The unexpected implications of shrinking fish populations

Why human behaviour is the wild card of economics.

“When I say I'm an economist, people expect I'll talk about monetary policy and interest rates,” says Dr Satoshi Yamazaki, a senior lecturer and researcher at the Tasmanian School of Business and Economics.

On the contrary, as an environmental economist with a focus on marine resources, Dr Yamazaki’s research has nothing to do with banking, and everything to do with fisheries management.

Putting his research into context, Dr Yamazaki explains: “Economics is actually about studies on human behaviour and how we manage scarce resources.”

Given that 55% of the world's oceans are now being fished, covering an area more than four times the size of that used for agriculture, it’s hardly surprising that wild-caught fish are an increasingly scarce resource. And it's not only biodiversity at stake.

“The depletion of fish stocks has many different implications,” says Dr Yamazaki, whose work focusses on both large-scale and small-scale commercial fisheries.

Both types of fisheries provide employment and food globally, and on a huge scale. In some developing countries, people rely on fish for up to 50% of the animal protein in their diet.

When it comes to developing strategies for the management of fisheries, the real wild card is how fishers will respond to changes in the environment, such as shrinking fish populations. That’s where the study of capricious human behaviour, through an economic lens, comes into play, and where much of Dr Yamazaki's research on small-scale fisheries is directed.

“When the stocks are depleted in a particular area, how the community members respond is one of my main interests,” he says.

“If you go to developing countries, or even coastal rural areas in Japan, the way they interact with the fisheries is quite significant,” he says.

It’s also often surprising, as the findings of his research in the Kei Islands of Indonesia illustrate.

“In the beginning we thought that, when the stock is depleted, the competition would become severe and that would result in conflict, but our result was the opposite,” Dr Yamazaki explains.

“In terms of intra-village conflict, we found that when people have a perception of declining fishing resources, they actually cooperate more to cope with this difficult situation.”

There were, however, increased levels of conflict between villages on the islands.

And in Japan’s Maizuru Bay, Dr Yamazaki and a local Japanese researcher found that fishers had been able to maintain their income despite the loss of a clam species that had been the mainstay of the local fishing industry for generations. On further investigation, it transpired that they had managed this by either catching other species, such as sea cucumbers, or branching out into aquaculture and cultivating oysters.

Dr Yamazaki wants to expand on this by looking at the trade-offs for maintaining income, such as having to invest more in equipment or work longer hours.

Through this and other studies in Asia, he is shining a light on the under-researched area of small-scale fisheries, and the complex social and economic implications of declining fish stocks in these communities.