In 1883, the eminent English biologist Thomas Henry Huxley made his now infamous proclamation on the infinite bounty of the sea:

Probably all the great sea fisheries are inexhaustible; that is to say, that nothing we do seriously affects the numbers of fish. Any attempt to regulate these fisheries seems consequently, from the nature of the case, to be useless.

A century later, numerous great fisheries had collapsed (including herring and cod, which Huxley specifically mentioned).

Despite Huxley’s awareness that new technology (“steam and refrigerating apparatus”) made it possible to “draw upon the whole world” for seafood, he could not foresee the immense increase in fishing capabilities - particularly from SONAR - that would occur during the 20th century.

Nor could Huxley account for the explosion in demand for seafood that would invariably follow a tripling of the human population in the 100 years following his 1883 prediction. Huxley’s “inconceivably great” sea fisheries could not support our yet greater appetite.

One hundred and thirty years on, and bad news outweighs the good. The Food and Agriculture Organization of the United Nations reported in 2012 that 57% of marine fisheries are fully exploited and 30% are overfished. Asia’s fishing effort has increased 25-fold since the 1950s, yet their catch is steadily declining. And the world would need to mothball around 2.6 million commercial fishing boats to make fishing sustainable.

There is debate among scientists about the values of these statistics, and rightly so, but, much like the informed climate change debate, it is focused on not whether the news is bad, but how bad.

The good news is that some fish stocks are stable, some are recovering, and some are well managed (the West Australian coast rock lobster fishery is renowned for its sustainability). Indeed, if you’re in Australia, the doom-and-gloom of global seafood may seem far from your experience at the fish market or your local fish-and-chip shop. There is plenty of choice, and you can always walk away with a fish.

In part, this reflects Australia’s well managed fish stocks. Oceania is the region least affected by overfishing, and if there continues to be an investment in fisheries research and management, the sustainability of Australian wild-caught seafood could be world-leading.

So does this mean we are a sustainable seafood nation?

Probably not. For one thing, Australia imports around 70% of its seafood, mostly as cans and frozen fillets. You may have come across basa in your local fish shop (a species of catfish farmed extensively in Asia). Basa is quickly becoming the most imported fish in many parts of the world, including Australia, and basa aquaculture could offer high sustainable production if carefully managed.

Without these imports, it is very unlikely Australia could sustainably satisfy current consumer markets with only Australian fish (even if we held on to our most popular exports - rock lobster and tuna). We must also remember that large ocean fisheries are harvested by many countries, and for fish like tuna, Australia’s contribution may only be part of a complicated international management effort.

What does this all mean for “seafood sustainability”?

Well firstly we must acknowledge that our demand for wild-caught seafood outstripped the ocean’s sustainable supply decades ago. If we rehabilitate the oceans, to the tune of $200 billion dollars, we could potentially increase our current harvest a little and keep it there sustainably. Even so, we would need more.

This brings us to the crucial point: there is no such thing as a sustainable type of seafood, only a sustainable harvest rate. If we are to demand truly sustainable fisheries, and we admit that harvests cannot continue to grow, then we conclude that what must change is our consumption. As long as humans demand ready access to seafood whenever they want it, there will be pressure to exceed these rates.

Can aquaculture fill this gap? Aquaculture already provides 47% of the world’s food fish production, and since 1990 has been the only thing fulfilling the increase in seafood consumption. It has not taken the pressure off our oceans, and significant improvements must be made before aquaculture becomes a predominantly sustainable industry. Nor is aquaculture likely to ever meet global demand for large ocean fish like tuna (over half of aquaculture production is freshwater fish).

We need to reevaluate what “sustainability” really means in the current climate of global development and consumption. The local consumer still has options for selecting seafood harvested at sustainable rates, and much information exists online. But the consumer must acknowledge that a constant supply of wild-caught fish is not sustainable.

When we fish, we hunt, and while industrial agriculture has accustomed us to a constant food supply at a steady price, our wild ocean fisheries cannot provide this same security.

The big picture is that a sustainable harvest of seafood will not meet global demand. It is possible to have global seafood sustainability, but only if we address the driving force of global consumption. Without doing so, without finding a way to rationalise the right of human reproduction with the right for global sustainability, then “sustainable” will be loose term applied and reapplied as we chase that shifting baseline, trying to maintain what is left.

Ultimately, we should not demand sustainable seafood – we should demand sustainable consumption.