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Forecasting effects of climate change on global fisheries

By Asaesja Young

May 1, 2017

school of fish
Bluefin Tuna are already being impacted by the changing climate. Image: Alistair Hobday/CSIRO

The world’s population is expected to grow to almost 10 billion by 2050, an increase of around 30 per cent.

Almost half the world’s population relies on food from the ocean as the primary source of protein, and with this anticipated population growth seafood will continue to be in high demand.

For many decades scientists have studied the changing climate and now have clear evidence of impacts on the ocean.

Late last year, the State of the Climate 2016 – a biennial collaboration between CSIRO and Bureau of Meteorology – reported that Australia would continue to see warmer oceans, increased acidification and more extreme weather events; concerns echoed by a recent global report produced by US-based National Oceanic and Atmospheric Administration.

CSIRO Scientist Dr Alistair Hobday specialises in understanding how marine species and resources are being impacted by these changes.

“Climate change has flow-on effects for marine plants and animals all around Australia,” says Dr Hobday.

“As with other animals impacted by climate change, marine species must be able to tolerate or adapt to the changes where they live. If they can’t do this they need to move location, or else they will die.

“For example, increased ocean temperatures can impact the growth rate of marine fishes and ocean acidification negatively impacts the ability of larval fishes to find their way to the coral reef.”

The seafood industry is already being impacted

Dr Hobday’s research shows changes to climate are already impacting Australia’s fishing and aquaculture industries.

“We are already seeing changes to the distribution, number and physiology of focal species, as well as significant changes to their habitats, food availability and the structure of ecological communities,” says Dr Hobday.

man with hat on boat holding fish he has caught
Dr Alistair Hobday with a Yellowtail kingfish.

In the Great Australian Bight, research shows that increased ocean temperatures have seen changes to where southern bluefin tuna can be found, a fish whose location has historically been very predictable. This has resulted in commercial fishers being unsure where to go in search of tuna, which increases the risk they will not catch their allocated quota.

“These impacts on commercial fishing and aquaculture as a result of climate change can flow on to coastal towns. Many Indigenous and rural communities rely on fishing not just for nutrition, but as their primary economic resource,” says Dr Hobday.

The decade for action

He adds: “We’ve been predicting climate impacts to fisheries and aquaculture for several decades, but there has been a lack of urgency to respond.”

“The next decade will be critical for the seafood industry.

“Over the next ten years we expect to see continued and rapid changes to the marine environment including marine heatwaves and increased disease of aquaculture stock. This will likely lead to further changes in abundance and distribution, quota allocations, and increased domestic and international market demands.

“We will also likely see increased competition for space in the ocean, with ocean renewable energy, shipping and oil and gas extraction all competing with each other.”

So what can be done?

“Given we’re locked into continued warming for at least the next few decades, we need to focus on helping the industry adapt and, where possible, mitigate further changes,” says Dr Hobday.

“One way this can be achieved is through delivery of environmental forecasts which can help fisheries and aquaculture decide when and where to fish, harvest, implement disease management strategies and transfer stock.”

Fish forecast models rely on information produced by the Australian Bureau of Meteorology using the Predictive Ocean Atmosphere Model for Australia (POAMA) and are already being used by fishers and managers involved in wild tuna, and farmed salmon and prawn businesses in Australia.

“While similar forecast models exist in other countries, Australia is leading the way in translating the science into useful advice which can be used by the industries,” says Dr Hobday.

“A key ingredient for building resilient fisheries and aquaculture is communication and engagement between scientists, industry and policy makers.”

The multi-year forecasting challenge

Fish forecasts currently provide information on the likely environmental conditions and the resulting distribution of fish several months ahead.

There is now demand from the seafood sector for similar forecasts of conditions but at time scales over several years.

These could be used to support fishing and aquaculture decisions that have long lead times, such as investment in fishing quotas for new regions, or development of new infrastructure.

CSIRO oceanographers are working to develop the ocean models that might provide this information, with testing currently underway.

Dr Hobday is optimistic that with such forecasts, and continued good management, the Australian seafood sector will be in a strong position to cope with a changing climate.

The approaches being developed in Australia will be applicable to other regions, and collectively will help better manage global seafood resources.

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