Big Questions: how to stop overfishing?

How do we preserve river ecology while meeting the needs of a growing population? This is the fundamental question driving a range of research projects at Charles Sturt University. Can sustainability provide the answer to how to stop overfishing?

Dr Lee Baumgartner is a fish ecologist and an expert in fisheries and river management. He’s a member of Charles Sturt’s research centre dedicated to environmental, social and economic research for rural and regional areas, the Institute for Land, Water and Society.

Dr Baumgartner outlined some of the important research that the university is engaged in around fisheries management, environmental preservation and food sustainability. This research is happening on three levels: local, national and international.

Working with regional communities to preserve native Australian fish

At the local level, our research is looking to prevent native fish species from disappearing altogether, as Dr Baumgartner explained.

“There are a number of issues affecting fish populations in the Riverina region. These include climate change, habitat destruction, changes in land use, changes in water availability, the introduction of invasive species and cold water pollution from dams (which makes the water too cold to breed in). All of these are important components that we include in our research.

“At the local level, we work in ecosystems around our regional communities. A lot of the work we have been doing is with threatened species. So, for instance, we’ve been working with local government departments, Local Land Services and the NSW Department of Primary Industries to look at the status and change in a whole range of threatened fish species in the region.

Students are involved in the research

“There are, for example, some creeks near our Albury-Wodonga campus that are home to fish species, like the southern pygmy perch, that are found at limited locations in New South Wales. Some species run the risk of becoming extinct in the next 20 years or less, so we are focusing a lot of the work on making sure that doesn’t happen. And the proximity to our campuses means that students can be involved, from Honours students and those doing higher degrees by research, to undergraduates working with us as part of work placements in their degree.

“We look at where fish are distributed, and how numbers may be fluctuating. And we particularly look at habitat associations with the fish, to understand what certain fish species need to survive and how we can preserve those habitats to help protect their numbers.

“The key question is the balance between biodiversity and sustainable human development. How much development can you have before you impact upon the species too much? And we need to address that at all levels, not just the local one.”

Combining river ecology with human engineering

On the national level, the interaction between native wildlife and the requirements of the human population can also threaten fish species, but on a vastly increased scale, as Dr Baumgartner outlined.

“There are two main strands to our research on the national level. Firstly, we’re working with the Snowy 2.0 project. The aim of the project is to double the capacity of the Snowy Mountains hydropower dams, in terms of water storage and electricity output.

“This is, of course, significant in terms of national energy supply. But it will also have a sizeable impact on fish species in the dam system. For instance, there is a risk that fish could move between dams when the new system is started up. One of these is an invasive species, so its migration could upset the native dam ecosystem elsewhere.

“So our researchers have developed some world-first technology: a hyperbaric chamber that can actually simulate the pressures that a fish would come under in the passage through the hydropower turbine. And we also can simulate the turbulence in the water that the new system would create. This enables us to see how fish could cope with the new conditions. And it helps us determine methods to prevent unwanted migrations.”

Interactions between fish and agriculture

The second strand, as Dr Baumgartner explained, concerns the interaction between fish populations and irrigation.

“We’ve been doing about 10 years of research on quantifying the interactions between irrigation and fish communities across south-eastern Australia. It might not be overfishing per se, but millions of fish are being extracted from their natural habitats by pumps or water diversions used for irrigation. The fish have no way to get back to the river once they have been pumped out. Some irrigation schemes, we’ve discovered, can pump up to 12,000 fish a day out of a river. We’ve also found that diversion channels that farmers and others construct to direct water from rivers to irrigation can divert millions of fish out of their rivers every year. These are numbers which are simply impossible to replace by restocking.

“The solution is simple. Put a screen over these pumps and diversion channels to prevent the fish being taken out of the river. We’re working with farmers and irrigation agencies to put adequate screens in place that allow water extraction without disrupting fish populations. The government is currently investing in modernising irrigation systems. It’s a real once-in-a-lifetime opportunity to get this right and incorporate ecology into planning. Plus, it’s quite cheap and farmers save money as their pumps have less downtime due to blockages.”

International efforts to prevent overfishing and promote food security

Irrigation systems – and food sustainability – is at the heart of Charles Sturt research efforts abroad, as Dr Baumgartner explained.

“At the international level, the major work we’re doing is around fish migration. Our projects in the lower Mekong basin and in Indonesia help fish migrate without being caught in irrigation systems. This not only preserves ecology, it can also mean that people who rely heavily on fish for nutrition should be able to harvest sufficient fish while maintaining fish stocks.

“So we’re working with governments and local organisations to design and install fish ladders. These allow fish to migrate while avoiding the irrigation systems. It started in Laos and we’re now scaling it up to five other countries in the region. The key is balancing sustainable fish ecology with the needs of people. For instance, one of the wetlands we work in, local people can harvest 60 kilos of fish per hectare. But with a fish ladder, you can double that amount while still maintaining a sustainable population of fish.

“One of the huge problems with overfishing is that people aren’t aware of the precarious position we’re in with regard to fish populations, at home and abroad. Investment in irrigation can bring security to people. However, if it is at the risk of decimating fish populations, the long-term effects will be disastrous.

“We are at the edge of a cliff when it comes to overfishing. As researchers we are trying to help us step back from the edge. Key to this is education and the dissemination of knowledge. So our students are furthering the knowledge base. We’re sharing our insights with governments and organisations. Plus, we’re providing education and training to help local people tackle overfishing, which is a global problem.”

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