Equipment to tag, track and collect biopsies from whales and dolphins : the ARTS, DFHorten and LKDart systems

Funding Information: A special thanks to all the members of the 3S team, and to FFI, for support during the development of the ARTS–DTAG setup. Furthermore, special acknowledgement to ICR (Institute of Cetacean Research, Japan) for the development of the new ARTS carrier (ARTSTBC).Of all animals considered subjects for instrumentation for behavioral or physiological studies, cetaceans probably represent the greatest challenge to the engineer and biologist. The marine environment being harsh to electronics, evasive behavior during tagging approaches and the short time window available to attach instruments, all imply a need for innovative tagging solutions to facilitate better understanding of their life cycle, migration, physiology, behavior, health and genetics. Several animal-attached tag packages holding specific data loggers, e.g., time depth recorders, position, orientation, acoustic and video recorders for short to medium term studies, as well as tags developed for large scale migration telemetry studies are available as off-the-shelf devices, or in many cases as custom made sensor packages. Deployment of those instruments is often the limiting factor for data collection. The Aerial Remote Tag System (ARTS) is a flexible system which can easily be adapted to deploy different tag sensor packages and biopsy collection devices. This paper presents the history and design of the ARTS, and accessories developed for instrumentation and biopsy sampling of cetaceans, such as the recent developed ARTS–LKDart for biopsy sampling. Deployment of archival tags usually requires radio tracking of the instrumented animal, or at least tracking of the tag for recovery. Thus, we also here describe the automatic digital signal processing radio direction finder, the Direction Finder Horten (DFHorten unit).Publisher PDFPeer reviewe

Persistence of skin marks on killer whales (Orcinus orca) caused by the parasitic sea lamprey (Petromyzon marinus) in Iceland

Lampreys have long been thought to be a cetacean ectoparasite, due to the observation of round marks on the skin of whales caught during whaling operations. Pike (1951), Nemoto (1955), and van Utrecht (1959) compared such marks on the skin of various cetacean species caught in the Pacific and Atlantic Oceans with the dentition of lampreys and concluded that most round marks had been caused by this parasite. However, lampreys were never collected from captured whales and, due to the lack of direct evidence, some discussion emerged as to the origin of these wounds. Jones (1971) later argued that crescent-shaped marks previously attributed to lampreys were in fact caused by cookie-cutter sharks (Isistius brasiliensis). However, he agreed that other round marks were undoubtedly caused by lampreys. Recently, photographs of sea lampreys (Petromyzon marinus) attached to northern right whales, Eubalaena glacialis (Nichols and Hamilton 2004), and minke whales, Balaenoptera acutorostrata (Nichols and Tscherter 2011), in the western North Atlantic conclusively showed that lampreys do associate with those species. Similar evidence for other cetaceans is still lacking

Cultural evolution of killer whale calls: background, mechanisms and consequences

Cultural evolution is a powerful process shaping behavioural phenotypes of many species including our own. Killer whales are one of the species with relatively well-studied vocal culture. Pods have distinct dialects comprising a mix of unique and shared call types; calves adopt the call repertoire of their matriline through social learning. We review different aspects of killer whale acoustic communication to provide insights into the cultural transmission and gene-culture co- evolution processes that produce the extreme diversity of group and population repertoires. We argue that the cultural evolution of killer whale calls is not a random process driven by steady error accumulation alone: temporal change occurs at different speeds in different components of killer whale repertoires, and constraints in call structure and horizontal transmission often degrade the phylogenetic signal. We discuss the implications from bird song and human linguistic studies, and propose several hypotheses of killer whale dialect evolution

High diving metabolic rate indicated by high-speed transit to depth in negatively buoyant long-finned pilot whales

The US Office of Naval Research and Strategic Environmental Research and Development Program (SERDP) supported the fieldwork as a part of the 3S study collaboration. This study was also supported by the program Bio-Logging Science of the University of Tokyo (UTBLS).To maximize foraging duration at depth, diving mammals are expected to use the lowest cost optimal speed during descent and ascent transit and to minimize the cost of transport by achieving neutral buoyancy. Here, we outfitted 18 deep-diving long-finned pilot whales with multi-sensor data loggers and found indications that their diving strategy is associated with higher costs than those of other deep-diving toothed whales. Theoretical models predict that optimal speed is proportional to (basal metabolic rate/drag)1/3 and therefore to body mass0.05. The transit speed of tagged animals (2.7±0.3 m s−1) was substantially higher than the optimal speed predicted from body mass (1.4–1.7 m s−1). According to the theoretical models, this choice of high transit speed, given a similar drag coefficient (median, 0.0035) to that in other cetaceans, indicated greater basal metabolic costs during diving than for other cetaceans. This could explain the comparatively short duration (8.9±1.5 min) of their deep dives (maximum depth, 444±85 m). Hydrodynamic gliding models indicated negative buoyancy of tissue body density (1038.8± 1.6 kg m–3, ±95% credible interval, CI) and similar diving gas volume (34.6±0.6 ml kg−1, ±95% CI) to those in other deep-diving toothed whales. High diving metabolic rate and costly negative buoyancy imply a ‘spend more, gain more’ strategy of long-finned pilot whales, differing from that in other deep-diving toothed whales, which limits the costs of locomotion during foraging. We also found that net buoyancy affected the optimal speed: high transit speeds gradually decreased during ascent as the whales approached neutral buoyancy owing to gas expansion.Publisher PDFPeer reviewe

Movements and site fidelity of killer whales (Orcinus orca) relative to seasonal and long-term shifts in herring (Clupea harengus) distribution

Predators specialising on migratory prey that frequently change migration route face the challenge of finding prey with an unpredictable distribution. Here, we used photo-identification data to investigate whether killer whales observed in herring overwintering and spawning grounds off Iceland follow herring year-round, as previously proposed, and have the ability to adapt to long-term changes in herring distribution. Of 327 identified whales seen more than once, 45% were seen in both grounds, and were thus presumed herring-specialists, likely following herring year-round, while others were only seen on one of the grounds, possibly following herring to unsampled grounds or moving to other locations and exploiting different prey. High seasonal site fidelity to herring grounds, long-term site fidelity to herring spawning grounds, and matches of individual whales between past and recently occupied herring overwintering grounds showed an ability to adapt to long-term changes in prey distribution as well as diversity of movement patterns which are maintained over time, likely as socially-learnt traditions. Such population structuring shows that the movement patterns and foraging ecology of herring-eating killer whales are more complex than previously assumed and must be taken into account in future population assessments. Identifying the factors driving these differences in movements and resource use will be relevant towards our understanding of how prey predictability may drive specialization in this and other top predator species

First indications that northern bottlenose whales are sensitive to behavioural disturbance from anthropogenic noise

-Although northern bottlenose whales were the most heavily hunted beaked whale, we have little information about this species in its remote habitat of the North Atlantic Ocean. Underwater anthropogenic noise and disruption of their natural habitat may be major threats, given the sensitivity of other beaked whales to such noise disturbance. We attached dataloggers to 13 northern bottlenose whales and compared their natural sounds and movements to those of one individual exposed to escalating levels of 1–2 kHz upsweep naval sonar signals. At a received sound pressure level (SPL) of 98 dB re 1 μPa, the whale turned to approach the sound source, but at a received SPL of 107 dB re 1 μPa, the whale began moving in an unusually straight course and then made a near 180° turn away from the source, and performed the longest and deepest dive (94 min, 2339 m) recorded for this species. Animal movement parameters differed significantly from baseline for more than 7 h until the tag fell off 33–36 km away. No clicks were emitted during the response period, indicating cessation of normal echolocation-based foraging. A sharp decline in both acoustic and visual detections of conspecifics after exposure suggests other whales in the area responded similarly. Though more data are needed, our results indicate high sensitivity of this species to acoustic disturbance, with consequent risk from marine industrialization and naval activity

Geographic variation in the time-frequency characteristics of high-frequency whistles produced by killer whales (Orcinus orca)

Investigating intraspecific variation in acoustic signals can indicate the extent of isolation and divergence between populations and adaptations to local environments. Here we analyze the variation in killer whale high frequency (>17 kHz) whistles recorded off Norway, Iceland, and in the North Pacific. We used a combination of methods including multivariate comparisons of spectral and temporal parameters and categorization of contours to types. Our results show that spectral and temporal characteristics of high-frequency whistles recorded in the North Pacific show significant differences from whistles recorded in the Northeast Atlantic, being generally stereotyped, lower in frequency, and slightly longer in duration. Most high-frequency whistles from the North Pacific were downsweeps, whereas this was one of the least common types recorded in the Northeast Atlantic. The repertoire of whistles recorded in Norway was similar to Iceland, but whistles produced in Norway had significantly lower maximum frequency and frequency range. Most methods were able to discriminate between whistles of the North Pacific and the Northeast Atlantic, but were unable to consistently distinguish whistles from Iceland and Norway. This suggests that macro- and microgeographic differences in high-frequency whistles of killer whales may reflect historical geographic isolation between ocean basins and more recent divergence between adjacent populations

Short-term responses of sperm whales Physeter macrocephalus to the attachment of suction cup tags

Animal-mounted data logging devices are used to study the behaviour, physiology, and ecology of free-ranging marine mammals, as well as their reactions to controlled exposures. It is important to consider whether collected data are representative of natural behaviour or biased by responses to tagging. In species with stereotypical diving behaviour, tagging responses can be quantified by identifying anomalous dives. Data from 36 suction cup tag deployments on sperm whales Physeter macrocephalus from 4 locations were analysed to consider whether tagging effects were evident within 5 dive parameters: Maximum dive depth, dive duration, descent speed, depth difference between start of clicking and first prey capture attempt, and buzz rate. Linear mixed models were generated for each response parameter and covariates for dive index were added to assess whether model fit improved when the order of dives was taken into account. Time-decaying tagging effects were noted in maximum dive depth (first dives were 25% shallower than average) and buzz rate (first dives contained 34% fewer buzzes per minute than average). In the Azores, the first 3 dives subsequent to tag attachment featured faster descent speeds than average. The whales were likely responding to the cumulative 'dose' of research activity at the surface: Multiple boat approaches, tag placement, and general disturbance. Disturbance should be minimised during tagging, and the extent and duration of responses should be quantified. Modelling of quantified tagging responses could enable correction of these responses in tag data.</p

Short-term responses of sperm whales Physeter macrocephalus to the attachment of suction cup tags

Animal-mounted data logging devices are used to study the behaviour, physiology, and ecology of free-ranging marine mammals, as well as their reactions to controlled exposures. It is important to consider whether collected data are representative of natural behaviour or biased by responses to tagging. In species with stereotypical diving behaviour, tagging responses can be quantified by identifying anomalous dives. Data from 36 suction cup tag deployments on sperm whales Physeter macrocephalus from 4 locations were analysed to consider whether tagging effects were evident within 5 dive parameters: Maximum dive depth, dive duration, descent speed, depth difference between start of clicking and first prey capture attempt, and buzz rate. Linear mixed models were generated for each response parameter and covariates for dive index were added to assess whether model fit improved when the order of dives was taken into account. Time-decaying tagging effects were noted in maximum dive depth (first dives were 25% shallower than average) and buzz rate (first dives contained 34% fewer buzzes per minute than average). In the Azores, the first 3 dives subsequent to tag attachment featured faster descent speeds than average. The whales were likely responding to the cumulative 'dose' of research activity at the surface: Multiple boat approaches, tag placement, and general disturbance. Disturbance should be minimised during tagging, and the extent and duration of responses should be quantified. Modelling of quantified tagging responses could enable correction of these responses in tag data.</p

Association matrix and individual supplementary details of Icelandic killer whales

First sheet with details for each individual (sex-age class, movement pattern, number of records - number of photographs -, number of total days sampled and number of different years seen). Second sheet with the association matrix for all individuals, no restrictions on the number of sightings, calculated using SOCPROG 2.6 software (half-weight index used)