Warming oceans are changing Australia’s fishing industry



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Ocean fish are changing where they live due to climate change.
Annie spratt/Unsplash, CC BY-SA

Alistair Hobday, CSIRO; Beth Fulton, CSIRO, and Gretta Pecl, University of Tasmania

A new United Nations report on fisheries and climate change shows that Australian marine systems are undergoing rapid environmental change, with some of the largest climate-driven changes in the Southern Hemisphere.

Reports from around the world have found that many fish species are changing their distribution. This movement threatens to disrupt fishing as we know it.

While rapid change is predicted to continue, researchers and managers are working with fishers to ensure a sustainable industry.




Read more:
Climate-driven species on the move are changing (almost) everything


Lessons from across the world

Large climate-driven changes in species distribution and abundance are evident around the world. While some species will increase, global models project declining seafood stocks in tropical regions, where people can least afford alternative foods.

The global concern for seafood changes led the UN Food and Agriculture Organisation (FAO) to commission a new report on the impacts of climate change on fisheries and aquaculture. More than 90 experts from some 20 countries contributed, including us.

The report describes many examples of climate-related change. For instance, the northern movement of European mackerel into Icelandic waters has led to conflict with more southerly fishing states, and apparently contributed to Iceland’s exit from negotiations over its prospective European Union membership.




Read more:
Loss of marine habitats is threatening the global fishing industry – new research


Changes in fish abundance and behaviour can lead to conflicts in harvesting, as occurred in the Maine lobster fishery. Indirect effects of climate change, such as disease outbreaks and algal blooms, have already temporarily closed fisheries in several countries, including the United States and Australia.

All these changes in turn impact the people who depend on fish for food and livelihoods.

Climate change and fisheries in Australia

The Australian chapter summarises the rapid ocean change in our region. Waters off southeastern and southwestern Australia are particular warming hotspots. Even our tropical oceans are warming almost twice as fast as the global average.




Read more:
Ecosystems across Australia are collapsing under climate change


More than 100 Australian marine species have already begun to shift their distributions southwards. Marine heatwaves and other extreme events have harmed Australia’s seagrass, kelp forests, mangroves and coral reefs. Australia’s marine ecosystems and commercial fisheries are clearly already being affected by climate change.

Summary of recent climate-related marine impacts in Australia. Warming on both coasts is also moving species southwards.
Author provided

In the Australian FAO chapter, we present information from climate sensitivity analysis and ecosystem models to help managers and fishers prepare for change.

We need to preparing climate-ready fisheries, to minimise negative impacts and to make the most of new opportunities that arise.

Experts from around Australia have rated the sensitivity of more than 100 fished species to climate change, based on their life-history traits. They found that 70% of assessed species have moderate to high sensitivity. As a group, invertebrates are the most sensitive, and pelagic fishes (that live in the open ocean sea) the least.

A range of ecosystem models have also been used to explore how future climate change will impact Australia’s fisheries over the next 40 years. While results varied around Australia, a common projection was that ecosystem production will become more variable.

As fish abundance and distribution changes, predation and competition within food webs will be affected. New food webs may form, changing ecosystems in unexpected ways. In some regions (such as southeastern Australia) the ecosystem may eventually shift into a new state that is quite different to today.

How can Australian fisheries respond?

Our ecosystem models indicate that sustainable fisheries are possible, if we’re prepared to make some changes. This finding builds on Australia’s strong record in fisheries management, supported by robust science, which positions it well to cope with the impacts of climate change. Fortunately, less than 15% of Australia’s assessed fisheries are overfished, with an improving trend.

We have identified several actions that can help fisheries adapt to climate change:

  • Management plans need to prioritise the most sensitive species and fisheries, and take the easiest actions first, such as changing the timing or location of operations to match changing conditions.



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  • As ecosystem changes span state and national boundaries, greater coordination is needed across all Australian jurisdictions, and between all the users of the marine environment. For example, policy must be developed to deal with fixed fishing zones when species distribution changes.

  • Fisheries policy, management and assessment methods need to prepare for both long-term changes and extreme events. Australian fisheries have already shifted to more conservative targets which have provided for increased ecological resilience. Additional quota changes may be needed if stock productivity changes.

  • In areas where climate is changing rapidly, agile management responses will be required so that action can be taken quickly and adjusted when new information becomes available.

  • Ultimately, we may need to target new species. This means that Australians will have to adapt to buying (and cooking) new types of fish.




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The ConversationResearchers from a range of organisations and agencies around Australia are now tackling these issues, in partnership with the fishing industry, to ensure that coastal towns with vibrant commercial fishing and aquaculture businesses continue to provide sustainable seafood.

Alistair Hobday, Senior Principal Research Scientist – Oceans and Atmosphere, CSIRO; Beth Fulton, CSIRO Research Group Leader Ecosystem Modelling and Risk Assessment, CSIRO, and Gretta Pecl, Professor, ARC Future Fellow & Editor in Chief (Reviews in Fish Biology & Fisheries), University of Tasmania

This article was originally published on The Conversation. Read the original article.

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Citizen scientist scuba divers shed light on the impact of warming oceans on marine life



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A volunteer diver surveys marine life at Lord Howe Island.
Rick Stuart-Smith/Reef Life Survey, Author provided

Madeleine De Gabriele, The Conversation

Rising ocean temperatures may result in worldwide change for shallow reef ecosystems, according to research published yesterday in Science Advances.

The study, based on thousands of surveys carried out by volunteer scuba divers, gives new insights into the relationship of fish numbers to water temperatures – suggesting that warmer oceans may drive fish to significantly expand their habitat, displacing other sea creatures.

Citizen science

The study draws from Reef Life Survey, a 10-year citizen science project that trains volunteer scuba divers to survey marine plants and animals. Over the past ten years, more than 200 divers have surveyed 2,406 ocean sites in 44 countries, creating a uniquely comprehensive data set on ocean life.

Reef Life Survey takes volunteers on surveying expeditions at hard-to-reach coral reefs around the world.
Rick Stuart-Smith/Reef Life Survey, Author provided

Lead author Professor Graham Edgar, who founded Reef Life Survey, said the unprecedented scope of their survey allowed them to investigate global patterns in marine life. The abundance of life in warm regions (such as tropical rainforests and coral reefs) has long intrigued naturalists. At least 30 theories have been put forward, but most studies have been based on relatively limited surveys restricted to a single continent or group of species.

By tapping into the recreational scuba diving community, Reef Life Survey has vastly increased the amount of information researchers have to work with. Professor Edgar and his colleagues provide one-on-one training to volunteers, teaching them how to carry out comprehensive scans of plants and animals in specific areas.

Dr Adriana Vergés, a researcher at the University of New South Wales specialising in the impact of climate change on ocean ecosystems, said that the Reef Life Survey has already substantially improved our understanding of the marine environment.

“For example, Reef Life Survey data has greatly contributed to our understanding of the factors that determine the effectiveness of effectiveness of marine-protected areas worldwide. The team have made all their data publicly available and more and more research is increasingly making use of it to answer research questions,” she said.

Some of the divers have been working with Reef Life Survey for a decade, although others participate when they can. One volunteer, according to Professor Edgar, was so inspired by the project that he began a doctorate in marine biology (he graduated this year).

There’s a strong link between fish numbers and water warmth, which means warming oceans are likely to change global fish distribution.
Rick Stuart-Smith/Reef Life Survey, Author provided

Warming oceans means fish on the move

One of the important insights delivered by the Reef Life Survey datatbase is the relationship between water temperature and the ratio of fish to invertebrates in an ecosystem. Essentially, the warmer the water, the more fish. Conversely, colder waters contain more invertebrates like lobster, crabs and shrimp.

Professor Stewart Frusher, director of the Centre for Marine Socioecology at the University of Tasmania (and a former colleague of Professor Edgar) told The Conversation that he believes we will see wide-scale changes in fish distribution as climate change warms the oceans.

“Species are moving into either deeper water or towards the poles. We also know that not all species are moving at the same rate, and thus new mixtures of ecosystems will occur, with the fast-moving species of one ecosystem mixing with the slower moving of another,” he said.

As species migrate or expand into newly warmed waters, according to Professor Frusher, they will compete with and prey on the species already living in that area. And while it’s uncertain exactly how disruptive this will be, we do know that small ecosystem changes can rapidly lead to larger-scale impacts.

In order to predict and manage these global changes, scientists need reliable and detailed world-wide data. Professor Frusher said that, with research funding declining, scientists do not have the resources to monitor at the scales required.

The Conversation“Well-developed citizen science programs fill an important niche for improving our understanding of how the earth is responding to change,” he said.

Madeleine De Gabriele, Deputy Editor: Energy + Environment, The Conversation

This article was originally published on The Conversation. Read the original article.

Warming seas will set marine life on the move, with some good news among the bad


David Schoeman, University of the Sunshine Coast and Jorge García Molinos, Scottish Association for Marine Science

How will climate change affect life in the oceans? In research to be published in Nature Climate Change* we, among several other authors, show that the answer is likely good and bad.

Our study models how species might move in response to different future climate scenarios. The good news is that overall, thanks to species migrations, most places will end up with greater numbers of species. According to our models, climate change is unlikely to directly cause extinction through warming waters for most species, except for those that can’t move or have very narrow thermal tolerances.

The bad news is that there are a few very special places that will lose species – particularly the spectacular ocean ecosystems of what’s known as the Coral Triangle, the epicentre of global marine biodiversity.

First, the good news

As ocean temperatures increase, marine life will likely move towards the poles – animals and plants will expand their ranges. We can already see this happening. In Australia, tropical species of fish are turning up in northern New South Wales.

We wanted to know how this would affect the overall numbers of animals and plants in the oceans – marine biodiversity – and the distinctive communities they comprise. While many things affect where marine life lives – habitat, competition, salinity – most species are affected fundamentally by temperature.

Using temperature to find out where species might move allowed us to look at an unprecedented number of species – nearly 13,000. These included animals and plants as diverse as fish, corals, jellies, snails, clams, crabs, shrimps and seaweeds.

We looked at two different climate scenarios, business as usual (known as RCP8.5) leading to warming of around 2.5ºC by 2100, and a scenario with medium mitigation (RCP4.5) leading to warming of around 1ºC over the same period.

Our model shows how fast different temperature zones will move and to where, using a measure known as “climate velocity”. This is a good way of predicting where species could move because it traces pathways connected by climate.

We should emphasise that our study shows where species could move. Our projections don’t necessarily mean that they will move, nor that they will successfully establish themselves at the locations where they arrive. That depends on a variety of factors, including their specific habitat requirements and how species interact with each other. But studies of invasive species suggest that species that can move will tend to do so.

Overall we found that biodiversity of the oceans will likely increase at local scales. As a result, we anticipate that marine ecosystems will become more similar. For instance, today on the east Australian coast, the types of species found along the central Queensland coast are quite different from those found in central New South Wales. As sea temperatures warm, we expect those boundaries to gradually break down, leading to what we call a “smearing” of biodiversity.

Bad news for the tropics

There are several theories as to why there are so many species in the tropics, and especially the Coral Triangle. Irrespective, we know that this area supports over 500 species of reef-forming corals, together with a massive diversity of fish, including whale sharks, and six of the seven extant species of sea turtles; it is also visited by many species of whales and dolphins. This concentration of marine biodiversity contributes significantly to livelihoods of the region’s 120 million or so human inhabitants.

Species living in tropical seas already live close to their thermal optimum. As temperatures increase, they will exceed the upper thermal limits of some species. When this happens, some species will adapt, for instance by seeking out micro-refuges, such as small patches of cool water caused by upwelling, or they might resort to living in deeper waters, if the water is clear enough.

But in the long term, most species will need to move. The reason we expect marine biodiversity to decrease in the tropics with warming is that there is no place warmer to act as a source of new species to replace those species moving out.

More than 5,000 of the 13,000 species we looked at in our study are found in the coral triangle. According to our projections, approximately 500 to 1,000 of these species will leave the region thanks to warming waters under RCP4.5 and RCP8.5, respectively.

What can we do?

Our modelling shows that the loss of marine life is strongly related to how much we mitigate climate change.

Even if we take only intermediate levels of action (under scenario RCP4.5), we can minimise the damage. But we can’t eliminate it entirely: under the emission-stabilisation RCP4.5 scenario we anticipate that the Coral Triangle will lose roughly half as many species as under the business-as-usual RCP8.5 scenario.

We can also look at how we manage the world’s oceans. Some regions, such as the northeast Atlantic and eastern Mediterranean, have seen greater impacts from people than others, and some of these overlap with regions likely to be affected by climate change.

Where there is overlap, we can look at alleviating the damage caused by people, such as pollution of coastal waters, or minimising the pressure on key species, for example by reducing fishing pressure on them.

In other areas, such as the poles, there is low human impact, but we project substantial changes in biodiversity. From a conservation perspective, we want representative sections of these areas to remain free from additional human pressure, for instance by using regulation to control future development.

And because climate change doesn’t respect national boundaries, all of these efforts will require international cooperation.

Only in that way will we ensure the seas remain rich and healthy in the future.

We acknowledge the contributions of all co-authors: Jorge Garcia Molinos, Benjamin S. Halpern, David S. Schoeman, Christopher J. Brown, Wolfgang Kiessling, Pippa J. Moore, John M. Pandolfi, Elvira S. Poloczanska, Anthony J. Richardson and Michael T. Burrows

*Update August 25: the paper on which this article is based has not yet been published. The article will be updated when the link is available.

The Conversation

David Schoeman is Associate professor, Biostatistics at University of the Sunshine Coast and Jorge García Molinos is Research Associate Climate Change Ecology at Scottish Association for Marine Science

This article was originally published on The Conversation. Read the original article.

Following Nemo: marine life is heading south


Tim O'Hara, Museum Victoria

Changing wildlife: this is the first article in a series looking at how key species such as bees, insects and fish respond to environmental change, and what this means for the rest of the planet.

The seas are warming. Collectively the oceans have absorbed more than 80% of the energy retained by the Earth through recent climate change.

However, actual warming of the water has been very uneven, with some seas heating up much more quickly than others. Temperate rises have been most extreme where there are strong currents flowing from hot tropical regions towards the poles.

And as warmer seas move further south, tropical wildlife is going with them, giving us a dramatic insight into how global warming is changing our oceans.

The EAC

The East Australian current (the famous “EAC” used by migrating turtles in the movie Finding Nemo) brings warm water from off Queensland down the New South Wales coast to Tasmania. Similar currents also exist off southwestern Australia, Japan, the eastern United States, southeastern Africa and southern Brazil.

Many marine creatures have a wandering larval stage in their life cycle. These are often microscopic creatures that are transported by waves and currents far from their parents. Some larvae can travel for months or even years before settling down in suitable habitat and metamorphosing into the more recognisable crab, shell, sea-star or fish that we see along the coast.

This life history means that marine animals can respond rapidly to changing water temperatures and currents. Like Nemo they can be swept down the coast and survive in newly warming environments.

So let’s follow Nemo and find out what is happening along the eastern coast of Australia right now.

Heading south, permanently

The Solitary Islands are off the New South Wales Coast, just north of Coffs Harbour. They are the front line in the tropicalisation of temperate oceans. Tropical herbivorous fish are settling in increasing numbers; parrotfish and surgeonfish scrape at rocks and coral to remove and eat seaweeds.

These fish demolish existing kelp beds and eat any young plants that attempt to grow. This in turn allows coral larvae brought down by the EAC to settle and thrive. Coral reefs are on the move.

Further south, the eastern coast of Tasmania is being invaded by animals that previously were only found in New South Wales. Recreational fishers, naturalists and scientists have recorded almost 50 newly arrived species, some in abundance.

The best documented is the long spined or black sea-urchin, which also grazes kelp and has created large “barrens” on rocky reefs all the way to southern Tasmania.

No room to move

So does this matter? Who cares if everything just gets moved around? Coral reefs in New South Wales may sound attractive but there are a variety of reasons why warming of marine environments is bad news.

The long spined sea urchin, which creates ‘barrens’ by grazing seaweeds, has become established in warming seas off Tasmania.
John Turnbull / Flickr

One big problem happens at the poleward end of large continents. Cooler species have nowhere to go. There is no suitable habitat to migrate to.

For example, there is a whole cluster of species that only occur in southern Tasmania, like the cute spotted handfish. Rising temperatures and invading species could easily drive this and other species off Tasmania to extinction.

The critically endangered spotted handfish lives only in southern Tasmania.
Rick Stuart-Smith / Reef Life Survey

Not all species have a larval stage that can travel long distances, and such species could become marooned in areas with unsuitable temperatures. Many economically important animals such as rock lobsters, abalone and scallops like cool water and will become restricted in range and abundance.

It’s not just the heat

Rising temperatures are not the only calamitous result of climate change.

Sea levels are rising as a result both of melting ice and of the expansion in volume that occurs when water warms. This will not only affect the hundreds of millions of humans that live next to the coastline, as their properties are inundated and they are forced to migrate, but also the specialised animal and plants that live along the coastline.

The additional carbon dioxide in the atmosphere is also a pollutant in its own right. Its effect on ocean chemistry is to make it more acidic. But this is perilous for animals like corals and molluscs that make their skeletons from calcium carbonate.

The deep sea will be affected as well. Coral beds living a kilometre or so below sea level on seamounts off southern Tasmania will get squeezed by rising temperatures and ocean acidification.

With rising seas, animals and plants that live on this wide Victorian rock platform will be pushed upwards to occupy a thin band on the cliff behind.
Museum Victoria

We do not lack scientific data on these issues. Nothing has arisen that has shaken the scientific consensus that there will be lethal problems for marine animals and plants from a changing climate.

It is now a social and engineering problem. They key thing is that we move rapidly to decarbonise the global economy.

We will be publishing more articles in this series in the coming days.


Tim will be on hand for an Author Q&A between 2 ans 3pm AEST on Wednesday, July 15. Post your questions in the comments section below.

The Conversation

Tim O'Hara is Senior Curator of Marine Invertebrates at Museum Victoria.

This article was originally published on The Conversation.
Read the original article.

There’s no “warming pause” — trade winds are burying heat in the Pacific


Grist

Global average land temperatures have not increased as quickly as many scientists had expected over the past 10 or 15 years, leading some climate skeptics to latch onto the bogus idea of a “global warming pause.” Last year researchersreported that much of the “missing heat” was not in fact missing but rather was being sucked up by the oceans.

Now new research helps explain why excess heat is being absorbed into the sea: big-ass winds.

A paper published in the journal Nature Climate Change suggests that the slowdown in surface warming and the acceleration in ocean warming has been largely driven by a phase in a natural ocean cycle called the Interdecadal Pacific Oscillation (IPO). That’s a frightfully cumbersome name, but it’s easy to break down: It’s a swing (“oscillation”) in Pacific Ocean weather that takes decades (“interdecadal”) to shift from one phase to another. Instead…

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