggests that the reproductive success of both allied males, and of nonallied juveniles, needs to be incorporated into an adaptive framework that seeks to explain alliance formation in male bottlenose dolphins.