Showing papers in "Endangered Species Research in 2016"
University of Exeter1, University of Florida2, IFREMER3, University of Barcelona4, University of Pisa5, University of Central Florida6, National Oceanic and Atmospheric Administration7, Wildlife Conservation Society8, Florida State University9, United States Geological Survey10, City University of Hong Kong11
TL;DR: A systematic review of the peer-reviewed literature (2014 and 2015) attributing papers to the original 20 meta-questions was conducted by as discussed by the authors, who found that significant research is being expended towards global priorities for management and conservation of sea turtles, including reproductive biology, biogeography, population ecology, threats and conservation strategies.
Abstract: In 2010, an international group of 35 sea turtle researchers refined an initial list of more than 200 research questions into 20 metaquestions that were considered key for management and conservation of sea turtles. These were classified under 5 categories: reproductive biology, biogeography, population ecology, threats and conservation strategies. To obtain a picture of how research is being focused towards these key questions, we undertook a systematic review of the peer-reviewed literature (2014 and 2015) attributing papers to the original 20 questions. In total, we reviewed 605 articles in full and from these 355 (59%) were judged to substantively address the 20 key questions, with others focusing on basic science and monitoring. Progress to answering the 20 questions was not uniform, and there were biases regarding focal turtle species, geographic scope and publication outlet. Whilst it offers some meaningful indications as to effort, quantifying peer-reviewed literature output is obviously not the only, and possibly not the best, metric for understanding progress towards informing key conservation and management goals. Along with the literature review, an international group based on the original project consortium was assigned to critically summarise recent progress towards answering each of the 20 questions. We found that significant research is being expended towards global priorities for management and conservation of sea turtles. Although highly variable, there has been significant progress in all the key questions identified in 2010. Undertaking this critical review has highlighted that it may be timely to undertake one or more new prioritizing exercises. For this to have maximal benefit we make a range of recommendations for its execution. These include a far greater engagement with social sciences, widening the pool of contributors and focussing the questions, perhaps disaggregating ecology and conservation.
208 citations
TL;DR: It is demonstrated that an eDNA approach to detecting largetooth sawfish can produce reliable outcomes and can be used as a survey tool to help with conservation efforts for this and other threatened elasmobranchs.
Abstract: Environmental DNA (eDNA) is a relatively new tool for the detection of rare, threatened and invasive species in water bodies. In this study we investigated the utility of an eDNA approach in detecting the Critically Endangered largetooth sawfish Pristis pristis in freshwater habitats in northern Australia. Water samples were collected from large aquaria mesocosms containing largetooth sawfish and other aquatic species, and floodplain waterholes and the main river channel of the Daly River, Northern Territory. Water samples were filtered using a 20 mu m nylon filter. DNA was extracted from filters and analysed with PCR using species-specific mitochondrial cytochrome c oxidase subunit I (COI) primers designed to amplify only largetooth sawfish DNA. PCR products were cleaned and the COI gene sequenced to confirm the species identity. Using 3 aquaria, with one containing a largetooth sawfish, this method positively identified sawfish only in the correct aquarium. In the field water samples, 7 of 8 floodplain waterholes produced a sawfish eDNA PCR product, while eDNA was not detected in the main river channel. Based on gillnet sampling and traditional ecological knowledge, largetooth sawfish were known to occur at half of the waterhole and floodplain sites that tested positive for sawfish eDNA. These results demonstrated that an eDNA approach to detecting largetooth sawfish can produce reliable outcomes and can be used as a survey tool to help with conservation efforts for this and other threatened elasmobranchs.
74 citations
TL;DR: Funding was provided by a variety of military and governmental funding sources from several nations acknowledged within referenced publications, notably the US Office of Naval Research, US Navy Living Marine Resources Program, and the navies of the USA, Norway, andThe Netherlands.
Abstract: Funding was provided by a variety of military and governmental funding sources from several nations acknowledged within referenced publications, notably the US Office of Naval Research, US Navy Living Marine Resources Program, and the navies of the USA, Norway, and the Netherlands. P.L.T. acknowledges the support of the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland) in the completion of this study. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.
72 citations
TL;DR: The first comprehensive survey of gibbons across Indonesian Borneo was carried out to determine whether densities of gibbon species are cor- related with vegetation characteristics, and if so, whether the same characteristics are correlated with density across all forest types, and to identify threats to the areas.
Abstract: The first comprehensive survey of gibbons (Hylobates spp.) across Indonesian Borneo was carried out over 3 years to (1) determine whether densities of gibbon species are cor- related with vegetation characteristics, and if so, whether the same characteristics are correlated with density across all forest types; and (2) determine population densities in the survey areas and identify threats to the areas. To achieve this, a total of 8 forest blocks were surveyed, involving 53 independent survey locations and repeat surveys in 3 forest blocks. Our data show that gibbons are ubiquitous where there is forest; however, the quality of forest affects population density, for- est block size affects longevity of populations, and populations are susceptible to the 'compression effect', i.e. populations occupy smaller fragments at unsustainably high densities. We show the effects of forest disturbance (logging, fire, fragmentation) on gibbon distribution and density and highlight issues for long-term conservation. We discuss the use of minimum cross-sectional area, habitat variables and presence of top foods to determine population density and to identify a threshold below which gibbons cannot persist. We discuss the conservation issues facing all Bornean gibbons, including natural hybrids (H. muelleri × H. albibarbis). The answers to these research questions will help mitigate threats to gibbons and their habitat, as well as identify key habitat for gibbon populations within and outside the protected area network.
65 citations
TL;DR: The results support increasing evidence of a complex and non-obligatory migratory behavior of Antarctic blue whales, potentially involving temporally and spatially dynamic migration routes and destinations, as well as variable timing of migration to and from the feeding grounds.
Abstract: Distribution and movement patterns of Antarctic blue whales Balaenoptera musculus intermedia at large temporal and spatial scales are still poorly understood. The objective of this study was to explore spatio-temporal distribution patterns of Antarctic blue whales in the Atlantic sector of the Southern Ocean, using passive acoustic monitoring data. Multi-year data were collected between 2008 and 2013 by 11 recorders deployed in the Weddell Sea and along the Greenwich meridian. Antarctic blue whale Z-calls were detected via spectrogram cross-correlation. A Blue Whale Index was developed to quantify the proportion of time during which acoustic energy from Antarctic blue whales dominated over background noise. Our results show that Antarctic blue whales were acoustically present year-round, with most call detections between January and April. During austral summer, the number of detected calls peaked synchronously throughout the study area in most years, and hence, no directed meridional movement pattern was detectable. During austral winter, vocalizations were recorded at latitudes as high as 69°S, with sea ice cover exceeding 90%, suggesting that some Antarctic blue whales overwinter in Antarctic waters. Polynyas likely serve as an important habitat for baleen whales during austral winter, providing food and reliable access to open water for breathing. Overall, our results support increasing evidence of a complex and non-obligatory migratory behavior of Antarctic blue whales, potentially involving temporally and spatially dynamic migration routes and destinations, as well as variable timing of migration to and from the feeding grounds.
53 citations
TL;DR: Although the model assumes a stable population and provides only a rough estimate of abundance, these results suggest that the current bycatch level should be regarded as unsustainable for Mediterranean turtle populations.
Abstract: Mediterranean populations of loggerhead Caretta caretta and green sea turtles Che- lonia mydas are subject to several anthropogenic threats, with documented mortality from inci- dental capture in fishing gear. However, how such mortalities actually affect the populations is uncertain without an estimate of population size. We derived a theoretical demographic structure for each species in the Mediterranean, assuming a stationary age distribution in a stable popula- tion with constant proportions of turtles in each life stage, using distributions of age-specific vital rates. We incorporated uncertainty into the main vital rate parameters to identify a likely order of magnitude of turtle abundance in different life stages. Through this approach, we aim to (1) pro- vide a rough estimate of all population stage classes, particularly the juvenile classes that are most subject to fisheries interactions, (2) provide an estimate of reproductive life span, (3) identify and review the key demographic parameters, and (4) identify the priority gaps in our information in need of further investigation. The range of population abundance estimates from the models con- structed with uncertainty (95% CI) was 0.81−3.38 million loggerheads and 0.26−2.21 million green turtles, Mediterranean-wide. When we calculated the potential biological removal for the segment of the population at risk of fisheries capture, our estimates were comparable to or lower than the estimated bycatch levels in fisheries. Although the model assumes a stable population and provides only a rough estimate of abundance, these results suggest that the current bycatch level should be regarded as unsustainable for Mediterranean turtle populations.
46 citations
TL;DR: The European hamster is probably the fastest-declining Eurasian mammal, its IUCN Red List status is still Least Concern as discussed by the authors, this categorization is based on the assumptions that the decline affects only Western Europe, where modern agriculture has led to an increase in the mortality of the species.
Abstract: Although the European hamster is probably the fastest-declining Eurasian mammal, its IUCN Red List status is still Least Concern. In addition to the huge distribution area, this categorization is based on the assumptions (1) that the decline affects only Western Europe, where (2) modern agriculture has led to (3) an increase in the mortality of the species. Since mortalityreducing protection measures in Western Europe have been unable to stop the decline, we reviewed the literature from 1765 to the present and reappraised the situation. We found support for none of these assumptions. The species has also vanished from more than 75% of its range in Central and Eastern Europe. In 48 of 85 Russian, Belarussian, Ukrainian and Moldovan provinces, its relative occurrence has decreased. It is now rare in 42 provinces and extinct in 8. Mortality has not increased, but the reproduction rate has shrunk since 1954 throughout the distribution area. Today the reproduction rate is only 23% of that between 1914 and 1935. Taking into account the mortality of this prey species, 1 female today raises only 0.5 females for next year’s reproduction. The extra polation of the literature data points to an extinction of the species between 2020 and 2038. We strongly recommend (1) changing the status of the European hamster on the IUCN Red List from Least Concern at least to Vulnerable or even Endangered and (2) supporting scientific research on the reproduction of European hamsters as a protection measure. Global threats such as climate change, light pollution or (in the past) fur trapping are more likely to be the ultimate reason for the decline of this species than modern agriculture.
44 citations
TL;DR: The National Oceanic and Atmospheric Administration (NOAA) is developing an agency-wide strategy that emphasizes the ocean spaces that these animals need, and the impor- tance of acoustic conditions in those places.
Abstract: Many marine animals have evolved over millions of years to rely on sound as a fun- damental component of their habitat. Over the last century, increasing noise from human activities has significantly affected the quality of underwater acoustic habitats. These changes can lead to reduced ability to detect and interpret environmental cues used to perform critical life functions (e.g. select mates, find food, maintain group structure and relationships, avoid predators, navi- gate). The National Oceanic and Atmospheric Administration (NOAA), as the US federal agency with primary responsibility for protecting marine animals and their habitats, is developing an agency-wide strategy that emphasizes the ocean spaces that these animals need, and the impor- tance of acoustic conditions in those places. This strategy seeks to reach beyond initial goals of reducing acute impacts due to noise (protecting hearing and reducing physical harm) to better account for the importance of underwater sound in marine ecosystems. This paper outlines sci- ence needs associated with acoustic habitat characterization and the assessment of noise impacts on habitats, which provide information critical to NOAA's prioritization of future place-based research and management. NOAA's spatial management tools are examined relative to acoustic habitat protection goals, which seek to match the ecological scales over which noise is impacting marine wildlife, including endangered species. Recommended actions are identified to address these broad spatial and long temporal scales, including international work on quieting technolo- gies, registries of accumulated noisy events, and an enhanced role for NOAA's National Marine Sanctuaries in science, management, and outreach associated with acoustic habitat protection.
35 citations
TL;DR: In this article, the authors investigate how the conservation science literature has been used to inform and guide management strategies in the marine system from coastal to pelagic environments and identify important gaps that must be considered in current conservation schemes.
Abstract: The protection of biodiversity is one of the most important goals in terrestrial and marine conservation. Marine conservation approaches have traditionally followed the example of terrestrial initiatives. However, patterns, processes, habitats, and threats differ greatly between the 2 systems — and even within the marine environment. As a result, there is still a lack of con- gruence as to how to best identify and prioritize conservation approaches moving from the static terrestrial and nearshore realm into a more fluid, 3-dimensional pelagic realm. To address this problem, we investigate how the conservation science literature has been used to inform and guide management strategies in the marine system from coastal to pelagic environments. As cumulative impacts on the health of the oceans continue to increase, conservation priorities have shifted to include highly dynamic areas of the pelagic marine system. By evaluating whether pri- orities match science with current place-based management approaches (i.e. marine protected areas, MPAs), we identify important gaps that must be considered in current conservation schemes. Effective pelagic MPA design requires monitoring and evaluation across multiple phys- ical, biological, and human dimensions. Because many threatened and exploited marine species move through an ephemeral and ever-changing environment, our results highlight the need to move beyond traditional, 2-dimensional approaches to marine conservation, and into dynamic management approaches that incorporate metrics of biodiversity as well as oceanographic fea- tures known to promote multilevel, trophic productivity.
34 citations
TL;DR: It is proposed that photo-ID sampling based on camera traps, and larger-scale photographic survey of the seals, should be implemented as a pop- ulation monitoring tool of the Saimaa ringed seal and support suggestions of natal site fidelity.
Abstract: Photo-identification (photo-ID) with camera traps was examined as a non-invasive method for studying and monitoring the endangered Saimaa ringed seal Phoca hispida saimensis. An average of 51 game cameras were set up at shoreline haul-out sites in central Lake Saimaa during the moulting seasons in each of the years from 2010 to 2014. Individuals were identified from their lifelong unique lateral fur patterns. A total of 220 000 digital images of seals were obtained from these game cameras and from digital cameras during this period, allowing 164 indi- viduals to be identified, 43% of which were re-sighted in successive years. In the majority of game camera images, both sides of the seal were shown, and it was possible to determine the sex of the seal. The average distance between sightings of individual seals in different years was 1.6 km, suggesting that Saimaa ringed seals exhibit a high degree of moulting site fidelity. In addition, the results support suggestions of natal site fidelity. We propose that photo-ID sampling based on camera traps, and larger-scale photographic survey of the seals, should be implemented as a pop- ulation monitoring tool of the Saimaa ringed seal. Further application of the photo-ID technique may facilitate mark-recapture population and survival rate estimates for this threatened seal spe- cies and provide significant insights into its life history and social behaviour.
32 citations
TL;DR: Low abundances of river dolphins compared to other Amazon rivers are identified and boto may not be sustainable at a population level, due primarily to population fragmentation which would result from the construc- tion of the proposed dams.
Abstract: River dolphins are strongly affected by the construction of hydroelectric dams. Poten- tial isolation in subpopulations above and below such dams and the resulting low genetic variability of these subpopulations can cause extinction at a local level. Here we aimed to estimate density and population size of South American river dolphins (boto Inia geoffrensis and tucuxi Sotalia fluviatilis), map their distribution, and estimate potential biological removal (PBR) limits in order to evaluate the effects of population fragmentation between planned dams in the Tapajos River, Amazonian basin, Brazil. Boat-based surveys were conducted following a line transect sampling protocol covering dif- ferent dolphin habitats in 2 stretches of the river divided by rapids. The mark−recapture distance sampling method was applied to account for animals missed on the trackline. After the estimation of population sizes by habitat, PBR was calculated. The farthest upriver sighting of tucuxis was close to the Sao Luiz do Tapajos rapids, whereas the farthest upriver sighting of botos was upstream of the rapids, suggesting that botos move upstream through the rapids. Estimated abundance of tucuxis (3372 ind., CV = 0.38) was twice as high as that estimated for botos (1815 ind., CV = 0.4). The PBR ranged from 11 to 18 ind. for boto and 21 to 34 for tucuxi. Throughout this study, we identified low abundances of river dolphins compared to other Amazon rivers. Boto may not be sustainable at a population level, due primarily to population fragmentation which would result from the construc- tion of the proposed dams. Precautionary measures are urgently needed before construction of dams begins in the Tapajos River.
TL;DR: Current noise conditions across the Gulf of Mexico are described with an intent to inform noise management strategies and investigate the potential ecological implications of elevated ambient noise.
Abstract: The Gulf of Mexico ecosystem represents the intersection between high marine biodiversity and extensive human use and impact. Anthropogenic marine activities are prominent in the Gulf, prompting concern regarding impacts of chronic elevated noise throughout the marine ecosystem. Since sound is a critical component of the marine environment and many marine animals in the Gulf utilize sound in different aspects of their life history, their basic ecology may be negatively affected by elevated anthropogenic noise. While there are data gaps regarding the impacts of noise on marine organisms, it is crucial to understand current ambient noise conditions to evaluate the implications of noise for the Gulf ecosystem. Ambient noise measurements provide a mechanism by which to sample the cumulative acoustic activity of an ecosystem, and holistically evaluate biotic, environmental, and human-induced acoustic contributions to the overall environment. In this study, acoustic data were collected at 7 sites in the northeastern Gulf of Mexico between July 2010 and February 2012. Ambient noise is presented in 3 frequency bands (low frequency [10–500 Hz], mid-frequency [500–1000 Hz], and high frequency [1000–3150 Hz]), with median sound levels of 112, 90, and 93 dB (re 1 μPa), respectively. Abiotic and anthropogenic noise sources significantly contributed to the ambient noise environment; however, seismic survey noise dominated the noise environment and chronically elevated noise levels across several paramount marine habitats. This study describes current noise conditions across the Gulf of Mexico with an intent to inform noise management strategies and investigate the potential ecological implications of elevated ambient noise.
TL;DR: This study demonstrates that some easily monitored demographic variables may serve as indicators of population change and contributes to a growing set of studies evaluating sea turtle demography for temporal variability and is the first for Hawaiian green turtles.
Abstract: Multiple populations of green sea turtles Chelonia mydas show signs of population recovery. In Hawaii (USA), green turtles have increased 5.4% yr−1 since 1973, but fluctuations in census counts of nesting females make recovery diagnosis difficult. Evaluating demographic rates for temporal change and in relation to population density, and indicators of recruitment to sea turtle nesting populations, will ultimately improve population assessments. Using linear mixed and multistate open robust design models, we estimated the demographic indicators (DIs) of size at maturity, nester carapace length, breeding probability, and adult female survival using 3677 tagged nesting green turtles from 1973 to 2010 in Hawaii. To evaluate changes with density, we correlated the DIs with nesting female counts. We estimated size at maturity, assuming that newly tagged nesters are new recruits and that first-time nesters have statistically significant smaller carapace length than recaptures, but the difference in size was only ~0.5 cm. Mean nester carapace length (range: 89.21−91.69 cm) and breeding probability (range: 0.0766−0.444 yr−1) showed directional changes over time, suggesting shifts in age structure that could be due to recruitment. The top-ranked model predicted constant female survival over time (S = 0.929 yr−1, 95% CI: 0.924−0.933, model likelihood = 1.00). Counter to our hypothesis based on density-dependence, breeding probability increases with increasing nester abundance. This work contributes to a growing set of studies evaluating sea turtle demography for temporal variability and is the first for Hawaiian green turtles. Our study demonstrates that some easily monitored demographic variables may serve as indicators of population change.
TL;DR: In this paper, the authors provide a discussion on how different acoustic metrics are derived and recommendations on how to report sound level measurements, as well as additional measures of noise besides level (e.g., spectral composition, duration) to provide further insight on the consequences of noise and will potentially help develop effective mitigation.
Abstract: Diverse biological consequences of noise exposure are documented by an extensive literature. Unfortunately, the aggregate value of this literature is compromised by inconsistencies in noise measurements and incomplete descriptions of metrics. These studies commonly report the noise level (in decibels, dB) at which a response was measured. There are many methods to characterize noise levels in dB, which can result in different values depending on the processing steps used. It is crucial that methods used for noise level measurement be reported in sufficient detail to permit replication and maximize interpretation of results, enable comparisons across studies, and provide rigorous foundations for noise management in environmental conservation. Understanding the differences in the acoustic measurements is vital when making decisions about acceptable levels or thresholds for conservation strategies, particularly for endangered species where mistakes can have irreversible consequences. Here we provide a discussion on how different acoustic metrics are derived and recommendations on how to report sound level measurements. Examples of additional measures of noise besides level (e.g. spectral composition, duration) are discussed in the context of providing further insight on the consequences of noise and will potentially help develop effective mitigation. It will never be possible to study all combinations of sources and species. Standardized methods of noise measurement and reporting are necessary to advance syntheses and general models that predict the ecological consequences of noise.
TL;DR: These relatively unperturbed populations provide a much needed opportunity to learn about sturgeon biology, habitat needs and reproductive potential in a natural riverine environment, which may facilitate conservation and recovery efforts in affected watersheds.
Abstract: Acipenseriformes (sturgeons and paddlefishes) are considered to be one of the most globally imperiled taxon, with 25 of the 27 species listed by the International Union for the Conservation of Nature (IUCN). Overharvest, habitat degradation, fragmentation and water quality issues have contributed to their decline worldwide. These stressors have been ameliorated in some areas, but in others they remain a limiting factor to sturgeon. Barriers impeding upstream migrations to natural spawning areas and manifesting alterations to natural flows continue to compromise sturgeon recruitment and limit natural recovery. Watersheds in the Northern Hemisphere have been categorized as being strongly affected, moderately affected or unaffected based on the degree of fragmentation and water flow regulation. An overlay (i.e. intersect) of the sturgeons’ status with this watershed categorization revealed that a small area remains in which sturgeon are not considered at risk and where rivers are unaffected in northern Canada. These relatively unperturbed populations provide a much needed opportunity to learn about sturgeon biology, habitat needs and reproductive potential in a natural riverine environment, which may facilitate conservation and recovery efforts in affected watersheds.
TL;DR: There was a change in the fatty acid profile of beluga blubber from the 1980s compared to the 1990s and 2000s, suggesting an increased consumption of capelin with a reduction in Arctic cod in summer in more recent years and dive behaviour suggested different foraging tactics across seasons.
Abstract: Cumberland Sound, an inlet on Baffin Island, Nunavut, Canada, is undergoing changes in sea ice cover, which is affecting the marine food web. A small population of beluga whales Delphina pterus leucas inhabits Cumberland Sound year round and this population is currently listed as threatened. Relatively little is known about the foraging behaviour of these belugas, but we expected that food web changes, primarily an increased abundance of capelin in the region, would have an impact on their diet and dive behaviour. We evaluated fatty acids in blubber samples collected from subsistence-hunted belugas in Cumberland Sound from the 1980s to 2010, and analyzed satellite tag information from 7 belugas tagged in 2006 to 2008 to gain a better understanding of their foraging behaviour. There was a change in the fatty acid profile of beluga blubber from the 1980s compared to the 1990s and 2000s. Specific fatty acids indicative of capelin and Arctic cod increased and decreased over time respectively, suggesting an increased consumption of capelin with a reduction in Arctic cod in summer in more recent years. Dive behaviour suggested different foraging tactics across seasons. Shallow short dives occurred in summer, which may indicate foraging on capelin, while deeper longer dives were made in autumn and winter, possibly indicating foraging on deeper prey such as Arctic cod and Greenland halibut. Potentially, autumn and winter are important foraging seasons for belugas, amassing energy reserves as blubber and creating a possible competitive conflict for resource use between belugas and expanding commercial fisheries.
TL;DR: The study demonstrates the benefit of using anti-predator responses as a reference of disturbance when evaluating the relative impacts of anthropogenic stimuli, which can be of particular interest in studies of threatened species such as sperm whales.
Abstract: A key issue when investigating effects of anthropogenic noise on cetacean behavior is to identify the biological significance of the responses. Predator presence can be considered a natural high-level disturbance stimulus to which prey animals have evolved adaptive response strategies to reduce their risk of predation by altering behavior away from fitness-enhancing activities such as foraging. By contrasting the type and magnitude (duration, severity, consistency) of behavioral responses to anthropogenic noise and playback of killer whale (KW) sounds that simulated predator presence, this study aimed to provide a relative index of the disturbance level as an indication of the biological significance of responses to the anthropogenic stimulus. Using multi-sensor tags as well as visual observations of surface behavior of adult male sperm whales, we assessed a comprehensive range of behavioral metrics that could reduce individuals' fitness if altered for a biologically relevant duration. Combining previously published results and new analyses, we showed that the responses to 1-2 kHz upsweep naval sonar and to KW playback were very similar, including horizontal avoidance, interruption of foraging or resting activities and an increase in social sound production. However, only KW playbacks elicited grouping behaviors, indicating that this social response component was specific to predator detection. Animals responded to a lesser extent to 6-7 kHz upsweep naval sonar, indicating weaker disturbance effects. Our study demonstrates the benefit of using anti-predator responses as a reference of disturbance when evaluating the relative impacts of anthropogenic stimuli, which can be of particular interest in studies of threatened species such as sperm whales. © The authors 2016.
TL;DR: In this article, the authors examined the effectiveness of efforts to minimize the behavioral responses of the whales to vessel proximity and sound during a seismic survey and concluded that the lack of evidence that the whales responded to seismic survey sound and vessel traffic by changing either their movement or respiration patterns indicates that the current mitigation strategy is effective.
Abstract: A seismic survey was conducted off the northeastern coast of Sakhalin Island, Russia in 2010. The survey area was adjacent to the only known near-shore feeding ground of the Critically Endangered population of western gray whales Eschrichtius robustus in the western Pacific south of the Aleutian Islands. This study examined the effectiveness of efforts to minimize the behavioural responses of the whales to vessel proximity and sound during the survey. Two shore-based behavioural observation teams monitored whale movements and respirations pre-, during and post-seismic survey. Theodolite tracking and focal-animal follow methods were used to collect behavioural data. Mixed linear models were used to examine deviations from 'normal' patterns in 10 movement and 7 respiration response variables in relation to vessel proximity, vessel/ whale relative orientations and 8 received sound metrics to examine if seismic survey sound and/or vessel activity influenced the whales' behaviour. Behavioural state and water depth were the best 'natural' predictors of whale movements and respiration. After considering natural variation, none of the response variables were significantly associated with seismic survey or vessel sounds. A whale's distance from shore and its orientation relative to the closest vessel were found to be significantly influenced by vessel proximity, which suggested some non-sound related disturbance. The lack of evidence that the whales responded to seismic survey sound and vessel traffic by changing either their movement or respiration patterns could indicate that the current mitigation strategy is effective. However, power analyses suggest that our sample sizes were too small to detect subtle to moderate changes in gray whale behaviour.
TL;DR: It is demonstrated that the North Atlantic right whale upcall does contain sufficient information to discriminate individual identity and age class, with average classification levels of 72.6 and 86.1%, respectively.
Abstract: Passive acoustic monitoring is a powerful tool that allows remote detection of marine mammals through their vocalizations. While call detection provides information on species presence, additional information may be contained within the vocalizations that could provide more information regarding the demographics and/or number of individuals in a particular area based on passive acoustic detections. The North Atlantic right whale Eubalaena glacialis produces a stereotyped upswept call, termed the upcall, that is thought to function as a long-distance contact call in this species. As such, the call is likely to contain cues providing information about the individual producing it. The goal of this study was to test whether the right whale upcall could potentially encode information related to the identity and age of the caller. Using upcalls recorded from 14 known individuals through non-invasive suction cup archival acoustic tags, we demonstrate that the upcall does contain sufficient information to discriminate individual identity and age class, with average classification levels of 72.6 and 86.1%, respectively. Parameters measured from the fundamental frequency, duration, and formant structure were most important for discrimination among individuals. This study is the first step in demonstrating the feasibility of obtaining additional data from passive acoustic monitoring to aid in the conservation efforts for this highly endangered species.
TL;DR: In this paper, mitochondrial DNA sequences of 90 immature green turtles at 2 foraging grounds in northwestern Sabah, Malaysia were analyzed and the inferred origins of turtles at the 2 locations were not different and indicated that the majority originated from 3 major popula- tions in Southeast Asia, the Turtle Islands of Sarawak in northwestern Borneo (29%), the Turtle Island Heritage Protected Area (TIHPA) (28%) and Peninsular Malaysia (25%).
Abstract: An understanding of population dynamics is needed to assess the viability of migra- tory species. Monitoring of marine turtles at foraging grounds may detect changes in population trends that would take decades to be seen at nesting beaches. Mixed Stock Analysis using molec- ular markers provides a tool for estimating the origin of turtles sampled at foraging grounds. Here, we analysed mitochondrial DNA sequences of 90 immature green turtles at 2 foraging grounds in northwestern Sabah, Malaysia. We used data from 30 Indo-Pacific green turtle rookeries as the baseline for tracing the origin of turtles at the 2 foraging grounds. The inferred origins of turtles at the 2 locations were not different and indicated that the majority originated from 3 major popula- tions in Southeast Asia, the Turtle Islands of Sarawak in northwestern Borneo (29%), the Turtle Islands Heritage Protected Area (TIHPA) (28%) and Peninsular Malaysia (25%). Previous analy- ses indicated a 1:4 female-biased sex ratio at the foraging grounds, and based on our results, this largely reflects the use of unshaded beach hatcheries at some of the source rookeries for decades, which resulted in mostly female hatchlings. This result is supported by differences in the origins of male and female turtles. The result suggests a greater proportion of males originating from Peninsular Malaysia and fewer males originating from Sarawak and possibly the TIHPA com- pared to females. We discuss the implications of hatchery practices that influence sex ratios of hatchlings and recommend future research to improve the management of marine turtles in the region.
TL;DR: This is the first study to demonstrate how birth timing and mother size are correlated with female reproductive success in a cetacean species, and confirms the importance of demographic stochasticity and reproductive hetero - geneity in small, threatened marine mammal populations.
Abstract: For threatened species or populations, variation in reproductive success among females may be explicitly linked with vulnerability to extinction. Thus, an understanding of factors that may cause variability in reproductive success is important. The population of bottlenose dolphins in Doubtful Sound, New Zealand, has a recent history of rapid population decline and low calf survival rates. A previous study has shown high variability in calf survival among multi- parous females. This study addresses the factors that seem most important in explaining variation in calf survival and thus reproductive success among females in this population. Reproductive data were sourced from a long-term photo-identification dataset, which allowed tracking the fate of 49 calves born into the population between 1995 and 2012. General linear mixed models combined with model averaging were used to assess how birth timing, maternal size, age and potential anthropogenic impacts contributed to variation in calf survival. Models show that a female's size and her ability to give birth at an optimum time in the calving season are significant predictors of calf survival to an age of 1 and 3 yr. This is the first study to demonstrate how birth timing and mother size are correlated with female reproductive success in a cetacean species. These results confirm the importance of demographic stochasticity and reproductive hetero - geneity in small, threatened marine mammal populations.
TL;DR: In this article, the authors document the disappearance of largetooth sawfish Pristis pristis from 5 estuaries on the central Brazilian coast, based on ecological and fisheries know ledge of local fishers and reveal that fishers' accounts of the protracted decline revealed clear inter-estuary differences in the timing of population declines, potentially influenced by local geomorphological features.
Abstract: Overfishing is considered one of the main threats to the health of global marine fish populations. Elasmobranchs that are characterized by low reproductive outputs may be particularly sensitive to intense fishing pressures. The sawfishes stand out as a highly threatened group, due in part to their life history in shallow coastal waters and their ease of capture. In Brazil, sawfish populations are now virtually extinct and these declines have gone undocumented, leaving their precise causes and timing poorly understood. Here, based on ecological and fisheries know ledge of local fishers, we document the disappearance of largetooth sawfish Pristis pristis from 5 estuaries on the central Brazilian coast. Fisher knowledge, combined with an estuarine morphology perspective, revealed important insights on this species, along with a timeline of its decline. Furthermore, fishers’ accounts of the protracted decline revealed clear inter-estuary differences in the timing of population declines, potentially influenced by local geomorphological features. The onset of sawfish population decline appears to have been earlier in estuaries with a direct connection to the sea than in estuaries connected to an inner bay, occurring in the former case from the 1930s onward. A second wave of intensifying decline began in the 1970s in more structurally complex estuaries. Pressures from artisanal and modern fishery practices appear to have led to an earlier population decline in structurally less complex estuaries, while in larger and more complex ones this decline occurred decades later. The replacement of traditional by more modern fishing practices may have triggered the initial phase of local sawfish extinctions.
JASCO Applied Sciences1, Cornell University2, National Oceanic and Atmospheric Administration3, Wildlife Conservation Society4, Colorado State University5, University of Montana6, Curtin University7, University of Washington8, College of William & Mary9, United States Geological Survey10, University of St Andrews11
TL;DR: This work was supported in part by a contract between BP Exploration (Alaska) Inc. and the University of California, Santa Barbara (E.F) as discussed by the authors, and by the North Slope Borough.
Abstract: This work was supported in part by a contract between BP Exploration (Alaska) Inc. and the University of California, Santa Barbara (E.F.), and by the North Slope Borough.
TL;DR: Findings should be interpreted with caution, given the low number of positive densities, due to success of the primary mitigation measure, which was to conduct the seismic survey as early in the feeding season as possible when few gray whales would be present.
Abstract: Some whale populations that were severely reduced by commercial whaling have shown strong recovery since becoming protected, while others remain depleted and of high con- servation concern. Small populations are particularly susceptible to anthropogenic threats, in - cluding acoustic disturbance from industrial activities such as seismic surveys. Here, we investi- gated if sound exposure from a 16 d seismic survey displaced gray whales Eschrichtius robustus from their coastal feeding area off northeastern Sakhalin Island, Russia. We conducted multiple shore-based surveys per day, weather permitting, and created daily 1 km 2 density surfaces that provided snapshots of gray whale distribution throughout the seismic activity. A Bayesian spatio- temporal analysis was used to examine possible effects of characteristics of sound exposure from seismic airguns on gray whale occupancy and abundance. Models suggested highest occupancy in areas with moderate sound exposure. Slightly decreased densities were associated with sound exposure when the pattern for the previous 3 d was high sound on Day 2 and low sound on Days 1 and 3. Our findings should be interpreted with caution, given the low number of positive densities. This was due to success of the primary mitigation measure, which was to conduct the seismic survey as early in the feeding season as possible when few gray whales would be present. It is also possible that observed differences in occupancy and density reflect changes in prey availability rather than noise. Prey distribution and abundance data were unavailable for our study, and this important covariate could not be included in models.
TL;DR: Habitat loss is a leading driver of biodiversity loss and environmental noise from human activities has increased rapidly in intensity and scale, representing a drastic yet often overlooked form of habitat loss.
Abstract: Habitat loss is a leading driver of biodiversity loss (Millennium Ecosystem Assessment 2005). Over the past century, environmental noise from human activities has increased rapidly in intensity and scale, representing a drastic yet often overlooked form of habitat loss (Andrew et al. 2002, McDonald et al. 2006, Slabbekoorn & Ripmeester 2008, Hildebrand 2009, Barber et al. 2010). This noise is primarily a consequence of human transportation, recreation, and development (Slabbekoorn & Ripmeester 2008, Hildebrand 2009, Barber et al. 2010), and transcends protected area boundaries (Barber et al. 2011). The loss of acoustic habitat, i.e. the components of the environment that enable an organism to effectively send and receive signals, impairs species’ abilities to perceive sounds critical to survival, reproduction, population health and ecosystem integrity (e.g. Halfwerk et al. 2011, Francis et al. 2009, 2012, Tennessen et al. 2014; see reviews by Warren et al. 2006, Slabbekoorn & Ripmeester 2008, Barber et al. 2010,
TL;DR: Otolith microchemistry was used to evaluate habitat use patterns of the endangered dusky grouper Epinephelus marginatus in southern Brazil and provided the first evidence for this species of prolonged estuarine habitat use (over a year), in particular during juvenile life stages.
Abstract: Otolith microchemistry (Sr:Ca, Ba:Ca) was used to evaluate habitat use patterns of the endangered dusky grouper Epinephelus marginatus in southern Brazil. Individual Sr:Ca profiles exhibited low variation, with an overall tendency to increase with age. Interestingly, indi- vidual Ba:Ca profiles presented 3 contrasting patterns: the first comprised most sampled indivi - duals (>80%), mostly indicative of the predominant use of marine waters throughout their life history; the second pattern (~10% of all individuals) indicated that dusky grouper may use or remain in or near estuarine waters for short time periods; finally, the third identified pattern (~5%) comprised individuals remaining in estuarine waters for long periods and provided the first evidence for this species of prolonged estuarine habitat use (over a year), in particular during juvenile life stages.
TL;DR: In this article, the authors investigated the effectiveness of two distinct tones for use as an alarm to alert whales to fishing gear presence and therefore reduce the chance of entanglement, and compared how whales responded in terms of changes of surface behaviour and changes in direc- tion of travel in response to 2 acoustic tones and when there was no alarm.
Abstract: Migratory Group V (Stock E1) humpback whales Megaptera novaeangliae are at risk of entanglement with fishing gear as they migrate north and south along the east coast of Aus- tralia. This study investigated the effectiveness of 2 distinct tones for use as an alarm to acousti- cally alert whales to fishing gear presence and therefore reduce the chance of entanglement. We compared how whales responded in terms of changes of surface behaviour and changes in direc- tion of travel in response to 2 acoustic tones and when there was no alarm. These 2 acoustic tones were a 5 kHz tone (5 s emission interval and 400 ms emission duration, similar to but higher fre- quency than the signal from a Future Oceans F3 TM 3 kHz Whale Pinger®) and a 2�2.1 kHz swept tone (8 s emission interval and 1.5 s emission duration). A total of 108 tracks (focal follows) were collected using a theodolite at Cape Solander, Sydney, Australia, during the whales' 2013 north- ern migration. Linear mixed effects models were used to determine the effect of the different acoustic tones on whale direction (heading), and behaviour (dive duration and speed). Whales showed no detectable response to either alarm. Whale direction and surfacing behaviour did not differ whether the alarm was 'on' or 'off'. Although the response may have been different if the alarms were attached to fishing gear, the lack of measurable response suggests that the types of tones used are not likely to be effective in alarms intended to reduce entanglement of northward migrating Australian humpback whales.
TL;DR: It is suggested that the traits-based framework used in this study can provide quantitative backing and added justification to selection of study species while expanding the inference space of study results.
Abstract: The bar for justifying the use of vertebrate animals for study is being increasingly raised, thus requiring increased rigor for species selection and study design. Although we have power analyses to provide quantitative backing for the numbers of organisms used, quantitative backing for selection of study species is not frequently employed. This can be especially important when measuring the impacts of ecosystem alteration, when study species must be chosen that are both sensitive to the alteration and of sufficient abundance for study. Just as important is providing justification for designation of surrogate species for study, especially when the species of interest is rare or of conservation concern and selection of an appropriate surrogate can have legal implications. In this study, we use a combination of GIS, a fish traits database and multivariate statistical analyses to quantitatively prioritize species for study and to determine potential study surrogate species. We provide two case studies to illustrate our quantitative, traits-based approach for designating study species and surrogate species. In the first case study, we select broadly representative fish species to understand the effects of turbine passage on adult fishes based on traits that suggest sensitivity to turbine passage. In our second case study, we present a framework for selecting a surrogate species for an endangered species. We suggest that our traits-based framework can provide quantitative backing and added justification to selection of study species while expanding the inference space of study results.
TL;DR: Statistical values obtained when comparing recorded S1 calling rates produced by gray whales during experimental periods in Laguna San Ignacio, Baja California Sur, Mexico are summarized in Table S1.
Abstract: Table S1. Statistical values (t = Student’s t-test; ANOVA) obtained when comparing recorded S1 calling rates produced by gray whales (Eschrichtius robustus) during experimental periods in Laguna San Ignacio, Baja California Sur, Mexico. Absence of values indicates no testing. *Indicates that significant differences occurred during pre/trial/post periods (p <0.05). NS = Not statistically significant (p >0.05). Short-term call rates are multiplied by four to obtain calls per hour for short versus long-term comparisons. Sample size = 42 calls for each short-term experiment; 80 calls for each long-term experiment.
TL;DR: In this paper, the authors summarize flipper tag recovery data of adult females moving between WCR States or between islands within States and suggest the existence of a Central Antillean nesting population nesting primarily within Guadeloupe, Dominica, Martinique, and Saint Lucia.
Abstract: Leatherback turtles Dermochelys coriacea nest across the Wider Caribbean Region (WCR), including at low densities in many Small Island Developing States (SIDS). Most (87.8%) WCR governments protect the species from direct harvest; however, gravid females are at risk as they pass through unprotected regimes, especially among Eastern Caribbean SIDS where mortal- ity can threaten the remnant nesting assemblages that characterize most Caribbean islands. We summarize flipper tag recovery data of adult females moving between WCR States or between islands within States. Between January 2002 and December 2013, WC-series tags obtained from WIDECAST's Marine Turtle Tagging Centre in Barbados were attached to 3151 leatherbacks. Most (64.3%) were tagged in Eastern Caribbean SIDS, with the remainder tagged in Guyana, Venezuela, and Costa Rica. The majority of females continued to nest at the location of tagging, but 211 tagged females were recovered elsewhere on 240 occasions, including 22 different sites in 17 countries. Females travelled significantly greater straight line distances between locations in different nesting seasons (x � = 218.9 km) than within nesting seasons (x � = 160.6 km). Rates of within- and between-season recoveries (2.8 and 4.3%, respectively) are similar to previously pub- lished estimates, but are likely to be underestimates, as few of the 470 known nesting beaches in the WCR are nocturnally monitored. Our data support a North Caribbean nesting population, a Southern Caribbean/Guianas stock, and suggest the existence of a Central Antillean nesting population nesting primarily within Guadeloupe, Dominica, Martinique, and Saint Lucia.