Abstract
Abstract We need reliable information about the spatial and temporal distribution of mobile species to effectively manage anthropogenic impacts to which they are exposed. Yet, we often cannot sustain dedicated annual surveys and data obtained from platforms of opportunity offer an alternative avenue to understand where these species spend time. Four odontocete species that occur in the four‐island region of Maui, Hawai'i, USA, are vulnerable to a range of human activities, but there is a lack of information regarding their distribution. We therefore do not know the extent of the risk these activities present for the conservation of these species (bottlenose dolphins, spinner dolphins, Pantropical spotted dolphins and false killer whales). We used a cross‐validated maximum entropy (MaxEnt) occupancy model to estimate the distribution of these four species in an area extensively observed from platforms of opportunity (PoP). We then determined in a similar fashion whether the calves of those species were more likely to be observed in particular areas and whether distribution changed with season. Maxent models relying on local environmental variables described dolphin observations well (AUC > 0.7). Their distribution differed for all species when calves were present, indicating that different environmental variables describe area use for schools with calves present. The number of sighting events of all species varied significantly with season. Bottlenose dolphins and false killer whales were more prevalent in winter, while spotted and spinner dolphins were more prevalent in summer. We show that an overlap in the distribution of dolphin schools with calves and vessel traffic in the region could result in collision and chronic stress risks. This suggests a need for specific regulations for mitigating anthropogenic influences, such as acoustic disturbance or chronic energetic disturbance from vessel traffic. This elevated risk associated with vessel traffic is likely of conservation concern in this region for the endangered population of false killer whales and for spinner dolphins.
Highlights
The extent to which anthropogenic impacts can cause conservation risks for highly mobile species depends on the degree of overlap in the distribution of human activities and those species (Pirotta et al, 2018)
Four odontocete species that occur in the four-island region of Maui, Hawai’i, USA, are vulnerable to a range of human activities, but there is a lack of information regarding their distribution
We show that an overlap in the distribution of dolphin schools with calves and vessel traffic in the region could result in collision and chronic stress risks
Summary
The extent to which anthropogenic impacts can cause conservation risks for highly mobile species depends on the degree of overlap in the distribution of human activities and those species (Pirotta et al, 2018). The conservation of populations that are not exposed to direct takes, but instead face chronic exposure to non-lethal disturbances, can be affected by reduced reproductive success (Béchet et al, 2004; Beissinger & Peery, 2007; Crooks, 2002; Manlik, 2019; Manlik et al, 2016; Pirotta et al, 2018; Raithel et al, 2007). For species facing chronic exposure to anthropogenic impacts, it is important to understand the extent of the overlap between their range and these human activities, but whether there is an overlap with areas where mothers and calves are more likely to be present. Areas known to have high occurrences of juveniles or that function as nursery areas are high priority for conservation efforts and protections (CBD, 2008; IUCN Marine Mammal Protected Areas Task Force, 2018)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
