Eubalaena Australis Research Articles

Artificial intelligence for right whale photo identification: from data science competition to worldwide collaboration

Photo identification is an important tool in the conservation management of endangered species, and recent developments in artificial intelligence are revolutionizing existing workflows to identify individual animals. In 2015, the National Oceanic and Atmospheric Administration hosted a Kaggle data science competition to automate the identification of endangered North Atlantic right whales (Eubalaena glacialis). The winning algorithms developed by Deepsense.ai were able to identify individuals with 87% accuracy using a series of convolutional neural networks to identify the region of interest, create standardized photographs of uniform size and orientation, and then identify the correct individual. Since that time, we have brought in many more collaborators as we moved from prototype to production. Leveraging the existing infrastructure by Wild Me, the developers of Flukebook, we have created a web-based platform that allows biologists with no machine learning expertise to utilize semi-automated photo identification of right whales. New models were generated on an updated dataset using the winning Deepsense.ai algorithms. Given the morphological similarity between the North Atlantic right whale and closely related southern right whale (Eubalaena australis), we expanded the system to incorporate the largest long-term photo identification catalogs around the world including the United States, Canada, Australia, South Africa, Argentina, Brazil, and New Zealand. The system is now fully operational with multi-feature matching for both North Atlantic right whales and southern right whales from aerial photos of their heads (Deepsense), lateral photos of their heads (Pose Invariant Embeddings), flukes (CurvRank v2), and peduncle scarring (HotSpotter). We hope to encourage researchers to embrace both broad data collaborations and artificial intelligence to increase our understanding of wild populations and aid conservation efforts.

Whales from space dataset, an annotated satellite image dataset of whales for training machine learning models

Monitoring whales in remote areas is important for their conservation; however, using traditional survey platforms (boat and plane) in such regions is logistically difficult. The use of very high-resolution satellite imagery to survey whales, particularly in remote locations, is gaining interest and momentum. However, the development of this emerging technology relies on accurate automated systems to detect whales, which are currently lacking. Such detection systems require access to an open source library containing examples of whales annotated in satellite images to train and test automatic detection systems. Here we present a dataset of 633 annotated whale objects, created by surveying 6,300 km2 of satellite imagery captured by various very high-resolution satellites (i.e. WorldView-3, WorldView-2, GeoEye-1 and Quickbird-2) in various regions across the globe (e.g. Argentina, New Zealand, South Africa, United States, Mexico). The dataset covers four different species: southern right whale (Eubalaena glacialis), humpback whale (Megaptera novaeangliae), fin whale (Balaenoptera physalus), and grey whale (Eschrichtius robustus).

Fetal growth, birth size and energetic cost of gestation in southern right whales.

The cost of reproduction greatly affects a species’ life history strategy. Baleen whales exhibit some of the fastest offspring growth rates in the animal kingdom. We quantified the energetic cost of gestation for southern right whales (Eubalaena australis) by combining whaling catch records of pregnant females with photogrammetry data on southern right whale mothers and calves from two breeding grounds in Argentina and Australia. The relationship between calf birth size and maternal length was determined from repeated measurements of individual females before and after giving birth. Fetal growth was determined from generalized linear models fitted to fetal length data from whaling operations between 1961 and 1967. Fetal length was converted to volume and mass, using the volume‐to‐length relationship of newborn southern right whales calves, and published tissue composition and energy content estimates. Fetal maintenance costs (heat of gestation) and the energy content of the placenta were predicted from published relationships and added to the fetal growth cost to calculate the total cost of gestation. Our findings showed that fetal growth rates and birth size increased linearly with maternal length, with calves being born at ∼35% maternal length. Fetal length increased curvilinearly through gestation, which resulted in an exponential increase in fetal volume and mass. Consequently, the cost of gestation was very low during the first (0.1% of total cost) and second trimester (4.9%), but increased rapidly during the last trimester (95.0%). The heat of gestation incurred the highest cost for pregnant females (73.8%), followed by fetal growth (21.2%) and the placental energy content (5.0%).Key points Baleen whales exhibit some of the fastest fetal growth rates in the animal kingdom. Despite this, the energetic cost of gestation is largely unknown, as well as the influence of maternal body size on fetal growth rates and calf birth sizes.We combined historical whaling records and drone photogrammetry data to determine fetal growth rates and birth sizes in southern right whales (Eubalaena australis), from which we estimated the cost of gestation.Calf birth size, and consequent fetal growth rates, increased positively with maternal body size.The cost of gestation was negligible for southern right whale females during the first two trimesters, but increased rapidly during the last trimester.These results show that late gestation incurs a significant cost for baleen whale females, and needs to be accounted for in bioenergetic models.

Southern right whale (Eubalaena australis) population demographics at major calving ground Head of Bight, South Australia, 1991–2016

Abstract Demographic parameters were estimated for southern right whales (SRWs), Eubalaena australis, using photo‐identification (photo‐ID) and count data collected during annual cliff‐based surveys at the Head of the Great Australian Bight (HoB), South Australia between 1991 and 2016. Photo‐ID and count data were contributed from the annual aerial surveys of the south‐western population in Australia (1993–2016). The HoB photo‐ID database included 1,186 non‐calf individuals, with 459 reproductive females. HoB is an open population and represents a relative proportion (0.48–0.21) of the overall south‐western population, which is decreasing with population growth. No change was detected in the growth rate at HoB over time (1992–2016) and there was no significant difference when compared to the overall south‐western population. The estimated mean rate of increase for all SRW was 3.2% (± 1.3) per annum and for females with a calf was 4.6% (± 1.7) per annum at HoB, compared to 5.5% (95% confidence interval (CI) 3.78, 7.36) and 6.01% (95% CI, 3.78, 7.36), respectively for the south‐western population during the same period. The apparent mean calving interval was 3.3 years (SD = 0.78, ± 0.14, 95% CI; 1996–2016), and a significant increase to 4 years was observed since 2015. The apparent mean age at first parturition was 9.0 years. The minimum estimated age of the oldest whale was 50 and oldest lactating female 41 years old. The SRW demographic data provides information for monitoring recovery, population status, species conservation management and global comparative studies. There is a need to understand fluctuations in calving intervals, threats to the population and implications for species recovery.

Historical reconstruction of the population dynamics of southern right whales in the southwestern Atlantic Ocean

Understanding the recovery of whale populations is critical for developing population-management and conservation strategies. The southern right whale (SRW) Eubalena australis was one of the baleen whale species that has experienced centuries of exploitation. We assess here for the first time the population dynamics of the SRW from the southwestern Atlantic Ocean at the regional level to measure numerically the effect of whaling and estimate the population trend and recovery level after depletion. We reconstructed the catch history of whaling for the period 1670–1973 by an extensive review of different literature sources and developed a Bayesian state-space model to estimate the demographic parameters. The population trajectory indicated that the pre-exploitation abundance was close to 58,000 individuals (median = 58,212; 95% CI = 33,329–100,920). The abundance dropped to its lowest abundance levels in the 1830s when fewer than 2,000 individuals remained. The current median population abundance was estimated at 4,742 whales (95% CI = 3,853–6,013), suggesting that the SRW population remains small relative to its pre-exploitation abundance (median depletion P2021 8.7%). We estimated that close to 36% of the SRW population visits the waters of the Península Valdés, the main breeding ground, every year. Our results provide insights into the severity of the whaling operation in the southwestern Atlantic along with the population´s response at low densities, thus contributing to understand the observed differences in population trends over the distributional range of the species worldwide.

Encounter Bay, South Australia, an important aggregation and nursery area for the southern right whale, Eubalaena australis (Balaenidae: Cetacea)

ABSTRACT Endangered Australian southern right whales, Eubalaena australis, are vulnerable to threats from human activities, particularly at calving aggregation areas. As the population increases, new calving areas are being established, which are important to monitor. In the Encounter Bay/Lacepede Bay region, South Australia, distribution, relative abundance, residency and site fidelity were studied using historical sightings (n = 1071, 1970–2013) and photo-identified individuals (n = 191, 2006–2019). Whales were observed throughout the study area and concentrated in Encounter Bay during April to November where an inshore core calving area was identified between Port Elliot and the River Murray Mouth. Annual maximum daily sightings increased from 2 to 8 ( = 2.9) whales during 1983–1997 to 1–25 ( = 8.6) after 2002. Numbers of identified female-calf pairs (CC) increased from 10 (2006–2012) to 31 (2013–2019). During 2013–2019, when survey effort increased, a mean of 4.4 (1–9 pairs/year) CC and 18.0 (7–40/year) unaccompanied animals (UA) visited Encounter Bay each season. Mean residency was greater for CC (51.3, 13–126 days) than UA (13.4, 2–40 days). Calving females that arrived pregnant had more than twice the residency time than those first sighted with a calf. A quarter of calving females returned in two or three subsequent seasons. Encounter Bay is an important calving area and requires re-classification by the Commonwealth from “emerging aggregation area” to “small, established aggregation area”. Ongoing research is needed to document southern right whale population dynamics at Encounter Bay in the context of the broader Australian population.

New sightings of the Southern right whales in West Antarctic Peninsula waters

Southern right whales (SRW) in the southwest Atlantic are recognized as slowly recovering after the massive population decline induced by harvesting. SRWs spend summer months in high-latitude feeding grounds and migrate to mid-latitude wintering grounds in autumn, where breeding occurs. Only a few sightings are known for the Antarctic waters as far south as 64° S. The West Antarctic Peninsula is a biologically productive area experiencing marine ecosystem transformations caused by climate changing at one of the fastest rates on Earth. The continental shelf of this region is important for krill stocks — a key prey source for SRW. The purpose of the present study was to reveal the austral summer and autumn presence of the SRWs in the waters of the West Antarctic Peninsula. In May—June 2009, vessel observations were made during a National Science Foundation research cruise. In March 2014, opportunistic surveys were conducted by researchers using the tour vessel as a platform of opportunity. During late March and April of 2018, January — July 2019 and March — April 2020, regular boat-based observations and vessel surveys were conducted in frames of the XXIII and XXIV Ukrainian Antarctic Expeditions, based at the Ukrainian Antarctic Akademik Vernadsky station. In our study we discuss four sightings of SRWs occurred at south of 64° S (2), and 65° S (2). On May 7, 2009, a single adult foraging SRW was sighted in Wilhelmina Bay. On March 22, 2014, an adult SRW was resting with two adult humpback whales in the northern part of the Lemaire Channel. On April 7, 2018, one SRW was sighted in a group with four humpback whales, and intensive interspecies social interactions happened. The last encounter of the SRW happened on April 24, 2020, in Gerlache Strait, near the southeastern coast of the Brabant Island — a single adult right whale was noticed while travelling. Results of our study indicate the autumn presence of some SRWs in the West Antarctic Peninsula waters — on the edge of the southern limit of known distribution for the species.

Estimating the cost of growth in southern right whales from drone photogrammetry data and long-term sighting histories

Animal body size and growth patterns play important roles in shaping the life history of species. Baleen whales include the largest animals on the planet, with somatic growth costs expected to be substantial. We used unmanned aerial vehicle photogrammetry and long-term individual sighting histories from photo identification (1991-2019) to estimate the cost of somatic growth for southern right whales (SRWs) Eubalaena australis. A Richards length-at-age growth model was developed, based on 161 calves, 20 yearlings, 1 juvenile and 23 adults, ranging in age from newborn to 27 yr. Predicted lengths were 4.7 m at birth, 12.5 m at minimum age of first parturition (6 yr) and an asymptotic length of 14.3 m. A volume-at-age curve was estimated from the body volume versus length relationship, and converted to a mass-at-age curve, using data on body tissue composition of North Pacific right whales E. japonica (n = 13). The energetic cost of growth was estimated using published estimates of tissue lipid and protein concentrations. The cost of growth for SRWs (in MJ d-1) was 2112 at birth, 544 at 4 mo, 314 at 1 yr (~weaning age), 108 at 5 yr (minimum age of sexual maturity), 51.5 at 10 yr and 5.2 at 30 yr. The cumulative cost to age 30 was 764.3 GJ, but varied widely (458-995 GJ) depending on the tissue energy content. Our estimates represent a healthy SRW population, and provide a baseline to investigate individual and population level impacts of anthropogenic disturbance (including climate change).

Coastal dolphins and marine megafauna in Exmouth Gulf, Western Australia: informing conservation management actions in an area under increasing human pressure

Context Exmouth Gulf is adjacent to the Ningaloo Marine Park, a UNESCO-listed area in Western Australia. The gulf remains largely unprotected, and is under increasing anthropogenic pressure from proposed industrial activities that pose threats to marine megafauna inhabiting the gulf. Threatened and near threatened species, such as the Australian humpback dolphin (Sousa sahulensis) and Indo-Pacific bottlenose dolphin (Tursiops aduncus), reside in the gulf; however, detailed information on their ecology and behaviour is lacking. Aims The aim was to (1) provide baseline data on the distribution, encounter rate, group size and behaviour of coastal dolphins over an area where current industrial developments are proposed, and (2) report on the occurrence of other marine megafauna within this area. Methods Boat-based photo-identification surveys were conducted on the western coastline of Exmouth Gulf along pre-determined line transects (150 km2) over austral autumn/winter 2021. Key results Across 809.35 km of surveyed waters (181 h), a total of 93 bottlenose dolphin, 15 humpback dolphin, and six interspecific dolphin groups were sighted. Bottlenose dolphin groups were encountered at a rate of 0.077/km, humpback dolphin groups at 0.015/km and interspecific dolphin groups at 0.005/km. Dolphins were predominantly recorded in shallow (mean 10 m) and warm (mean 21°C) waters, and were commonly travelling and foraging. In total, 199 individual bottlenose dolphins and 48 humpback dolphins were photo-identified (excluding calves). There were 30 bottlenose dolphin calves (including three newborns) and four humpback dolphin calves (including two newborns) identified. Other marine megafauna group sightings included humpback whales (Megaptera novaeangliae; n = 32), southern right whales (Eubalaena australis, n = 1), dugongs (Dugong dugon, n = 25), turtles (n = 54), sea snakes (n = 27), manta rays (Mobula alfredi, n = 13) and sharks (n = 2). Conclusions The presence of threatened marine species feeding, socialising, and resting highlights the importance of these waters for the identified species. Implications The information provided is applicable for the spatial management and conservation efforts of these species, and aids in informing environmental impact assessments of individual and cumulative pressures.

Potential endocrine correlation with exposure to domoic acid in Southern Right Whale (Eubalaena australis) at the Península Valdés breeding ground.

In waters off Península Valdés (PV), Argentina, southern right whales (SRW, Eubalaena australis) are occasionally exposed to domoic acid (DA), a neurotoxin produced by diatoms of the genus Pseudo-nitzschia. Domoic acid toxicity in marine mammals can cause gastrointestinal and neurological clinical signs, alterations in hematologic and endocrine variables, and can be fatal in extreme cases. In this study, we validated an enzyme immunoassay to quantify fecal glucocorticoid metabolites (fGCm) in 16 SRW fecal samples from live and dead stranded whales in PV from 2013 to 2018 and assessed fGCm levels associated with DA exposure. Overall, fGCm levels were significantly lower in SRWs with detectable fecal DA (n = 3) as compared to SRWs with undetectable fecal DA levels (n = 13). The highest fecal DA was observed in a live lactating female, which had low fGCm compared to the other lactating females studied. The highest fGCm was observed in a lactating female with undetectable DA; interestingly, at the time of sample collection, this female was sighted with two calves, an extremely unusual occurrence in this species. Though the sample size of these exceptionally rare breeding-season fecal samples was unavoidably small, our study provides evidence of potential adrenal alterations in whales exposed to an environmental neurotoxin such as DA.

Antofagasta Region in northern Chile, a potential nursing ground for the Southern right whale Eubalaena australis

The Chile-Peru subpopulation (CPe) of the Southern right whale (Eubalaena australis) is classified as Critically Endangered following intense whaling in past centuries. Due to their very low abundance, information on breeding and feeding grounds is also scarce. Unmanned aerial vehicles (UAVs) are increasingly applied in marine mammal research thanks to their low cost and relative ease of use. This case study documents a Southern right whale nursing in Bahía Moreno (23º S), Antofagasta, in northern Chile through high-resolution images taken by UAV of an adult in July 2019 and the same whale with a neonate in August. Combined with earlier data we hypothesize that the Antofagasta Region may be a potential calving and nursing ground for the CPe subpopulation. Given the intense shipping traffic and fishing activities around the Mejillones Peninsula and Antofagasta port, priorly recommended marine spatial planning to help avoid net entanglements and vessel collisions of fin and humpback whales may also contribute to the conservation of the CPe stock.

Use of satellite imagery to identify southern right whales (Eubalaena australis) on a Southwest Atlantic Ocean breeding ground

AbstractSatellite imagery has been used to improve scientific research worldwide. In this study, the southern right whale (Eubalaena australis) was chosen to test the use of medium, high, and very high resolution (VHR) satellite images, on the Brazilian breeding ground. These images were used to identify the whales and were compared to aerial survey data collected in the same area. The VHR satellite images from the Pleiades‐1A satellite, available on Google Earth, displayed the best results when compared to those from Sentinel 2, Landsat 8, Rapid Eye, and Planet Scope. No significant differences were observed (Mann‐Whitney U test) between the possible whales recorded in the satellite images and of real whales recorded in situ by aerial surveys, while considering either the number of groups (p = .841, n = 5) or the total number of animals (p = .222, n = 5). Further, when using VHR images, the geographical positions of the whales recorded in situ had a positive correlation with the positions generated from the satellite images (Mantel test: r = 0.52, p = .001, n = 13). This technique may represent an important tool for detecting right whales, especially in countries where research funding is scarce.

Calving rates, long-range movements and site fidelity of southern right whales (Eubalaena australis) in south-eastern Australia

Within New Zealand and eastern Australia, over 58,000 southern right whales were harvested by commercial whalers between 1790 and 1980, with approximately 19,000 harvested from south-eastern Australia. Local extirpation is believed to have led to a loss of cultural memory of calving areas, contributing to the limited recovery of the south-eastern Australian population. While the number of whales observed using the south-eastern Australian coastline is increasing, there has been no change over three decades in the annual abundance of cow-calf pairs at Logans Beach in Warrnambool, Victoria, the only established calving ground in the region. Knowledge of life history parameters of the south-eastern Australian population is lacking. Here, we examine sightings and photo-identification data from southern Australia to investigate calving intervals, long range movements and fidelity to the Logans Beach nursery ground. Sightings data revealed at least 93 calves were born at Logans Beach between 1980 and 2018 (an average of 2.6 per year) with a mean calving interval of 3.5 ± 1.0 years (± SE, n = 34). Comparison between photo-identification catalogues compiled for south-eastern and south-western Australian populations shows that southern right whales are wide ranging within southern Australian waters. Females can be sighted at locations as far apart as 3,800 km across seasons and there is overlap in the wintering range of the south-eastern and south-western populations, with at least 7% of whales using both regions. We also provide the first report of an Australian southern right whale female with strong site fidelity to a calving area in one region relocating long-term to a calving area in another region. This work highlights several knowledge gaps, such as; the location of feeding and conception grounds for this population as well as the degree of mixing between the two Australian populations outside their wintering areas. In addition, the proportion of female calves born at Logans Beach returning to their natal site to calve remains unclear. Our work provides the first assessment of calving rates, movement and site fidelity within the south-eastern Australian population, critical for understanding constraints to recovery and informing conservation management of southern right whales in Australia. Targeted, long-term monitoring programs across the south-eastern Australian region are needed to provide demographic information on which to base predictions of the impacts of anthropogenic threats such as noise disturbance, entanglement and vessel strike.

Southern right whales generally appear not to react to transiting research vessels

AbstractReactions of southern right whales (SRWs) related to whale‐watching boats have been reported in Patagonia, but there are no quantitative data showing how these whales react to boats not preforming whale‐watching trips. The objective of this study was to investigate the reaction of SRWs to transiting vessels. Data were collected off the coast of Puerto Madryn city, and were analyzed by means of cumulative logit models, using the whales' intensity of behavioral response as an ordinal dependent variable. During the experimental approaches of a research vessel, we found that the response of SRWs differed depending on the number of whales present. The results of this study show that the probability of response to transiting vessels is low, unless there are only a few whales in a group, or it is a mating group. This response is different from that of an approaching whale‐watching vessel. In this study, the lack of reaction of whales to the research vessel suggests that whales would not consider it as a threat. This study represents an important piece of information for the conservation of southern right whales.

Optimizing hormone extraction protocols for whale baleen: Tackling questions of solvent:sample ratio and variation

Obtaining endocrine data from alternative sample types such as baleen and other keratinized tissues has proven a valuable tool to investigate reproductive and stress physiology via steroid hormone quantification, and metabolic stress via thyroid hormone quantification in whales and other vertebrates. These alternative sample types provide an integrated measure of plasma levels over the period that the structure was growing, thus capturing months or even years of an individual's endocrine history. Additionally, their robust and stable keratin matrix allows such samples to be stored for years to decades, enabling the analysis and comparison of endocrine patterns from past and modern populations. However, the extraction and analysis of hormones from baleen and other keratinized tissues remains novel and requires both biological and analytical validations to ensure the method fulfills the requirements for its intended use. We utilized baleen recovered at necropsy from southern right whales (Eubalaena australis) that died at Península Valdés, Argentina, using a commercially available progesterone enzyme immunoassay (EIA) to address two methodological questions: 1) what is the minimum sample mass required to reliably quantify hormone content of baleen samples analyzed with commercially available EIAs, and 2) what is the optimal ratio of solvent volume to sample mass, i.e., the ratio that yields the maximum amount of hormone with high accuracy and low variability between replicates. We concluded that masses of at least 20 mg should be used whenever possible, and extraction is best performed using an 80:1 ratio of solvent to sample (volume of solvent to sample mass; μl:mg). These results can help researchers to make informed methodological decisions when using a destructive extraction method with rare or unique specimens.

Patterns of blubber fat deposition and evaluation of body condition in growing southern right whale calves (Eubalaena australis)

AbstractMarine mammals rely on blubber mainly for energy storage, buoyancy, and streamlining. Mysticetes are born with a relatively thin fat layer that grows rapidly during nursing. However, little information on blubber deposition patterns is available for baleen whale calves. We measured blubber thickness at nine body locations in 350 southern right whale (Eubalaena australis) newborn to 4–6‐month‐old calves that died on the Península Valdés (Argentina) calving ground from 2003 to 2019, to document changes in blubber thickness with growth. Additionally, we looked for differences in blubber thickness and lipid content of the outer/superficial blubber in calves that died in years with high (2003, 2005, 2007–2013) and low calf mortality (2004, 2006, 2014–2019) to test whether the former were suffering from gross nutritional stress. Blubber thickness increased at all body locations with calf length. Along the cranio‐caudal axis, blubber increased in the dorsal and ventral planes, but decreased laterally towards the peduncle, possibly to improve streamlining. We found no difference in blubber thickness and lipid content between high and low mortality years, suggesting that individuals were not undernourished. This is the first study to describe progressive increases in calf blubber during growth and contributes knowledge to right whale health and ontogeny.

Investigation of keratinase digestion to improve steroid hormone extraction from diverse keratinous tissues

Monitoring the physiology of wild populations presents many technical challenges. Blood samples, long the gold standard of wildlife endocrinology studies, cannot always be obtained. The validation and use of non-plasma samples to obtain hormone data have greatly improved access to more integrated information about an organism’s physiological state. Keratinous tissues like skin, hair, nails, feathers, or baleen store steroid hormones in physiologically relevant concentrations, are stable across decades, and can be used to retrospectively infer physiological state at prior points in time. Most protocols for steroid extraction employ physical pulverization or cutting of the sample, followed by mixing with a solvent. Such methods do produce repeatable and useful data, but low hormone yield and detectability issues can complicate research on small or rare samples. We investigated the use of keratinase, an enzyme that breaks down keratin, to improve the extraction and yield of corticosterone from vertebrate keratin tissues. Corticosterone content of keratinase-digested extracts were compared to non-keratinase extracts for baleen from three species of whale (blue, Balaenoptera musculus; bowhead, Balaena mysticetus; southern right, SRW; Eubalaena australis), shed skin from two reptiles (tegu lizard, Salvator merianae; narrow-headed garter snake, Thamnophis rufipunctatus), hair from arctic ground squirrel (AGS; Urocitellus parryii), feathers from Purple Martins (PUMA; Progne subis), and spines from the short-beaked echidna (Tachyglossus aculeatus). We tested four starting masses (10, 25, 50, 100 mg) for each sample; digestion was most complete in the 10 and 25 mg samples. A corticosterone enzyme immunoassay (EIA) was validated for all keratinase-digested extracts. In all sample types except shed skin from reptiles, keratinase digestion improved hormone yield, with PUMA feathers and blue whale baleen having the greatest increase in apparent corticosterone content (100% and 66% more hormone, respectively). The reptilian shed skin samples did not benefit from keratinase digestion, actually yielding less hormone than controls. With further optimization and refinement, keratinase digestion could greatly improve yield of steroid hormones from various wildlife epidermal tissue types, allowing more efficient use of samples and ultimately improving understanding of the endocrine physiology of wild populations.

Acute and chronic behavioral effects of kelp gull micropredation on southern right whale mother-calf pairs off Península Valdés, Argentina

Kelp gullsLarus dominicanus(KG) feed on the skin and blubber of living southern right whalesEubalaena australis(SRWs) off Península Valdés (PV), Argentina. The whales respond strongly to KG micropredation by changing their immediate (acute) behavior during attacks and their overall (chronic) surfacing pattern and body posture to minimize gull exposure. The energetic and large-scale behavioral consequences of these attacks are unknown. To address this knowledge gap, we quantified the effect size of both acute (during attacks) and chronic (not during attacks) responses by comparing the respiration rates, swim speed, and nursing behavior of PV SRWs to undisturbed (control) SRW mother-calf pairs in Head of Bight, Australia, using unmanned aerial vehicle focal follows. Even when gulls were not attacking, PV SRW mothers and calves demonstrated ~50 and ~25% higher respiration rates, respectively, than whales in Australia. During attacks, PV calf respiration rates increased by an additional 10%. PV SRW mothers also frequently (>76% of respirations) exhibited irregular breathing postures, causing the whales to potentially expend extra energy by working against their natural buoyancy. Despite no significant increase in average maternal swim speed, 76 and 90% of gull attacks elicited strong behavioral reactions from mothers and calves, respectively. Overall, PV calves spent less time nursing during individual bouts compared to those in Australia but entered suckling position more frequently. Furthermore, kelp gulls seemed to show a preference for attacking previously wounded calves and at a higher rate. These chronic and acute behavioral effects may carry energetic costs, which could have long-term consequences for SRW survival and reproduction.

Trophic ecology and foraging areas of cetaceans sampled in the coastal waters of south-eastern Brazil assessed through skin δ13C and δ15N

AbstractWe investigated the habitat use and feeding ecology of 10 cetacean species encountered along the south-eastern coast of Brazil (24–26°S) using carbon (δ13C) and nitrogen (δ15N) stable isotopes. Hierarchical cluster analysis distinguished two main groups based on their isotopic patterns. One group included migratory baleen whales (Megaptera novaeangliae and Eubalaena australis) with the lowest δ13C and δ15N values, reflecting baseline isotopic values of their Subantarctic feeding grounds and consumption of lower trophic level prey. Resident species and those occasionally occurring in Brazilian coastal waters highly differed from the migratory whales in their isotopic values. In this group, Tursiops truncatus had the highest δ13C and δ15N values, indicating coastal habits and relatively higher trophic position. Similar δ13C values were observed in Sotalia guianensis, Pontoporia blainvillei, Orcinus orca and Steno bredanensis. However, the former two species had lower δ15N values than the latter two, indicating different trophic positions. The relatively lower δ13C values observed in Stenella frontalis suggest greater influence of pelagic prey in their diet. Furthermore, the lower δ13C values observed in Delphinus delphis and Balaenoptera edeni were associated with upwelling events that occur along the region, affecting the isotopic values of their main prey. Juvenile M. novaeangliae had higher δ13C and δ15N than the adults, which may indicate feeding in areas with different isoscapes and consumption of pelagic schooling fish with relatively higher trophic levels than krill. This study provides preliminary information that are useful to understand the habitat use and coexistence of cetacean species occurring in south-eastern Brazil.

Integrating morphology and DNA barcoding to assess cetacean diversity in Brazil

Stranded cetaceans (whales, dolphins, and porpoises) are frequently used to obtain data on species occurrence and demographic trends. Accurate species-level identification of these individuals is crucial, but often challenging or impossible when relying solely on morphological features (e.g., for highly decayed specimens). To aid in the development of a reliable molecular assay for cetacean DNA-based identification, we tested the efficacy of the standardized DNA barcode segment of the coxI gene in identifying cetaceans occurring off the Brazilian coast and in its continental waters. We generated coxI sequences from 150 specimens (collected by 16 Brazilian institutions), most of which included voucher material (skulls, skeletons and/or images) deposited in scientific collections. This allowed a direct comparison between their morphological and molecular identification. CoxI sequences correctly identified ~93% of the samples, comprising 33 species (70% of the 47 cetaceans reported for Brazilian waters). Two species (Berardius arnuxii and Phocoena dioptrica) were sequenced for coxI for the first time. For only two dolphins (Stenella coeruleoalba and S. clymene) and a right whale (Eubalaena australis), coxI failed to identify the species due to overlapping distributions of intra- vs. interspecific divergences. Only one right whale species occurs in the southern hemisphere, facilitating identification in this case. Stenella dolphins present extensive sympatry and potential inter-species hybridization, suggesting that nuclear markers may be required for their reliable identification. These results indicate that DNA barcoding can reliably identify most stranded cetaceans and highlight the importance of voucher materials to validate the construction of a reliable DNA-based identification system.