Paula A. Olson

Blue whale vocalizations recorded around New Zealand: 1964–2013

Previous underwater recordings made in New Zealand have identified a complex sequence of low frequency sounds that have been attributed to blue whales based on similarity to blue whale songs in other areas. Recordings of sounds with these characteristics were made opportunistically during the Southern Ocean Research Partnerships recent Antarctic Blue Whale Voyage. Detections of these sounds occurred all around the South Island of New Zealand during the voyage transits from Nelson, New Zealand to the Antarctic and return. By following acoustic bearings from directional sonobuoys, blue whales were visually detected and confirmed as the source of these sounds. These recordings, together with the historical recordings made northeast of New Zealand, indicate song types that persist over several decades and are indicative of the year-round presence of a population of blue whales that inhabits the waters around New Zealand. Measurements of the four-part vocalizations reveal that blue whale song in this region has changed slowly, but consistently over the past 50 years. The most intense units of these calls were detected as far south as 53°S, which represents a considerable range extension compared to the limited prior data on the spatial distribution of this population.

New Zealand Blue Whales: Residency, Morphology, and Feeding Behavior of a Little-Known Population

Abstract: Blue whales are infrequently reported from New Zealand and their taxonomic status is unclear. Here we present new information on the residency, external morphology, and habitat use of blue whales encountered in New Zealand waters. Thirty-one blue whales were photo-identified around the North and South Islands of New Zealand from 2004 to 2014 in seven different months of the year. One photographic match was found between June 2011 and March 2013: the first evidence that an individual blue whale has remained in or returned to New Zealand waters in different years and seasons. Observations of the external morphology of blue whales encountered off the South Island confirm that there is a shorter, non-Antarctic form of blue whale occurring near New Zealand. Body length and proportion, head shape, body condition, and skin condition were similar to Australian but not Antarctic blue whales. In 2013, feeding behavior was observed off the South Islands west coast and strong evidence of feeding was observed off the east coast and is the first reported occurrence of feeding for these locations. Feeding behavior was also observed in the Hauraki Gulf in November 2010. Feeding in these widely spread locations, in addition to the recently reported foraging ground in the South Taranaki Bight, suggest that New Zealand coastal waters are a feeding area for blue whales.