Modern Australian

Genome and satellite technology reveal recovery rates and impacts of climate change on southern right whales

  • Written by Emma Carroll, Rutherford Discovery Fellow, University of Auckland

After close to a decade of globe-spanning effort, the genome of the southern right whale has been released this week, giving us deeper insights into the histories and recovery of whale populations across the southern hemisphere.

Up to 150,000 southern right whales were killed between 1790 and 1980. This whaling drove the global population from perhaps 100,000 to as few as 500 whales in 1920. A century on, we estimate there are 12,000 southern right whales globally. It’s a remarkable conservation success story, but one facing new challenges.

A southern right whale calf breaches in the subantarctic Auckland Islands. A southern right whale calf breaches in the subantarctic Auckland Islands. University of Auckland tohorā research team, Author provided

The genome represents a record of the different impacts a species has faced. With statistical models we can use genomic information to reconstruct historical population trajectories and patterns of how species interacted and diverged.

We can then link that information with historical habitat and climate patterns. This look back into the past provides insights into how species might respond to future changes. Work on penguins and polar bears has already shown this.

But we also have a new and surprising short-term perspective on the population of whales breeding in the subantarctic Auckland Islands group — Maungahuka, 450km south of New Zealand.

Spying on whales via satellite

Known as tohorā in New Zealand, southern right whales once wintered in the bays and inlets of the North and South Islands of Aotearoa, where they gave birth and socialised. Today, the main nursery ground for this population is Port Ross, in the subantarctic Auckland Islands.

Adult whales socialise at both the Auckland and Campbell Islands during the austral winter. Together these subantarctic islands are internationally recognised as an important marine mammal area.

In August 2020, I led a University of Auckland and Cawthron Institute expedition to the Auckland Islands. We collected small skin samples for genetic and chemical analysis and placed satellite tags on six tohorā. These tags allowed us to follow their migrations to offshore feeding grounds.

It matters where tohorā feed and how their populations recover from whaling because the species is recognised as a sentinel for climate change throughout the Southern Hemisphere. They are what we describe as “capital” breeders — they fast during the breeding season in wintering grounds like the Auckland Islands, living off fat reserves gained in offshore feeding grounds.

Females need a lot in the “bank” because their calves need a lot of energy. At 4-5m at birth, these calves can grow up to a metre a month. This investment costs the mother 25% of her size over the first few months of her calf’s life. It’s no surprise that calf growth depends on the mother being in good condition.

Read more: I measure whales with drones to find out if they're fat enough to breed

Females can only breed again once they’ve regained their fat capital. Studies in the South Atlantic show wintering grounds in Brazil and Argentina produce more calves when prey is more abundant, or environmental conditions suggest it should be.

The first step in understanding the relationship between recovery and prey in New Zealand is to identify where and on what tohorā feed. The potential feeding areas for our New Zealand population could cover roughly a third of the Southern Ocean. That’s why we turn to technologies like satellite tags to help us understand where the whales are going and how they get there.

Where tohorā go

So far, all tracked whales have migrated west; away from the historical whaling grounds to the east near the Chatham Islands. As they left the Auckland Islands, two whales visited other oceanic islands — skirting around Macquarie Island and visiting Campbell Island.

It also seems one whale (Bill or Wiremu, identified as male using genetic analysis of his skin sample) may have reached his feeding grounds, likely at the subtropical convergence. The clue is in the pattern of his tracks: rather than the continuous straight line of a whale migrating, it shows the doughnuts of a whale that has found a prey patch.

Genome and satellite technology reveal recovery rates and impacts of climate change on southern right whales Migratory track of southern right whale Bill/Wiremu, where the convoluted track could indicate foraging behaviour.

The subtropical convergence is an area of the ocean where temperature and salinity can change rapidly, and this can aggregate whale prey. Two whales we tracked offshore from the Auckland Islands in 2009 visited the subtropical convergence, but hundreds of kilometres to the east of Bill’s current location.

As Bill and his compatriots migrate, we’ve begun analysing data that will tell us about the recovery of tohorā in the past decade. The most recent population size estimate we have is from 2009, when there were about 2,000 whales.

Read more: Humans threaten the Antarctic Peninsula's fragile ecosystem. A marine protected area is long overdue

I am using genomic markers to learn about the kin relationships and, in doing so, the population’s size and growth rate. Think of it like this. Everybody has two parents and if you have a small population, say a small town, you are more likely to find those parents than if you have a big population, say a city.

This nifty statistical trick is known as the “close kin” approach to estimating population size. It relies on detailed understanding of the kin relationships of the whales — something we have only really been able to do recently using new genomic sequencing technology.

Global effort to understand climate change impacts

Globally, southern right whales in South Africa and Argentina have bred less often over the past decade, leading to a lower population growth rate in Argentina.

Concern over this slowdown in recovery has prompted researchers from around the world to work together to understand the relationship between climate change, foraging ecology and recovery of southern right whales as part of the International Whaling Commission Southern Ocean Research Partnership.

The genome helps by giving us that long view of how the whales responded to climate fluctuations in the past, while satellite tracking gives us the short view of how they are responding on a day-to-day basis. Both will help us understand the future of these amazing creatures.

Authors: Emma Carroll, Rutherford Discovery Fellow, University of Auckland

Read more https://theconversation.com/genome-and-satellite-technology-reveal-recovery-rates-and-impacts-of-climate-change-on-southern-right-whales-147168

NEWS

New research suggests immunity to COVID is better than we first thought

Early in the pandemic, many researchers feared people who contracted COVID could be reinfected very quickly. This was because several earlystudies showed antibodies seemed to wane after the first few...

who is Antony Blinken, Biden's pick for secretary of state?

US Secretary of State-designate Antony Blinken promises both awkwardness and opportunity for Australia’s Morrison government.Blinken could hardly represent a more striking contrast with his soon-to-be predecessor Mike Pompeo in his...

Think taxing electric vehicle use is a backward step? Here's why it's an important policy advance

The South Australian and Victorian governments have announced, and New South Wales is considering, road user charges on electric vehicles. This policy has drawn scorn from environmental advocates and...

what’s the best way to conduct Australia’s Great Koala Count?

ShutterstockFederal environment minister Sussan Ley this week announced A$2 million for a national audit of Australia’s koalas, as part of an A$18 million package to protect the vulnerable species.The funding...

Data from 45 countries show containing COVID vs saving the economy is a false dichotomy

ShutterstockThere is no doubt the COVID-19 crisis has incurred widespread economic costs. There is understandable concern that stronger measures against the virus, from social distancing to full lockdowns, worsen...

Mining companies are required to return quarried sites to their 'natural character'. But is that enough?

New Zealand has more than 1,100 registered quarries. Some of these mined sites are small, rural operations, but a significant number are large and complex, and within a city’s urban...

the fraught history of women and swearing in Australia

Kath and Kim (aka Jane Turner and Gina Riley): the suburban hornbags used swearing in clever ways in their 2002-2007 TV series.Riley Turner ProductionsWomen have had a fraught historical relationship...

From here on our recovery will need more than fiscal policy, it'll need redistribution

From the 1980s right through to the global financial crisis, the standard response in Australia and elsewhere to too weak or too strong an economy has been monetary policy —...

Forensic linguists can make or break a court case. So who are they and what do they do?

shutterstockIf you’re an avid viewer of crime shows, you’ve probably come across cases in which an expert, often a psychologist, is called in to help solve a crime using their...

Officials' engagement with China especially important in tense times: Morrison

Scott Morrison has encouraged federal public servants to engage with their Chinese counterparts, saying these are important connections particularly given the tensions in the bilateral relationship.Answering a question during a...

two views on increasing the super contribution

The increase in the compulsory superannuation contribution, legislated to rise next July from 9.5% to 10%, is being fiercely debated following the release of the retirement income report.In this podcast...

Victoria is boosting disability support in schools by A$1.6 billion. Here are 4 ways to make the most of it

ShutterstockThe Victorian government has announced an investment of nearly A$1.6 billion for public schools to ensure students with disability are supported in the classroom. The money will double the number...



News Co Media Group

Content & Technology Connecting Global Audiences

More Information - Less Opinion













Popular articles from Modern Australian

Your New Home Needs A Great GardenHow To Identify Signs Of Stress In Your ChildInstalling Shade Sails On your Garden10 Tips for Clearing a Blocked DrainCarpet Cleaning: Where Is It Headed In The Future?Common Repairs to Shipping ContainersThe lifestyle Choices of the Australian Millennials5 Tips For Creating a Kid-Friendly BackyardWhat Happens When You Choose a Wrong Cosmetic Dentist Sydney?Garlic In Your Life: The Health Benefits and How To Grow Your Own GarlicPost-Coronavirus Camping - 5 Tips To Help You Have A Safe And Happy Camping TripEasy Ways to Stop Your Mechanic from Ripping You Off12 Helpful Tips to Increase Your Savings This SummerHow to Organize Your Kid’s Nursery On A Budget