Abstract
Hawaiian spinner dolphins (Stenella longirostris) rest during the day in the islands’ coastal waters where they are susceptible to human disturbance. Due to concerns over the negative impacts of human activity, the Pacific Islands Regional Office of the National Oceanic and Atmospheric Administration (NOAA) has proposed a 50-yard approach rule for spinner dolphins and is also considering time-area closures of certain important spinner dolphin resting areas. However, gaps still persist in the understanding of how spinner dolphin populations on different Hawaiian Islands use coastal waters, raising questions about the efficacy of the proposed rules. To better understand how spinner dolphins use the waters in the Maui Nui region (Maui, Moloka‘i, Lāna‘i, and the ‘Au‘au channel), a study was conducted using a combination of passive acoustic monitoring and vessel surveys to document spinner dolphin occurrence and movements. Bottom-moored acoustic recorders were deployed at eight locations in Maui Nui, and at one previously established resting bay off west O‘ahu for comparison. The amount of whistles, clicks, and burst pulses at each location was quantified and averaged by the hour of the day. Acoustic activity was greater at the O‘ahu site than at any of the Maui Nui sites, and was greatest between sunrise and noon. Acoustic activity and vessel surveys both reveal that spinner dolphins occur and exhibit resting behaviors in the ‘Au‘au channel between Maui and Lāna‘i, and also along west Maui and southeast Lāna‘i. Spinner dolphins resting in a channel between islands appears to be unique to Maui Nui and differs from resting patterns described along Hawai‘i Island and O‘ahu. Because spinner dolphins appear to use both the coastlines and the channel to rest in Maui Nui, the 50-yard approach rule appears to be a more suitable management option for the region than time-area closures.
Highlights
The spinner dolphin (Stenella longirostris) is a well-studied odontocete species distributed across tropical and subtropical oceans of the world
Spinner dolphin habitat-use patterns in Maui Nui do not follow the same patterns of consistent use of specific bays that has been documented off the Kona coast of Hawai‘i Island and the Wai‘anae coast of O‘ahu (Norris et al, 1994; Lammers, 2004; Thorne et al, 2012)
Based on the combination of passive acoustic monitoring and vessel surveys, the evidence from this study suggests that Maui Nui spinner dolphins utilize a combination of the west Maui coastline, the southeast Lana‘i coastline, and the ‘Au‘au channel during their daytime resting
Summary
The spinner dolphin (Stenella longirostris) is a well-studied odontocete species distributed across tropical and subtropical oceans of the world. Spinner Dolphins in Maui Nui dolphins are reliably found along the island’s sloping coastlines where they follow predictable, daily behavioral routines (Norris et al, 1994). These routines consist of nocturnal foraging, during which spinner dolphins feed on vertically migrating mesopelagic fish, and mesopelagic and epipelagic squid typically found in deeper waters of the island slopes along the 1000-fathom contour (Klinowska, 1991; Norris et al, 1994; Benoit-Bird et al, 2001; Benoit-Bird and Au, 2003). The highly dispersed school tightens into subgroups as it moves into shallower, protected bays to rest (Norris et al, 1994)
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.
