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Southern right whales (Eubalaena australis) are listed as Endangered under the Australian EPBC Act 1999. They migrate to shallow, coastal waters during the winter to mate, calve and nurse their young. During this time, they are easily accessible to the boat-based whale-watching industry. The aim of the study was to determine if whale-watching at 300 m distance affects the behaviour of southern right whales. To achieve this, behavioural focal follows on mother-calf pairs were conducted using unmanned aerial vehicles (UAVs) in the presence and absence of a commercial whale-watching vessel. There was no significant effect of phase (control, before, during, after) on the whales’ respiration rate, swim speed, nursing rate and duration, maternal rate of active behaviours, tactile contact or calf pectoral fin contact. There was a significant reduction in resting between control and after phases, for both mothers (from 62% to 30%) and calves (from 16% to 1%). At 300 m distance and slow speed, vessel noise was measured to be slightly above ambient noise at the lower TOL0.25 kHz band, however, vessel noise was masked by ambient noise within the higher frequency TOL2–10 kHz bands. A factor which may have contributed to a decline in resting after whale-watch approaches, was an increase in vessel speed upon departure, which consequently increased vessel noise. Based on this, we recommend that vessels maintain a slow speed (e.g., ≤10 knots) within 1 km distance from the whales whilst conducting whale-watch activities.

The number and size of whale-watching and swim-with-cetacean vessels are increasing worldwide, but the noise impact on targeted species depends on vessel source characteristics, which remain largely unquantified. Here, we report the acoustic characteristics from 13 whale-watching vessels from Australia and Canary Islands. Acoustic recorders were deployed to measure the frequency-weighted sound levels (for low [LF], mid [MF] and high frequency [HF] cetacean hearing types) of motor sailing, catamarans, and motor vessels operating at 4–8 kn representing the slow speed of whale-watch scenarios. The highest estimated source levels (SLs) were represented from large catamarans with inboard engines (LF = 160 ± 3, MF = 148 ± 2, HF = 146 ± 2 dB re 1 µPa m). The lowest SLs were from smaller motor vessels and particularly by a hybrid vessel powered by electrical outboard engines (LF = 140 ± 3, MF = 136 ± 2, HF = 134 ± 2 dB re 1 µPa m). We demonstrate that at the same speed and distance, different vessels may produce very different received levels to the animals. To reduce disturbance to cetaceans we recommend tourism vessels meet a broadband (0.2–10 kHz) SL limit of

Obtaining morphometric data on free-ranging marine megafauna is difficult, as traditional methods rely on post-mortem or live-capture techniques. We linked stereo-laser photogrammetry with long-term demographic data to compare length-at-age (LaA) growth curves of two well-studied populations of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in south-western (SW) and Shark Bay (SB), mid-western Australia. First, we determined the relationship between total length (TL) and blowhole-to-dorsal fin (BH-DF) length from post-mortem subjects (R2 = 0.99, n = 12). We then predicted TL from laser-derived BH-DF measurements of 129 and 74 known-age individuals in SW and SB, respectively. Richards growth models best described our LaA data. While birth length (103–110 cm) was similar between study regions, TL estimates at 1, 3, 12, and 25 years differed significantly (p

Vessel noise is a primary driver of behavioural disturbance in cetaceans, which are targeted during whale-watch activities. Despite the growing, global effort for implementing best-practice principles, to date, there are no regulations on whale-watch vessel noise levels. Here, we test the hypothesis that a whale-watch vessel with a low noise emission will not elicit short-term behavioural responses in toothed whales compared to a vessel with a louder engine. We measured behavioural responses (n = 36) of short-finned pilot whales (Globicephala macrorhynchus) to whale-watch vessel approaches (range 60 m, speed 1.5 kn). Treatment approaches with a quieter electric engine (136–140 dB) compared to the same vessel with a louder petrol engine (151–139 dB) (low-frequency–mid-frequency weighted source levels, re 1 µPa RMS @ 1 m) were examined. Focal whales were resting mother and calves in small group sizes. During petrol engine treatments, the mother’s mean resting time decreased by 29% compared to the control (GLM, p = 0.009). The mean proportion of time nursing for the calf was significantly influenced by petrol engine vessel passes, with a 81% decrease compared to the control (GLM, p = 0.01). There were no significant effects on behaviour from the quieter electric engine. Thus, to minimise disturbance on the activity budget of pilot whales, whale-watch vessels would ideally have source levels as low as possible, below 150 dB re 1 µPa RMS @ 1 m and perceived above ambient noise.

Kelp gulls Larus dominicanus (KG) feed on the skin and blubber of living southern right whales Eubalaena australis (SRWs) off Península Valdés (PV), Argentina. The whales respond strongly to KG micropredation by changing their immediate (acute) behavior during attacks and their overall (chronic) surfacing pattern and body posture to minimize gull exposure. The energetic and large-scale behavioral consequences of these attacks are unknown. To address this knowledge gap, we quantified the effect size of both acute (during attacks) and chronic (not during attacks) responses by comparing the respiration rates, swim speed, and nursing behavior of PV SRWs to undisturbed (control) SRW mother-calf pairs in Head of Bight, Australia, using unmanned aerial vehicle focal follows. Even when gulls were not attacking, PV SRW mothers and calves demonstrated ~50 and ~25% higher respiration rates, respectively, than whales in Australia. During attacks, PV calf respiration rates increased by an additional 10%. PV SRW mothers also frequently (>76% of respirations) exhibited irregular breathing postures, causing the whales to potentially expend extra energy by working against their natural buoyancy. Despite no significant increase in average maternal swim speed, 76 and 90% of gull attacks elicited strong behavioral reactions from mothers and calves, respectively. Overall, PV calves spent less time nursing during individual bouts compared to those in Australia but entered suckling position more frequently. Furthermore, kelp gulls seemed to show a preference for attacking previously wounded calves and at a higher rate. These chronic and acute behavioral effects may carry energetic costs, which could have long-term consequences for SRW survival and reproduction.

Insights into the food habits of predators are essential for maintaining healthy predator populations and the functioning of ecosystems. Stomach content and stable isotope analyses were used to investigate the foraging habits of an apex predator, the Indo-Pacific bottlenose dolphin (Tursiops aduncus) in south-western Australia. A total of 2,594 prey items from 26 families were identified from the stomachs of 10 deceased stranded dolphins. Fish otoliths from stomach contents were used to identify fish to family or species level. Ninety-three percent of identified stomach contents were perciforme fishes, however, perciformes comprised only 30% of the catch during prey sampling. Gobiidae species, small fish generally 15N) and carbon (δ13C) ratios. From stable isotope analyses and boat-based dolphin photo-identification surveys (n = 339, 2007–2011), results indicated niche differentiation between coastal and inshore (bay and estuarine habitat) dolphins. Carbon signatures showed that coastal dolphins had a more pelagic diet compared to a benthic diet observed in the inshore dolphins. Whereas, nitrogen signatures of inshore dolphins showed higher nitrogen levels than coastal dolphins, likely attributed to feeding on enriched prey typical of estuarian environments. Overall, these results indicated that bottlenose dolphins in the study area were selective foragers and that their foraging is specialized by the habitats most frequently used.

Ryan, C. (2020). Lipid content of whale blubber cannot be measured using biopsies. J. Exp. Biol. 223, jeb227710. [doi:10.1242/jeb.227710][1] [1]: https://doi.org/10.1242/jeb.227710

Disturbance from whale-watching can cause significant behavioural changes with fitness consequences for targeted whale populations. However, the sensory stimuli triggering these responses are unknown, preventing effective mitigation. Here, we test the hypothesis that vessel noise level is a driver of disturbance, using humpback whales (Megaptera novaeangliae) as a model species. We conducted controlled exposure experiments (n = 42) on resting mother-calf pairs on a resting ground off Australia, by simulating whale-watch scenarios with a research vessel (range 100 m, speed 1.5 knts) playing back vessel noise at control/low (124/148 dB), medium (160 dB) or high (172 dB) low frequency-weighted source levels (re 1 μPa RMS@1 m). Compared to control/low treatments, during high noise playbacks the mother’s proportion of time resting decreased by 30%, respiration rate doubled and swim speed increased by 37%. We therefore conclude that vessel noise is an adequate driver of behavioural disturbance in whales and that regulations to mitigate the impact of whale-watching should include noise emission standards., eLife digest Whale-watching is a multi-billion-dollar industry that is growing around the world. Typically, tour operators use boats to transport tourists into coastal waters to see groups of whales, dolphins or porpoises. There is, however, accumulating evidence that boat-based whale-watching negatively affects the way these animals behave and so many countries have put guidelines in place to mitigate activities that may disturb the animals. These guidelines generally stipulate the boat’s angle of approach, how close the boat can get and the speed at which it can pass by the animals. In general, these guidelines are based on the assumption that the animals are disturbed by the closeness of the whale-watching boats. However, whales, dolphins and porpoises have very sensitive hearing, and only have a short range of vision underwater. Therefore, it seems plausible that the animals hear whale-watching boats long before they see them and so the loudness of underwater noise from the boats may be enough to disturb these animals' behaviour. To test this hypothesis, Sprogis et al. performed experiments where they simulated a whale-watching vessel approaching humpback whale mothers and calves who were resting off the northwest coast of Australia. A small motorised research boat travelling at a low speed passed different mother-calf pairs at a target distance of 100 meters, which is a common whale-watching distance guideline in many countries. The boat had an underwater speaker that played recordings of the boat noise at different volumes, while a drone with a video camera flew overhead to record the whales’ behaviours in detail and to identify individual animals. These “controlled exposure experiments” showed that the quiet boat noise did not appear to disturb the mothers and calves. However, compared to when the quiet boat passed the animals the louder boat noise decreased how long the mother whale rested on the surface by 30%, made her swim 37% faster, and doubled the number of breaths she took per minute. If there are many disturbances from humans, then it can negatively impact the energy the mother and calf have available for nursing, fending off males and predators, and migrating back to their feeding ground nearer the Earth’s poles. Based on these findings, it is shown that the loudness of the underwater noise from boats can explain why whales may be disturbed during whale-watching activities. To help reduce this disturbance, Sprogis et al. recommend that noise emission standards should be added to the current whale-watching regulations such that boats should be as quiet as possible and ideally around the volume of the ambient background noise. This would allow operators to approach the animals in a responsible, sustainable manner and offer tourists a view of undisturbed wildlife.

An animal's body condition provides valuable information for ecophysiological studies, and is an important measure of fitness in population monitoring and conservation. While both the external body shape of an animal, as well as its internal tissues (i.e. fat content) can be used as measures of body condition, the relationship between the two is not always linear. We compared the morphological body condition (external metric obtained through aerial photogrammetry) of migrating humpback whales (Megaptera novaeangliae) with their outer blubber lipid concentration (internal metric obtained through blubber biopsy sampling) off south-west Australia early and late in the breeding season (spanning ∼4.5 months). The external body condition index of juvenile and adult humpback whales decreased with 26.9 (from 18.8 to −8.1%) and 12.0 percentage points (from 8.6 to −3.4%) between the early and late phase, respectively. In contrast, we found no intra-seasonal change in blubber lipid concentration, and no difference between reproductive classes (juveniles, adults and lactating females), however the small sample size prevented us from effectively testing these effects. Importantly however, in the 33 animals for which paired metrics were obtained, we found no correlation between the morphometric body condition index and the blubber lipid concentration of individual whales. The lack of a linear relationship suggest that changes in outer blubber lipid concentration do not reflect external changes in body shape, thus limiting the utility of outer blubber lipid reserves for individual body condition evaluation. The wider spectrum of change in body morphometry captured with aerial photogrammetry, supports the use of body morphometry as a reliable and well tested method.

Effective management of wildlife populations rely on knowledge of their abundance, survival, and reproductive rates. Maintaining long‐term studies capable of estimating demographic parameters for long‐lived, slow‐reproducing species is challenging. Insights into the effects of research intensity on the statistical power to estimate demographic parameters are limited. Here, we investigate implications of survey effort on estimating abundance, home range sizes, and reproductive output of Indo‐Pacific bottlenose dolphins (Tursiops aduncus), using a 3‐year subsample of a long‐term, capture–recapture study off Bunbury, Western Australia. Photo‐identification on individual dolphins was collected following Pollock's Robust Design, where seasons were defined as “primary periods”, each consisting of multiple “secondary periods.” The full dataset consisted of 12 primary periods and 72 secondary periods, resulting in the study area being surveyed 24 times/year. We simulated reduced survey effort by randomly removing one, two, or three secondary periods per primary period. Capture–recapture models were used to assess the effect of survey intensity on the power to detect trends in population abundance, while individual dolphin sighting histories were used to assess the ability to conduct home range analyses. We used sighting records of adult females and their calving histories to assess survey effort on quantifying reproductive output. A 50% reduction in survey effort resulted in (a) up to a 36% decline in population abundance at the time of detection; (b) a reduced ability to estimate home range sizes, by increasing the time for individuals to be sighted on ≥30 occasions (an often‐used metric for home range analyses) from 7.74 to 14.32 years; and (c) 33%, 24%, and 33% of annual calving events across three years going undocumented, respectively. Results clearly illustrate the importance of survey effort on the ability to assess demographic parameters with clear implications for population viability analyses, population forecasting, and conservation efforts to manage human–wildlife interactions.

Food-provisioning of wildlife can facilitate reliable up-close encounters desirable by tourists and, consequently, tour operators. Food-provisioning can alter the natural behavior of an animal, encouraging adverse behavior (e.g. begging for food handouts), and affect the reproductive success and the viability of a population. Studies linking food-provisioning to reproductive success are limited due to the lack of long-term datasets available, especially for long-lived species such as marine mammals. In Bunbury, Western Australia, a state-licensed food-provisioning program offers fish handouts to a limited number of free-ranging bottlenose dolphins (Tursiops aduncus). Coupled with long-term historical data, this small (200 individuals), resident dolphin population has been extensively studied for over ten years, offering an opportunity to examine the effect of food-provisioning on the reproductive success of females (n

Swim-with-whale tourism is a lucrative and rapidly growing industry worldwide. Whale-watching can cause negative effects on the behaviour of targeted animals. Although this is believed to be particularly true for close-up interactions, such as swim-with operations, few empirical studies have investigated this. In 2016, the Western Australian State Government commenced a swim-with humpback whale (Megaptera novaeangliae) trial in the Ningaloo Marine Park, where 11 commercial licences were granted. The swim-with trial was conducted during both the northern and southern whale migration (August to November), during which we assessed potential short-term behavioural effects on humpback whales to swim-with activities. From both an independent research vessel (n = 300 h) and on-board commercial swim-with vessels (n = 357 h), we collected group-follow data (n = 224) on whale behaviour before, during and after swim-with activities. Behavioural effects on whales were investigated, including movement patterns (deviation and directness index, heading, swim speed), surfacing patterns (dive duration and respiration rate) and occurrence of agonistic behaviours. Results showed that the most common type of vessel approach to place swimmers in the water was in the path of whales (89.8% of interactions). During in-path approaches, vessels travelled significantly faster (P =.002) compared to when approaching from the side (side/line abreast approaches). When vessels approached in the whales' path, whales exhibited horizontal and vertical avoidance strategies by adopting a less predictable path (deviating from 32° to 46°), increasing turning angles away from the vessel (heading from 73° to >90°), increasing swim speeds (from 1.68 to 1.89 ms −1), and decreasing the duration of their dives (from 224 to 194 s). Whales displayed a higher frequency of agonistic behaviours when a swim-with vessel was 100 m away (P =.011). Young-of-year calves were present during 19.6% (18 of 92) of group-follows that included swim attempts. To reduce potential impacts on whales and increase swimmer safety, we recommend to avoid in-path vessel approaches, not place swimmers in the water with groups of whales that perform agonistic behaviours, and avoid swimming with young-of-year calves.

Food-provisioning of wildlife can facilitate reliable up-close encounters desirable by tourists and, consequently, tour operators. Food-provisioning can alter the natural behavior of an animal, encouraging adverse behavior (e.g. begging for food handouts), and affect the reproductive success and the viability of a population. Studies linking food-provisioning to reproductive success are limited due to the lack of long-term datasets available, especially for long-lived species such as marine mammals. In Bunbury, Western Australia, a state-licensed food-provisioning program offers fish handouts to a limited number of free-ranging bottlenose dolphins (Tursiops aduncus). Coupled with long-term historical data, this small (ntotal = 63; nprovisioned females = 8). Female reproductive success was estimated as the number of weaned calves produced per reproductive years and calf survival at year one and three years old was investigated. The mean reproductive success of provisioned and non-provisioned females was compared using Bayes factor. We also used generalized linear models (GLMs) to examine female reproductive success in relation to the occurrence of food-provisioning, begging behavior and location (within the study area). Furthermore, we examined the influence of these variables and birth order and climatic fluctuations (e.g. El Niño Southern Oscillation) on calf survival. Bayes factor analyses (Bayes factor = 6.12) and results from the best fitting GLMs showed that female reproductive success and calf survival were negatively influenced by food-provisioning. The negative effects of food-provisioning, although only affecting a small proportion of the adult females’ population (13.2%), are of concern, especially given previous work showing that this population is declining.

An animal's body condition will affect its survival and reproductive success, which influences population dynamics. Despite its importance, relatively little is known about the body condition of large whales and its relationship to reproduction. We assessed the body condition of humpback whales (Megaptera novaeangliae) at a breeding/resting ground from aerial photographs recorded using an unmanned aerial vehicle (UAV). Photogrammetry methods were used to measure the surface area of individual whales, which was used as an index for body condition. Repeated measurements of the same individuals were not possible; hence, this study represents a cross-sectional sample of the population. Intraseasonal changes in the body condition of four reproductive classes (calves, immature, mature, and lactating) were investigated to infer the relative energetic cost that each class faces during the breeding season. To better understand the costs of reproduction, we investigated the relationship between female body condition (FBC) and the linear growth and body condition of their dependent calves (CBC). We documented a linear decline in the body condition of mature whales (0.027 m2/d; n = 20) and lactating females (0.032 m2/d; n = 31) throughout the breeding season, while there was no change in body condition of immature whales (n = 51) and calves (n = 32). The significant decline in mature and lactating female's body condition implies substantial energetic costs for these reproductive classes. In support of this, we found a positive linear relationship between FBC and CBC. This suggests that females in poorer body condition may not have sufficient energy stores to invest as much energy into their offspring as better conditioned females without jeopardizing their own body condition and survival probability. Measurement precision was investigated from repeated measurements of the same animals both from the same and different photographs, and by looking at residual errors in relation to the positioning of the whales in the photographs. The resulting errors were included in a sensitivity analysis to demonstrate that model parameters were robust to measurement errors. Our findings provide strong support for the use of UAVs as a noninvasive tool to measure the body condition of whales and other mammals.

Inherent difficulties in determining the sex of free-ranging, sexually monomorphic species often prevents a sex-specific focus on estimating abundance, movement patterns and survival rates. This study provides insights into sex-specific population parameters of Indo-Pacific bottlenose dolphins (Tursiops aduncus). Systematic, boat-based photo-identification surveys (n = 417) were conducted year-round from 2007 to 2013 in coastal and estuarine waters off Bunbury, Western Australia. Pollock's Robust Design was used to quantify population parameters for three datasets: (i) adults and juveniles combined, (ii) adult females and, (iii) adult males. For all datasets, abundance estimates varied seasonally, with general highs during summer and/or autumn, and lows during winter. Dolphins had seasonally structured temporary emigration rates with similar trends between sexes. The derived return rate (1-γ') of temporary emigrants into the study area was highest from winter to spring, indicating that dolphins had a high probability of return into the study area during spring. We suggest that the return of dolphins into the study area and increase in abundance is influenced by the breeding season (summer/autumn). Prey availability is likely a main driver responsible for the movement of dolphins out of the study area during winter. Seasonal apparent survival rates were constant and high (0.98–0.99) for all datasets. High apparent survival rates suggest there is no permanent emigration from the study area. Our sex-specific modeling approach offers a comprehensive interpretation of the population dynamics of a top predator in a coastal and estuarine environment and acts as a model for future sex-based population studies on sexually monomorphic species.