Marine megafauna catch the sun

Enabling a sustainable World

When it comes to crossing the ocean, all marine megafauna – from penguins, to seabirds, to turtles, to whales – use the same navigational compass – the sun. Using big data, scientists have worked with the global fishing fleet to uncover their movements.

Data from more than three million locations is being used to track the movements of over 5000 of the world’s marine megafauna all over the world.

An international research team is using cutting-edge data capture techniques to access the tracking devices mounted on all large fishing vessels and build their understanding of 50 different species of marine vertebrates. These megafauna are the ocean’s apex predators and key to its biodiversity.

The team has assembled huge data sets from the tagged animals. Their first breakthrough has shown that marine mammals, birds and turtles all have similar movement patterns. Published as the cover feature in the “Proceedings of the National Academy of Sciences of the United States of America” earlier this year, their influential paper shows that habitat determines marine megafaunas’ movement strategies.

Animals in and above the open ocean move in long, straight lines, while those in coastal habitats move more randomly as they search for prey.

Based within Deakin University’s Centre for Integrative Ecology, Alfred Deakin Professor Graeme Hays – a world expert on turtle behaviour – is working with 10 other scientists, IT specialists physicists and mathematicians in the US, Europe and Australia to capture, analyse and interpret the data.

“The fact that type of habitat, rather than species, influences movement was unexpected,” Professor Hays said.

“We detected a remarkable convergence in the distribution of speed and turning angles across organisms, ranging from whales to turtles (which are like the slowest animals on land, but not at sea).

“You would expect that penguins or turtles would have their own ways of navigating through the oceans, but in fact, they use the same techniques. They are driven by their habitat. This is very different to land-based animals where species have evolved their own navigation strategies. Insects and birds can learn landmarks. Homing pigeons use the earth’s magnetic field, while bats use echolocation, for instance. We now have good evidence that all these marine species use the sun as their compass.”

The animals may move by paddling (and walking), swimming or flying. Due to the previous difficulty of tracking their movements, their distribution, abundance, and the ways they influence their ecosystems have not been well understood, noted Professor Hays.

Through the international project, called Marine Megafauna Movement Analytical Program (MMMAP), the scientists are seeking to develop measures to conserve marine megafauna.

“As we increase our understanding of the threats they face, we can determine how we can help them best. Threats include fishing, where these animals may be by-catch (non-targeted species), or ship strikes, which particularly affect whales.”
Alfred Deakin Professor Graeme Hays
Alfred Deakin Professor Graeme Hays Centre for Integrative Ecology

He emphasised that the project will aim to achieve “win-win” solutions with fishing fleets and other stakeholders. For instance, identifying whale routes will reveal areas that vessels can avoid so neither whales nor vessels are impacted.

Data is being collected by satellite as part of the fishing fleet’s global positioning systems. All large vessels on the ocean are required to use an Automatic Identification System (AIS) that broadcasts the ship’s identity and location, with these data being retained in the data-base that can be freely accessed.

Professor Hays explained that his involvement in the MMMAP project evolved out of marine research on abundance trends of sea turtles around the world, which also sought to identify threats and develop measures to protect them.

“Using tracking satellites, we developed the ability to follow individual turtles for far longer, anywhere in the world,” he said.

“Turtles have a hard shell that retains glue like nail polish. We managed to nearly perfect the tracking technology over the past 25 years. The first tags only lasted a few weeks, but the ones we use now can withstand the rigours of the sea for up to a year.

“Sea turtles are a good success story for conservation. They were at risk through over-consumption by humans, being killed for their shells (for jewellery), and being incidentally caught by fishermen. Numbers were in decline in the early 20th century, but moves to protect eggs, and reduce consumption and poaching have been very successful.”

“The marine megafauna information we are collecting now will support evidence-based decisions that will engage the international community. It will be considered by bodies such as the United Nations for improving international laws, which will filter through to policy makers in individual countries and, hopefully, protect our marine biodiversity for coming generations.”

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Main photograph: Gail Schofield


Published by Deakin Research on 9 November 2018

Centre for Integrative Ecology

At the Centre for Integrative Ecology (CIE), we want to know: how do living things react to change, both short term and long term? We aim to eliminate traditional borders between conventional fields of ecological research by promoting an integrative, multi-faceted, interdisciplinary research approach.