ArticlePDF Available

Beaked Whale Strandings and Naval Exercises

Abstract and Figures

Mass strandings of beaked whales (family Ziphiidae) have been reported in the scientific liter-ature since 1874. Several recent mass strandings of beaked whales have been reported to coincide with naval active sonar exercises. To obtain the broad-est assessment of surface ship naval active sonar operations coinciding with beaked whale mass strandings, a list of global naval training and anti-submarine warfare exercises was compiled from openly available sources and compared by location and time with historic stranding records. This list includes activities of navies of other nations but emphasizes recent U.S. activities because of what is available in publicly accessible sources. Of 136 beaked whale mass stranding events reported from 1874 to 2004, 126 occurred between 1950 and 2004, after the introduction and implementation of modern, high-power mid-frequency active sonar (MFAS). Of these 126 reports, only two reported details on the use, timing, and location of sonar in relation to mass strandings. Ten other mass strand-ings coincided in space and time with naval exer-cises that may have included MFAS. An additional 27 mass stranding events occurred near a naval base or ship but with no direct evidence of sonar use. The remaining 87 mass strandings have no evidence for a link with any naval activity. Six of these 87 cases have evidence for a cause unrelated to active sonar. The large number of global naval activities annually with potential MFAS usage in comparison to the relative rarity of mass stranding events suggests that most MFAS operations take place with no reported stranding events and that for an MFAS operation to cause a mass stranding of beaked whales, a confluence of several risk factors is probably required. Identification of these risk factors will help in the development of measures to reduce the risk of sonar-related strandings.
Content may be subject to copyright.
A preview of the PDF is not available
... Echosounder pulses have the potential to alter diving and acoustic behaviors and mask signals. Earlier research has focused on the use of mid-frequency (1-10 kHz) active sonar on odontocetes [14][15][16][17][18][19] after several mass stranding events followed naval exercises [20][21][22][23]. More recently, the influence of high-frequency (>10 kHz) and multi-beam echosounders on cetaceans has been examined [24][25][26][27][28]. Again, the focus has been on toothed whales, as the operational frequencies of the systems overlap with the frequency range in which their hearing is most sensitive (10-150 kHz; [28,29]). ...
Article
Full-text available
The spatial extent of a dual-frequency echosounder and its potential impact on cetacean species were examined. Sound emissions of output frequencies of 83 kHz and 200 kHz were tested at a maximum distance of 400 m. This is the minimum vessel approach distance for killer whales (Orcinus orca) in southern British Columbia, which was introduced as a measure for limiting disturbance of southern resident killer whales (SRKWs). The experiment was conducted in shallow (34 m) and deep (220–235 m) water. Recordings were made at depths of 5 and 30 m for both locations, as well as at 100 and 200 m in the deeper water to examine the effect of the echosounder through the water column and at SRKW diving depths. The recordings showed that 200 kHz echosounder emissions were contained within a 250 m radius of the source, with most of the acoustic energy focused within 100 m in shallow waters. For the 83 kHz signal and for deeper water testing of the 200 kHz signal, the echosounder transmissions exceeded the 400 m threshold, intimating that whales could experience noise additions of 30 dB or more above the ambient level at the minimum vessel approach distance. Evaluating the noise additions to the ambient level from the echosounder in frequencies used by SRKWs for echolocation (15–100 kHz) further showed the potential impact on whales in close proximity to vessels (≤400 m) when using echosounders or fish-finders.
... Marine mammals rely on sound production and detection for communication, navigation, predator avoidance and foraging (Tyack 1997, Noad et al. 2000, Curé et al. 2013. Human sounds may mask their abilities to detect important sounds (Erbe et al. 2016), produce aversion responses that could restrict behavioural and movement options affecting reproduction and survival, or cause direct injury and even death (Ketten 1995, D'Amico et al. 2009, Kight & Swaddle 2011. ...
... Here we test whether the distinctive features of beaked whale diving behaviour and group cohesiveness have quantitative benefits to reduce risk of predator encounters. We do so by analysing biologging data from Blainville's and Cuvier's beaked whales, that are among the best-known beaked whale species and also those most commonly found in mass strandings related to naval sonar (D'Amico et al. 2009). We propose that fear of predation shapes the minute-by-minute behaviour of these long lived, elephant-sized marine mammals which pay this heavy cost to access a privileged foraging niche and mitigate interception by a stealthy large-brained cosmopolitan predator. ...
Article
Full-text available
Background As levels of anthropogenic noise in the marine environment rise, it is crucial to quantify potential associated effects on marine mammals. Yet measuring responses is challenging because most species spend the majority of their time submerged. Consequently, much of their sub-surface behavior is difficult or impossible to observe and it can be difficult to determine if—during or following an exposure to sound—an observed dive differs from previously recorded dives. We propose a method for initial assessment of potential behavioral responses observed during controlled exposure experiments (CEEs), in which animals are intentionally exposed to anthropogenic sound sources. To identify possible behavioral responses in dive data collected from satellite-linked time–depth recorders, and to inform the selection and parameters for subsequent individual and population-level response analyses, we propose to use kernel density estimates of conditional distributions for quantitative comparison of pre- and post-exposure behavior. Results We apply the proposed method to nine Cuvier’s beaked whales (Ziphius cavirostris) exposed to a lower-amplitude simulation of Mid-Frequency Active Sonar within the context of a CEE. The exploratory procedure provides evidence that exposure to sound causes animals to change their diving behavior. Nearly all animals tended to dive deep immediately following exposure, potentially indicating avoidance behavior. Following the initial deep dive after exposure, the procedure provides evidence that animals either avoided deep dives entirely or initiated deep dives at unusual times relative to their pre-exposure, baseline behavior patterns. The procedure also provides some evidence that animals exposed as a group may tend to respond as a group. Conclusions The exploratory approach we propose can identify potential behavioral responses across a range of diving parameters observed during CEEs. The method is particularly useful for analyzing data collected from animals for which neither the baseline, unexposed patterns in dive behavior nor the potential types or duration of behavioral responses is well characterized in the literature. The method is able to be applied in settings where little a priori knowledge is known because the statistical analyses employ kernel density estimates of conditional distributions, which are flexible non-parametric techniques. The kernel density estimates allow researchers to initially assess potential behavioral responses without making strong, model-based assumptions about the data.
Article
Behavioral responses of beaked whales (family Ziphiidae) to naval use of mid‐frequency active sonar (MFAS) have been quantified for some species and regions. We describe the effects of MFAS on the probability of detecting diving groups of Blainville's beaked whales on the U.S. Navy Pacific Missile Range Facility (PMRF) in Hawaii and compare our results to previously published results for the same species at the Atlantic Undersea Test and Evaluation Center (AUTEC) in the Bahamas. We use passive acoustic data collected at bottom‐mounted hydrophones before and during six naval training exercises at PMRF along with modelled sonar received levels to describe the effect of training and MFAS on foraging groups of Blainville's beaked whales. We use a multistage generalized additive modeling approach to control for the underlying spatial distribution of vocalizations under baseline conditions. At an MFAS received level of 150 dB re 1 μPa rms the probability of detecting groups of Blainville's beaked whales decreases by 77%, 95% CI [67%, 84%] compared to periods when general training activity was ongoing and by 87%, 95% CI [81%, 91%] compared to baseline conditions. Our results indicate a more pronounced response to naval training and MFAS than has been previously reported.
Article
Knowledge of Cuvier’s beaked whale Ziphius cavirostris behavior has expanded through the utilization of animal-borne tags. However, many tag types do not record sound—thus preventing echolocation click detections to identify foraging—or have short deployments that sample a limited range of behaviors. As the quantity of such non-acoustic tag data grows, so too does the need for robust methods of detecting foraging from non-acoustic data. We used 692 dives from 5 sound-recording tags on Cuvier’s beaked whales in southern California, USA, to develop extreme gradient boosting tree models to detect foraging based on 1 Hz depth and 16 Hz triaxial acceleration data. We performed repeated 10-fold cross validation using classification accuracy to tune 500 models with randomly partitioned training and testing datasets. An average of 99.9 and 99.2% of training and testing dataset dives, respectively, were correctly classified across the 500 models. Dives without associated sound recordings (n = 2069 from 7 whales including 4 non-acoustic tags) were classified via a model that maximized training information using dive depth and duration, ascent and descent rates, bottom-phase average vertical speed, and roll circular variance during dive descents and bottom phases. Of all long, deep dives (conventionally assumed to include foraging), 2.4% were classified as non-foraging dives, while 0.3% of short, shallow dives were classified as foraging dives. Results confirm that conventional depth and/or duration classifiers provide reasonable estimates of longer-term foraging patterns. However, additional variables previously listed enhance foraging detections for unusual dives (notably non-foraging deep dives) for southern California Cuvier’s beaked whales.
Article
Full-text available
Significance Acoustic signals travel efficiently in the marine environment, allowing soniferous predators and prey to eavesdrop on each other. Our results with four cetacean species indicate that they use acoustic information to assess predation risk and have evolved mechanisms to reduce predation risk by ceasing foraging. Species that more readily gave up foraging in response to predatory sounds of killer whales also decreased foraging more during 1- to 4-kHz sonar exposures, indicating that species exhibiting costly antipredator responses also have stronger behavioral reactions to anthropogenic noise. This advance in our understanding of the drivers of disturbance helps us to predict what species and habitats are likely to be most severely impacted by underwater noise pollution in oceans undergoing increasing anthropogenic activities.
Article
Full-text available
Beaked whales are cryptic and difficult to study species, often distributed in deep offshore waters and only briefly visible at the surface. A diverse range of cetacean species has been documented in the Bay of Biscay, including several species of beaked whales. However, little is known about how persistent their presence is. Citizen science data collected during ferry-based surveys between 2006 and 2018 were analysed to investigate how encounter rates varied across space and time, and their drivers for beaked whale species. Approximately 244,400 km were surveyed, and there were 419 encounters with beaked whales recorded including Cuvier’s beaked whales, ( n = 260), Northern bottlenose whales ( n = 19), Sowerby’s beaked whales ( n = 13), and True’s beaked whales ( n = 1). Generalized Additive Models revealed that encounters were generally more frequent in the southern bay, on northern facing slopes, with all species except Sowerby’s showing a preference for both deep waters and shallow shelf waters. Animals were recorded in each of the eight surveyed months, suggesting that beaked whales may be present year-round, with increased encounter rates in summer months. This study is the first to indicate that beaked whales may persist in this area throughout the year, which is key information for appropriate management.
Article
Full-text available
Experimental research has shown that beaked whales exhibit strong avoidance reactions to naval active sonars used during antisubmarine warfare training exercises, including cessation of echolocation and foraging activity. Behavioural responses to sonar have also been linked to strandings and mortality. Much of the research on the responses of beaked whales and other cetaceans to naval active sonar has occurred on or near U.S. naval training ranges, and the impacts of sonar in other regions remain poorly understood, particularly as these impacts, including mortality, are likely to go unobserved in offshore areas. In September 2016 the multinational naval exercise ‘CUTLASS FURY 2016’ (CF16) was conducted off eastern Canada. We used passive acoustic recordings collected in the region to quantify the occurrence and characteristics of sonar signals, measure ambient noise levels, and assess changes in the acoustic activity of beaked and sperm whales. The number of hours per day with echolocation clicks from Cuvier’s beaked whales and sperm whales were significantly reduced during CF16, compared to the pre-exercise period in 2016 (sperm whales) and to control data from 2015 (both species). Clicks from an unidentified Mesoplodont beaked whale species, sporadically detected prior to CF16, were absent during the exercise and for 7 days afterward. These results suggest that beaked and sperm whales ceased foraging in the vicinity of CF16 and likely avoided the affected area. Such disturbance may have energetic, health, and fitness consequences.
Article
Full-text available
Forty-one additional cetacean records are reported for the Leeward Dutch Antilles, expanding the list of documented records to 70 (53 sightings and 17 strandings). First records are given for the melon-head whale Peponocephala electra (Gray), such that now 13 species are confirmed for these islands. The most sighted whales are Bryde's whale and shortfin pilot whale, whereas the most sighted dolphins are spinner and bottlenose dolphins. Most cetacean movement is upstream and towards the east/southeast. Reported strandings have been on the rise, of which 47% involved beaked whales (goosebeak whale and Antillean beaked whale).
Article
The advantages and environmental impacts of the new generation of low-frequency active sonars (LFAS) used in anti-submarine warfare (ASW) applications, are discussed. The LFAS systems exploit the major advances in signal and data processing and take advantage of the excellent propagation characteristics. These systems exploit the favorable propagation conditions in the deep sound channels and offer the potential for future bistatic and multistatic operations with other sources and receivers. But there is public concern over the use of LFAS system because the high underwater sound levels can seriously affect the aquatic life, particularly whales and dolphins, which rely on acoustics for navigation, feeding, communication and mating.
Article
Two hundred and sixty-seven cetaceans, in 102 stranding events, were recorded between 1970 and 1998 on Sable Island off the coast of Nova Scotia. Seventeen species were represented: Blue Whale (1 single stranding), Fin Whale (1 single stranding), Minke Whale (3 single strandings), Humpback Whale (4 single strandings), Sperm Whale (8 strandings, 13 animals), Pygmy Sperm Whale (3 strandings, 4 animals), Dwarf Sperm Whale (2 single strandings), Northern Bottlenose Whale (3 single strandings), Sowerby's Beaked Whale (1 single stranding), Killer Whale (1 single stranding), Long-finned Pilot Whale (37 strandings, 173+ animals), White-beaked Dolphin (1 stranding, 2 animals), Atlantic White-sided Dolphin (9 strandings, 13 animals), Risso's Dolphin (1 single stranding), Striped Dolphin (8 strandings, 22 animals), Short-beaked Common Dolphin (4 strandings, 6 animals), Harbour Porpoise (11 strandings, 13 animals). The records of the Dwarf Sperm Whale and that of the Risso's Dolphin are the first for eastern Canada. The record of the Sowerby's Beaked Whale is the first reported stranding in Nova Scotia. Humpback, Minke, and Killer whales, and Short-beaked Common Dolphins have not previously been recorded stranded on Sable Island. The majority of stranding events (84) were of a single animal; nine involved two animals; eight involved 3-10 animals; and one event involved over 130 animals. Recorded strandings increased from 1.9 strandings/year between 1970-1989 to 7.1 strandings/year between 1990-1998. Mass strandings of multiple male Sperm Whales have occurred three times (all since 1990). All Atlantic White-sided Dolphin strandings investigated were also comprised of male animals.
Article
The stranding of four Cuvier’s Beaked Whales, Ziphius cavirostris , on the Lesser Antillean Island of Bonaire on April 3, 1974 is reported. The death of the animals was most probably caused by some kind of underwater explosion.