Southern Resident Killer Whales Research Articles

Effects of duty cycles on passive acoustic monitoring of southern resident killer whale (Orcinus orca) occurrence and behavior

Long-term passive acoustic monitoring of cetaceans is frequently limited by the data storage capacity and battery life of the recording system. Duty cycles are a mechanism for subsampling during the recording process that facilitates long-term passive acoustic studies. While duty cycles are often used, there has been little investigation on the impact that this approach has on the ability to answer questions about a species' behavior and occurrence. In this study, the effects of duty cycling on the acoustic detection of southern resident killer whales (SRKW) (Orcinus orca) were investigated. Continuous acoustic data were subsampled to create 288 subsampled datasets with cycle lengths from 5 to 180 min and listening proportions from 1% to 67%. Duty cycles had little effect on the detection of the daily presence of SRKW, especially when using cycle lengths of less than an hour. However, cycle lengths of 15–30 min and listening proportions of at least 33% were required to accurately calculate durations of acoustic bouts and identify those bouts to ecotype. These results show that the optimal duty cycle depends on the scale of the research question and provide a framework for quantitative analysis of duty cycles for other marine species.

Implications of wind and vessel noise on the sound fields experienced by southern resident killer whales Orcinus orca in the Salish Sea

The soundscape of critical habitat for southern resident killer whale (SRKW) Orcinus orca in the Salish Sea, the waters around southern British Columbia, Canada, and northern Washington State, USA, is shaped by wind and wave noise as well as heavy commercial and recreational vessel traffic loads. First, we used recordings from 6 passive acoustic moorings to characterize the acoustic landscape experienced by SRKW in this region, focusing on the frequencies used for communication and echolocation. Mid-frequency wind noise was prevalent in winter sound fields, whereas higher-frequency noise levels associated with increased numbers of recreational vessels increased during summer. Commercial vessel presence was consistent, with acoustic inputs prevalent in the western part of the study area. The potential implications of these additions on SRKW acoustics use were then explored for the frequency band 1-40 kHz to represent communication calls and at 50 kHz to consider echolocation. The inputs of wind were extrapolated from modelled hourly wind speed measures and commercial shipping noise. The noise impact was expressed as a proportional reduction of communication and echolocation extent compared to maximum acoustic ranges at ‘minimum ambient’ levels, void of vessel and abiotic noise. The reductions calculated were substantial, with the presence and impact of vessel noise greater than wind-derived additions and the greatest impacts around shipping lanes. Impacts were found for SRKW foraging areas, with implications for group cohesion and feeding success. This interpretation of the influence of natural and vessel noise more clearly demonstrates the potential implications of altered soundscapes for SRKW.

Bacterial microbiomes from mucus and breath of southern resident killer whales (Orcinus orca).

Opportunities to assess odontocete health are restricted due to their limited time at the surface, relatively quick movements and large geographic ranges. For endangered populations such as the southern resident killer whales (SKRWs) of the northeast Pacific Ocean, taking advantage of non-invasive samples such as expelled mucus and exhaled breath is appealing. Over the past 12years, such samples were collected, providing a chance to analyse and assess their bacterial microbiomes using amplicon sequencing. Based on operational taxonomic units, microbiome communities from SRKW and transient killer whales showed little overlap between mucus, breath and seawater from SRKW habitats and six bacterial phyla were prominent in expelled mucus but not in seawater. Mollicutes and Fusobacteria were common and abundant in mucus, but not in breath or seawater, suggesting these bacterial classes may be normal constituents of the SRKW microbiome. Out of 134 bacterial families detected, 24 were unique to breath and mucus, including higher abundances of Burkholderiaceae, Moraxellaceae and Chitinophagaceae. Although there were multiple bacterial genera in breath or mucus that include pathogenic species (e.g. Campylobacter, Hemophilus, Treponema), the presence of these bacteria is not necessarily evidence of disease or infection. Future emphasis on genotyping mucus samples to the individual animal will allow further assessment in the context of that animal's history, including body condition index and prior contaminants burden. This study is the first to examine expelled mucus from cetaceans for microbiomes and demonstrates the value of analysing these types of non-invasive samples.

Shifting phenology of an endangered apex predator mirrors changes in its favored prey

The timing, or phenology, of predator activity in relation to their prey is critical for survival and fitness, yet rarely quantified for marine species, even those of conservation concern. We use a large database of professional and crowd-sourced observations analyzed with hierarchical spline occupancy models to quantify seasonal variation in occurrence of an endangered apex predator, the southern resident killer whale (SRKW)Orcinus orca, in inland waters of the northeast Pacific Ocean. We find that timing of SRKW occurrence has shifted in their summer core habitat within the central Salish Sea: the day of year of peak occurrence probability shifted later at rates of 1-5 d yr-1over 2001-2017 (resulting in shifts of 17-85 d across this 17 yr time period). These shifts are consistent with shifts in their preferred prey, Fraser River Chinook salmonOncorhynchus tshawytscha, as the relative number of fish returning to spawn in the spring has declined compared to numbers returning in summer and fall. The shift in timing of fall/winter SRKW occurrence outside the summer core habitat, however, is not consistent with shifts in other prey populations (Chinook, cohoOncorhynchus kisutch, chumOncorhynchus ketasalmon) returning to nearby rivers. Our findings demonstrate the complexity of consumer phenological responses and highlight gaps in our understanding of links between management actions that affect resource phenology and consequences for organisms relying on those resources.

Measuring speed of vessels operating around endangered southern resident killer whales (Orcinus orca) in Salish Sea critical habitat

Motorized vessels are a major source of anthropogenic noise and can have adverse effects on species relying on sound for communication and feeding. Monitoring noise levels received by endangered southern resident killer whales (SRKWs) requires knowing the number, distance, and speed of surrounding vessels, including small boats that do not have Automatic Identification Systems (AIS). A method for estimating their speed is required to predict received noise levels and compliance with vessel regulations. We compared theodolite and photogrammetry methods to estimate the number, distance, and speed of vessels in SRKW Salish Sea summertime critical habitat. By treating AIS as “truth”, we found photogrammetry-derived ranges and speeds were more variable than theodolite estimates. Error in photogrammetry-derived speeds increased with range. Overall, we found time saved in the field using photogrammetry was more than offset by long analysis time. Theodolite data were relatively easy to collect, and produced accurate and precise results.

International harmonization of procedures for measuring and analyzing of vessel underwater radiated noise

The habitat of the endangered southern resident killer whale (SRKW) overlaps major international shipping lanes near the Port of Vancouver, British Columbia. Shipping is a dominant source of underwater noise, which can hinder SRKW key life functions. To reduce environmental pressure on the SRKWs, Vancouver Fraser Port Authority offers incentives for quieter ships. However, the absence of a widely accepted underwater radiated noise (URN) measurement procedure hinders the determination of relative quietness. We review URN measurement procedures, summarizing results to date from two Canadian-led projects aimed at improving harmonization of shallow-water URN measurement procedures: One supports the International Organization for Standardization (ISO) in the development of a URN measurement standard; the other supports the alignment of URN measurement procedures developed by ship classification societies. Weaknesses in conventional shallow-water URN metrics are identified, and two alternative metrics proposed. Optimal shallow-water measurement geometry is identified.

Estimating animal utilization distributions from multiple data types: A joint spatiotemporal point process framework

Models of the spatial distribution of animals provide useful tools to help ecologists quantify species-environment relationships, and they are increasingly being used to help determine the impacts of climate and habitat changes on species. While high-quality survey-style data with known effort are sometimes available, often researchers have multiple datasets of varying quality and type. In particular, collections of sightings made by citizen scientists are becoming increasingly common, with no information typically provided on their observer effort. Many standard modelling approaches ignore observer effort completely which can severely bias estimates of an animal’s distribution. Combining sightings data from observers who followed different protocols is challenging. Any differences in observer skill, spatial effort and the detectability of the animals across space all need to be accounted for. To achieve this, we build upon the recent advancements made in integrative species distribution models and present a novel marked spatiotemporal point process framework for estimating the utilization distribution (UD) of the individuals of a highly mobile species. We show that, in certain settings, we can also use the framework to combine the UDs from the sampled individuals to estimate the species’ distribution. We combine the empirical results from a simulation study with the implications outlined in a causal directed acyclic graph to identify the necessary assumptions required for our framework to control for observer effort when it is unknown. We then apply our framework to combine multiple datasets collected on the endangered Southern Resident Killer Whales to estimate their monthly effort-corrected space-use.

Presidential Address: The orca conjecture

AbstractIn this address, I argue that the Southern Resident Killer Whale (SRKW) population has been negatively affected by commercial vessel traffic, tied to international trade, in the post‐1998 period. I present new data showing a dramatic increase in both the volume of kilometres travelled and the composition of vessel traffic in the Salish Sea. By exploiting recent work in biology linking vessel noise to changes in foraging and socializing behaviour, I argue that these changes have degraded their habitat significantly. Moreover, because SRKWs and Northern Resident Killer Whales (NRKWs) share prey, this negative vessel disturbance shock to the SRKW is magnified by the existence of across‐population competition. Vessel disturbance magnified by competition for prey has placed the SRKW on a slow‐motion path towards extinction.

Southern resident killer whales encounter higher prey densities than northern resident killer whales during summer

The decline of southern resident killer whales (Orcinus orca) may be due to a shortage of prey, but there is little data to test this hypothesis. We compared the availability of prey (Chinook salmon, Oncorhynchus tshawytscha) sought by southern residents in Juan de Fuca Strait during summer with the abundance and distribution of Chinook available to the much larger and growing population of northern resident killer whales feeding in Johnstone Strait. We used ship-based multifrequency echosounders to identify differences in prey fields that may explain the dynamics of these two killer whale populations. Contrary to expectations, we found that both killer whale habitats had patchy distributions of prey that did not differ in their frequencies of occurrence, nor in the size compositions of individual fish. However, the density of fish within each patch was 4–6 times higher in the southern resident killer whale habitat. These findings do not support the hypothesis that southern resident killer whales are experiencing a prey shortage in the Salish Sea during summer and suggest a combination of other factors is affecting overall foraging success.

Characterizing Southern Resident killer whale calls using a particle filter for frequency contour extraction

With only 74 Southern Resident killer whales (SRKWs) remaining in the waters of the eastern Pacific, understanding these marine mammals is vital to their conservation. Invasive techniques such as focal follows or tagging whales could introduce stress to SRKWs. Instead, passive acoustic monitoring that uses a network of hydrophones one preferred tracking method, particularly in their critical habitat that overlaps the shipping lanes in the Salish Sea. The acoustic data, if processed in real-time using modern deep learning methods, can be used to detect whales and alert ships of the potential for spatial overlap to reduce risks of collision. In this project, we consider the differences in SRKW whale call types from archived recordings of each of J, K, and L pods recorded on regional hydrophones. The whale calls are extracted as functional observations in the time and frequency space from underwater recordings using a particle filter. Functional data analysis (e.g., functional clustering) are performed to characterize the whale calls and represent the variations in call types. Such statistical insights between pod-level call types should be useful for improving machine learning whale detection algorithms, and for identifying SRKW movement in a high ship traffic region of their critical habitat.

Integrating visual and acoustic observations to build an “intelligent” killer whale movement forecast system

Shipping traffic continues to grow in the Salish Sea with considerable marine industrial developments planned for the region. With this comes an increase in the risk of cetaceans being disturbed, harassed, and potentially colliding with commercially operating vessels. One key conservation concern is these waters coincide with designated Critical Habitat for the endangered population of Southern Resident killer whales (SRKW). Monitoring technologies such as hydrophones provide the promise of real-time animal detection and localisation. To use these continuous streams of real-time whale location data, we are developing algorithms that automate acoustic detection and classification of SRKW calls using deep learning models trained on extensive new and updated annotated datasets from the region. We are developing open-source models for pod-level classification, while also differentiating SRKW from other ecotypes and species. We are developing a forecasting system to merge these whale detections with opportunistic visual observations. This is based on sequential data assimilation methods using advanced animal movement models to estimate SRKW pod locations with probabilistic predictions of whale directional movement. These methods will be transformative for shipping by providing forecasting with a lead time of a few hours allowing vessels to adjust their speed or pathway to minimize whale-vessel interactions.

Echolocation click characteristics of two fish-eating killer whale populations

Acoustic disturbance has been identified as a threat to the survival of the endangered Southern Resident killer whale (SRKW) population whose critical habitat in the Salish Sea overlaps with busy commercial shipping lanes and popular recreational boating areas. Vessel noise has the potential to mask important sounds used by the whales for navigating, communicating, and foraging. To investigate the impact on foraging, acoustic characteristics of the whales’ echolocation clicks must be known. We collected data on SRKW in the wild using a 2 × 2 m2 23-hydrophone array deployed at short ranges (<500 m). We also acquired data on a neighboring population of Northern Resident killer whales (NRKW), whose numbers are increasing. Comparable results were obtained for most parameters between the two populations. Average peak-to-peak apparent source levels were 203 and 196 dB re 1 μPa at 1 m for SRKW and NRKW, respectively. The two populations had similar mean centroid and peak frequencies ranging between 26–29 kHz and 19–21 kHz, respectively. However, root-mean-square bandwidths differed significantly between the populations, with averages of 52 and 39 kHz for SRKWs and NRKWs, respectively. These results will be used to investigate masking potential under varying ambient noise conditions.

Acoustic survey of Southern resident killer whale occurrence at the Lime Kiln hydrophone observatory, Haro Strait, Washington

The aim of this study is to explore temporal and diurnal variation in Southern Resident Killer Whale (SRKW) acoustic activity and their relationship to other marine mammal events and to anthropogenic activity in Haro Strait, Washington. In support of the Vancouver Fraser Port Authority-led ECHO (Enhancing Cetacean Habitat and Observation) Program, six years (2016–2021) of summer/fall acoustic data from the Lime Kiln live hydrophone system (range: 10 Hz–100 kHz) in Haro Strait has been analyzed using PAMGuard software (64-bit Version: 1.15.11; Gillespie et al., 2008). Automated whistle detectors and echolocation click detectors and classifiers were parameterized to detect marine mammals, ships, and echosounders in the dataset. PAMGuard Viewer Mode was then used to review the data and mark all marine mammal and anthropogenic events. The dataset provides important long-term information on marine mammal occurrence and anthropogenic activity in a well described core area of SRKW critical habitat. Daily event logs compiled using custom R script have been used by the ECHO program to better understand the effectiveness of multi-year voluntary commercial vessel slow-downs through Haro Strait and considerable year-to-year and monthly variation in SRKW detections have been identified. Coupled with long-term day-time visual observations of SRKW, the dataset is also useful for assessing the efficacy of PAM detection mitigation methods and night-time activity levels.

Passive acoustic monitoring of Southern Resident Killer Whales: Occurrence, residency and movement data in support of conservation

Passive acoustic monitoring (PAM) of cetaceans offers valuable spatio-temporal information on presence and residency time to support population management and recovery strategies. Acoustic detections can be used to evaluate diel and seasonal occurrence patterns when visual detection opportunities are limited (e.g., night or winter), and acoustic encounter duration can inform habitat use patterns (e.g., travelling/shorter duration vs foraging/longer duration). Additionally, detection data from strategically placed recorders may also be used in the development of predictive movement models. Here we use PAM data to evaluate critical habitat use by the Endangered Southern Resident Killer Whale (SRKW) population in Juan de Fuca Strait and the Salish Sea, near the southwest coast of Vancouver Island, British Columbia. Continuous recordings were collected at three locations from May to October, 2018–2020, and used to assess presence and acoustic encounter duration. As this area experiences significant commercial vessel traffic and recreational vessel use, mitigation of risk from acoustic disturbance is a high priority for recovery. These PAM detection and encounter duration data were used to provide advice for management actions in support of SRKW recovery in Canadian Pacific waters.

Orcasound: Open source software for catalyzing conservation of endangered Southern Resident killer whales in real-time

Over the last 20 years, Orcasound has evolved from a cooperative network of real-time hydrophones to an open source software and hardware project. Orcasound connects cabled hydrophones deployed in critical habitat of the Southern Resident killer whales (SRKWs) with a web app that enables community scientists to listen and tag audio data in real-time. The live audio feeds are also monitored by automated algorithms (e.g., OrcaHello), archived in Amazon data “buckets” which are publicly accessible for free and governed by a Creative Commons license that promotes non-commercial data sharing and specifies appropriate attribution. Many of these open data have been annotated through crowd-sourcing tools built by the Orcasound community, like Pod.Cast and OrcaAL, generating open test and training data sets needed for development of more advanced classifiers. We present the latest version of Orcasound’s live-listening app as a novel conservation tool, and describe our evolving architecture for: generating audio streams with low-cost hydrophones and hardware, and free software; deploying diverse algorithms, including on non-Orcasound hydrophone data streams; validating, annotating, and analyzing acoustic detections; aggregating them in an open data cooperative along with regional data from sighting networks; and issuing notifications to network members as well as conservation stewards.

Auditory masking in killer whales (Orcinus orca) with realistic signals and noise

Killer whales are the largest delphinid odontocete, a top predator and are globally distributed. Southern resident killer whales, which inhabit the Pacific coastal region of the northwest United States and Canada, are listed as endangered. Anthropogenic noise has been identified as a major threat to this populations of killer whales. This paper will cover recent results from killer whale auditory masking experiments using a variety of signals and noise types. Signal types included pure tones and recordings of killer whale calls. Noise types included Gaussian noise and recordings of seismic surveys and continuous active sonar. Potential auditory mechanisms that govern the resulting masking patterns, including dip listening, off-frequency listening, and comodulation masking release are discussed. These data will help to better understand and predict how killer whales can acoustically communicate, navigate, and locate prey in an increasingly noisy environment.

Soundscapes experienced by southern resident killer whales (Orcinus orca) in the Salish Sea and implications of vessel noise

Endangered southern resident killer whales (SRKW, Orcinus orca) use waters of the Salish Sea around southern British Columbia and northern Washington State to forage, following the in- migration of prey. However, these waterways experience heavy vessel traffic, with important SRKW foraging areas near to international shipping lanes. Here we use recordings from six passive acoustic moorings to characterize the soundscape, and determine spatiotemporal patterns on daily to annual scales. Particular focus is given to the noise levels in frequencies used by SRKW to communicate and echolocate. A numerical model is used to map the sound field between the mooring locations and examine the anthropogenic inputs in SRKW critical habitat in the Salish Sea by commercial traffic. Extrapolation of the model output to higher frequencies allows an examination of the impact this may have on the range of effective acoustics use, with implications for SRKW navigation, foraging success and group cohesion. Finer scale analysis of vessel signatures as they transit the study area aids in identifying areas of increased risk of disturbance for whales. In addition, differences in modelled to observed data will help the characterisation of other sonic inputs to the soundscape, including smaller recreational vessels.

Southern Resident killer whale acoustic monitoring and noise measurements to inform noise mitigation and potential management strategies

SMRU Consulting, in collaboration with the ECHO Program, the San Juan County MRC and DFO, has been monitoring Salish Sea underwater soundscapes for the presence of Southern Resident killer whales (SRKW), to measure ambient noise levels, evaluate the efficacy of noise mitigation measures and inform potential management strategies. This talk will highlight results from four projects across the years 2019–2021. This includes measurements from a cabled observatory at Lime Kiln Point State Park in support of the ECHO Program’s Haro Strait commercial vessel slowdowns; measurements from autonomous recorders at five locations in Burrard Inlet for the ECHO Program and the Tsleil-Waututh Nation to monitor trends in ambient noise and marine mammal presence; measurements from Coastal Acoustic Buoys at eight locations south of San Juan Island in support of San Juan County’s management efforts, and a Coastal Acoustic Buoy for Offshore Wind deployment near Point Roberts to allow DFO to evaluate acoustic technology. This talk will discuss the pros and cons of these four different acoustic systems and highlight trends in the data that may help inform mitigation and management strategies.

Recent developments, observations and lessons learned in the use of real-time passive acoustic monitoring from ocean gliders in order to mitigate harm to North Atlantic Right Whales and Southern Resident Killer Whales

JASCO’s novel passive acoustic monitoring (PAM) system, OceanObserver was deployed in Canada’s Gulf of Saint Lawrence (GoSL) in autumn 2018 aboard a Slocum G3 glider. The purpose of this mission was to assist in the search for endangered North Atlantic Right Whales and other threatened cetaceans, and to report detections in near-real-time so that appropriate mitigation actions could be taken. This proposed presentation will provide results and lessons learned based upon the rigorous analysis and comparison of the real-time, in situ detections with the automated and manual detections derived from post-trial analysis of the recorded raw acoustic data. This post analysis has permitted an assessment of the performance of the automated detectors deployed at sea and the effectiveness of the real-time communication management software in getting marine mammal detections to shore-based stakeholders in a timely manner. It also has permitted the evaluation of the effectiveness of shore-based acoustic analysts tasked with the validation of the automated detections sent to shore.Whether the mission objective of “no false positives” in order to ensure the correctness of mitigation decisions will be discussed. The method of assessing performance will be described and empirical results presented. The application of this technology to SRKW conservation will be discussed.

Managing vessel-generated underwater noise to reduce acoustic impacts to killer whales

Launched in 2014, the Enhancing Cetacean Habitat and Observation (ECHO) Program, led by the Vancouver Fraser Port Authority, is a regional, collaborative program designed to better understand and reduce the cumulative effects from commercial shipping activities on at-risk whales. The program advances a number of research projects and operational initiatives, with a key focus on reduction of vessel-generated underwater noise to support recovery of the endangered Southern Resident Killer Whale (SRKW). To reduce vessel noise in key killer whale habitat, the ECHO Program manages seasonal voluntary slowdowns of large commercial traffic and lateral displacement of inshore traffic, and advances projects to better characterize vessel-generated noise. Determining the efficacy of vessel noise reduction efforts requires careful consideration of confounding factors to assess acoustic reductions, and estimate the resulting benefits to SRKW. This presentation will highlight results of noise mitigation efforts conducted to date, and identify some of the technical challenges faced in the acoustic analysis, including decisions on data filtering techniques. Methods used by the ECHO Program for evaluating potential effects of noise exposure on killer whale behavior and foraging will also be discussed.