An acoustic survey of baleen whales off Great Barrier Island, New Zealand

Abstract

Acoustic recordings of baleen whale calls were analysed for the calendar year 1997 from a pair of fixed hydrophones located 5 km east of Great Barrier Island, New Zealand. The primary goal of the study was to examine blue whale seasonally and song type as part of a larger worldwide study. Calls were recorded from blue whales of two song types, fin whales, humpback whales, Bryde's whales, and of two unknown call types, each probably produced by Bryde's whales. The peak of calling density was May through September for the blue, fin, and humpback whales. The known Bryde's whale calls occurred year-round and the probable Bryde's whale calls occurred from May through December. Blue whale songs of a type so far known only from New Zealand waters were detected within 2 km of shore and occurred four times from June to December, whereas the Southern Ocean blue whale songs were detected only further offshore in mid-winter. Bryde's whale calls were the most abundant type and often occurred near the hydrophones. These data provide a baseline from which future recordings from the same hydrophones could be compared.

Overlooking a potential hotspot at Great Barrier Island for the nationally endangered bottlenose dolphin of New Zealand

“…Additionally, a recently reported mortality event at GBI involved a fatal boat strike to a juvenile bottlenose dolphin (Dwyer et al 2014). Adult survival estimates for GBI are slightly higher than those reported for BOI (0.928, SE = 0.008) for − 2006(Tezanos-Pinto et al 2013) but similar to Bunbury (0.95, SE = 0.02) for 2007−2009 (Smith et al 2013).…”

“…Great Barrier Island (GBI) is situated in the outer Hauraki Gulf and within the home range of the North Island population (Constantine 2002); however, previous marine mammal research efforts in the GBI re gion have been limited to large whale acoustics (Kibble white et al 1967, Helweg 1998, McDonald 2006. No dedicated delphinid studies have been conducted in the GBI area, likely due to a combination of an absence of direct interest from stakeholders and the logistical constraints of fieldwork in this comparatively remote location.…”

Documentation of a New Zealand blue whale population based on multiple lines of evidence

“…Acoustic data were collected from 23 January to 30 June 2016, and 11 July to 29 December 2016 (MARU refurbishment occurred during the brief interim period). While a New Zealand blue whale call type has previously been documented and described (McDonald 2006), the source level is unknown. The estimated source level for pygmy blue whale song in the eastern Indian Ocean is 179 ± 2 dB re 1 µPa at 1 m (Gavri lov et al 2011), and the estimated maximum acoustic detection range is 50 to 200 km (Gavrilov & Mc Cauley 2013), depending on the recorder capabilities, ambient noise levels, and sound propagation conditions.…”

Validating the reliability of passive acoustic localisation: a novel method for encountering rare and remote Antarctic blue whales

“…By using a high spectral resolution when viewing spectrograms of whale calls, the 26 Hz tone of Unit A is sufficiently distinguishable from vocalisations produced by blue whales around New Zealand (McDonald 2006, pygmy blue whales in the Indian Ocean (Gavrilov et al 2011, Gavrilov & McCauley 2013, Samaran et al 2013, and those of Chilean blue whales in the southeast Pacific (Buchan et al 2010(Buchan et al , 2014; thus, the risk of misclassification would be minimal.…”