Behavior Of Marine Mammals Research Articles

Automated Video Surveillance for the Study of Marine Mammal Behavior and Cognition

Automated Video Surveillance for the Study of Marine Mammal Behavior and Cognition

Long range sound propagation modeling for assessing seismic survey noise impacts on marine mammals

Despite of small land area, Japan has vast EEZ, which is expected to have potential mineral resources. Extensive seismic surveys have been conducted for those targets. However, airguns used for the survey generate intense and low-frequency impulse sound, which could disturb or harm marine mammal behavior and auditory system. In June 2016, NOAA released “Ocean Noise Strategy Roadmap” that recommends modeling of sound propagation in the context of realistic environmental parameters to assess noise impacts on marine creatures. Japan has remarkable seasonal climate changes and complex ocean-bottom topography with trenches and seamounts; therefore, such model is worthwhile. Here, we propose a modeling method utilizing ARGO data includes seasonal climate changes and LEVITUS data, and ocean-bottom topographic configuration data from Google Earth. We calculated long range propagation of airgun sounds in different sound profiles and ocean-bottom topographic configurations around Ogasawara Islands, which is known as a cetacean habitat. Results showed that seasonal climate change and the precision of the ocean-bottom topographic configuration caused significant differences in sound propagation. These findings suggest that the realistic environmental parameters is essentially needed for the modeling of sound propagation and proposed method is a useful tool to assess noise impacts on marine mammals.

Studying cetacean behaviour: new technological approaches and conservation applications

Animal behaviour can provide valuable information for wildlife management and conservation. Studying the detailed behaviour of marine mammals involves challenges not faced by most animal behaviour researchers due to the size, mobility and lack of continuous visibility of these animals. We describe several methods developed by marine mammal scientists to study behaviour, primarily of cetaceans, focusing on technological advances: unmanned aerial systems (UAS), satellite-linked telemetry, passive acoustics and multisensor high-resolution acoustic recording tags. We then go on to explain how the data collected by these methods have contributed to and informed conservation actions. We focus on examples including: satellite data informing the interactions between cetaceans and offshore oil and gas development; passive acoustics used to track distributions of several species of cetaceans, including their movements near shipping lanes; and high-resolution acoustic recording tags used to document responses of cetaceans to anthropogenic activities. Finally, we discuss recent efforts to link animal behaviour to individual fitness and, particularly for behavioural disturbances, to population-level consequences, which can be helpful for informing conservation efforts. The infusion of technological advancements into studies of cetacean behaviour combined with emerging analytical techniques brings us to the next 20+ years of studying these animals. These developments will improve our capabilities in areas such as testing whether their behaviour adheres to traditional behavioural theory, and will certainly assist the guiding of conservation efforts.

Marine Mammal Behavior: A Review of Conservation Implications

The three orders which comprise the extant marine mammals exhibit a wide range of behaviors, varying social structures and differences in social information use. Human impacts on marine mammals and their environments are ubiquitous; from chemical and noise pollution, to marine debris, prey depletion and ocean acidification. As a result, no marine mammal populations remain entirely unaffected by human activities. Conservation may be hindered by an inadequate understanding of the behavioral ecology of some of these species. As a result of social structure, social information use, culture and even behavioral syndromes, marine mammal social groups and populations can be behaviorally heterogeneous. As a result responses to conservation initiatives, or exploitation, may be complex to predict. Previous commentators have highlighted the importance of incorporating behavioral data into conservation management and we review these considerations in light of the emerging science in this field for marine mammals. Since behavioral canalization may lead to vulnerability, whereas behavioral plasticity may provide opportunity for resilience, we argue that for many of these socially complex, cognitive species understanding their behavioral ecology, capacity for social learning and individual behavioral variation, may be a central tenant for their successful conservation.

The effect of operational measures on shipping sound in the North Sea

From studies into marine biology, it is known that the behavior of marine mammals and fish can be influenced by the ambient underwater sound level. In busy seas like the North Sea in Europe, sound from shipping traffic is largely responsible for the low frequency part of the ambient sound. In this work, possibilities to regulate the underwater radiated sound of ship traffic are investigated. This involves measures that look at traffic flows and operational use of the vessels, to determine what can be done to reduce the shipping sound levels in certain marine areas. Three types of operational measures are considered: (1) the effect of spatial planning (for example, changing the location of shipping routes), (2) the introduction of a radiated sound limit for vessels in a certain area, and (3) the introduction of a speed limit for vessels in a certain area. The proposed measures have been analyzed on their effect and effectiveness, by means of numerical analysis. Calculations have been performed for a generi...

Vast assembly of vocal marine mammals from diverse species on fish spawning ground.

Observing marine mammal (MM) populations continuously in time and space over the immense ocean areas they inhabit is challenging but essential for gathering an unambiguous record of their distribution, as well as understanding their behaviour and interaction with prey species. Here we use passive ocean acoustic waveguide remote sensing (POAWRS) in an important North Atlantic feeding ground to instantaneously detect, localize and classify MM vocalizations from diverse species over an approximately 100,000 km(2) region. More than eight species of vocal MMs are found to spatially converge on fish spawning areas containing massive densely populated herring shoals at night-time and diffuse herring distributions during daytime. We find the vocal MMs divide the enormous fish prey field into species-specific foraging areas with varying degrees of spatial overlap, maintained for at least two weeks of the herring spawning period. The recorded vocalization rates are diel (24 h)-dependent for all MM species, with some significantly more vocal at night and others more vocal during the day. The four key baleen whale species of the region: fin, humpback, blue and minke have vocalization rate trends that are highly correlated to trends in fish shoaling density and to each other over the diel cycle. These results reveal the temporospatial dynamics of combined multi-species MM foraging activities in the vicinity of an extensive fish prey field that forms a massive ecological hotspot, and would be unattainable with conventional methodologies. Understanding MM behaviour and distributions is essential for management of marine ecosystems and for accessing anthropogenic impacts on these protected marine species.

Monitoring population‐level responses of marine mammals to human activities

AbstractWe provide guidance for monitoring whether human activities affect the physiology or behavior of marine mammals and, if so, whether those effects may lead to changes in survival and reproduction at the population level. We suggest that four elements be included in designing and implementing such a monitoring program. The first is development of a theory of change: a set of mechanistic hypotheses that outline why a given activity might be expected to have one or more measurable effects on individuals and populations, and ideally the magnitude, timing, and duration of the effects. The second element, definition of biologically meaningful effect sizes, ultimately facilitates the development of a monitoring program that can detect those magnitudes of effect with the desired levels of precision. The third element, selection of response variables for monitoring, allows inference to whether observed changes in the status of individuals or populations are attributable to a given activity. Visual observations, passive acoustic and tagging instruments, and direct physical measurements all can provide data that facilitate quantitative hypothesis testing. The fourth element is specification of the temporal sequence of monitoring. These elements also can be used to inform monitoring of the responses of other taxonomic groups to human activities.

The Challenges of Analyzing Behavioral Response Study Data: An Overview of the MOCHA (Multi-study OCean Acoustics Human Effects Analysis) Project.

This paper describes the MOCHA project which aims to develop novel approaches for the analysis of data collected during Behavioral Response Studies (BRSs). BRSs are experiments aimed at directly quantifying the effects of controlled dosages of natural or anthropogenic stimuli (typically sound) on marine mammal behavior. These experiments typically result in low sample size, relative to variability, and so we are looking at a number of studies in combination to maximize the gain from each one. We describe a suite of analytical tools applied to BRS data on beaked whales, including a simulation study aimed at informing future experimental design.

Memories Stanley (Stan) A. Kuczaj II (1950-2016)

On 14 April 2016, the scientific community lost Dr. Stan Kuczaj, professor at the University of Southern Mississippi and Director of the Marine Mammal Behavior and Cognition Laboratory. He was a beloved teacher, researcher, friend, mentor, and colleague. By age 65, this well-liked, respected professor had achieved world-renowned status in multiple disciplines—comparative psychology, behavioral sciences, and developmental psychology. His tremendous success in these areas resulted in a legacy of more than 50 master’s- and doctoral-level students working in a variety of fields; he also had hundreds of collaborators from around the world. Stan significantly contributed to and influenced the current direction of these fields and had many plans and research projects still to accomplish.

Comparing multiple sampling platforms for measuring the behavior of humpback whales (Megaptera novaeangliae)

AbstractMultiple platform approaches for measuring the behavior of marine mammals may strengthen data quality and quantity. However, if this approach is chosen, reconciliation of behavioral measures between each platform is required. This study compared typical measures of humpback whale (Megaptera novaeangliae) behavior collected from three different sampling platforms; land‐based, boat‐based, and digital tags (Dtags), to explore similarities and/or discrepancies in data. Visual observations from land‐based platforms significantly underestimated group blow rate when compared to boat‐based platforms, whereas broad‐scale spatial movements (speed and course traveled) were measured similarly by these two platforms. Dtags were used to define dive behavior based on a time and depth criteria, where bouts of short shallow respiration dives (≤80 s and ≤10 m) were separated from longer, deeper dives (>80 s and >10 m). At a group level, land and boat platforms agreed on the number of long dives but land platforms missed bouts of short dives. At an individual level, the number of short and long dives observed by boat‐based platforms agreed with Dtag recordings. This study highlights the importance of data exploration prior to analyses in multiple platform studies to identify potential discrepancies and appropriately account for any biases.

Going with the flow: Tidal influence on the occurrence of the harbour porpoise (Phocoena phocoena) in the Marsdiep area, The Netherlands

One of the most important factors explaining the distribution and behaviour of coastal marine mammals are tides. Tidal forces drive a large number of primary and secondary processes, such as changes in water depth, salinity, temperature, current velocity and direction. Unravelling which tidal process is the most influential for a certain species is often challenging, due to a lack of observations of all tide related covariates, strong correlation between them, and the elusive nature of most marine organisms which often hampers their detection.In the Marsdiep area, a tidal inlet between the North Sea and the Dutch Wadden Sea, the presence of harbour porpoises (Phocoena phocoena) was studied as a function of tide related covariates. Observations were carried out in early spring from a ferry crossing the inlet on a half hourly basis. Environmental and sightings data were collected by one observer, while an on-board Acoustic Doppler Current Profiler (ADCP) and temperature sensor continuously recorded current velocity profiles and temperature, respectively. Sea surface temperature and salinity were measured at a nearby jetty. Sightings (n=134) were linked to tidal elevation, geographical position, local depth-averaged current velocity, water temperature (with and without trend correction) and salinity.Variation in sighting rate was best described by salinity, with highest sighting rate at high levels of salinity (>30gkg−1), indicating that porpoises enter the area in bodies of (more saline) North Sea water. Second best variable was time of day, with the highest sighting rate early morning, and decreasing during the day. However, surveys in the morning happened to coincide more often with high water and hence, the apparent time of day effect could be due to collinearity. Most porpoises were present in the northern part of the Marsdiep, particularly during high tide.Tide dependent sighting rates confirmed that porpoises reside in the North Sea, and enter the western Wadden Sea during the flood and leave during ebb. This tidal influx is most likely related to prey availability, which corresponds to other recent studies in this area showing higher fish abundance during high tide. Documenting information on tide related patterns could be used in practice, when e.g. planning anthropogenic activities or assessing critical habitats for this species.

Temporal segregation of the Australian and Antarctic blue whale call types (Balaenoptera musculus spp.).

We examined recordings from a 15-month (May 2009–July 2010) continuous acoustic data set collected from a bottom-mounted passive acoustic recorder at a sample frequency of 6kHz off Portland, Victoria, Australia (38°33′01″S, 141°15′13″E) off southern Australia. Analysis revealed that calls from both subspecies were recorded at this site, and general additive modeling revealed that the number of calls varied significantly across seasons. Antarctic blue whales were detected more frequently from July to October 2009 and June to July 2010, corresponding to the suspected breeding season, while Australian blue whales were recorded more frequently from March to June 2010, coinciding with the feeding season. In both subspecies, the number of calls varied with time of day; Antarctic blue whale calls were more prevalent in the night to early morning, while Australian blue whale calls were detected more often from midday to early evening. Using passive acoustic monitoring, we show that each subspecies adopts different seasonal and daily call patterns which may be related to the ecological strategies of these subspecies. This study demonstrates the importance of passive acoustics in enabling us to understand and monitor subtle differences in the behavior and ecology of cryptic sympatric marine mammals.

Tracking marine mammals in 3D using electronic tag data

Summary Information about at‐depth behaviour of marine mammals is fundamental yet very hard to obtain from direct visual observation. Animal‐borne multisensor electronic tags provide a unique window of observation into such behaviours. Electronic tag sensors allow the estimation of the animal's 3‐dimensional (3D) orientation, depth and speed. Using tag flow noise level to provide an estimate of animal speed, we extend existing approaches of 3D track reconstruction by allowing the direction of movement to differ from that of the animal's longitudinal axis. Data are processed by a hierarchical Bayesian model that allows processing of multisource data, accounting for measurement errors and testing hypotheses about animal movement by comparing models. We illustrate the approach by reconstructing the 3D track of a 52‐min deep dive of a Blainville's beaked whale Mesoplodon densirostris adult male fit with a digital tag (DTAG) in the Bahamas. At depth, the whale alternated regular movements at large speed (>1·5 m s ‐1) and more complex movements at lower speed (<1·5m s‐1) with differences between movement and longitudinal axis directions of up to 28. The reconstructed 3D track agrees closely with independent acoustic‐based localizations. The approach is potentially applicable to study the underwater behaviour (e.g. response to anthropogenic disturbances) of a wide variety of species of marine mammals fitted with triaxial magnetometer and accelerometer tags.

Unusually loud ambient noise in tidewater glacier fjords: A signal of ice melt

AbstractIn glacierized fjords, the ice‐ocean boundary is a physically and biologically dynamic environment that is sensitive to both glacier flow and ocean circulation. Ocean ambient noise offers insight into processes and change at the ice‐ocean boundary. Here we characterize fjord ambient noise and show that the average noise levels are louder than nearly all measured natural oceanic environments (significantly louder than sea ice and nonglacierized fjords). Icy Bay, Alaska, has an annual average sound pressure level of 120 dB (referenced to 1 μPa) with a broad peak between 1000 and 3000 Hz. Bubble formation in the water column as glacier ice melts is the noise source, with variability driven by fjord circulation patterns. Measurements from two additional fjords, in Alaska and Antarctica, support that this unusually loud ambient noise in Icy Bay is representative of glacierized fjords. These high noise levels likely alter the behavior of marine mammals.

Target‐specific acoustic predator deterrence in the marine environment

AbstractAcoustic deterrent devices (ADDs) have often been considered a benign solution to managing pinniped predation. However, ADDs have also been highlighted as a conservation concern since they can inflict large‐scale habitat exclusion in toothed whales (odontocetes). We tested a new method that selectively inflicted startle responses in harbour seals (Phoca vitulina) at close ranges to the loudspeaker but not in a non‐target species, the harbour porpoise (Phocoena phocoena), by using a frequency range where porpoise hearing was less sensitive than that of phocid seals. The sound exposure consisted of isolated 200 ms long, 2–3 octave‐band noise pulses with a peak frequency of 1 kHz, which were presented at a source level of ∼180 dB re 1 μPa. Field tests were carried out within a 2‐month period on a fish farm on the west coast of Scotland where marine mammal behaviour was observed within three distance categories. Seal numbers dropped sharply during sound exposure compared with control observation periods within 250 m of the sound source but were unaffected at distances further away from the farm. A Poisson regression model revealed that the number of seal tracks within 250 m of the device decreased by ∼91% during sound exposure and was primarily influenced by sound exposure with no evidence for a change in the effect of treatment such as habituation, throughout the experiment. In contrast to seals, there was no shift in the number of porpoise groups in each distance category as a result of sound exposure and porpoises were regularly seen close to the device. We also sighted six common minke whales during sound exposure while only one was seen during control periods. Our data demonstrate that the startle method can be used to selectively deter seals without affecting porpoises.

Marine mammals and ocean noise: Future directions and information needs with respect to science, policy and law in Canada

Marine mammals are ecologically and culturally important species, and various countries have specific legislation to protect the welfare of individual marine mammals and the conservation of their populations. Anthropogenic noise represents a particular challenge for conservation and management. There is a large and growing body of research to support the conclusion that anthropogenic noise can affect marine mammal behavior, energetics, and physiology. The legal, policy, and management issues surrounding marine mammals and noise are similarly complex. Our objective is twofold. First, we discuss how policy and legal frameworks in Canada have some important differences from other jurisdictions covered in previous reviews, and provide a useful general case study. Secondly, we highlight some priority research areas that will improve marine mammal conservation and management. Our examples focus on the research needed to meet stated conservation objectives for marine mammal species in waters under Canadian jurisdiction.

200 kHz commercial sonar systems generate lower frequency side lobes audible to some marine mammals.

The spectral properties of pulses transmitted by three commercially available 200 kHz echo sounders were measured to assess the possibility that marine mammals might hear sound energy below the center (carrier) frequency that may be generated by transmitting short rectangular pulses. All three sounders were found to generate sound at frequencies below the center frequency and within the hearing range of some marine mammals, e.g. killer whales, false killer whales, beluga whales, Atlantic bottlenose dolphins, harbor porpoises, and others. The frequencies of these sub-harmonic sounds ranged from 90 to 130 kHz. These sounds were likely detectable by the animals over distances up to several hundred meters but were well below potentially harmful levels. The sounds generated by the sounders could potentially affect the behavior of marine mammals within fairly close proximity to the sources and therefore the exclusion of echo sounders from environmental impact analysis based solely on the center frequency output in relation to the range of marine mammal hearing should be reconsidered.

Instrumentation and handling effects on Antarctic fur seals (Arctocephalus gazella)

The use of biologging instruments has greatly improved our understanding of the behaviour, physiology and ecology of free-ranging marine mammals. However, handling wild animals and attaching instruments to streamlined bodies can cause stress and potentially influence behaviour and swimming/diving energetics. The goals of this study, undertaken on Bouvetøya, were (1) to determine if the first trip to sea after instrumentation is representative of subsequent trips in lactating Antarctic fur seals, to explore potential handling effects and assess possible biases in having multiple short-duration deployments (inflating N, using a limited number of tags) and (2) to evaluate potential effects of two different instrument combinations (SMRU satellite data relay loggers and very high frequency radio transmitters versus Wildlife Computers time–depth recorders and very high frequency radio transmitters) on trip durations, dive parameters, female body condition and pup growth. Handling did not appear to have any effects on the parameters studied; data from the first and second trips did not differ significantly. This implies that multiple short-term deployments are unlikely to result in biased data in this species. Instrument type did have measurable effects; time-at-sea was greater and pup growth was lower for pairs in which mothers carried bulkier instruments. This suggests that instrument streamlining is important to avoid negative impacts and that bulkier equipment should be deployed on lactating females with caution and only for short periods. The study highlights that instrument effects should be taken into account when comparing data from experiments collected using different equipment packages.Keywords: Bioenergetics; biologging; instrument effects; SRDLs; TDRs; VHFs(Published: 21 February 2014)Citation: Polar Research 2014, 33, 21630, http://dx.doi.org/10.3402/polar.v33.21630

Drag of suction cup tags on swimming animals: Modeling and measurement

AbstractBio‐logging tags are widely used to study the behavior and movements of marine mammals with the tacit assumption of little impact to the animal. However, tags on fast‐swimming animals generate substantial hydrodynamic forces potentially affecting behavior and energetics adversely, or promoting early removal of the tag. In this work, hydrodynamic loading of three novel tag housing designs are compared over a range of swimming speeds using computational fluid dynamics (CFD). Results from CFD simulation were verified using tag models in a water flume with close agreement. Drag forces were reduced by minimizing geometric disruptions to the flow around the housing, while lift forces were reduced by minimizing the frontal cross‐sectional area of the housing and holding the tag close to the attachment surface. Hydrodynamic tag design resulted in an experimentally measured 60% drag force reduction in 5.6 m/s flow. For all housing designs, off‐axis flow increased the magnitude of the force on the tag. Experimental work with a common dolphin (Delphinus delphis) cadaver indicates that the suction cups used to attach the types of tags described here provide sufficient attachment force to resist failure to predicted forces at swimming speeds of up to 10 m/s.

Behavioral responses of California sea lions (Zalophus californianus) to controlled exposures of mid-frequency sonar signals

Acoustic dose-response functions can be used to explore the relationship between anthropogenic noise exposure and changes in marine mammal behavior. Fifteen sea lions participated in a controlled exposure study to determine the relationship between the received sound pressure level (SPL) of a mid-frequency sonar signal (1-s duration, 3250-3450 Hz) and behavioral deviations from a trained behavior. Sea lions performed 10 control trials followed by 10 exposure trials within an open-water enclosure. Acoustic playbacks occurred once during each exposure trial when the sea lion crossed the middle of the enclosure. Received levels, ranging from 125 to 185 dB re 1 μPa (rms) SPL, were randomly assigned but were consistent across all trials for each individual. Blind scoring of behavioral responses was performed for all trials. A canonical correlation analysis indicated that cessation of the trained behavior, haul-out, a change in respiration rate, and prolonged submergence were reliable response indicators. Sea lions showed both an increased responsiveness and severity of response with increasing received SPL. No habituation to repeated exposures was observed, but age was a significant factor affecting the dose-response relationship. Response patterns and factors affecting behavioral responses were different from those observed in bottlenose dolphins and are indicative of species-specific sensitivities.