Cetaceans Research Articles

Proteome profiling reveals opportunities to investigate biomarkers of oxidative stress and immune responses in blubber biopsies from free-ranging baleen whales.

Over 25% of cetacean species worldwide are listed as critically endangered, endangered or vulnerable by the International Union for Conservation of Nature. Objective and widely applicable tools to assess cetacean health are therefore vital for population monitoring and to inform conservation initiatives. Novel blubber biomarkers of physiological state are examples of such tools that could be used to assess overall health. Proteins extracted from blubber likely originate from both the circulation and various cell types within the tissue itself, and their expression is responsive to signals originating from other organs and the nervous system. Blubber proteins can therefore capture information on physiological stressors experienced by individuals at the time of sampling. For the first time, we assess the feasibility of applying shotgun proteomics to blubber biopsy samples collected from free-ranging baleen whales. Samples were collected from minke whales (Balaenoptera acutorostrata) (n = 10) in the Gulf of St Lawrence, Canada. Total protein was extracted using a RIPA cell lysis and extraction buffer-based protocol. Extracted proteins were separated and identified using nanoflow Liquid Chromatography Electrospray Ionization in tandem with Mass Spectrometry. We mapped proteins to known biological pathways and determined whether they were significantly enriched based on the proteome profile. A pathway enrichment map was created to visualize overlap in tissue-level biological processes. Amongst the most significantly enriched biological pathways were those involved in immune system function: inflammatory responses, leukocyte-mediated immunity and the humoral immune response. Pathways associated with responses to oxidative stress were also enriched. Using a suite of such protein biomarkers has the potential to better assess the overall health and physiological state of live individuals through remote biopsy sampling. This information is vital for population health assessments to predict population trajectories, and ultimately guide and monitor conservation priorities and initiatives.

Integrated Conservation Strategy for Endangered Small Cetaceans: Insights from the Case of the Yangtze Finless Porpoise

The Yangtze finless porpoise (YFP) is an endemic freshwater cetacean species that exclusively inhabits the middle and lower reaches of the Yangtze River basin. Since the late 1970s, the YFP has experienced a drastic population decline and was classified as critically endangered by the IUCN in 2013. To save this unique species, a range of integrated conservation measures have been implemented, including strengthening natural habitat protection (in-situ), enhancing insurance populations (ex-situ), and advancing captive breeding and research initiatives. These efforts have yielded significant progress in the conservation of the YFP. The natural population has been starting to increase after a sharp decline, and the establishment of three insurance populations has provided a solid foundation for recovery. Additionally, advancement in captive breeding and research has delivered crucial technical support for population conservation. As a flagship species of Yangtze River biodiversity and an indicator of the river’s ecosystem health, the YFP’s integrated conservation strategy not only benefits its own population but also offers valuable insights for the protection of other endangered aquatic species in the Yangtze River and other threatened small cetaceans worldwide.

Tying up loose ends together: Cetaceans, maritime traffic and spatial management tools in the Strait of Gibraltar

Abstract The transboundary area of the Strait of Gibraltar is home to seven protected cetacean species that are threatened by high intensity of maritime traffic. More comprehensive knowledge of cetaceans and maritime traffic is required, together with analyses of legislations, strategies and policies. This study quantitatively investigates cetacean distribution and maritime traffic intensity and, for the species of community interest bottlenose dolphin, habitat suitability. Results are qualitatively discussed considering the overlap of cetacean hot spots with different maritime activities and the consistency of spatial conservation management measures in force. The Fixed Line Transect Mediterranean Monitoring Network protocols were followed for 59 visual surveys using ferries as observation platforms for monitoring cetaceans and maritime traffic. Surveys were carried out along the transects between Algeciras and Ceuta and between Algeciras and Tanger‐Med, in 2018 and 2019. 264 cetacean sightings, including seven different species and four near‐miss collision events (involving pilot, sperm and fin whales), were reported. Monitoring cetaceans from ferries in the Strait provided insights into cetacean distribution and maritime traffic, enabling the identification of cetacean hot spots, suitable habitats and maritime traffic high‐risk zones. A transboundary management effort is required, together with an adaptive approach for protecting highly mobile species such as cetaceans. Proposals include a long‐term cetacean monitoring program carried out by dedicated observers on board ferries as a cost‐effective methodology and mandatory training for crew members, to increase cetacean knowledge and reduce collision risk. The designation of an international temporal or, in some zones, permanent speed reduction area (i.e., Cetacean Critical Navigation Zone, with a maximum speed of 13 knots) and of a micro‐sanctuary with a seasonal no‐take zone in the Bay between Algeciras and Gibraltar, together with international surveillance, are recommended measures for the enhancement of conservation efforts in the Strait.

The WhaleReport Alert System: Mitigating threats to whales with citizen science

Ship strikes are a pervasive threat to cetaceans globally. Real-time observations of cetaceans reported by citizen scientists unlock an opportunity to develop ship strike mitigation tools. The Ocean Wise Sightings Network (OWSN) is an example of a long-running and expansive citizen science program. The OWSN curates sightings data collected by coastal communities, mariners, and tourists into a database that can be utilized to monitor the 23 cetacean species inhabiting British Columbia and Washington State waters. Recently, the OWSN mobilized real-time sightings data into a mitigation tool, the WhaleReport Alert System (WRAS), which alerts professional mariners to the presence of cetaceans within their vicinity, allowing them to take action (e.g., slow down or divert course), to mitigate the risk of ship strike. The success of the WRAS (550 registered users) can be largely attributed to outreach events conducted in coastal communities which recruit new observers who report sightings to the WhaleReport app. Partnering with mariners to develop the WRAS has resulted in its continued support from and use by marine industry. We highlight the critical role of a sightings network for mitigating threats to cetaceans, emphasize the need to collaborate with marine industry, non-governmental, and government bodies to support endorsement of the tool, and stress the importance of metrics to evaluate success of the WRAS. This approach taken by Ocean Wise has resulted in the delivery of >20,000 WRAS alerts and is a framework which could be integrated into existing sightings networks globally to mitigate the risk of ship strikes on cetaceans.

The non-consumptive economic value of wildlife: the case of three cetacean species

The conservation of wildlife is one of the most pressing issues in the current times, but wildlife conservation economic values have often been largely ignored due to an absence of market prices, as setting an economic value on biodiversity or whole ecosystems can be challenging. Nevertheless, valuing wildlife can be of great significance to improve decision-making in the conservation field, as it can provide a complementary perspective based on economic principles. Whale-watching provides an opportunity for the economic valuation of wildlife. Specifically, it offers a framework in which the economic revenue allows the economic valuation of the targeted cetaceans to be estimated through the direct and indirect expenditure of the tourists who purchase whale-watching tours. Here, we performed an economic analysis based on population abundances of the three main species targeted by the whale-watching companies in the Strait of Gibraltar (Spain): long-finned pilot whales (Globicephala melas), common dolphins (Delphinus delphis) and killer whales (Orcinus orca). These species generated a total annual income of €4,089,056, €1,876,833, and €505,389, respectively, and each individual would generate an average of €14,048, €951, and €36,099 each year, respectively. Incorporating life expectancy, this corresponded to a total population value of €112,426,185, €16,685,147, and €19,171,107, respectively, over their lifetime. These values provide an idea of the potential contribution of cetaceans to the local economy but only represent their non-consumptive value based on tourism. Our results reinforce the idea that a sustainable, high-quality whale-watching culture, under ACCOBAMS High-Quality Whale-Watching requirements, should be promoted to ensure a sustainable industry, stable economic income and the viability of cetacean populations in the Strait of Gibraltar.

Drivers of morphological evolution in the toothed whale jaw

Toothed whales (odontocetes) emit high-frequency underwater sounds (echolocate)-an extreme and unique innovation allowing them to sense their prey and environment. Their highly specialized mandible (lower jaw) allows high-frequency sounds to be transmitted back to the inner ear. Echolocation is evident in the earliest toothed whales, but little research has focused on the evolution of mandibular form regarding this unique adaptation. Here, we use a high-density, three-dimensional geometric morphometric analysis of 100 living and extinct cetacean species spanning their ∼50-million-year evolutionary history. Our analyses demonstrate that most shape variation is found in the relative length of the jaw and the mandibular symphysis. The greatest morphological diversity was obtained during two periods of rapid evolution: the initial evolution of archaeocetes (stem whales) in the early to mid-Eocene as they adapted to an aquatic lifestyle, representing one of the most extreme adaptive transitions known, and later on in the mid-Oligocene odontocetes as they became increasingly specialized for a range of diets facilitated by increasingly refined echolocation. Low disparity in the posterior mandible suggests the shape of the acoustic window, which receives sound, has remained conservative since the advent of directional hearing in the aquatic archaeocetes, even as the earliest odontocetes began to receive sounds from echolocation. Diet, echolocation, feeding method, and dentition type strongly influence mandible shape. Unlike in the toothed whale cranium, we found no significant asymmetry in the mandible. We suggest that a combination of refined echolocation and associated dietary specializations have driven morphology and disparity in the toothed whale mandible.

Finless Porpoise Bycatch and Stranding along the Shandong Peninsula, China, Based on Public Reports from 2000 to 2018.

The Shandong Peninsula is located on the western coast of the Pacific and is adjacent to the Bohai Sea (BS) and the Yellow Sea (YS) to the east. The East Asian finless porpoise Neophocaena asiaeorientalis sunameri, a subspecies of the narrow-ridged finless porpoise N. asiaeorientalis, is the dominant cetacean resident along the Shandong Peninsula. However, there is insufficient monitoring data to determine the status of the cetacean species in this region. Based on the publicly available literature, media, and internet social website, this study investigated the spatial-temporal distribution of porpoise stranding and bycatch along the coast of the Shandong Peninsula. Data on over five hundred porpoises from two hundred reports between 2000 and 2018 were compiled and analyzed. Results showed that the bycatch and stranding of porpoises occurred widely across the peninsula throughout all months and increased rapidly between 2010 and 2017. The incidents were more frequent in the area where the BS and YS converged during the spring and early summer than in other seasons. The mean body length of bycaught porpoises was smaller than that of those found stranded. Fishing activities could be the principal cause of local finless porpoise incidents. However, limited data hindered a quantitative evaluation of the living conditions of finless porpoises in this area. Establishing a comprehensive monitoring system, which includes standardized reporting, rescue operations, and scientific research, is essential to finless porpoise protection along the Shandong Peninsula.

Predicting cetacean habitats beyond surveyed regions in Indonesian waters: species distribution model transferability may not always be preferable

Understanding the distribution of cetaceans in Indonesian waters is imperative for their conservation management, however such information is lacking for the country. Our study predicted the species distributions of two cetacean species (common bottlenose dolphin and sperm whale) beyond the surveyed regions in Indonesian Exclusive Economic Zone (EEZ). This was done by using a combination of presence-only data, randomly generated pseudo-absences and environmental predictors variables within the Biomod2 framework in R. Ten potential predictor variables were identified, of which five were selected after correlation tests. Local Random Forest models were built to the extent of four small study regions, and later projected to the whole Indonesian EEZ. The common bottlenose dolphin local models showed preference for areas close to the coast and shallower waters. Sperm whale local predictions were located further into the open waters and at deeper waters. The extrapolated predictions into the Indonesian EEZ, however, showed some unexpected results. The high occurrences for common bottlenose dolphins were not only located close to the islands, but also more into open waters. In contrast, sperm whale distributions have high occurrences near coastal areas and in the vicinity of islands than in the open oceans. This information suggested that the transferability of species distribution models may not always be preferable, because provide low accuracy. Sighting data, choices of variables and model settings influenced the outcome of the extrapolated models. Despite the unpreferable of the extrapolations, the results are still beneficial for cetacean conservation purposes, since the study was able to identify potential habitats in unsurveyed regions.

Optimization and validation of a micro–QuEChERS method for phthalates detection in small samples of cetacean blubber

In this study, an innovative method was developed to detect and quantify phthalates in fresh cetacean blubber. An adaptation of the ammonium formate QuEChERS method was used and adapted as a micro-extraction for small quantities of samples. Significantly, this technique utilized minimal quantities of reagents and salts, with the additional implementation of rigorous Quality Assurance/Quality Control protocols to further reduce background contamination. To ensure the reliability of this method, comprehensive validation procedures were conducted, with a specific focus on two widely studied cetacean species: the common bottlenose dolphin (Tursiops truncatus) and the short-finned pilot whale (Globicephala macrorhynchus). Determination coefficients (R2) for matrix-matched calibration were >0.93 with limits of quantifications (LOQ) of the method in the range of 5–10 ng/g. Mean recovery values were between 40 and 100 %. This novel methodology holds particular relevance for environmental research studies, offering the capability to detect emerging contaminants with minimal sample requirements. This aspect is particularly valuable in investigations that involve free-ranging animals and rely on biopsy sampling. It allows for the assessment of contaminant levels in healthy individuals within wild populations, enhancing our understanding of ecological impacts and potential conservation measures.•A micro-extraction adaptation of the ammonium formate QuEChERS method was developed and applied to a small quantity of fresh cetacean blubber to detect phthalates.•Small quantities of reagents and salts were used, and additional Quality Assurance/ Quality Control procedures were taken to further minimize background contamination.•Method validation was carried out for two cosmopolitan and extensively studied cetacean species: the common bottlenose dolphin (Tursiops truncatus) and the short-finned pilot whale (Globicephala macrorhynchus).

Genome-wide analysis of the harbour porpoise (Phocoena phocoena) indicates isolation-by-distance across the North Atlantic and potential local adaptation in adjacent waters

The harbour porpoise (Phocoena phocoena), a highly mobile cetacean species of the Northern Hemisphere, inhabits basins that vary broadly in salinity, temperature, and food availability; such variation can drive divergent adaptation among local populations. To shed light on range-wide population structure and local adaptation, we generated ddRAD sequencing data spanning the entire North Atlantic and the Baltic Sea, as well as the Black Sea as an outgroup, and mapped this data to the high-quality draft genome of the species. We identified 11,978 genome-wide SNPs from 150 individuals, which we used for population genetic inferences. Our results support genetic differentiation between North Atlantic and Baltic Sea populations, with Kattegat as a transition zone. Across the North Atlantic the population differentiation is subtle from west to east, congruent with an isolation-by-distance pattern, but indicates a separation of southern North Sea harbour porpoises. We identified genomic outlier regions, i.e., scaffold regions where SNPs with high FST across North Atlantic populations co-occur. Together with the draft genome annotation, these regions could point towards candidate genes for differential local adaptation processes among populations. Furthermore, they enable the development of a SNP panel for routine population assignment which will be useful in a conservation and management context. We identified six outlier loci putatively under positive selection, based on the population structure inferred from the complete SNP set. Our study highlights the value of genome resources in conservation and management and provides a crucial additional resource for the study of harbour porpoise evolution and phylogeny.

Relationship between red blood cell lifespan and endogenous carbon monoxide in the common bottlenose dolphin and beluga.

Certain deep-diving marine mammals [i.e., northern elephant seal (Mirounga angustirostris), Weddell seal (Leptonychotes weddellii)] have blood carbon monoxide (CO) levels that are comparable with those of chronic cigarette smokers. Most CO produced in humans is a byproduct of heme degradation, which is released when red blood cells (RBCs) are destroyed. Elevated CO can occur in humans when RBC lifespan decreases. The contribution of RBC turnover to CO concentrations in marine mammals is unknown. Here, we report the first RBC lifespans in two healthy marine mammal species with different diving capacities and heme stores, the shallow-diving bottlenose dolphin (Tursiops truncatus) and deep-diving beluga whale (Delphinapterus leucas), and we relate the lifespans to the levels of CO in blood and breath. The belugas, with high blood heme stores, had the longest mean RBC lifespan compared with humans and bottlenose dolphins. Both cetacean species were found to have three times higher blood CO content compared with humans. The estimated CO production rate from heme degradation indicates some marine mammals may have additional mechanisms for CO production, or delay CO removal from the body, potentially from long-duration breath-holds.NEW & NOTEWORTHY This is the first study to determine the red blood cell lifespan in a marine mammal species. High concentrations of carbon monoxide (CO) were found in the blood of bottlenose dolphins and in the blood and breath of belugas compared with healthy humans. Red blood cell turnover accounted for these high levels in bottlenose dolphins, but there may be alternative mechanisms of endogenous CO production that are contributing to the CO concentrations observed in belugas.

Cetacean and Sea Turtle Observations in the Remote Mid-Atlantic (NW) Ocean

Due to its remoteness, little is known about the occurrence and abundance of cetaceans and sea turtles in the pelagic mid-Atlantic Ocean. Data on cetacean and sea turtle occurrence and distribution were collected by dedicated biological observers to address U.S. monitoring and mitigation requirements associated with a vessel-based academic geophysical survey in international waters in the northwestern and mid-Atlantic Ocean from 14 June through 16 July 2018. A total of 6,949 km (503 h) of visual observations occurred while surveying north from Bermuda and ending in Woods Hole, Massachusetts. A total of 928 cetaceans representing at least 14 species and 15 sea turtles representing three species were observed. The most frequently observed cetacean species was the Atlantic white-sided dolphin (Lagenorhynchus acutus) (340 individuals; 37%) followed by the short-beaked common dolphin (Delphinus delphis) (286 individuals; 31%) and pilot whales (Globicephala spp.) (95 individuals; 10%). These sighting data also included an extralimital sighting of a sperm whale (Physeter macrocephalus) calf at 43.44° N latitude and 36.85° W longitude, and extralimital sightings of Atlantic white-sided dolphins below 38° N latitude. Loggerhead sea turtles (Caretta caretta) were seen most frequently (6 individuals). This study addresses a data gap in documented occurrence and lack of occurrence of cetaceans and sea turtles over a large pelagic area in the northwestern Atlantic Ocean during summer.

The first baleen whale marine protected area proposed for Bryde's whales in the Beibu Gulf, China

AbstractThe establishment of marine protected areas (MPAs) for cetaceans is an important strategy to mitigate human disturbance and protect biodiversity. Despite abundant cetacean species, there are only a few MPAs dedicated to cetacean conservation in China, all of which are for inshore dolphins. Bryde's whales, the only nearshore baleen whale population in mainland China, are conflicting with intensive human activities, yet an effective conservation strategy is lacking. This study used species distribution models to analyze distribution patterns and suitable habitats of Bryde's whales in the Beibu Gulf and proposes the first baleen whale MPA in China. Our results showed Bryde's whales have a seasonal distribution pattern in the Beibu Gulf, and that the waters around Weizhou Island and the southeastern coast of Vietnam were their core habitats. The seasonal nighttime light data indicated a negative relationship between the number of ship lights and Bryde's whale sightings and suggest that Bryde's whales might be threatened by fisheries. We proposed an MPA based on the results, suggesting that the waters within 20 km around Weizhou Island should be declared a protected area. Furthermore, we recommend that anthropogenic activities in the waters around Weizhou Island are better managed to reduce negative impacts on marine life.

Automated Detection and Tracking of Marine Mammals in the Vicinity of Tidal Turbines Using Multibeam Sonar

Understanding how marine animals behave around tidal turbines is essential if we are to quantify how individuals and populations may be affected by the installation of these devices in the coming decades. Our particular interest is in collision risk, and how this may be affected by the fine-scale behaviour of seals and small cetacean species around devices. We report on a study in which multibeam sonar data were collected close to an operational tidal turbine in Scotland continuously over a twelve-month period. The sonars provide high-resolution (a few cm) data over a 120° angle out to a range of 55 m at a rate of 10 frames per second. We describe a system which uses automatic computer algorithms to detect potential targets of interest, verified by human analysts using a sophisticated computer user interface to confirm detections and assign target species. To date, we have identified 359 tracks of marine mammals in the data, as well as several thousand tracks from fish and diving birds. These are currently being parameterised to study how these species react to the moving turbine rotors, and the data are now being used to explore the development of improved automated detection and classification algorithms.

Guiana dolphins use mangrove margins as a natural barrier to chase fish prey

AbstractThe behavioral plasticity among and within cetacean species can be driven by their prey sources, local adaptations to environmental features, and/or interactions with human activities. One of the tactics displayed by cetaceans is the barrier feeding, in which individuals or groups herd fish schools against natural and non‐natural barriers to restrict movements of their prey. Coastal odontocetes, for example, are known for using shorelines and underwater slopes to trap their prey. Here, we documented two distinct populations of Guiana dolphin using the mangrove margins as a natural barrier to herd and capture fish. The observations took place in the Cananéia estuary, São Paulo State, southeastern Brazil, and in the Paranaguá estuary, Paraná State, southern Brazil. A total of 63 dolphins over eight encounters were observed performing six different events using mangroves as a natural barrier, summing both study areas. These findings not only expand our understanding of the behavior plasticity of the species but also call attention to the importance of the mangrove ecosystem directly to Guiana dolphins and indirectly to the components of their food web.

New insights into the pathogenesis and transmission of Brucella pinnipedialis: systemic infection in two bottlenose dolphins (Tursiops truncatus).

Brucella spp. are zoonotic pathogens that can affect both terrestrial and marine mammals. Brucella ceti has been identified in various cetacean species, but only one sequence type (ST27) has been reported in humans. However, it is important to conduct surveillance studies to better understand the impact of marine Brucella species on marine mammals, a typically understudied host group. Here, we describe a systemic infection by two related strains of Brucella pinnipedialis (ST25) in a couple of live-stranded bottlenose dolphins, with more severe lesions in the younger animal. Furthermore, B. pinnipedialis was first detected in milk from a female cetacean that stranded with its offspring. Our study reveals novel insights into the epidemiology and pathological consequences of B. pinnipedialis infections in cetaceans, emphasizing the crucial importance of ongoing surveillance and accurate diagnosis to understand the impact of this pathogen on marine mammal populations.

Legacy and emerging contaminants in marine mammals from Argentina

Marine mammals are recognized sentinels of ecosystem health. They are susceptible to the accumulation and biomagnification of pollutants, which constitute one of the greatest threats to their survival. Legacy, such as organochlorine pesticides, and emerging contaminants, like microplastics and pharmaceuticals, may have effects on marine mammals' health at individual and population levels. Therefore, the evaluation of the risks associated with pollutants in this group is of great importance. The aim of this review is to provide information on the occurrence of legacy and emerging contaminants in marine mammals that inhabit Argentine waters. Also, to identify knowledge gaps and suggest best practices for future research. Reports of legacy contaminants referring to organochlorine pesticides and polychlorinated biphenyls were found in five species of cetaceans and two of pinnipeds. With respect to emerging pollutants, the presence of plastics was only evaluated in three species. Reported data was from at least a decade ago. Therefore, it is necessary to update existing information and conduct continuous monitoring to assess temporary trends in pollutants. All the studies were carried out in the province of Buenos Aires and Northern Patagonia indicating a knowledge gap in the southern zone of the Argentine Sea. In addition, pollutants of global environmental concern that have not been studied in Argentina are discussed. Future studies should fill these gaps and a greater effort to understand the relationships between pollutants and their effects on marine mammals is suggested. This issue will make it possible to determine thresholds for all the substances and species evaluated in order to carry out more detailed risk assessments and make decisions for the conservation of marine mammals in Argentine waters.

What do small cetaceans tell us about trace elements pollution on the Argentinean coast? Franciscana dolphin as a biomonitor

Trace elements (TEs) constitute the oldest emerging pollutants globally, most occur from natural sources, but a few are derived from anthropogenic sources. Marine mammals are considered bioindicators of ecosystem contamination. The aims of this review is compile reports on essential and nonessential TEs occurrence in small cetaceans from Argentinean waters; and to review the existing information on the concentration of TEs in the Franciscana dolphin, a biomonitor species of the Argentine coastal marine ecosystem. We searched reports where levels of TEs were present in small cetaceans from and eight species were analysed: Pontoporia blainvillei, Tursiops truncatus gephyreus, Kogia breviceps, Delphinus delphis, Lagenorhynchus obscurus, Lagenodelphis hasei, Cephaloryhchus commersonii and Ziphius cavirostris. Essential TEs like Zn, Cu, Mn, Cr, Fe, Co, Ni, Mo, Se, As, Au, Ag, Sn, and nonessential TE as Pb, Cd, Hg, As was considered. The reports compiled in this article analysed kidney, liver, muscle and occasionally brain, skin, lung and spleen, covering a temporal range of 30 years, from 1982 to 2016. Of data analysis, we identify knowledge gaps, species of small cetaceans for which the concentration of trace metals is not yet known and areas on the Argentine coast where there are no reports that analyse them. The most recent information corresponds to the 2010 decade, and in those subsequent publications, the samples were taken at that time. This emphasizes the importance of reviewing this data, in order to compare old and new datasets, create contamination timelines and evaluate possible increases or decreases of contaminants in different study areas. The information recopilated will serve as valuable baselines to detect the future impact of increasing human, even natural, activities on marine ecosystems in the South Atlantic Ocean.

Assessment of cetacean exposure to underwater noise in the southwestern Atlantic ocean

Cetacean exposure to underwater noise in the Southwestern Atlantic Ocean is largely unknown. With the goal to characterize sound pressure and sound exposure levels in different environments, we have employed data from one month of passive acoustic monitoring in a coastal and an oceanic location to register sound pressure level variations and to calculate sound exposure levels to which cetacean species are subjected. Noise profiles varied between locations; Rio de Janeiro coastal area had higher levels than the Vitória-Trindade Seamount Chain area. At both sites, low-frequency hearing cetaceans were the group under higher exposure during day and night. For high-frequency and very high-frequency groups, the day period presented higher levels. Results highlight the conditions of these unexplored soundscapes and the necessity for taking underwater noise into consideration for space-time regulation of marine areas in cetacean conservation efforts.

Who’s knocking? Gray whale acoustic detection along California’s central coast

Passive acoustic monitoring (PAM) efforts are essential to marine mammal conservation. Bioacoustic techniques can be preferred as visual surveys are time intensive, costly, and limiting. California’s coastline is a biodiversity hotspot and a known migration corridor of multiple cetacean species, including gray whales, according to stock assessments provided by NOAA. Certain studies have indicated that gray whales vocalize during migration which can help confirm cetacean presence throughout the year. Off the coast of San Luis Obispo, California in an area that overlaps with the gray whale’s southern migration, our team detected an unidentified knocking noise. Although gray whale vocalizations can be difficult to confirm, we believe these knocks are produced by this transient species. In order to determine the source of these knocking sounds, the goals of this project are to (1) classify the repetitive noise as biotic or abiotic, (2) perform a comparative analysis of various species to narrow down possible biotic candidates, (3) utilize records from local whale watching companies for more accurate evidence of species presence at the time of our deployment, and (4) examine temporal variation in the occurrence of this knocking sound. Acoustic monitoring provides information about migration of gray whales necessary for conservation efforts.