NZ-Australia Antarctic Ecosystems Voyage to the Ross Sea - Marine Mammal Data

Brief description

This metadata record is a parent for all data on Antarctic blue whales collected during the 2015 New Zealand-Australia Antarctic Ecosystems Voyage. Description of specific data sets can be found in the Voyage Science Plan and within child datasets.

Lineage

Progress Code: completed

Statement: See the child records for more information.

Notes

Purpose
The New Zealand-Australia Antarctic Ecosystems Voyage was a 42-day research expedition to the Ross Sea region between the 29 January and 11 March 2015. The focus of the voyage was multidisciplinary ecological studies of marine foodwebs of importance to top predators. This dataset primarily describes the research related to the Antarctic Blue Whale Project of the IWC-Southern Ocean Research Partnership. Two phases of blue whale research occurred during the voyage (8-14 February and 24 February-2 March). During these periods the ship’s position was guided by bearings to calling blue whales detected using DIFAR sonobuoys. Over the voyage 310 sonobuoys were deployed that detected over 40,000 individual blue whale calls over 520 hours of recordings. These calls indentified 4,000 triangulated positions of calling blue whales. There was a marked increase in the rate of blue whale calling after 8 February. Total visual sightings effort was 467 hours yielding a total of 480 sightings of approximately 1297 cetaceans, including 29 confirmed sightings of approximately 81 Antarctic blue whales. Photo-identification data were collected from 58 blue whales. The acoustic and visual data suggest the blue whales were very strongly aggregated in a region approximately centred around 69 S, 178 W. Photogrammetry was used to describe the behaviour of the blue whales and active acoustic surveys, meso-pelagic trawling and oceanographic data were collected to describe the prey field and habitat characteristics of the blue whale aggregation. Preliminary analyses of the active acoustic surveys suggest the blue whale aggregation was associated with an area populated by very dense but patchily distributed krill swarms at depths less than 100 m.