Partnership advances whale research
Over the past eight years the International Whaling Commission’s Southern Ocean Research Partnership (IWC-SORP)* has driven a range of innovative new whale research, resulting in significant advances in tracking, detecting, and ageing marine mammals. Following are some of the highlights.
Tracking and movement instrumentation
IWC-SORP scientists have worked with manufacturers to develop, test and refine satellite tags that contain a suite of sophisticated sensors.
In 2012–13, long-term satellite tags deployed on minke, blue and humpback whales in Antarctica, were used to describe their broad-scale foraging movements and migratory behaviour. The satellite tags provided insights into how the whales move around their feeding grounds in search of prey, where they go when they leave the feeding grounds, and where they go for their winter breeding (Australian Antarctic Magazine 24: 4–5, 2013).
On the same voyage, scientists also deployed short-term, high resolution movement tags on minke, humpback and killer whales. The tags provided information on the whales’ three-dimensional movements, such as dive depth, fluke strokes, acceleration, and the pitch and roll of their bodies. The scientific team was also able to observe the whales’ movements and activity when they dived below the water to feed, while simultaneously assessing prey distribution.
Australian Antarctic Division scientists continued this research off the West Antarctic Peninsula in 2016 and early 2017 (see 'Whale cams' reveal secret life of ocean giants), deploying additional long-term satellite tags on minke whales. The team also deployed suction-cup video tags on the backs of humpback whales, providing a remarkable ‘whale’s eye view’ of where the whales went and what they were eating.
Altogether, information from this tag development and telemetry work is contributing to sophisticated statistical models that are used to derive estimates of whale abundance and foraging ecology. The work will ultimately help scientists determine which areas and prey types are important to the various whale species, for conservation purposes.
Passive acoustic detection and tracking
Before the advent of whaling there were over 200 000 blue whales in the Southern Ocean. Today there are less than 4000, making finding and counting the whales, to assess their recovery, difficult.
Now, novel passive acoustic tracking methods and software have been developed that use ‘directional sonobuoys’ (underwater listening devices) to detect vocalising blue whales up to 1000 km away. The technology allows Antarctic blue whales to be tracked over vast distances and is a huge improvement on previous detection methods that relied on getting close enough to sight whales visually – usually within a 10 km range.
The sonobuoys were used to locate hundreds of Antarctic blue whales, including large aggregations of up to 80 individuals, during the 2010 and 2013 Antarctic Blue Whale voyages (Australian Antarctic Magazine 24: 16–17, 2013) and the 2015 New Zealand-Australia Antarctic Ecosystems voyage.
As a result of this increased encounter rate, scientists were able to conduct the first ecological studies of these rare and endangered animals (Australian Antarctic Magazine 28: 4–5, 2015).
“By matching the sounds recorded by the sonobuoys, with movements recorded by a shipboard video camera, coupled to a GPS and gyro compass, we may be able to identify sounds associated with feeding or breeding,” Australian Antarctic Division acoustician, Dr Brian Miller, said.
“On our 2015 voyage, we always found krill when we saw whales. We think that blue whale aggregations could be driven by foraging and that dense swarms of krill suit the whales, allowing them to feed quickly and efficiently.”
In just a few years, IWC-SORP voyages have contributed over a quarter of all photographs of individual Antarctic blue whales to the circumpolar Antarctic Blue Whale catalogue. The database originated in the early 1990s and is used to assess the total number and recovery of the species.
IWC-SORP voyages have also contributed images to photo-identification catalogues for humpback whales, and the Australian Antarctic Division’s Australian Marine Mammal Centre (AMMC) has developed the Australasian Right Whale Photo-Identification Catalogue for southern right whales. The Australian Antarctic Division also hosts the online National Marine Mammal Data Portal, to which all sightings of cetaceans in Australian waters and the Southern Ocean can be added.
Head of the AMMC, Dr Mike Double, said the catalogues and databases are essential for archiving valuable images and metadata, and sharing them with the international scientific community to maximise the potential for cross-identification and matching of individual whales.
“Ultimately, photo-ID catalogues and databases can help us estimate population abundance, delineate stock structure between different populations of the same species, and piece together movement patterns for recovering whale populations,” Dr Double said.
Underwater listening stations
In 2013, scientists involved in the ‘IWC-SORP Acoustic Trends Project’ commenced an exciting new long-term data collection effort called the Southern Ocean Hydrophone Network (SOHN). This network of 20 underwater listening stations, moored on the sea floor around Antarctica, passively monitors ocean noise for the sounds generated by blue and fin whales.
The SOHN is an international collaboration of scientists from France, Germany, Australia, South Africa, Chile, and the United States and United Kingdom. The underwater listening network will continue to expand as additional resources are made available and additional partners join the network.
The project partners are continuing to improve the recording devices and new loggers are sensitive to a broader spectrum of frequencies, allowing them to detect not only Antarctic whales, but dolphins and seals as well.
Non-lethal genetic ageing
IWC-SORP scientists were the first to apply non-lethal ageing methods to whales, based on changes in the ‘DNA methylation’ of genes involved in the ageing process (Australian Antarctic Magazine 26: 16–17, 2014).
DNA methylation is a biochemical process where a methyl group (CH3) is added to specific DNA building-blocks, altering the expression of genes. DNA methylation is involved in processes like sex determination and the development of many cancers, but it has only recently been shown to be involved in the ageing process.
Estimating age is important for monitoring the recovery of whale populations following commercial whaling. When combined with genetic information about the relatedness of individuals in a population (parents, siblings, offspring), age data improves methods for estimating the size of whale populations and helps scientists understand how the biological characteristics of whales change with age.
Survey design and statistical analyses
IWC-SORP scientists have invested significant effort in determining the most appropriate and efficient survey methods that will provide a new circumpolar abundance estimate for Antarctic blue whales.
This in turn has driven the development of a novel survey approach called ‘kin-based mark-recapture’. The method uses genetic identification of close relatives and can provide an assessment of population size, adult survival and even population trend. The method has since been applied in many commercial fish stocks assessments and has the potential to revolutionise the monitoring of previously intractable species in marine and other environments.
Why does it matter?
The research partnership has contributed valuable data to international bodies, such as the International Whaling Commission, to help conserve and manage whales. The methods and technologies developed and advanced by IWC-SORP scientists have demonstrated that whales do not need to be killed to be studied.
Wendy Pyper1 and Elanor Bell2
1Corporate Communications, Australian Antarctic Division
2Australian Marine Mammal Centre, Australian Antarctic Division
*What is the IWC-SORP?
The Southern Ocean Research Partnership (SORP) was established in March 2009 to enhance cetacean conservation and the delivery of non-lethal whale research to the International Whaling Commission (IWC).
The partners – including Australia, Argentina, Belgium, Brazil, Chile, France, Germany, Italy, New Zealand, Norway, South Africa and the United States – aim to maximise conservation results through research into the status, health, dynamics and environmental linkages of whale populations and the threats they face. The main focus of the partnership is the large whale species managed by the IWC, including the humpback, blue, fin, Antarctic minke, sei, southern right and sperm whales. The partnership is coordinated through the Australian Marine Mammal Centre at the Australian Antarctic Division.
The work of IWC-SORP described in this article has been supported by the governments of its partnering nations, One Ocean Expeditions, WWF-Australia and the International Fund for Animal Welfare.