Vessel noise levels drive behavioural responses of humpback whales with implications for whale-watching

Sprogis, Kate R.; Videsen, Simone K. A.; Madsen, Peter T.

doi:10.7554/elife.56760

Cited by 65 publications

(41 citation statements)

References 39 publications

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“…We ran a backwards PCoD model to determine if a "worst case" exposure regime would lead to population-level consequences via increased calf mortality. Here, we assumed the repercussion of the seismic survey was the reduced opportunity for nursing, given a decrease in resting behavior (and likely nursing) has been found in humpback whales in the presence of vessels (Morete et al, 2007;Sprogis et al, 2020). The maximal amount of milk a calf can receive is limited by the rate of delivery from the mother and the time available for feeding.…”

Section: Discussionmentioning

confidence: 99%

Assessing Population-Level Effects of Anthropogenic Disturbance on a Marine Mammal Population

et al. 2021

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The Population Consequences of Disturbance (PCoD) model is a conceptual framework used to assess the potential for population-level consequences following exposure of animals to a disturbance activity or stressor. This framework is a four-step process, progressing from changes in individual behavior and/or physiology, to changes in individual health, then vital rates, and finally to population-level effects. Despite its simplicity, there are few complete PCoD models available for any marine mammal species due to a lack of data available to parameterize many of the steps. Here, we present an application of the PCoD framework for migrating humpback whales exposed to a simulated commercial seismic survey scenario. We approached the framework in two ways; first, progressing sequentially forwards through the steps and basing our assessment on lactating females. This cohort was considered to be the most vulnerable in terms of energetic costs of disturbance, and most likely to influence any change in population growth due to future breeding success. Field measurements of behavioral responses of migrating humpback whales to seismic air guns from a previous study were used to parameterize an agent-based model (ABM). This ABM was used to estimate the probability of response, where a response was defined as a change in the migratory movement of female-calf pairs, and the duration of any resulting delay in migration. We then estimated the energetic consequences of any delay in migration for the lactating females and created population growth models with which to assess any population-level effects. The results of the forwards approach suggested a low potential for population consequences of seismic surveys on migrating humpbacks. Working backwards through the framework, we investigated “worst case” scenarios that could potentially lead to a population-level effect. Here, we started with increasing calf mortality and assumed that an exposure time greater than 48 h would increase mortality risk. We determined the most likely context in which this exposure would occur (resting area) and then tested this context within an ABM. This backwards approach illustrates how the PCoD model can be used to make management decisions regarding animal populations and exposure to anthropogenic stressors.

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Section: Discussionmentioning

confidence: 99%

Assessing Population-Level Effects of Anthropogenic Disturbance on a Marine Mammal Population

et al. 2021

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“…Additionally, considering that the noise of the boats generated by the propeller cavitation produces adverse reactions in whale behavior (Erbe et al, 2019), and that more noise is produced at higher speed (Walker et al, 2019), the behavioral change of the animals may be due to the increase in the boats speed. Although we did not use the speed and path direction of the boats moving away as predictive variables, there is evidence that these variables negatively impact the behavior of large cetaceans (Heckel et al, 2001;Argüelles et al, 2016;Fiori et al, 2019), since this avoidance strategy increases the energetic cost for the animals (Williams et al, 2009;Sprogis et al, 2020b). We recommend that future studies incorporate other variables to describe the boat behavior, such as speed and direction of arriving and departing boats, to identify other potentially relevant factors in the responses of fin whales to WW.…”

Section: Discussionmentioning

confidence: 99%

“…However, there is currently a strong concern over whether WW is an activity that really promotes the conservation of the subject species (Forestell, 2007). It has been widely reported in the literature that inadequate management of WW is an important source of perturbation for the animals, both in the short-and long-term (e.g., Corkeron, 2004;Bejder et al, 2006a;Argüelles et al, 2016;Sprogis et al, 2020b). Important sources of perturbation include a high number of boats in a confined area, very close proximity to the animals, the time and manner of approaching (and leaving) the animals, and lack of regulations or non-compliance with existing norms and regulations (Hoyt and Parsons, 2014).…”

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confidence: 99%

“…It has been shown that the displacement trajectory of orcas (Orcinus orca) becomes more linear as the number of boats increases, indicating that the evasion tactic (increase in reorientation) may not be effective in the presence of a larger number of boats (Williams and Ashe, 2007;Williams et al, 2009). If evasive tactics are not effective, cetaceans must use strategies that are more energetically costly (Morete et al, 2007;Sprogis et al, 2020a,b), such as an increase in the velocity of displacement in the presence of boats Sprogis et al, 2020b). Another energetically expensive tactic used by cetaceans is vertical evasion, in which cetaceans increase their diving time (Stamation et al, 2010;Schaffar et al, 2013) and/or increase the rate of respiration .…”

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confidence: 99%

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Impacts of Whale-Watching on the Short-Term Behavior of Fin Whales (Balaenoptera physalus) in a Marine Protected Area in the Southeastern Pacific

et al. 2021

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Whale-watching (WW) is an activity which has been increasing worldwide due to the great interest of tourists and the economic benefits it provides to local communities. However, it has been reported that this activity affects the behavioral patterns of some cetaceans, although for some species such as the fin whale (Balaenoptera physalus) this has not been extensively studied. To identify the effects of WW on the behavioral patterns of this species, we studied its traveling and resting behaviors in a locality of north-central Chile from 2015 to 2018. Using a theodolite, we calculated the response variables of swim speed, directness index, and reorientation for each behavior. We used the number of WW boats and the WW scenarios of “before”, “during”, and “after” the presence of boats as possible factors to explain the differences in the response variables of the whales, along with the factors of year, month, group size, and distance from the observation point. Reorientation increased significantly and the directness index decreased significantly for both traveling and resting behaviors from “before” to “during” WW scenarios, indicating more erratic and sinuous movements in the presence of boats. These changes in movement patterns are a commonly reported evasion response of cetaceans to the presence of WW boats. For traveling behavior, the swimming speed significantly increased, and trends showed increased reorientation and a decrease in the directness index in the “after” WW scenario, which suggests perturbation of the whales potentially associated with the speed and the direction in which the boats left. During resting behavior, the trajectories of the fin whales became straighter (decrease in reorientation) as the number of boats increased, thus evasion (more erratic and sinuous movements) is a behavior used less by fin whales as the number of boats increases. Notwithstanding the fact that tourism development in the study area is small in scale, we found that WW generates adverse effects that are reflected in changes in the whales’ movement patterns. This kind of information is valuable to the adjustment and/or design of management strategies for the species, which is fundamental for WW to continue to be a sustainable activity.

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“…However, behavioral changes can occur before boats enter this threshold distance (e.g., Watkins, 1986;Baker and Herman, 1989;Sprogis et al, 2020a). Sprogis et al (2020b) demonstrated that vessel noise drives the behavioral response of humpback whales to boats. Although, we recorded the number of boats and their timing with the whales, the limitations imposed by the distance of the land-based survey, precluded us to unravel the role of noise of the boats on the behavior of the whales.…”

Section: Sampling Methodsmentioning

confidence: 99%

Energetic Effects of Whale-Watching Boats on Humpback Whales on a Breeding Ground

et al. 2021

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Interactions between whale-watching boats and cetaceans can lead to changes in their behavior. From a management perspective, it is important to understand how this type of disturbance can be translated into physiological effects, such as changes in their energetic metabolism. Humpback whales (Megaptera novaeangliae) typically do not feed while in breeding grounds, thus they depend on finite energy reserves. The effect of whale-watching boats on the energetic metabolism of humpback whales, in the breeding ground of northern Peru (4°10′35″S, 81°08′03″W) was evaluated. Groups of humpback whales were tracked from land, under the following scenarios: with, without, and before-during-after the presence of whale-watching boats. Mass-specific cost of transport (COT) was used as a proxy of energetic efficiency and calculated from swimming speed and breath frequency estimations. No differences were detected in breath frequency, swimming speed, and COT when comparing whales with and without boats. However, in the presence of boats, swim speed increased, and COT decreased as the number of boats increased. Exponential increment in breathing frequency at higher swimming speed was not detected. The absence of swimming speeds beyond the assumed optimal range suggested no shifts into metabolic inefficiency. Our results suggest optimal swimming speed between 2 and 4.05 m/s, representing COT values between 0.020 and 0.041 J × (kg × m)–1. In light of our results, we encourage the implementation of regulations of the activity, particularly limiting the number of boats interacting with the same group of humpback whales.

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Vessel noise levels drive behavioural responses of humpback whales with implications for whale-watching

Cited by 65 publications

References 39 publications

Assessing Population-Level Effects of Anthropogenic Disturbance on a Marine Mammal Population

Assessing Population-Level Effects of Anthropogenic Disturbance on a Marine Mammal Population

Impacts of Whale-Watching on the Short-Term Behavior of Fin Whales (Balaenoptera physalus) in a Marine Protected Area in the Southeastern Pacific

Energetic Effects of Whale-Watching Boats on Humpback Whales on a Breeding Ground

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