Small Cetaceans Research Articles

Assessing the Viability of the Sarasota Bay Community of Bottlenose Dolphins

Population models, such as those used for Population Viability Analysis (PVA), are valuable for projecting trends, assessing threats, guiding environmental resource management, and planning species conservation measures. However, rarely are the needed data on all aspects of the life history available for cetacean species, because they are long-lived and difficult to study in their aquatic habitats. We present a detailed assessment of population dynamics for the long-term resident Sarasota Bay common bottlenose dolphin (Tursiops truncatus) community. Model parameters were estimated from 27 years of nearly complete monitoring, allowing calculation of age-specific and sex-specific mortality and reproductive rates, uncertainty in parameter values, fluctuation in demographic rates over time, and intrinsic uncertainty in the population trajectory resulting from stochastic processes. Using the Vortex PVA model, we projected mean population growth and quantified causes of variation and uncertainty in growth. The ability of the model to simulate the dynamics of the population was confirmed by comparing model projections to observed census trends from 1993 to 2020. When the simulation treated all losses as deaths and included observed immigration, the model projects a long-term mean annual population growth of 2.1%. Variance in annual growth across years of the simulation (SD= 3.1%) was due more to environmental variation and intrinsic demographic stochasticity than to uncertainty in estimates of mean demographic rates. Population growth was most sensitive to uncertainty and annual variation in reproduction of peak breeding age females and in calf and juvenile mortality, while adult survival varied little over time. We examined potential threats to the population, including increased anthropogenic mortality and impacts of red tides, and tested resilience to catastrophic events. Due to its life history characteristics, the population was projected to be demographically stable at smaller sizes than commonly assumed for Minimum Viable Population of mammals, but it is expected to recover only slowly from any catastrophic events, such as disease outbreaks and spills of oil or other toxins. The analyses indicate that well-studied populations of small cetaceans might typically experience slower growth rates (about 2%) than has been assumed in calculations of Potential Biological Removal used by management agencies to determine limits to incidental take of marine mammals. The loss of an additional one dolphin per year was found to cause significant harm to this population of about 150 to 175 animals. Beyond the significance for the specific population, demographic analyses of the Sarasota Bay dolphins provide a template for examining viability of other populations of small cetaceans.

Nutritional status and prey energy density govern reproductive success in a small cetacean

A variety of mammals suppress reproduction when they experience poor physical condition or environmental harshness. In many marine mammal species, reproductive impairment has been correlated to polychlorinated biphenyls (PCBs), the most frequently measured chemical pollutants, while the relative importance of other factors remains understudied. We investigate whether reproductively active females abandon investment in their foetus when conditions are poor, exemplified using an extensively studied cetacean species; the harbour porpoise (Phocoena phocoena). Data on disease, fat and muscle mass and diet obtained from necropsies in The Netherlands were used as proxies of health and nutritional status and related to pregnancy and foetal growth. This was combined with published life history parameters for 16 other areas to correlate to parameters reflecting environmental condition: mean energy density of prey constituting diets (MEDD), cumulative human impact and PCB contamination. Maternal nutritional status had significant effects on foetal size and females in poor health had lower probabilities of being pregnant and generally did not sustain pregnancy throughout gestation. Pregnancy rates across the Northern Hemisphere were best explained by MEDD. We demonstrate the importance of having undisturbed access to prey with high energy densities in determining reproductive success and ultimately population size for small cetaceans.

Abundance estimates of three cetacean species in the coastal waters of Matang, Perak, Peninsular Malaysia

Abstract The paucity of baseline data on coastal cetaceans due to a lack of research in developing countries frequently precludes assessment of their status and informed management actions for conservation. This study provides the first abundance estimates of Indo‐Pacific humpback dolphins, Irrawaddy dolphins, and Indo‐Pacific finless porpoises in the coastal waters of Matang, Peninsular Malaysia. Boat‐based surveys covering 1,152 km2 of coastal waters with 4,108 km of survey effort were conducted between 2013 and 2016 to collect data for line transect analysis of Irrawaddy dolphins and finless porpoises. Photo‐identification data of humpback dolphins were concurrently collected for mark–recapture analysis. Estimates of abundance from four sampling strata totalled 763 Irrawaddy dolphins (CV = 13%, 95% confidence interval (CI) [588, 990]) and 600 Indo‐Pacific finless porpoises (CV = 27%, 95% CI [354, 1,016]). The annual abundance estimates of humpback dolphins ranged between 171 (95% CI [148, 208]) in 2014–2015 and 81 (95% CI [67, 98]) in 2015–2016, likely due to the presence of offshore individuals that moved in and out of the study area. The estuarine strata were inhabited by 68 (95% CI [63, 73]) inshore humpback dolphins in 2013–2014 to 87 (95% CI [78, 97]) dolphins in 2014–2015. As an International Union for Conservation of Nature important marine mammal area, the productive coastal waters of Matang are shown to support a high density of small coastal cetaceans, and the results serve as an important baseline for future studies to identify population trends for conservation management plans.

Form, function, and divergence of a generic fin shape in small cetaceans.

Tail flukes as well as the dorsal fin are the apomorphic traits of cetaceans which appeared during the evolutionary process of adaptation to the aquatic life. Both appendages present a wing-like shape associated with lift generation and low drag. We hypothesized that the evolution of fins as lifting structures led to a generic wing design, where the dimensionless parameters of the fin cross-sections are invariant with respect to the body length and taxonomy of small cetaceans (Hypothesis I). We also hypothesized that constraints on variability of a generic fin shape are associated with the primary function of the fin as a fixed or flapping hydrofoil (Hypothesis II). To verify these hypotheses, we examined how the variation in the fin's morphological traits is linked to the primary function, species and body length. Hydrodynamic characteristics of the fin cross-sections were examined with the CFD software and compared with similar engineered airfoils. Generic wing design of both fins was found in a wing-like planform and a streamlined cross-sectional geometry optimized for lift generation. Divergence in a generic fin shape both on the planform and cross-sectional level was found to be related with the fin specialization in fixed or flapping hydrofoil function. Cross-sections of the dorsal fin were found to be optimized for the narrow range of small angles of attack. Cross-sections of tail flukes were found to be more stable for higher angles of attack and had gradual stall characteristics. The obtained results provide an insight into the divergent evolutionary pathways of a generic wing-like shape of the fins of cetaceans under specific demands of thrust production, swimming stability and turning control.

Using acoustically visible gillnets to reduce bycatch of a small cetacean: first pilot trials in a commercial fishery

Bycatch of protected species, particularly small cetaceans, in gillnets is a worldwide concern. One hypothesis for this is that echolocating cetaceans entangle because they do not perceive conventional gillnets as impenetrable barriers, owing to the gillnet’s faint echo. A gillnet modified for improved acoustical visibility was tested in a first pilot trial in a commercial gillnet fishery targeting turbot (Scophthalmus maeoticus) on the Turkish Black Sea coast. This study is the first demonstration of the viability of using a gillnet equipped with small acrylic glass spheres to reduce bycatch of harbor porpoises in a commercial fishery and provides the basis for full-scale sea trials of the gear in commercial fisheries through a power analysis. In these pilot experiments, the focus lied on the handling of the gear and identification of requirements for a full-scale trial, but results include promising bycatch data for an endangered echolocating marine mammal (Phocoena phocoena) and no reduction in catch efficiency of a bottom-dwelling, vulnerable species (Raja clavata).

Contribution of flippers and dorsal fins to the lateral/directional inherent stability during straight‐line swimming in small cetaceans

AbstractFins are among the most important morphological appendages of aquatic animals. Although sall cetaceans have flippers and dorsal fins with a variety of morphologies and postures, the diversity and function of the fins have not attracted much attention thus far. In this study, we recorded the behaviour of five captive species of small cetaceans, including two species lacking dorsal fins, and examined the contribution of the dihedral angles of their flippers and dorsal fins in the lateral/directional inherent stability during straight‐line swimming. All the species were found to maintain their flippers at a specific negative dihedral angle during straight‐line swimming, and a significant difference was observed between species with and without dorsal fins: species without dorsal fins were found to swim by maintaining the dihedral angle of their flippers closer to 0° compared to species with dorsal fins. The rolling moment generated by the dihedral angle of the fins in all the species was a relatively small roll‐promoting moment that ensures manoeuvrability. In summary, small cetaceans are likely to have one of two characteristics, either left and right flippers with a near‐zero‐degree dihedral angle or a dorsal fin, to reduce the roll‐promoting moment. Our results highlight important aspects of swimming stability in dolphins, providing essential insights into the movement mechanisms of aquatic fish and mammals.

Harbour porpoises exhibit localized evasion of a tidal turbine

Abstract Tidal energy generators have the potential to injure or kill marine animals, including small cetaceans, through collisions with moving turbine parts. Information on the fine scale behaviour of animals close to operational turbines is required to inform regulators of the likely impact of these new technologies. Harbour porpoise movements were monitored in three dimensions around a tidal turbine for 451 days between October 2017 and April 2019 with a 12‐channel hydrophone array. Echolocation clicks from 344 porpoise events were localized close to the turbine. The data show that porpoises effectively avoid the turbine rotors, with only a single animal clearly passing through the rotor swept area while the rotors were stationary, and none passing through while rotating. The results indicate that the risk of collisions between the tidal turbine and porpoises is low; this has important implications for the potential effects and the sustainable development of the tidal energy industry.

Cetacean Research and Citizen Science in Kenya

In 2011, several non-governmental and government agencies established the Kenya Marine Mammal Network (KMMN) to provide a platform for the consistent collection of data on marine mammals along the Kenyan coast, identify areas of importance and engage marine users and the general public in marine mammal conservation. Prior to the KMMN, relatively little was known about marine mammals in Kenya, limiting conservation strategies. The KMMN collects data nationwide through dedicated surveys, opportunistic sightings and participative citizen science, currently involving more than 100 contributors. This paper reviews data on sightings and strandings for small cetaceans in Kenya collated by the KMMN. From 2011 to 2019, 792 records of 11 species of small cetaceans were documented. The most frequently reported inshore species were the Indo-Pacific bottlenose dolphin and Indian Ocean humpback dolphin. Offshore species, included killer whales, short-finned pilot whale and long-snouted spinner dolphin. Indo-Pacific bottlenose dolphins, long-snouted spinner dolphins, striped dolphins and Risso’s dolphins were recorded through stranding reports. The efforts of the KMMN were disseminated through international meetings (International Whaling Commission, World Marine Mammal Conference), national status reports, outreach and social media. Data has also supported the identification of three IUCN Important Marine Mammal Areas and one Area of Interest in Kenya. Further research is needed to improve estimates of cetacean abundance and distribution, particularly in unstudied coastal areas, and to assess the extent of anthropogenic threats associated with fisheries, coastal and port development, seismic exercises and unregulated tourism. The expansion of the network should benefit from the participation of remote coastal fishing communities, government research agencies, tourism and seismic operations, among others. The KMMN demonstrated the value of dedicated and citizen science data to enhance marine mammal conservation strategies to boost awareness and eco-tourism and to bring the public and science closer together, promoting research and effective conservation efforts.

Spatial Distribution and Abundance of Small Cetaceans in the Pacific Waters of Guatemala

The establishment of marine protected areas (MPAs) requires a thorough assessment of the abundance, distribution, and habitat preferences of a variety of marine species. Small cetacean spatial distribution and abundance were examined in the Pacific waters of Guatemala to provide this information. Boat surveys were conducted for 38 months between January 2008 and June 2012. A total of 64,678 cetaceans in 505 sightings from nine Delphinidae species were recorded. Three species, referred to as common species, accounted for 90% (n= 456) of all sightings. They includedTursiops truncatus(56%,n= 278),Stenella attenuata(29%,n= 143), andStenella longirostris(7%,n= 35). Group size was significantly different among the common species (p< 0.001).S. longirostrishad the largest group size (444 ± 75 dolphins), followed byS. attenuata(28 ± 5 dolphins), andT.truncatus(15 ± 2 dolphins).T. truncatuswas the most common in the study area (0.02 ± 0.002 sightings/km of survey effort), andS. attenuata(0.37 ± 0.16 dolphins/km) andS. longirostris(1.62 ± 0.41 dolphins/km) were the most abundant in the neritic (≤200 m depth) and oceanic zones (≥200 m depth), respectively. The wide-ranging distribution ofT. truncatusoverlapped with the distribution ofS. attenuatain the neritic zone andS. longirostrisin the oceanic zone. Little overlap was observed in the distribution ofS. attenuataandS. longirostris. Most hot spots (∼66%) were in the oceanic zone and no hot spots were near or in the MPAs. Hot spots were identified along the 200 m isobath, the Middle America trench, and the San José Canyon. These could be areas of high productivity where dolphins concentrate to feed. To the north of the San José Canyon, five species of small cetaceans were observed in a stretch of the neritic zone including three MPAs. No other section of this zone had such high diversity. Results need to be taken with caution given the small sample size. Our results suggest that the protection of small cetaceans needs to consider the creation of oceanic MPAs that should be integrated into the existing network.

The plasma phospholipidome of Tursiops truncatus: From physiological insight to the design of prospective tools for managed cetacean monitorization.

Plasma biochemical analysis remains one of the established ways of monitoring captive marine mammal health. More recently, complementary plasma lipidomic analysis has proven to be a valid tool in disease diagnosis and prevention, with the potential to validate and complement common biochemical analysis, providing a more integrative approach. In this study, we thoroughly characterized the plasma polar lipid content of Tursiops truncatus, the most common cetacean species held under human care. Our results showed that phosphatidylcholine, lysophosphatidylcholine, and sphingomyelins (CerPCho) are the most represented phospholipid classes in T. truncatus plasma. Palmitic, oleic, and stearic acids are the major fatty acid (FA) present esterified to the plasma polar lipids of this species, although some n-3 species are also remarkably present, namely eicosapentaenoic and docosahexaenoic acids. The polar lipidome identified by HILIC LC-MS allowed identifying 304 different lipid species. These species belong to the phosphatidylcholine (103 lipid species), lysophosphatidylcholine (35), phosphatidylethanolamine (71), lysophosphatidylethanolamine (20), phosphatidylglycerol (13), lysophosphatidylglycerol (5), phosphatidylinositol (15), lysophosphatidylinositol (3), phosphatidylserine (6) lysophosphatidylserine (1), and sphimgomyelin (32) classes. This was the first time that the dolphin plasma phospholipid profile was characterized, providing a knowledge that will be important to further understand lipid metabolism and physiological regulation in small cetaceans. Furthermore, this study proved the practicability of the use of plasma lipid profiling for health assessment in marine mammals under human care.

Characterization of the cardiac phospholipidome of small cetaceans provides adaptational insight and a foundation for indirect population health screening

AbstractThe maintenance of a tightly regulated heart lipidome is a general hallmark of mammal health. However, in the case of cetaceans, heart tissue lipid composition remains obscure. This work represents a first in‐depth state‐of‐the‐art characterization of the lipid content of small cetacean hearts, namely those of Delphinus delphis, Phocoena phocoena, and Stenella coeruleoalba. Phospholipid classes identified were similar to those found in terrestrial mammals. Regarding fatty acid profiles, they revealed a much higher n‐3 fatty acid content than that reported for terrestrial counterparts. Phospholipidome characterization allowed identification of 198 lipid species, including phospholipids, lysophospholipids, and sphingomyelins, generally characterized by a high content of species with esterified n‐3 fatty acids. The cardiac lipid profile of the three cetacean species is similar in terms of lipid classes, fatty acids, and even molecular lipid species present. However, quantitative differences suggest a divergence of S. coeruleoalba from the other species in terms of fatty acid and phospholipid profile. The identified differences regarding terrestrial counterparts will contribute to better understanding the details of small cetacean cardiac physiology. Moreover, the characterization of cardiac phospholipidome may represent an opportunity to establish lipidomic‐based practical tools to reliably and reproducibly assess small cetacean health population status by remote sampling.

Empty promises: The European Union is failing to protect dolphins and porpoises from fisheries by‐catch

AbstractBy‐catch is the primary global conservation threat to populations of dolphins and porpoises. Despite protection for these protected species under its Habitats Directive, the European Union (EU) has failed to adequately assess and, where necessary, mitigate the by‐catch of small cetaceans. Management authority is diffuse, and the EU has no over‐arching, quantitative conservation objectives. To address this, we recommend that the EU adopt a comprehensive plan to conserve dolphins and porpoises in European waters. This plan should include regular formal assessments of small cetacean populations, including establishment of quantitative management objectives, generation of estimates of abundance and by‐catch mortality, and agreement on biological reference points that will guide management actions to ensure that by‐catch does not exceed sustainable levels.

Annex I: Fishery bycatch of small cetaceans entered into the Progress Report Database in 2020

How to cite: International Whaling Commission, 2021. Report of the Scientific Committee: Annex I. J. Cetacean Res. Manage. Suppl. 22: 208-218.

Annex J: Direct takes of small cetaceans in Japan by type of fishery and prefecture of departure port, 1997-2018

How to cite: International Whaling Commission, 2021. Report of the Scientific Committee: Annex J. J. Cetacean Res. Manage. Suppl. 22: 219-222.

Disentangling Natural and Anthropogenic Forms of Mortality and Serious Injury in a Poorly Studied Pelagic Dolphin

Killer whale (Orcinus orca) populations specialize in both prey and prey acquisition tactics around the world and may be a primary evolutionary driver of the habits of small cetaceans. Entanglement in fishing gear is the most significant anthropogenic threat to the survival of cetaceans worldwide. Distinguishing between natural and human-caused sources of mortality and injury is a key task in marine mammal conservation and management. In British Columbia (BC), Canada, mammal-eating killer whales co-occur with Pacific white-sided dolphins (Lagenorhynchus obliquidens). Bycatch mortality rates are unknown here due to lack of systematic fisheries observer coverage. Drawing from more than three decades of first-hand observations of killer whale attacks on Pacific white-sided dolphins, we identify common themes with respect to predatory behavior of killer whales and anti-predatory responses of dolphins. With input from veterinary pathologists, we outline clues to distinguish killer whale rake marks from scars and wounds likely to be caused by fishery interactions. We examined photographs of 415 well-marked Pacific white-side dolphins for evidence of injuries and scars consistent with either killer whale attacks or fishery interactions. In this case study, healed scars from interactions with killer whale predators were ∼8× more common than scars from fishery interactions (3.9 vs. 0.5%), suggesting that predation is a much bigger threat to Pacific white-sided dolphins in the study area than anthropogenic impacts, or that dolphins are much less likely to survive a fishery interaction than a predation attempt. To advance our knowledge on poorly studied species, multiple lines of evidence will be needed.

A Visitor of Tropical Waters: First Record of a Clymene Dolphin (Stenella clymene) Off the Patagonian Coast of Argentina, With Comments on Diet and Metazoan Parasites

The poorly known Clymene dolphin (Stenella clymene) is a small oceanic cetacean distributed in tropical and subtropical waters of the Atlantic Ocean. In this study, we report, for the first time, a vagrant individual of Clymene dolphin in Argentina (Rada Tilly) that represents the current southern-most record for this cetacean species. We provide a molecular identification of the dolphin, based on partial sequences of the mitochondrial cytochrome b gene, generated from DNA extracted from its metazoan parasites. Three prey species, namely Argentine hake, Patagonian squid and lobster krill were identified from hard pieces collected in the stomach. Seven metazoan parasite taxa (three in adult stage, one immature stage and three in larval stage) were identified using morphological and molecular data, i.e., the digenean Pholeter gastrophilus (new host record), the cestodes Tetrabothrius (Tetrabothrius) forsteri, Clistobothrium grimaldii unidentified phyllobothriid plerocercoids, the nematodes Anisakis pegreffii (new host record), Halocercus delphini and the acanthocephalan Corynosoma australe (new host record). Our study provides the first molecular exploration of the metazoan parasite diversity in delphinids from the southwestern Atlantic, and contributes significantly to understand the poorly known parasite fauna of the Clymene dolphin.

Artisanal and Aboriginal Subsistence Whaling in Saint Vincent and the Grenadines (Eastern Caribbean): History, Catch Characteristics, and Needs for Research and Management

Whaling has been a contentious international environmental issue for decades and carries complex ecological and socioeconomic implications. In Saint Vincent and the Grenadines (SVG), a small archipelagic nation located in the Eastern Caribbean, present-day whaling traces its origin to local interaction with American-based whalers during the nineteenth and early twentieth centuries. When American whaling in the region ceased, local shore-based whaling arose to fill the niche and to exploit the remaining, though diminished, stocks of large whales, as well as stocks of small cetaceans that the American whalers had not targeted as heavily. After a period of expansion throughout the late nineteenth and early twentieth centuries, which saw shore-whaling operations established on at least 11 islands in the region, Eastern Caribbean whaling experienced a period of attrition, during which most local whaling operations ceased. Two operations, both based in SVG, continue regularly today. This paper reviews the past and present status of whaling activities in SVG from the literature and using recent data collected from 2007 to 2017 through logbook data, interview surveys, and ethnographic observations. Small cetacean captures have been documented since 1949, and at least 15 species of odontocetes have been captured (primarily delphinids). From 1949 to 2017, a total of 13,856 small cetacean captures has been recorded, including 5,896 short-finned pilot whales (Globicephala macrorhynchus), 109 killer whales (Orcinus orca), and 7,851 other small cetaceans. Small cetacean catch records are largely incomplete and total catch estimates could not be attempted. Reliable abundance estimates do not exist. Consistent records for the take of large whales are only available for the period 1986–2020, during which 45 humpback whales (Megaptera novaeangliae) and 2 Bryde’s whales (Balaenoptera edeni) were taken. Additionally, 8 sperm whale (Physeter macrocephalus) captures were reported from 1967 and 1974. We also review whaling practices, existing national policy on whaling, management techniques outside of formal policy regimes, research needs, and future management perspectives. Future monitoring and management of whaling activities in SVG are strongly needed to assess the sustainability of small cetacean exploitation.

Microsatellite markers for the endangered franciscana dolphin (Pontoporia blainvillei).

The franciscana (Pontoporia blainvillei) is the most threatened small cetacean in the South Atlantic. In this study we report the development of 13 microsatellite markers for franciscanas through next-generation sequencing, and the characterization of those loci in 38 samples from the species' northernmost population (Espírito Santo, Brazil). Besides providing diversity indices for the new, specific loci, we also report on the transferability of heterologous loci which had not been screened in franciscanas before, and review all loci used in previous studies. Expected heterozygosity in the new loci ranged between 0.107 and 0.595, and all but one were in Hardy Weinberg Equilibrium. These are the first microsatellite loci isolated from franciscanas, and they are an important addition to heterologous markers that were available previously.

The Challenges of Managing Depredation and Bycatch of Toothed Whales in Pelagic Longline Fisheries: Two U.S. Case Studies

Direct interactions with fisheries are broadly recognized as the leading conservation threat to small cetaceans. In open-ocean environments, one of the primary gear types implicated in these interactions is the pelagic longline. Unlike accidental entanglement in driftnets or deliberate entrapment by purse-seines, interactions between cetaceans and longlines are often driven by attraction of the animals to feed on bait or fish secured on the gear, a behavior known as depredation. Many small and medium-sized delphinid species have learned to exploit such opportunities, leading to economic costs to fisheries and a risk of mortality to the animals from either retaliation by fishermen or hooking or entanglement in fishing gear. Two pelagic longline fisheries in the United States experience depredation and bycatch by odontocete depredators: the Hawai‘i deep-set longline fishery, which is depredated primarily by false killer whales (Pseudorca crassidens), and the Atlantic pelagic longline fishery depredated primarily by short-finned pilot whales (Globicephala macrorhynchus). These fisheries are among the most intensively documented and managed pelagic longline fisheries in the world, with high levels of observer coverage, and bycatch mitigation measures required to reduce the mortality of seabirds, sea turtles and cetaceans. Both fisheries have active, multi-stakeholder “Take Reduction Teams,” enacted under the U.S. Marine Mammal Protection Act (MMPA), that are tasked to develop measures to reduce the bycatch of cetaceans below statutory reference points. Consequently, these two Teams represent model processes within which to address depredation and bycatch, having access to detailed, high-quality data on the nature and frequency of interactions with cetaceans, meaningful stakeholder involvement, resources to test potential solutions, and the institutional will to improve outcomes. We review how mitigation strategies have been considered, developed, and implemented by both Teams and provide a critical analysis of their effectiveness in addressing these problems. Notably, in the absence of straightforward avoidance or deterrence strategies, both Teams have developed gear and handling strategies that depend critically on comprehensive observer coverage. Lessons offered from these Teams, which have implemented consensus-driven management measures under a statutory framework, provide important insights to managers and scientists addressing other depredation problems.

Drone-Monitoring: Improving the Detectability of Threatened Marine Megafauna

Unmanned aerial vehicles (UAVs; or drones) are an emerging tool to provide a safer, cheaper, and quieter alternative to traditional methods of studying marine megafauna in a natural environment. The UFES Nectology Laboratory team developed a drone-monitoring to assess the impacts on megafauna related to the Fundão dam mining tailings disaster in the Southeast Brazilian coast. We have developed a systematic pattern to optimize the available resources by covering the largest possible area. The fauna observer can monitor the environment from a privileged angle with virtual reality and subsequently analyzes each video captured in 4k, allowing to deepening behavioral ecology knowledge. Applying the drone-monitoring method, we have observed an increasing detectability by adjusting the camera angle, height, orientation, and speed of the UAV; which saved time and resources for monitoring turtles, sea birds, large fish, and especially small cetaceans efficiently and comparably.